Drones.

A flurry of advances in military technology over the past decade that has helped the U.S. and its allies redefine modern warfare. None of these advancements have had a greater impact on America's missions in the Middle East than the maturation of remotely piloted aircraft (RPA), also known as unmanned aerial vehicles (UAVs) or, more generically, drones. The U.S. Army's drone armada alone has expanded from 54 drones in October 2001, when U.S. combat operations began in Afghanistan, to more than 4,000 drones performing surveillance, reconnaissance and attack missions in Afghanistan, Iraq and Pakistan (pdf). There are more than 6,000 of them throughout the U.S. military as a whole, and continued developments promise to make these controversial aircraft—blamed for the deaths of militants as well as citizens—far more intelligent and nimble.

Whereas drones themselves are certainly not a new concept—their origins can be traced back to the 1840s—since 9/11 they can now be loaded with a variety of sensors and weapons and are controlled by highly trained operators using a joystick and video monitor thousands of kilometers from a combat zone.

"One of the most significant things that has occurred since 9/11 is the shift from, if you will, peer-to-peer warfare to a focus on irregular warfare," says U.S. Air Force chief scientist Mark Maybury. RPAs, as the Air Force refers to them because they are indeed operated by pilots, are helping U.S. troops and their allies adjust to that shift by delivering reconnaissance data and attack support against enemies difficult to spot because of their ability to blend in with noncombatants and the rugged terrain of their surroundings. [View a slide show featuring different drones used by the U.S. military]

Use of drones has grown across several branches of the military as well as the CIA (one of the earliest users of unmanned aircraft). The Air Force, for example, logged its first 250,000 hours of drone flight time between 1995 and May 2007. The next 250,000 hours of drone flight time, however, took only a year and a half, from May 2007 to November 2008. The Air Force achieved its third set of 250,000 flight-time hours in just one year, from December 2008 to December 2009.

The Department of Defense's 2012 plan calls for "purchasing more of the existing unmanned aircraft systems for current operations, improving the systems already in service, and designing more-capable unmanned aircraft systems for the future," according to a Congressional Budget Office (CBO) report published in June (pdf). The CBO estimates that the Defense Department will spend about $36.9 billion across its different branches on 730 new medium-sized and large drones through 2020.

This expansion of the military's unmanned aircraft campaign brings with it a degree of concern as drones have come under fire by critics. Some dispute the military's accuracy claims and point to unmanned aircraft as the cause of thousands of civilian deaths in the war-torn Middle East over the past decade. Others note that the fight against terrorist organizations such as al Qaeda embedded in civilian zones—most notably the killing of Osama bin Laden—has primarily been carried out using time-tested intelligence methods rather than drone-launched Hellfire air-to-surface missiles.

Dawn of the drone
The use of unmanned aircraft in war goes back 162 years, when Austria used pilotless balloons to drop bombs on Venice in 1849. As Scientific American reported at the time: "In a favorable wind the balloons will be launched and directed as near to Venice as possible, and on their being brought to vertical positions over the town, they will be fired by electro magnetism by means of a long isolated copper wire with a large galvanic battery placed on the shore. The bomb falls perpendicularly, and explodes on reaching the ground."

In the early 20th century the U.S. military recruited remote-controlled airplanes to serve as decoys or even to attack enemy targets during the First and Second World wars. From the 1950s, these aircraft began to support troops with the aid of cameras, sensors, communications equipment or other payloads. "In terms of modern use, drones really started in the early 1990s, where they were an advanced concept technology demonstration at DARPA [the Defense Advanced Research Projects Agency]," Maybury adds.

General Atomics Aeronautical Systems, Inc.'s Predator drones were introduced to combat in the mid-1990s and deployed in the U.S.'s 1999 Kosovo air campaign for surveillance and reconnaissance. Predators (which have a 20-meter wingspan) were first used in Afghanistan in October 2001 to provide intelligence and a strike capability to Operation Enduring Freedom, the official name used by the U.S. government for the war in Afghanistan. A CIA-controlled Predator drone firing a Hellfire missile killed six suspected al Qaeda terrorists in Yemen on November 3, 2002—the first use of an armed Predator as an attack aircraft outside of a theater of war such as Afghanistan, according to the Federation of American Scientists (FAS).

Stepping up drone missions
In the past year alone, the Air Force has supported more than 400 firefights involving RPAs, Maybury says. In 2010 they captured 30,000 hours of full motion video during their missions along with 11,000 high fidelity images. "We call them remotely piloted aircraft because in fact we have professionals—both pilots and sensor operators—operating them," Maybury says. "I don't even like the word 'drones.' It sounds boring personally."

The Air Force's large-scale RPA deployment began after 9/11; it had a single RPA in operation in 2001. The Air Force now operates at least four different models of medium-sized or large unmanned aircraft. In addition to its 175 Predators, there are 14 jet-powered Northrop Grumman RQ-4 Global Hawks, the largest RPAs in the Air Force's fleet with wingspans of 35 to 40 meters. About 40 turboprop-powered General Atomics MQ-9 Reapers (a larger version of the Predator) were supposed to be entering the fleet this year. The Air Force also uses the Lockheed Martin RQ-170 Sentinel, a "stealthy reconnaissance aircraft whose existence has only recently been acknowledged by the Air Force," the CBO reports.

Last year, for the first time in its history, the Air Force trained more RPA pilots than fixed-wing pilots. RPAs are often equipped with full-motion cameras, infrared cameras to provide night vision, signals intelligence sensors to eavesdrop on communications and a variety of other sensors. In addition to a pilot, each RPA has a sensor operator who directs the cameras and signals sensors during a mission. All of this information is fed to a system of "exploiters," Air Force personnel who analyze all of that streaming video and other signal intelligence coming in and feed information as needed back to the pilot and sensor operator.

Other branches of the military, as well as the CIA, have also come to rely heavily on drones. The Army primarily operates three medium-sized models of unmanned aircraft—Northrop Grumman MQ-5B Hunters, AAI Corp. RQ-7 Shadows (also used by the Marines), and two different types of Predators. The CBO estimates that the Army alone will spend about $5.9 billion in the next five years to add to its drone fleet.

The Navy is testing two new types of RPA—the long-endurance Broad Area Maritime Surveillance (BAMS) aircraft—a Global Hawk variant—and the Northrop Grumman MQ-8B Firescout unmanned helicopter. The Navy's plans call for purchasing 65 BAMS through 2026 and 168 Firescouts through 2028, according to the CBO.

ROVER ground stations
This wide variety of drones enables attacks on a diversity of enemy positions, but perhaps as significant is the ability to communicate with troops on the ground. This is done with the help of Remotely Operated Video Enhanced Receiver (ROVER) ground stations that combine a ruggedized laptop, software, a handset and a radio to give troops live, overhead intelligence from a variety of platforms—manned aircraft, unmanned aircraft, just about anything with a camera able to stream a data feed, says Chris Bronk, an information technology policy research fellow at Rice University's James A. Baker III Institute for Public Policy in Houston and a former U.S. State Department diplomat. "This helps American soldiers see beyond the next hill, in real time," he adds. The original ROVER system, developed in 2002, required a Humvee to lug it around. Newer systems can fit into a backpack.

ROVERs "are particularly transformational because now you have people on the ground who can see what the aircraft is seeing in the air in real time while also communicating with the DCGS [distributed common ground station] back in the U.S.," Maybury says. Troops with ROVERs can even request that RPA pilots and sensor operators fly or scan in a particular direction or over a particular area.

A key development in RPA operation over the past five years has been the ability to install systems of multiple cameras such as the Gorgon Stare video capture system and the Autonomous Real-time Ground Ubiquitous Surveillance Imaging System (ARGUS-IS). "Now we're able to see not just a single full-motion video but actually wide area motion imagery [WAMI], which provides multi-spot infrared imagery," Maybury says. "Ten years ago, you get a single feed, today we're looking at 65 spots of two frames a second around a wide area." A ROVER can dial into a particular channel or tell a sensor operator to follow a particular vehicle on a particular channel.

Micro air vehicles
Military and intelligence units have become increasingly interested in smaller drones that can improve reconnaissance and surveillance operations. Some of these drones are hand launched while others are even smaller and resemble birds and insects.

The Air Force Research Laboratory Air Vehicles Directorate Micro Air Vehicle Integration & Application Research Institute at Wright-Patterson Air Force Base in Ohio is dedicated to the development and testing of micro air vehicles (MAVs). Less than 0.6 meters in length, a MAV is capable of operating below rooftop level in an urban environment. It may have a fixed wing, rotary wing (helicopter), flapping wing or even no wings. The Air Force has been developing MAVs as a way of getting in close on enemy fighters, although such small devices are difficult to control (even a wind gust can take them out of position).

AeroVironment, Inc. is developing even smaller drones that weigh less than 20 grams. DARPA contracted the Monrovia, Calif., company to design and build a flying prototype "hummingbird-like" aircraft for the Nano Air Vehicle (NAV) program. In February AeroVironment introduced its 16-centimeter-long Nano Hummingbird, capable of climbing and descending vertically, flying sideways left and right, flying forward and backward, as well as rotating clockwise and counter-clockwise under remote control and carrying a small video camera.

The biologically inspired prototype is in the second phase of a three-phase DARPA NAV program, started in 2005. AeroVironment is one of four companies with phase-one contracts to develop miniature drones. The Charles Stark Draper Laboratory, Inc., in Cambridge, Mass., and Lockheed Martin have built rotary-wing NAVs, while AeroVironment and Oakland, Calif.,-based MicroPropulsion Corp. focused on flapping-wing aircraft.

Collateral damage
Drones are promoted to the American public as a way to strike against threats to the U.S. without putting airmen or soldiers in harm's way. Another purported benefit of drones is the precision with which they attack America's enemies. Numerous reports of civilian casualties, however, indicate that these robotic aircraft are precise only to a certain degree. The CIA and White House have been quick to point out they have found no evidence of collateral deaths from U.S. counterterrorism operations outside of Afghanistan or Iraq, a claim disputed on several fronts, most recently in a report compiled by British and Pakistani journalists.

Reports of the number of civilian deaths attributed drone strikes vary, particularly in Pakistan. The Long War Journal, a Web site produced by nonprofit Public Multimedia Inc., claims that, since 2006 in Pakistan alone, drone strikes have killed 2,080 leaders and operatives from Taliban, al Qaeda, and allied extremist groups as well as 138 civilians. Meanwhile, the U.S. government claims that its drones have killed more than 2,000 militants in Pakistan and about 50 noncombatants since 2001. The Bureau of Investigative Journalism, a not-for-profit organization based at City University in London, disputes the U.S. government statistics, saying its research concluded that of the 2,292 people killed in U.S. attacks since 2004, 385 were civilians, including more than 160 children.

In an August 14 New York Times editorial, former director of national intelligence Dennis Blair, a retired admiral, pointed out that, particularly in Pakistan, "drone strikes are no longer the most effective strategy for eliminating al Qaeda's ability to attack us." His reasoning: "Drone strikes hinder Qaeda fighters while they move and hide, but they can endure the attacks and continue to function." In the meantime civilian casualties from drone strikes discourage support within Pakistan for the U.S.'s efforts to eliminate al Qaeda from that region, he wrote. Blair, however, does not call for an end to drone strikes but rather closer coordination between the U.S. and Pakistan militaries when planning such strikes.

The Future
One of the U.S. military's goals is to increase the use of drones on a variety of mission types. In addition to adding MAVs and NAVs to the mix, Maybury sees Air Force RPAs delivering fuel and other supplies to troops in the field. RPAs will also become increasingly autonomous, monitored but not necessarily piloted by humans. This will not be easy as autonomous systems must have the capability to adapt to changing conditions with the help of artificial intelligence that aids in decision making. Still, a long-term goal is to create fleets of RPAs that can travel as a self-coordinated unit and strike in concert. The Air Force claims it will build in override controls that enable pilots on the ground to reassign or reroute RPAs if necessary.

Missions for unmanned aircraft systems are expected to expand from reconnaissance and attacking ground targets to a much wider array of missions, including personnel recovery, airborne refueling, medical evacuation, and missile defense (pdf), according to FAS.

In addition to launching missiles, future drones may someday be able to fire directed energy weapons, including lasers to disrupt or destroy enemy equipment and high-power microwave systems designed to burn enemy combatants without being lethal.

Drones will also be able to stay in the air for years, rather than hours or days, at a time. "Last year, we did a lot of work in energy, which includes ultra-long endurance aircraft such as the Vulture and Integrated Sensor Is the Structure (ISIS), which are powered in part by lightweight solar cells," Maybury says.

Regardless of how far drone technology advances it is clear that the utility they have demonstrated in supporting U.S. troops over the past 10 years will ensure that these remotely controlled aircraft are here to stay.

Satellite Based AIS (Automatic Identification System)

Satellite-Based AIS (Automatic Identification System)

All international ships of more than 300 tons and all passenger vessels, irrespective of size, are mandated by the International Convention for the Safety of Life at Sea to carry a transponder that broadcasts their position, course and speed as a collision avoidance system. This tracking system, called the automatic identification system (AIS), sends information to other nearby vessels so it can be displayed and utilized in conjunction with radar. AIS data is transmitted through very high frequency (VHF) radio waves, so its horizontal range has generally been limited to approximately 50 nautical miles or less. 

AIS data is used for more than just collision avoidance. Maritime authorities, recognizing the benefits of tracking a ship’s identification, location, heading, speed and cargo, have installed AIS receivers on shore that capture relevant ship information, allowing tracking of ships close to shore. The use of AIS information in congested shipping areas has become standard practice for many nations. 

However, there still exists a need to know the exact location of ships as they travel beyond the limits of the coastal AIS service. Since the introduction of AIS, the global positioning system and other technology has progressed, and several solutions have provided greater visibility of ship locations on a worldwide basis. One such initiative is an International Maritime Organization-mandated service, long-range identification and tracking (LRIT), which requires certain classes of ships engaged in international voyages to report their position every six hours using onboard communications. However, the costs and long refresh rates of LRIT make it inadequate for some uses. 

ORBCOMM Satellite AIS

In 2004, ORBCOMM negotiated with the U.S. Coast Guard to launch a concept demonstration satellite equipped with an AIS receiver. ORBCOMM also developed additional satellites with AIS receivers, and a total of six AIS-equipped satellites were launched by June 2008. With these satellites, ORBCOMM became the first commercial service provider of satellite AIS services. Licensing of the service began in late 2008. 

Satellite AIS can track ships when they are out of range of coastal AIS systems. This is because while VHF signals have a horizontal range of about 50 nautical miles, VHF signals extend much farther into space, where satellites equipped with AIS receivers can capture this information and relay it to the ground. By using existing AIS technology already installed on ships, the AIS satellite service does not require additional ship-based hardware to be installed. 

Using its terrestrial global network of 15 gateway Earth stations to receive this satellite information, ORBCOMM provides licensees with a ship’s name, position, course and speed, which can then be displayed at AIS-equipped facilities for coastal AIS, providing users with an extended view of the shipping network. When combined with shipping informational databases, a complete picture of the ship’s course and all relevant information can be displayed, tracked and recorded. The satellite AIS system allows a ship to be tracked in near real time from the time it departs a port to the time it arrives at its destination. 

Refresh rates on AIS data have been in the low single-digit hours, but it is anticipated that when all ORBCOMM satellites are deployed, the refresh rate will be less than an hour. The reason for the current slower refresh rates is because a satellite cannot upload its captured AIS information until it is above a gateway Earth station. This refresh rate will improve as more AIS-equipped satellites become operational. 

Satellite AIS will never approach the same refresh rate obtained from coastal AIS, which captures and displays all three or six second transmissions. This is not an issue, as quick refresh rates for ships in the middle of the Indian or Pacific Ocean is not a necessity. As shipping gets closer to the shore—i.e., between 50 and 120 nautical miles—the need for improved refresh rates becomes increasingly important, which satellite AIS can provide. 

AIS information is collected by ORBCOMM satellites. These satellites relay this data to Earth once above a Gateway Earth Station, where data can be sent to customers.

Vessel Management

Port authorities were some of the first to identify the benefit of the satellite AIS service. The Port of Rotterdam in the Netherlands quickly took advantage of the new global AIS information. Data, including ORBCOMM satellite AIS information, are supplied to port officials via ORBCOMM partner LuxSpace Sarl (Betzdorf, Luxembourg) and Royal Dirkzwager (Maassluis, Netherlands). 

The Rotterdam system provides near-real-time data on all ships bound for the port and requires no intervention, providing a clear global picture of incoming traffic. The system also tells port authorities about incoming cargo and an estimated arrival time so they can gather the necessary resources for rapid unloading of the cargo, which maximizes productivity of the berth facility. For shipowners, the ability to dock quickly, unload and sail in a short time provides improved utilization of capacity and can improve revenue. 

Satellite AIS by itself will not provide the sophistication that is needed to manage the activity of a port. When combined with other vessel and port management tools, however, satellite AIS provides a much broader picture of ship traffic and port loading. It can also make the port authority quickly aware of delays caused by weather, malfunctions and other unforeseen incidents so it can plan accordingly. 

Search-and-Rescue Applications

As more AIS-equipped satellites come online, AIS information will continue to grow in importance as a powerful aid in search and rescue, environmental incidents and maritime domain awareness. 

When dealing with search and rescue, it has become apparent that the most important use of satellite AIS is to determine what ships are closest to the vessel or incident. Vessels today are equipped with beacons that transmit a distress signal. However, especially in the Pacific and Indian oceans, a vessel in distress can be thousands of nautical miles from the nearest search-and-rescue organization. Satellite AIS can provide an immediate picture of all shipping close to the distressed vessel, allowing search-and-rescue authorities to contact these vessels and direct them to provide assistance. 

This functionality proved to be useful for a search-and-rescue effort offshore Australia. By using satellite AIS, responders were able to determine the closest vessel to a yacht sinking in the middle of the Indian Ocean. Rescue workers contacted nearby ships, which changed course and rescued two sailors from the sinking sailboat. 

Environmental and Security Applications

Satellite AIS can also play a role in identifying suspected polluters. If pollution is found, satellite AIS can identify all ships traversing the area. With this information, maritime authorities can then follow to identify the “DNA” of the ship and determine which vessel was responsible for the pollution. 

The use of satellite AIS for security and monitoring is particularly advantageous in areas where coastal AIS is not economical. Examples of this would be in the Arctic around such countries as Canada, where the installation and operation of coastal AIS becomes cost-prohibitive. In addition, countries generally have limited resources in the Arctic regions and satellite AIS will give them some ability to identify ships traveling through Arctic waters. 

Additional Satellites and Conclusions

Satellite AIS is a continuous service that will steadily improve toward a more rapid refresh rate. ORBCOMM intends to launch four satellites in 2011 (August 18 they have launched 2 at the same time). During the following two years, ORBCOMM intends to launch a further 16 satellites. 

ORBCOMM’s experience over the last two years has shown that increasing the number of satellites and ground stations improves the refresh rate on the AIS display and the information provided. The move to the constant flow of shipping data will aid the maritime world and will give it a more real-time picture of shipping around the world. With more than 60,000 large ships equipped with AIS transponders, it is now possible to know where practically all ships are, where they are going and when they will get there. 

James Webb Space Telescope

Even while construction of the James Webb Space Telescope is underway on the most advanced infrared vision of any space observatory, its technologies are already proving useful to human eye health here on Earth. "The Webb telescope program has enabled a number of improvements in measurement technology for astronomy, mirror fabrication, and measurement of human eyes, diagnosis of ocular diseases and potentially improved surgery," said Dr. Dan Neal, Research Fellow at Abbott Medical Optics Inc. in Albuquerque, N.M. 

The Webb telescope will be the most scientifically powerful telescope NASA has ever built - 100 times more powerful than the Hubble Space Telescope. The Webb telescope will find the first galaxies that formed in the early universe. It will also peer through dusty clouds to see stars and planets being born, connecting star formation in our own galaxy with the solar system. "The advanced wavefront sensing technology developed for testing the Webb telescope's 18 primary mirrors led to the new applications in other areas," said Tony Hull of L3 Integrated Optical Systems Division-Tinsley Facility in Richmond, Calif., where the Webb's mirrors were recently polished to accuracies of less than one millionth of an inch. 

"Wavefront sensing" is used to measure shape of the mirrors during fabrication and control the optics once the telescope is in orbit. Ophthalmologists routinely use wavefront technology to measure aberrations of the eye. Those measurements help with diagnosis, research, characterization and planning treatment of eye health issues. "The technology also provides more accurate eye measurements for people about to undergo Laser Refractive Surgery," Neal said. "To date 10-12 million eyes have been treated with Lasik procedures in the U.S. alone. As technology improves, so does the quality of these procedures." 

A new "scanning and stitching" technology developed for the Webb telescope led to a number of innovative instrument concepts for more accurate measurement for contact lenses and intra-ocular lenses. Another benefit to eye health is that this technique can help "map" the topography of the eye more accurately. Think of the surface of your eye as being as dented as the surface of the moon. Precise measurements of your eye's surface are helpful when assessing eyes for contact lenses. The scanning and stitching technology improvements have enabled eye doctors to get much more detailed information about the shape and "topography" of your eye, and do it in seconds rather than hours. 

Four patents have been issued as result of innovations driven by the Webb telescope program. "These tools are now used to align and build the next generation of measuring devices for human eyes," Neal said. "The lasting impact of the Webb telescope may go beyond the vision of astronomers seeking to see the distant universe; the impact may be a better national technology base and better vision for people everywhere," Hull said. 

The 50th Operations Group at Schiever Air Force Base.

SCHRIEVER AIR FORCE BASE, Colo.  -- When it opened for business in 1985, the installation now known as Schriever Air Force Base didn't operate any satellites at all. During the following few years, as operations floors were constructed, satellite control operations slowly transferred from Onizuka Air Force Station, Calif. Falcon AFS was originally planned to be a small, operations focused installation, with most of its support functions coming from the main installation at nearby Peterson AFB. That all had changed by 1992, when Air Force leaders decided neighborhood encroachment wouldn't pose a problem on the rolling foothills east of Colorado Springs -- and the 50th Space Wing took root. "We controlled roughly 20 Global Positioning System satellites, a few weather vehicles and some communications satellites," said 50 SW historian Randy Saunders. "We operated around 40 satellites at the time." Nearly twenty years later, the sheer number of satellites and systems operated by the 50 SW has grown by at least a third. With the recent addition of six Defense Meteorological Satellite Program satellites and three of the most technologically advanced satellite systems ever imagined during the past year, the 50 SW has entered an era of unprecedented expansion and operations tempo. "The 50th Operations Group has a greater and more diverse mission set than in any time in its history," said Col. John Shaw, 50 OG commander. "And we're rising to the occasion." Colonel Shaw should know, he's worked at Schriever in one capacity or another for many of the past 20 years, serving here as a lieutenant during the early 1990s and later as a squadron commander. Twenty years ago, the 1st Space Operations Squadron held the mantle as Schriever's largest squadron, conducting GPS launch, early orbit and anomaly resolution as well as operating Defense Meteoroligical Satellite Program satellites and a few Defense Support Program satellites. The 2 SOPS conducted day-to-day operations on what was then a very small constellation of vehicles. The 3 SOPS controlled a small number of MILSATCOM satellites and 4 SOPS didn't even exist yet. By the turn of the new century 3 SOPS had taken on the Defense Satellite Communication System constellation. Today, 3 SOPS Airmen also operate the follow-on system to DSCS, the Wideband Global SATCOM system. "Each one of these satellites is more powerful in terms of capacity than the entire DSCS constellation," Shaw said. "That's how fast we jump ahead in technology. I went away for three years, came back and now see that we have three of these WGS satellites, with more on the way soon." While 3 SOPS has switched gears to a more modern, technologically advanced system, 4 SOPS is in the midst of a significant technological jump as well, as the follow-on to the Milstar system moves toward operational status. The first Advanced Extremely High Frequency satellite is set to reach orbit later this year. Like WGS to DSCS, AEHF represents another advancement that will improve communications capacity and capability exponentially. Most are well versed in 2 SOPS' mission as they operate the Global Positioning System. "I think people everywhere are starting to realize how much space affects their lives," Saunders said. "From navigational tools, to banking and finance -- space is involved in practically everything." With the launch of the first GPS IIF satellite last year, 2 SOPS has taken control of the next generation of GPS satellites. The squadron is set to control several more GPS IIFs in the next two years, before moving up to the GPS block III, tentatively scheduled for launch in 2014. "This truly is an unprecedented mission set for the 50 SW," Shaw said. "However, what 1 SOPS is doing has opened up a whole new vista for us here. We took on satellite control authority of TacSat-3 last year. That's the first ever intelligence-surveillance-reconnaissance asset to come to the wing and also the first Space Based Space Surveillance satellite, which surveys the heavens and improves our space situational awareness." The expansion for 1 SOPS doesn't end there. The squadron also assumed SCA of the Advanced Technology Risk Reduction satellite, a former Missile Defense Agency payload, with space situational awareness capabilities. Its fourth anticipated ISR platform, Operationally Responsive Space-1, launched on June 29 and should be operational by the end of July. All told the 50 OG currently controls 61 satellites, by far the most in its history. With ORS-1, GPS IIF-2, and AEHF-1 expected to become operational in the next few months, that number will likely reach 64 by year's end. The next WGS and AEHF satellites are due to launch early next year, so the pace will continue. This news comes with some clear challenges. For one, the 50 OG won't be gaining any new operators, managers or support personnel. "We are operating more satellites today, with drastically increased complexity, in an ever more contested and congested operational environment, with noticeably less personnel than we had even 10 years ago," said Lt. Col. Jean Eisenhut, 3 SOPS commander. "But, the increased operations tempo has also brought about new command and control systems with extensive automation capabilities, which have the potential to reduce operator workload." Eisenhut hinted that determining the right balance of operator control and automated system control is critical in order to best utilize these capabilities. "Our automation capabilities are driving us to develop space professionals here, something the command and the Air Force is counting on," she said. "For 3 SOPS in particular, we are working through reduced manning by redesigning the operational crew construct (at Vandenberg AFB), reallocating and streamlining training requirements between in-house and the school house - all to put even more emphasis on each individual's weapon system expertise, while at the same time ensuring operations support functions." With such a jump in operations tempo, Shaw points out that the importance of the 50 SW and its mission set to the warfighter, to national security and to human society, has never been greater. "We've been known here at Schriever for excellence in flying satellites since the late 1980s," he said. "But times have changed - just flying satellites well is not enough. We need to also be experts at defending and responding to threats against our systems, and above all to ensure we're providing decisive space effects wherever they are needed across the globe."

SVN - 63 Satellite

GPS IIF-2, renamed SVN-63, launched on a United Launch Alliance Delta IV vehicle 6 July at 2:41 a.m. Eastern time from Cape Canaveral Air Force Station. Controllers confirmed initial contact with the spacecraft at 6:14 a.m. Eastern time at a ground station on Diego Garcia in the Indian Ocean. GPS signals from the spacecraft payload will be turned on for test purposes over the coming days. 

The ULA team is the launch provider for the U.S. Air Force (USAF) Global Positioning System (GPS) Directorate by delivering replenishment satellites aboard Atlas V and Delta IV rockets. GPS satellites serve and protect our warfighters by providing navigational assistance for U.S. military operations on land, at sea, and in the air. 

This satellite delivery continues Boeing's history of support to the Air Force, and joins the previous 39 mission-compliant satellites from the GPS Block I, Block II/IIA and GPS IIF missions represented by more than 35 years of teamwork," said Craig Cooning, vice president and general manager of Boeing Space & Intelligence Systems. "GPS IIF contributes to building a robust GPS constellation by providing increased accuracy through improved atomic clock technology; a more jam-resistant military signal; and a more powerful and secure civilian signal to help commercial airline operations and search-and-rescue missions." 

Following launch, the Delta IV vehicle placed SVN-63 into medium Earth orbit. With safety checks completed, checkout will begin under the direction of the Air Force GPS Directorate. Checkout includes payload and system checks to verify operability with the GPS constellation of satellites, ground receivers, and the Operational Control Segment system. Boeing will officially turn over SVN-63 to the Air Force 50th Space Wing and the 2nd Space Operations Squadron this fall after the spacecraft completes on-orbit checkout. 

Civilian users around the world also use and depend on GPS for highly accurate time, location, and velocity information. GPS IIF-2 is one of the next generation GPS satellites, incorporating various improvements to provide greater accuracy, increased signals, and enhanced performance for users. 

=GPS uses 24 satellites, in six different planes, with a minimum of four satellites per plane, positioned in orbit approximately 11,000 miles above the Earth’s surface. The satellites continuously transmit digital radio signals pertaining to the exact time (using atomic clocks) and exact location of the satellites. The GPS IIF series have a design life of 12 years. With the proper equipment, users can receive these signals to calculate time, location, and velocity. 

The signals are so accurate that time can be measured to within a millionth of a second, velocity within a fraction of a mile per hour, and location to within feet. 

Receivers have been developed for use in aircraft, ships, land vehicles, and to hand carry. As a result of increased civil and commercial use as well as experience in military operations, the USAF has added the following capabilities and technologies to the GPS IIF series to sustain the space and control segments while improving mission performance:

• Two times greater predicted signal accuracy than heritage satellites.
• New L5 signals for more robust civil and commercial aviation.
• An on-orbit, reprogrammable processor, receiving software uploads for improved system operation.
• Military signal “M-code” and variable power for better resistance to jamming hostile environments, meeting the needs of emerging doctrines of navigation warfare.

Overview DELTA IV MEDIUM+ (4,2) LAUNCH VEHICLE 

Expanded The Delta IV Medium+ (4,2) consists of a single Delta IV common booster core (CBC), the Delta cryogenic second stage (DCSS), and two solid rocket motors (SRM). The CBC and the DCSS are connected by a composite cylindrical interstage adapter (ISA). The SRMs are connected to the booster by two ball-and-socket joints and structural thrusters. 

The SRMs, with a 60 in diameter and 53 ft length, are constructed of a graphite-epoxy composite. The SRMs burn for approximately 94 seconds and are jettisoned approximately 100 seconds into the flight. 

The Delta IV booster tanks are structurally rigid and constructed of isogrid aluminum barrels, spun-formed aluminum domes, machined aluminum tank skirts, and a composite centerbody. Delta IV booster propulsion is provided by the RS-68 engine system. 

The RS-68 burns cryogenic liquid hydrogen and liquid oxygen and delivers 663,000 lb of thrust at sea level. The booster’s cryogenic tanks are insulated with a combination of spray-on and bond-on insulation and helium-purged insulation blankets. 

The Delta IV booster is controlled by the DCSS avionics system, which provides guidance, flight control, and vehicle sequencing functions during CBC and DCSS phases of flight. 

The boost phase of flight ends 6 seconds after main engine cutoff (MECO), when the separation charge in the interstage adapter is fi red and 16 pneumatic actuators push the spent Delta IV CBC stage and the DCSS apart. 

The DCSS stage propellant tanks are structurally rigid and constructed of isogrid aluminum ring forgings, spun-formed aluminum domes, machined aluminum tank skirts and a composite intertank truss. The DCSS is also a cryogenic liquid hydrogen/liquid oxygen-fueled vehicle. It uses a single RL10B-2 engine that produces 24,750 lb of thrust. Like the CBC, the DCSS cryogenic tanks are insulated with a combination of spray-on and bond-on insulation, and helium-purged insulation blankets. 

An equipment shelf attached to the aft dome of the DCSS liquid oxygen tank provides the structural mountings for vehicle electronics. The structural and electronic interfaces with the satellite are provided via the payload attach fitting (PAF). The GPS missions use a 4-m diameter payload fairing (PLF). The PLF is a composite bisector (two-piece shell) fairing. The vehicle’s height, with the 38.5-ft tall PLF, is approximately 206 ft.

Dextre - Robotic Refueling Mission

An experiment riding on the final voyage of NASA's space shuttle Atlantis is set to test out technologies that could be used on future robotic spacecraft.

The experiment, called the Robotic Refueling Mission (RRM), is a satellite mockup that Atlantis delivered to the International Space Station when it docked on Sunday (July 10 2011). The experiment will be installed on the exterior of the outpost  (July 12 2011) during   a spacewalk conducted by two space station astronauts.RRM will serve as a trial for the orbiting lab's twin-armed Dextre robot, testing the ability to refuel and otherwise maintain a satellite in space.

Scientists will watch carefully how Dextre performs these tasks over the next two years. The information they gather could help pave the way for highly capable robotic mechanics that patrol Earth orbit, fixing or refueling satellites in space.

"We anticipate it enabling future missions, future capabilities, for the international aerospace community," Benjamin Reed, RRM deputy project manager at NASA's Satellite Servicing Capabilities Office, told reporters last week at Kennedy Space Center

The dishwasher-size RRM box is full of knobs and nozzles similar to the ones found on actual satellites. The RRM payload also includes four specialized tools, which Dextre will use to manipulate these knobs and nozzles. 

During tomorrow's (july 12 2011) spacewalk, one of the two astronauts will affix the RRM box to the exterior of the space station. Dextre, which sits at the end of the station's 57-foot-long (18-meter) Canadarm2 robotic arm, will move the box to its permanent location on the station's truss. Then the robot's dexterity test will begin.

Simulated satellite refueling is a major part of this test. This task is tricky and involved, requiring the use of all four tools to access a heavily protected satellite fuel valve.

For example, Dextre — guided by human operators in a variety of locations on Earth — will use a cutting tool to snip some securing wires around the valve, then employ two other implements to remove two different kinds of caps. Finally, it will pick up yet another tool to access the valve and introduce the simulated fuel.

Such a complex robotic operation has never been demonstrated in space before, researchers said. Dextre will also perform a variety of other similarly complicated tasks.

If everything goes well with RRM, the next step would be to launch a mission to a satellite running low on fuel. That could happen by 2013, NASA officials have said.

Laying the foundation for robotic mechanics in space

Astronauts have serviced spacecraft in orbit before. Five different shuttle missions, for example, helped fix or upgrade NASA's Hubble Space Telescope. But RRM aims to demonstrate a robotic capability that could apply across many different types of satellites — even those that weren't designed to be serviced.

This ability could end up extending the lives of many spacecraft in orbit, saving millions of dollars for the satellites' operators. RRM researchers hope the experiment provides a convincing demonstration that this technology works, and that it's worth pursuing further.  

"We're going to make this data available to everybody," said Frank Cepollina, RRM project manager at the Satellite Servicing Capabilities Office. "That is, all commercial industry that may want to leap off and start their own ventures."

RRM is a joint effort of NASA and the Canadian Space Agency.

ORS -1 Operationally Responsive Space Satellite.

ORS-1

ORS-1 is the first satellite in the DOD’s Operationally Responsive Space Office (ORS) program designed to support Combatant Command operations as an operational prototype. The payload leverages a SYERS-2 sensor, the primary imaging sensor on the U-2 reconnaissance plane. The ORS-1 payload was built by the Goodrich Corporation, who also served as prime contractor, while the spacecraft bus was built by ATK Spacecraft Systems & Services, Beltsville, Md. It includes an integrated propulsion system as well as other critical subsystems for communications, attitude control, thermal control and command and data handling. ORS-1 will provide crucial battlespace awareness supporting U.S. Central Command.

Col. Carol P. Welsch, Acting Director of the Space Development and Test Directorate, and the mission director for ORS-1 shared some background and thoughts on the mission.

“In 2008, the Operationally Responsive Space Office approached the Space Development and Test Directorate and suggested a partnership to meet an urgent warfighter need. We knew this would be a tough challenge, but we were eager to do whatever we could to assist US Central Command. I want to thank Dr. Wegner for his confidence in the Space Development and Test Directorate. As a result of this partnership, the Space Development and Test Directorate was tasked to provide the satellite, command and control system, test capabilities, and the launch vehicle. We are immensely proud to field space capabilities supporting U.S. Central Command and our forces engaged in the fight.

“In order to meet the timelines requested by US Central Command, we tailored the Space and Missiles Systems Center’s standard approach to space acquisition to accept a higher risk posture than other than other space system acquisition programs. For example, ORS-1 uses some components which have not been qualified to standards for space flight. To mitigate some of the risk, the team introduced measures such as memory error detection and correction algorithms to help detect and repair any upsets to the on-board memory. Along the way we’ve learned many lessons in the art of rapid space acquisitions, and once ORS-1 is on-orbit, we will continue to learn how to more rapidly provide space capabilities. This combined government and contractor team has demonstrated great dedication and persistence to meet the challenge of developing a new satellite and supporting ground system in record time.

“On the launch vehicle side, this mission represents another milestone for the Minotaur program. This will be the 10th launch of the Minotaur I and the 4th launch for the Minotaur program from the Wallops Flight Facility.”

The Space Development and Test Directorate’s mission is to deliver small, responsive space capabilities to users across the National Security Space community. The Directorate consists of a combined team of 1,000+ military, government civilians and contractors responsible for the development, acquisition, launch, demonstration, test and operations of Department of Defense and civil space systems. As the Director of the DOD Space Test Program, Col. Welsch is responsible for executing the DOD Space Test Program, providing access to space for over 73 space experiments from across the DOD Services and Agencies.

Aquarius Satellite.

Seeking a missing ingredient to understanding Earth's environmental changes, a new satellite conceived through unique international collaborations was launched today to map the planet's salty seas from space.

The Satelite de Aplicaciones Cientificas-D spacecraft blasted off aboard a United Launch Alliance Delta 2 rocket at 7:20 a.m. local (10:20 a.m. EDT; 1420 GMT) from Vandenberg Air Force Base, California on 8 june 2011.

The 12-story rocket escaped the ground-hugging marine layer blanketing the Central Coast, thundering southward to eventually reach a 408-mile-high sun-synchronous orbit and successfully living up to its reputation of dependability.

Built by Argentina, the SAC-D satellite is equipped with multiple scientific instruments from several countries including NASA's Aquarius sensor package designed to make exceptionally precise global measurements of salt content at the ocean surface.

"Measuring ocean surface salinity from space is NASA's latest technology achievement and it's really going to be a great leap forward for the science of oceanography," said Eric Lindstrom, Aquarius program scientist at NASA Headquarters.

"For many of you, salinity is a rather obscure quantity, but I must tell you it's of critical importance in the ocean circulation, in the climate system and in diagnosing the flow of fresh water through our Earth system."

Standing 16.4 feet tall and 9 feet wide within the Delta rocket's protective nose cone, the SAC-D spacecraft weighed 2,977 pounds at launch. The two-stage launcher reached a preliminary parking orbit about 11 minutes after liftoff, then coasted around the South Pole and soared towards Africa when the booster performed a final maneuver to inject the satellite into the desired orbit. Deployment of the payload occurred as expected 56-and-a-half minutes into flight.

NASA has spent $287 million on the Aquarius project, which includes paying for the satellite's launch. A Delta 2 rocket has never faltered in its 48 missions for the space agency over the past two decades.

The large oval antenna reflector and three microwave radiometers at the heart of Aquarius will work like highly sensitive radio receivers to detect variations in the electrical conductivity of seawater, enabling scientists to deduce the ocean salinity levels.

"Salinity is the glue that bonds two major components of Earth's complex climate system: ocean circulation and the global water cycle," said Aquarius principal investigator Gary Lagerloef of Earth & Space Research in Seattle. "Aquarius will map global variations in salinity in unprecedented detail, leading to new discoveries that will improve our ability to predict future climate."

The satellite will orbit the planet every 98 minutes, covering a swath 242 miles wide for Aquarius to accumulate entire global maps of the planet each week.

"Salinity is the amount of salt dissolved in seawater and you might be surprised to know it varies through the ocean," Lindstrom said. "It's measured in grams of salt in kilograms of seawater. It's typical range is from 32 parts per thousand to 38 parts per thousand. These are small numbers, small differences, but they make enormous difference in the circulation and climate."

Scientists have collected a few million measurements of ocean salinity over the last hundred years, but vast stretches of the planet have never been sampled. Gaining a complete picture every seven days should revolutionize scientists' knowledge of the oceans by unveiling for the first time how salinity changes across the entire globe month-to-month, season-to-season and year-to-year.

"We stand to discover a lot from the Aquarius measurements by having year-round measurements of salinity," said Lindstrom.

"The temperature in the winter in the Southern Ocean or in the Greenland Sea is horrible, you don't want to go do that, you'd be much better to get that from space. So I'm all in favor of this. I don't want to spend any more days out in 50-foot waves!"

What's more, the accuracy promised by Aquarius is two parts in 10,000, the equivalent of a 1/8th teaspoon of salt into a gallon of water. Aquarius will be able to detect that tiny amount of salinity change.

Aquarius and SAC-D join a constellation of other environmental research satellites and ocean observers that study sea temperatures, levels, colors and surface winds.

"The addition of Aquarius to this suite of instruments helps create a more complete picture of our oceans and the impact on Earth's climate," said Eric Ianson, Aquarius program executive from NASA Headquarters.

"This important Earth science mission is NASA's first attempt to measure ocean surface salinity from space. Obtaining global measures of salinity is key to our better understanding of ocean circulation, climate and the Earth's water cycle."

"A key missing piece that is really in demand by the ocean science community is salinity. Together with surface temperature, salinity determines the density of the surface water of the ocean. Density variations and wind drive the ocean circulation. So this is why we want to get this missing piece. Particularly, the deep waters of the ocean get their properties at the sea surface in winter, so their temperature and salinity are set for their lifetime, they get dense and sink to the bottom of the ocean and fill up the ocean basins," Lindstrom explained.

Never before has the U.S. entrusted such a key instrument to fly aboard an Argentinian satellite. But the cooperation between the nations' space agencies -- NASA and CONAE -- has seen American rockets launch the earlier SAC-A on the shuttle Endeavour in 1998, SAC-B on a Pegasus in 1996 and SAC-C on a Delta 2 in 2000.

The SAC-D spacecraft, which also carries instruments contributed by Canada, France and Italy, was assembled in Argentina, then shipped to Brazil for pre-flight testing before finally traveling to Vandenberg Air Force Base for launch. The mission is expected to run at least several years to answer fundamental questions about the climate.

"Another grand problem in Earth science is to understand the water cycle -- evaporation from the ocean, clouds, rain, formation of ice, runoff from the land back into the sea -- and the ocean salinity really turns out to be a pretty useful diagnostic of the big-picture in the water cycle," said Lindstrom.

A 50-year trend of the limited sampling shows that salty places are getting saltier and the freshwater places are getting fresher.

"Is this an indication we're having an acceleration of the planet's water cycle? The salty places in the subtropical (areas) are having more evaporation, the rain belts are having more precipitation and the ocean is giving us this signal," said Lindstrom.

"This is an indicator but there could be other explanations for this. It could be the ocean circulation is changing, it could be ocean mixing is changing. What we really need to do as oceanographers is dig into this more deeply and Aquarius will help us illuminiate these processes. It's a diagnostic for the water cycle but it can also help us tell about ocean circulation and mixing."

Once Aquarius is commissioned and ready for service in about three months, scientists plan a field campaign with ships, buoys, floats and gliders to compare data with the satellite instrument as the mission commences in earnest. 

Deep Space Network

The Origin and Evolution of the Deep Space Network 

NA SA’s system for communication with solar-system exploration 

spacecraft began as a Cold War crash program, but iis evolution was 

carefully planned from the starl 

Thirty-four years ago, a single principal antenna, installed the 

previous year (1958) on a crash basis in an isolated location of the 

Mojave Desert of California, supported Pioneer 4, the first United 

States spacecraft to escape the Earth’s gravitational pull and travel 

toward another solar-system body, namely the Moon, the nearest 

such body to Earth. 1 hat lone antenna, situated near the Goldstone 

Dry Lake Bed within the Department of the Army’s Fort Irwin, would 

become the cornerstone clf NASA’s Deep Space Network, a system 

currently composed of 13 antennas of various designs and sizes that 

collectively have the capability of continuously communicating with 

spacecraft at distances ranging from high altitudes above the Earth 

to the outer edge of the solar system. 

When the Goldstone antenna was procured, however, NASA had 

not yet come into being. It was instead the Department of Defense 

that provided the funding for the procurement, fabrication, erection, 

and testing of this antenna during a relatively short eight-month 

period in 1958.  The antenna, as well as the series of early lunar- 

probe attempts of which Pioneer 4 was a part, was, as we shall  

show, approved on a crash-program basis as one aspect of the Cold 

War then raging between the United States and the Soviet Union. It 

would not have been surprising if an antenna so hurriedly

manufactured and installed for a short-term goal would 

subsequently abandoned when NASA began setting up a 

have been 

permanent 

system for later lunar and planetary probes. The fact that it was 

not was a reflection of careful planning by the procurer of the 

Goldstone antenna, a group of engineers at the Jet Propulsion 

laboratory (J Pi.), an Army facility in Pasadena, California, that 

became a part of NASA in late 1958. The early evolution of the Deep 

Space Network illustrates how a major communication system can 

be firmly established through a combination of carefully chosen 

initial elements, put in place during a period of limited time and 

funding, arid later additions, installed as requirements become more 

ciemanding and further resources (such as funding and cooperating 

agencies) become available. 

The Cold War origin of solar-system exploration 

An official requirement for a system to communicate with 

space probes developed for the first time on 7 March 1958, when 

the Eisenhower Administration, through the Department of Defense’s 

new Advanced Research Projects Agency, authorized a program of 

five lunar-probe attempts, three by the Air Force and two by the 

Army, all to be conducted within a year.  The Administration publicly 

characterized the program (shortly to be named Pioneer) as a 

scientific project an effort “to determine our capability of 

exploring space in the vicinity of the moon, to obtain useful data 

concerning the moon, and provide a close Iook at the moon. ” Archival 

records show, however that the major impetus for the program disapproval was a desire by many inside and outside of government to 

find some quick means of restoring international prestige to the 

United States, after the Soviet Union’s successful orbiting the 

previous October of WJIDK  the world’s first artificial satellite, 

had shattered a widely-held percepticln of American technological 

superiority. 

In the six months between this event and Pioneer program 

announcement, in fact, numerous proposals for immediate “Moon 

shots” had been submitted to the Pentagon, and many cited the 

perceived Soviet threat. one of the first institutions to do so was 

JP1 . In a proposal entitled “Project Fled Socks” issued on 21 October 

1957, the lab observed that the launching of Sputnik 1 ICNS than 

three wcmks earlier “has had a tremendous impact on people 

everywhere” and that it “has significance which is both technical 

and political. ” The proposal stated that it was “immediately 

imperative that the United States regain its stature in the eyes of 

the world by producing a significant technological advance over the 

Soviet Union.” Pointing out that all had “some fairly sophisticated 

instrumentation and communication” capability that would allow it 

to achieve a successful lunar flyby mission, the lab advocated that 

the country “go to the moon instead of just going into orbit.” 

JPL was not alone in perceiving a potential political benefit 

deriving from a successful lunar mission. F{amo Wooldrige’s newly 

formed Space Technology Laboratories (S1 L ), located in I os Angeles, 

California, argued, in a proposal entitled “Project 13aker” issued on 

27 January 1958, that an early lunar flight with a moderate payload 

of scientific instruments could make a determination of conditions 

on the Moon that would be valuable for planning later flights with 

much heavier payloads that were certain to come within a few years. 

The firm also suggested, however, that “Of greater national 

importance may be the prestige of sencfing the first rocket to the 

moon, with clear proof that it reached its objective. ” 

Scientists and politicians, however,  were initially not 

enthusiastic about these and other lunar-probe proposals. The 

director William  Flickering recalled that members of the Office of 

Defense Mobilization’s Scientific Advisory Committee (ODMSAC) 

“were not sure that [the Red Socks proposal] was more of a stunt, as 

it were, and were not really that enthusiastic about it from a 

scientific point of view. ” Deputy Secretary of Defense Donald A. 

Quarles testified before Congress in late November 1957 that he 

found “no cause for national alarm” in the existence of the USSF1’s 

Sputnik satellites and argued that the United States “must not be 

talked into ‘hitting the moon with a rocket’ just to be first, unless 

by doing so we stand to gain something of real scientific or military 

significance. ” Eisenhower himself tolci colleagues that he would not 

be drawn into a “pathetic race” with the Soviet Union, and he 

characterized a lunar probe as “useless. ” 

The views of the scientists and politicians regarding “Moon 

shots” gradually changed, however, especially after the United 

States’ first attempt to launch a satellite (Vanguard) on 

1957 ended in spectacular failure--the explosion of the first stage 

of the launch vehicle within seconds of liftoff was recorded on live 

television. On 17 February 1958 the Space Science Panel of the new 

President’s Scientific Advisory Committee (reorganized from the old.J- 

OLMSAC) held a meeting in the Executive Office Eluilding (next to the 

White House) at which panel member Herbert York announced, to 

attending representatives from JPL and S-IL, that “it had been 

decided to attempt a lunar mission with the objectives of: a. Making 

contact with the moon as soon as possible, but with the limitation, 

 that the contact be of a type that has significance such that the 

public can admire it. ” York further stated that the panel had 

concluded, given the second objective, that “some kind of visual 

reconnaissance” (e.g., a camera to take a picture of the back side of 

the Moon) was the most significant experiment that a lunar vehicle 

could carry. PSAC’S endorsement c)f an early lunar mission would 

lead to the aforementioned Pioneer program authorization in late 

March. 

Supporting the Pioneer probes: S71 ‘s short-term approach 

The 

of launch 

would trai 

positions, 

for withou 

Pioneer program would require simultaneous development 

vehicles, spacecraft, and ground-support stations that 

lsrnit commands to the spacecraft, determine their 

and receive data from thcm. The stations were important, 

them no close-up photograph of the Moon could be 

c] btaincd and, more fundamentally, no confirmation that tho 

spacecraft were anywhere near the Moon was possible. 

[Iut what kind of network of stations should be set. Should 

it be cicsigneci solely to support the Pioneer program and its limited 

objective of photographing the Moon? Or shou Id a more elaborato 

system be constructed that would meet not only the requirements of

the pioneer program but also the anticipated needs of future 

programs not yet authorized? 

STL, initially under the leadership of Frank Lehan, had little 

choice but to undertake the short-term approach. Because of the 

more ready availability of their iaunch vehicles (1 hor IRF3M and 

Vanguard upper stages, the. three Air Force probes would be launched 

first, beginning in nlid-August 1958. l-his situation wouid allow the 

Air Force and STL the initial opportunity to reap the glory of a 

successful first lunar mission, but it allowed the latter less than 

five months to set up a network of ground-support stations. 

By necessity, the antennas used at the two principal stations 

had to be already erected or at least manufactured, and their 

locations were governed by the roles they would play in 

communicating with the lunar probes while they were in the vicinity 

of the Moon. For example, a 60-ft-diameter parabolic antenna with a 

transmitter a modification of the l“LM-18 antenna that Foundation, 

Inc., was currently manufacturing for we in the forthcoming Air 

Force Discoverer reconnaissance-satellite program--was installed 

at South Point on the island of t Iawaii because there it would have a 

favorable look-angle at the probes at the time of their fourth-stage 

retrorocket firings. 

S-l L planned for the picture taking to occur as soon as the 

probes entered orbit, before anything might go wrong with the 

spacecraft, and this milestone was expected to occur over about the 

0° longitude, which crossed parts of Europe and Africa. Lehan and 

his colleagues knew that the quality c]f the picture taking would 

improve as the diameter of the receiving ground-based antennaincreased, but the time constraint, as well as diplomatic and funding 

considerations, did not permit the installation overseas of a new 

large antenna, possibly one 200 ft or more in diameter. l-he 

University of 

Jodrell Bank, 

an Air Force 

Bank facility, 

Manchester’s 250-f t-diameter  radio telescope at 

however, already existed. A secret meeting between 

officer and Bernard Lovell, the director of the Jodrell 

enabled STL to install temporarily an appropriate feed 

and other specialized equipment on the antenna in support of the 

picture-taking activity. 

S1 

- 

The engineers appear to have given little thought initially as 

to what might constitute a permanent system of stations for 

supporting an ongoing program of unmanned solar-system spacecraft 

exploration, and whether any of the antennas installed or modified in 

1956 could become part of such a permanent system. JP1. engineers, 

by contrast, began planning for a permanent system even before the 

Pioneer lunar-probes authorization was issued. 

JP1. looks to the future 

Probably the strongest advocate for s ch a permanent system 

/ Y,< /,, J) 

was Lberhardt Flechtin, chief of JPL’s CEO Research S@ion. 

More aware than his colleagues in the propulsion field of the likely 

advances in electronics and the potential distances that could be 

reached in space communications (l-able xx), he strongly urged, in 

the spring of 1958, the development of a launch vehicle (Juno IV) 

capable of delivering a 550-pound payload to the Moon and a 300- 

pound payload to the planet Mars. Such a vehicle, he argued, was 

needed “to accomplish significant missions competitive with the 

USSR; lesser vehicles will only keep us to the rear in 

accomplishment of missions. ” Juncl IV’S capability of soft landing on 

the Moon, Rechtin pointed out, could eventually permit the 

establishment of “quite stable” radio and optical telescopes on the 

lunar surface. 

As for Mars, Rechtin argued that the often discussed similarity 

of this planet to the Earth would rnakc photographic exploration of it 

“one of the major goals of prestige between the United States and 

the USSR. ” Looking further into the future, he noted that 

meteorological and surface-condition instrumentation could 

determine “the practicality of putting people on Mars.” Rechtin 

predicted that “if conditions on Mars are even slightly more suitable 

than anticipated, the past success of the human race in new 

exploration will unquestionably start the drive to Mars. Based on 

human history, it will then be first come-first served on Mars. ” l-eft 

unsaid, but most likely implied, was the desire that the United 

States get there before the USSR. 

Rechtin was not alone at JP1 in perceiving Mars and other 

planets of the solar system as the ultimate goals of space 

exploration. Albert Hibbs, who became the first chief of JF)l’s new 

Space Science Division, recalled in an interview that “[W]e wanted a 

good challenge, and that was & technical challenge, getting a 

useful payload to a planet. It was really tops in engineering 

challenge--propulsion, guidance, communications, you name it. ” 

It was for this envisioned amt]itious program of lunar anc~ 

planetary missions that JP1 , and particularly F{echtin and his fellowcommunications engineers, desired in early 1958 to build a 

permanent network of stations that could transmit commands 

spacecraft, determine their positions relative to the Earth or 

to 

other 

objects, and receive scientific and cngirrcering telemetry data from 

them. Rechtin’s conception of a permanent network was based on a 

consideration of the apparent motions of space probes and a 

requirement, sure to be iniposed by any funding agency, to keep costs 

to a minimum.  

He knew that after a space probe launched from Cap& Canaveral 

completed its injection phase, during which it would move rapidly to 

the east, it would (due to a decreasing angular velocity as it gained 

altitude) have an apparent motion from east to west that closely 

approximated that of a fixed radio source. During this post- 

injection phase the greatest components 

motion will be due to the rotation of the 

 Obviously results in the probe apparently 

the eastern to the western horizon of a 

of the probe’s apparent 

Earth, and such rotation 

moving across the sky from 

particular antenna station 

once each day. Simple geometry dictates that the minimum number 

of principal antenna stations that permits continuous, overlapping 

monitoring (necessary as missions became more complex and longer 

in duration) after the injection phase is three . Because 

the world is divided into 360° of longitude, the three stations should 

ideally be located 120° apart in longitude. 

d Confid&rt that solar-system exploration would “continue in the 

coming years, ” Rechtin and his colleagues--particularly Walter K. 

Victor, head of the Electronics Research Section, and Robertson 

Stevens, head of the Guidance 1 echniques Research Section--sought 

a communication system design that would “be commensurate with 

the projected state of the art, specifically with respect to 

parametric and maser amplifiers, increased power and efficiency in 

space vehicle transmitters, and future attitude-stabilized 

spacecraft .“ Because of the later availability of the Army lunar- 

probe launch vehicles (Jupiter IF{BM and a cluster of upper stages 

employing Baby Sergeant rocket motors), they had just enough extra 

time to design and install a communication system that could not 

only support the Pioneer lunar probes, but also evolve into a 

permanent system for supporting future solar-system exploration 

spacecraft. 

Choosing an antenna design

With regard to antenna design, Rechtin, Victor, and Stevens 

ciesired an instrument with an accuracy of 2 minutes of arc or 

better, Operation on a 24-hour basis dictated that this accuracy 

would have’ to be maintained regardless of solar exposure and rapid 

ambient temperature changes. Furthermore, “since missile [la 

vehicle] firings cannot bc held up because the wind is blowing 

somewhere around the earth nor can the bird [spacecraft] be 

Inch 

whistled back from a space mission when the wind comes up,  the 

antenna would have to be usable in winds of 60 mph and be capable 

of withstanding (in a stowed position) winds of 120 mph. 

Rechtin assigned William Mcrrick (head of the Antenna 

Structures and Optics Group) to icientify an antenna design that could 

satisfy these demanding requirements. Confident that JPL wouldreceive an lunar-mission assignment but aware that the “ 

procurement, fabrication, and erection of the antennas would be the 

“longest lead time item” for carrying out such an assignment, 

Rechtin made this assignment on 7 February 1958, nearly seven 

weeks before the Pioneer authorization. Merrick concluded that the 

desired antenna would have to combine the best features of a 

precision radio-astronomy antenna and a precision guidance or 

tracking radar. Merrick recalled later’ that the radio astronomers 

and suppliers he consulted “questioned our sanity, competence in the 

field ar)d/or our ability to accomplish the scheduled date [initially 

November 1958] even on an ‘around the clock’ basis.” 

Merrick and his colleagues rejected many existing antenna 

designs because of foreign manufacture, high cost, inadequate 

aperture, and/or acknowledged design flaws. Others, such as the 

CSIRO’S 21 O-ft diameter antenna at F’arkes, Australia, and NRAO’S 

140-f t-diameter antenna at Green Bank, West Virginia, were 

eliminated from consideration because these prototypes would not 

be completed until 1960 or later. 1 he Jodrell Elank type c)f antenna 

was rejected because it was “too big and expensive” and its design 

and assembly had required seven years. 

Merrick and his colleagues ultimately chose a design that had 

been initiated at the Naval Research laboratory in 1953, developed 

further by t-toward W. 1 atel at the Carnegie Institution of 

Washington, and refined by the Associated Universities, Inc. (AUI), 

and that had just been completed by the E31aw Knox manufacturing 

company in Pittsburgh. the 26-m-diameter (85-ft) antenna had a 

cantilevered-equatorial mounting and very large hour-angle and

. 

dcclination drive gears that gave high driving accuracy for relatively 

low tooth accuracy and a low tooth loading during high winds. EIlaw 

Knox, which priced the antenna at about $250,000, had already 

received orders from the University of Michigan and AU I (for 

erection at Ann Arbor and Green Bank, respectively), but neither had 

been completed when JPL placed an order, with ARPA’s approval, for 

Eventually, citing national priority, the 

three antennas in April. . 

Army was able to move one of these probe-supporting antennas to 

the front of the manufacturing line, 

Choosing a station site

That first antenna was slated for a site in the United States. 

Rechtin later recalled the planned overseas stations “so rapidly 

became bogged down in approval red tape” that their earliest 

possible activation date gradually moved beyond the second Army 

lunar-probe attempt. Three stations would be essential for possible 

future long-duration flights to the planets, but the limited objective 

of the Army lunar probes allowed JPL engineers to make do 

temporarily with one antenna. Continuous around-the-clock 

monitoring of the probes was of course impossible, but JPL 

engineers could deliberately select a trajectory that would cause 

them to arrive at the vicinity of the Moon when they were in the line 

of sight of the single principle antenna. Also, they, unlike their 

counterparts at S3 L., had no need for a separately located 

transmitter station.the probes were slated to fly by the Moon (thus 

requiring no retrorocket firing commands), and the desired pictureswould be taken automatically when a photocell mechanism indicated 

that the probes were within a certain distance of the Moon. 

With the expectation that probes would eventually be sent to 

the planets and thus their received signals would be extremely 

weak, JPL communication engineers desired a site for their single 

initial principal antenna that would minimize outside radio 

interference as much as possible. In addition to avoiding areas with 

power lines, radio stations, radar transmitters, and/or considerable 

numbers of aircraft passing overhead, they sought in particular a 

natural bowl, so that the surrounding terrain could shield the 

antenna from nearby towns and passing vehicles. The underlying soil 

had to be suitable for accurate and stable support of the antenna, 

and an access road, for transport of the sizable steel components of 

the antenna, would have to be built for what was likely to be a 

remote site. Finally, the more immediate funding and time 

constraints of the Pioneer program mandated use of Govern merit- 

owneci land. 

Thanks to a search two years earlier for an off-lab site to test 

rocket engines, JPL engineers were aware that an area near 

Goldstone Dry [Lake at the Army’s Fort Irwin, located in the Mojave 

Desert about 150 mi northeast of Pasadena, would meet these 

criteria. After General John B. Medaris, the head of the Army 

Ballistic Missile Agency, in mid-May 1958 overruled another general 

who wanted to use the Goldstonc area for a proposed missile firing 

range, the work needed to convert the site into the desired antenna 

station swung into high gear. Carefully avoiding unexploded 

ordinance lying in the area, workers constructed access roads, laid

the antenna foundation, and constructed support buildings during the 

late spring and early summer. Soon after he steel components 

arrived in mid-August, a crew from the Ratio Construction Company 

began erecting the antenna. After the crew completed its work two 

months later, the feed was installed and various optical and radio- 

frequency tests were conducted to establish the system tracking 

accuracy. 

Choosing an operating frequency 

Unlike their counterparts at S1-L, JPL engineers, led by Victor, 

chose not to operate at the 108 Mtlz frequency being used for the 

Vanguard and Explorer satellites. With future missions clearly in 

mind, they noted in an early report that the presence of interference 

at frequencies below 500 MHz would “seriously limit the growth 

potential of any space communication technique” using a frequency 

in this region. Victor at first favored a frequency in the region 

between 1365 and 1535 MH7, where he anticipated significant 

hardware developments for improving receiver sensitivities because 

the region bracketed the astronomically important 21 -cm hydrogen 

line. Colleagues soon convinced him that a stable, efficient 

spacecraft transmitter operating in that region could not be built in 

time for the Pioneer probe missions, however, and he instead opted 

for a 960 MHz (L-band) operating frequency. 

l-he hard work that ST1.. and JPL communications engineers 

expended in setting LJp their respective systems of antenna stations 

(which included several with smaller antennas at launch-point anddownrange locations) in relatively short time periods paid off in 

very satisfactory operation during the actual missions. Various 

rocket failures, however, prevented all but the second Army probe 

(launched on 3 March 1959) from reaching escape velocity, and this 

probe (Pioneer 4) passed too far away (37,000 mi) from the Moon to 

activate the camera system. By then, the USSR’s .luna 1, launched on 

2 January, had already passed within 6,000 mi of the lunar surface, 

l.una 3, launched on 4 October 1959, took the first photographs of 

the far side of the Moon. 

Gaining approval for a permanent system 

The expansion of JPL’s ground-support system for the Pioneer 

lunar probes into a complete worldwide three-station network was 

not inevitable. The first challenge to JPL’s plans came from STL, 

which in late June 1958 iSSLJed a proposal that called for the 

construction of three 250-f t-diameter antennas to be located in 

t{awaii, Singapore or Ceylon, and near the eastern coast of Brazil. 

The firm claimed that diSCLJSSiOnS with JPL and “a thorough analysis 

of foreseeable space programs” (including a series of new probes 

aimed at the planets Venus and Mars that STL was simultaneously 

proposing) indicated that “the long-range interests of the United 

States in high-altitude communications relay satellites and in 

interplanetary space programs could best be served” by the 

establishing of two networks of three stations each, placed at 

intervals of about 60° around the equator of the earth.

- 16 

Rechtin thought otherwise; he considered the proposal “a ploy 

to block JPL’s [network plans] by forcing a study and reconsideration 

of JP1.’s ARPA order [for three 26-m-ciiameter antennas]. ” He may 

have been right. The estimated overall cost of STL’S proposed new 

sy$tem was $34 million. How STL expected the government to 

(

approve such a large sum in so short a time (the company claimed 

that it could “realistically” complete construction of the first 

antenna in Hawaii by 15 October 1959) is unclear. The proposal, in 

any case, was not funded. 

A greater threat came in early July 1958, when Deputy 

Secretary of Defense Donald @larlOs questioned why S1’L and JPL 

were developing two separate systems for supporting the Pioneer 

lunar probes. In response, Rechtin traveled immediately to 

Washington, and in a 8 July meeting at the Pentagon with Richard 

Cesaro, chairman of an AFIPA advisory panel on tracking, he 

acknowledged that JPL was using the extra time afforded by the 

later launch dates of the Army lunar probes “to begin a longer range 

space tracking program using the proper parameters. ” These 

parameters included the 960 Mtlz operating frequency and the 26-m- 

ciiameter antennas that would be “capable of tracking all vehicles 

from a 330-mile altitude satellite to space probes to Mars. ” 

Cesaro was impressed with Flechtin’s presentation, but asked 

that JPL prepare a formal proposal for a “World Net” that would 

consider as well the communications requirements of other intended 

ARPA space programs. J P L ‘s Aetianeta . 

rv T-racking 

Network, issued on 25 July, considered (despite its title) such 

requirements for six different space programs that the UnitedStates planned to undertake--manned space flight, meteorological 

satellites, reconnaissance satellites, communications satellites 

(both geosynchronous and low-Earth-orbiting), scientific satellites, 

and space probes--as well as the detection of “noncooperative” (i.e., 

foreign) satellites. Comparing all the requirements ), 

Rechtin and several colleagues suggested that two principal 

overseas antennas could be most advantageously placed, for 

supporting space probes and certain other space programs, at 

Woomera, Australia, and somewhere in Spain. 

Cesaro was once again impressed with JPL’s work, and 

indicated to Rechtin his intention to recommend that “all the 

tracking and computational facilities should be handled under 

administration with JPL as the technical arm. ” Rechtin was 

delighted with this recommendation, but nevertheless cautious. 

believed  that Cesaro “may be way over optimistic” in thinking 

Army 

He 

that 

“ARPA certainly has the power to do this and would put down any 

rebel lion.” In particular, Rechtin warned a JP1 colleague that “we 

should expect considerable uproar from the Naval Research 

Laboratory who probably figures it knows more about tracking than 

anybody else. ” The NRL’s Radio lracking Branch, under the leadership 

of John 1. Mengel, had developed the Minitrack tracking system for 

the Vanguard satellite program. 

1 he basis for Rechtin’s caution was his knowledge that 

Congress in the summer had approved President Eisenhower’s 

request 

Nation 

into being 

for establishing a civilian space agency, and as a result the 

Aeronautics and Space Administration was slated to come 

 on 1 October 1958. NASA’s impending formation meant

that ARPA was gradually losing its status as the interim United 

States space agency. 

Furthermore, by early January it became clear that not only did 

the Defense Department want a station network separate from any 

set up by NASA (because their need for secrecy conflicted with the 

new space agency’s professed openness), but also those involved in 

setting up NASA’s manned-space-flight, satellite, and space-probe 

programs desired separate station networks. As Rechtin feared, 

JPL’s plans were also strongly opposed by Mengel, whose group had 

already been transferred into NASA. Mengel claimed that the 

installation of more Minitrack stations was more essential than 

than overseas space-probe-supporting stations, because “the 

satellite experiments and their associated tracking was more 

important [than space probes] as far as NASA plans were concerned.” 

Despite Mengel’s views, on 10 January 1959 NASA, which had 

supported since early November JPL.’s development of a recommended 

set of future lunar and planetary probes and had also acquired JP1. 

from the Army, signed an agreement with the Department of Defense 

that called for, among other things, installation of stations for 

deep-space probes at Woomera and in South Africa. The preference 

by NASA and JPL for South Africa as the host country for a dedicated 

probe-supporting station derived from the fact that most space 

probes would pass over southern Africa during the injection phase of 

their flights, when it was vitally important to establish their actual 

trajectories for later accurate pointing of the other probe- 

supporting antennas.Overseas expansion 

In establishing the overseas stations, Rechtin insisted that 

they be operated by local nationals rather than “displaced 

Americans. ” Desiring the best possible performance from each of 

the stations, he reasoned (and was supported by later experience) 

that this could be obtained from professionals “proud of their work, 

held responsible, and cooperatively cc)mpetitive in spirit. ” NASA and 

JP1. fortunately identified in Australia and South Africa 

organizations--the Department of Supply’s Weapons Research 

Establishment (WRE) and the Council for Scientific and Industrial 

Research’s National Institute for Telecommunication Research 

(NITR), respectively--that were eager to cooperate in the 

establishment of the network for supporting space probes. 

l-he WRE was managing the Woomera rocket range at which the 

United Kingdom and Australian governments had been conducting 

high-altitude missile firings over the past decade, and WF3E; 

superintendent Bill Boswell anticipatecj that the addition of an 26- 

m-diameter antenna could not only expand support of these firings 

but also ensure Woomera “a leading place in satellite and space 

research, ” NITR director Frank Hewitt anticipated that the antenna 

would be a “most valuable scientific tclol” that could be used 

between missions to conduct radio-astronomy research. He also 

believed that the techniques involved with the antenna would be 

fundamental to future intercontinental communications an activity 

of great performance to a country quite distant from Europe and the

United States--and that therefore the NITR should become familiar 

with them. 

NASA sent site-survey teams to Australia and South Africa in 

February and September-October 1959. With extensive assistance 

from WRE, NITR, and other local officials, NASA and JPL eventually 

identified and selected two appropriate sites: a semi circular bowl 

open to the south at the edge of a dry lake bed known as Island 

lagoon about 18 mi from the village of Woomera and about 30 mi 

south of the range head, and a Y-shaped valley near the town of 

Hartebeesthoek about 30 mi northwest of Johannesburg and 18 mi 

west of Pretoria. 

NASA funded the construction of the overseas stations and 

sent field crews to erect the antennas and install the electronics, 

but it was WRE and NITR that bore the responsibility for acquiring 

the land, constructing access roads and support buildings, and hiring 

staff to operate the station. With a new program of Ranger lunar- 

impact probes scheduled to be launched beginning in mid-1961, both 

agencies worked hard with NASA and JPL to ensure that the stations 

would be ready in time. NITR’s success in doing so was made more 

difficult by delays (occasioned by the Sharpeville township 

disturbance and the Soviet Union’s downing of a United States U-2 

spyplane in March and May 1960) in the signing of a diplomatic 

agreement governing the station and other NASA facilities in South 

Africa, By the time Ranner 1 was launched on 23 August 1961, 

however, both stations were ready and the Deep Space 

Instrumentation Facility (renamed the Deep Space Network in 1963) 

at long last had become operational.Subsequent evolution 

Anticipating that space probes would become more 

sophisticated in future years and would eventually travel beyond the 

orbits of Venus and Mars (in contrast to the fixed range of Earth- 

orbiting satellites), Rechtin sought and received from NASA a 

continuing commitment that a relatively fixed portion (generally 

about 10 percent) of the Deep Space Network budget would be 

devoted to research and development. This commitment allowed the 

Network to evolve in a timely way in subsequent years, as new 

requirements were anticipated and means to meet them were 

conceived, tested, and installed. 

In early 1961, for example, Flechtin recognized that NASA’s 

deep-space program would soon be expanding very rapidly (further 

Rangers, Mariner flybys of Venus and Mars, Lunar Orbiters, Surveyor 

lunar soft-landings, and Apollo manned lunar landings). He could 

foresee occasions when “so many flights [would be] operating at any 

one time . . . that a single antenna at each DSIF station could not 

conceivably carry the load. ” Rechtin envisioned a future situation 

when project managers could be “confronted with impossible choices 

between probes measuring dangerous solar flares, observing violent 

effects c]n Mars, roving among the crevasses on tho Moon, and 

carrying men into deep space. ” 

New 26-m-diameter antennas were thus needed (to be 

accompanied by a change in operating frequency to S-band (2388 

MHz)), and the first of these antennas was installed at Goldstone in

early 1962. Although the Woomera and Hartebeesthoek stations 

would continue to operate through the early 1970s, neither was the 

site of the new overseas antennas. WRE; had difficulties fully 

staffing the Woomera station, due to its isolated location (in the 

outback about 200 mi north of Adelaide) and insufficient housing 

staff members and their families. Although the WRE gradually 

for 

resolved the staffing and housing problems at Woomera, the long- 

term solution was to find a new adequately shielded site nearer a 

center of population. Officials from JPL. and the Australian 

Departments of Supply and Interior eventually identified such a site 

in the Tidbinbilla Valley, located 11 rni sC)lJt west of Canberra 

(Australia’s capital) along the northeastern edge of the Australian 

Alps. The station constructed at this site became operational in 

March 1965. 

NASA and JPL were quite satisfied with 

the station at Hartebeesthoek, but Rechtin in 

that relations between the governments of the 

South Africa might eventually deteriorate, due 

NITR’s operation of 

particular was fearful 

United States and 

to condemnation in 

the United States and abroad of the latter’s apartheid policies, to a 

point where operations at this station would have to be sharply 

limited and curtailed. He argued that any expansion of the station 

would make it more costly for NASA to duplicate the station 

elsewhere at a later date. 

An initial survey of sites in Italy proved unsuccessful, A 

# 

survey team found natural bowls on the island of Sard~nia, but such 

,., 

a location would be difficult to support logistically. Potential sites 

near Rome would not have this difficulty, but they were less wellshielded and would create coverage gaps between a station here and 

the one at Goldstone. 

NASA and JPL ultimately chose a site in a valley near the 

village of Robledo de Chevala, 31 mi west of Madrid, Spain, for the 

location of a 26-m-diameter antenna. A second such antenna was 

subsequently installed near the town of Cebreros, 8 mi southwest of 

Robledo de Chevala, These stations became operational in July 1965 

and January 1967. Despite some misgivings about dealing with the 

Franco authoritarian government, NASA had been quite pleased with 

assistance rendered by the Spanish government’s Instituto National 

de T6cnica Aeronautic (INTA) in the operation of a Project Mercury 

station in the Canary Islands, and this organization became NASA’s 

cooperating agency for the new Deep Space Network stations in 

Spain as well. 

A major evolutionary step was the design and installation of 

new 21 O-ft-diameter antennas at Goldstone, Tidbinbilla, and 

Robledc) de Chevala. These were built in response to the expected 

advent of more sophisticated spacecraft (as launch vehicles became 

more powerful), which would create a requirement for an increasing 

rate in the communication of data from the spacecraft back to Earth. 

JPL considered a number of alternatives for meeting this 

requirement increasing the power of the spacecraft transmitter, 

electronic arraying of two or more 26-m-diameter antennas, and use 

of existing large radio-telescope antennas--but economics and 

availability considerations ultimately dictated the construction of 

new large antennas up to 250 ft in diameter. After two years of 

design studies and nearly four years of contract negotiation, ground

preparation, support-building construction, and antenna erection, the 

first of the Deep Space Network’s large antennas became operational 

in May 1966. Two other such antennas became operational at 

Tidbinbilla and Robledo de Chevalla in April and September 1973. 

The Deep Space Network expanded the newer of the 26-m- 

diameter antennas at Goldstone in 1978 in order to add X-band (8.4 

GHz) capability and increase the antenna gain (received signal 

strength) for the two Voyager outer-planet missions. Antennas at 

Tidbinbilla and Robledo de Chevala were similarly expanded in 1980, 

This improvement was sufficient for the Jupiter and Saturn 

encounters (1979-81) of the two spacecraft. The extension of the 

VQ2U mission to include encounters with the more distant 

planets Uranus in 1986 and Neptune in 1989, however, forced 

Voyager and Network engineers to find new means to compensate for 

a still more severe decrease in signal strength and thus avoid an 

undesirable great limitation on the science data return. 

One means was the installation of new 34-m diameter high- 

efficiency antennas (so-called because their reflector surfaces’ are 

precision-shaped for maximum signal-gathering capability) at 

Goldstone in 1984, Tidbinbilla in 1985, and Robledo de Chevala in 

1987. The 64-m diameter antenna and the two 34-m-diameter 

antennas could now form a three-element array. This combination 

(together with a reprogramming of two of the Voyager computers to 

accommodate an image data compression technique) permitted a 

higher data rate (19 kilobits/see). 

Because a still higher data rate would be needed to meet the 

imaging science requirements at Uranus and Neptune, Deep SpaceNetwork engineers sought and received permission from Australia’s 

Commonwealth Scientific and Research Organization to add 

temporarily (in 1986 and 1989) their 64-m-diameter radio 

telescope at Parkes to t 

link. The Network made 

when the twenty-seven 

 Tidbinbilla array via a ground microwave 

use of a second interagency array in 1989, 

25-m-diameter radio-telescope antennas of 

the National Radio Astronomy Observatory’s Very Large Array in New 

Mexico were linked with the Goldstone’s antennas. 

One further step taken for the Neptune encounter was the 

extension of the 64-m diameter antennas at each station to a 

diameter of 70 m and the the reshaping of their reflector surfaces 

to improve their efficiency. These improvements, which increased 

the effective signal capture of these antennas by 5:lp~r ce t where 

completed at Tidbi#Ma.and Robledo de Chevala in+) and 

Goldstone in 1988. 

The Deep Space Network continues to evolve even today. The 

original 26-m diameter antennas installed in the 1958-61 period 

are no longer in service the one at Goldstone is now a national 

monument, the one at Woomera has been scrapped, and th& one at 

Hartebeesthoek is now used by South Africans for radio-astronomy 

research. The second set of such antennas (those extended to 34 m 

in the late 1970s) are nearing the end of their usefulness. The onset 

of metal fatigue and the mechanical limitations of their late 1950s 

design do not permit further upgrades to improve performance. l-he 

Deep Space Network will therefore soon be replacing these antennas 

with 34-m-diameter multifrequency bearn-waveguide antennas. 

These new antennas will allow critical weather-sensitive

microwave components to be located in an equipment room in the 

antenna pedestal rather than on the rotating and tipping main 

reflector. The first of these new antennas was recently installed at 

Goldstone and will shortly become operational after completion of 

performance testing. 

To probe further 

The author is nearing completion of a book-length history of 

the Deep Space Network that will be based on published sources, oral 

history interviews, and unpublished dc]cuments in archives in the 

United States, Australia, South Africa, and Spain. Photocopies of 

the documentation supporting the book (and the article above) will 

be deposited in the JPL Archives. His article “Designing the United 

States’ Initial ‘Deep Space Networks . ...” jEEE Antennas and 

+Qtion ‘aaazine’ vol. 35, no. 1, February 1993, provides 

additional detail concerning the choices of antenna design, operating 

frequency, and antenna location made by STL. and JPL for supporting 

the Pioneer lunar-probe attempts of 1958-59. 

William R. Corliss’s A History gf the Deep Space Netw@