Space Surveillance Telescope.

The Air Force and the Defense Advanced Research Projects Agency (DARPA) have just created the world’s sharpest telescope:

 The Space Surveillance Telescope (SST) uses image-capturing CCD (curved charge coupled device) technology and boasts a wide field-of-view and large-aperture optics.

This combination helps the SST to move easily so it can quickly scan the sky - perfect for watching for strange spacecrafts or debris "The SST will give us in a matter of nights the space surveillance data that current telescopes take weeks or months to provide," explained Air Force Lt. Col. Travis Blake, DARPA's Space Surveillance Telescope program manager.

Beyond providing faster data collection, the SST is very sensitive to light, which allows it to see faint objects in deep space that currently are impossible to observe.

The detection and tracking of faint objects requires a large aperture and fast optics. The SST uses a 3.5 meter primary mirror, which is large enough to achieve the desired sensitivity.

The system is an f/1.0 optical design, with a large-area mosaic CCD camera constructed from the curved imagers and a high-speed shutter allowing for fast scanning at the high sensitivity.

Some of the missions assigned to the SST include watching for debris in low earth orbit to help avoid satellite collisions, tracking objects in deep space and taking wide-angle pictures of stars and comets for astronomers.

 The Pentagon's DARPA has begun deploying new ground-based telescopes that can take wide-angle views of small deep-space objects and keep the space sentinels safe.

"Currently we have a 'soda straw' view of deep space, where we can only see one narrow segment of space at a time," Blake said. "The Space Surveillance Telescope should give us a much wider 'windshield' view of deep space objects, significantly enhancing our space situational awareness."

DARPA's telescope uses curved charge coupled device (CCD) technology similar to what exists in digital cameras. That helps create a compact size which helps the new telescope survey the sky more rapidly on its moveable mount – it represents one of the most agile telescopes ever built for its size.

The telescope's CCD camera consists of curved imagers and a high-speed shutter that allows for both fast scans and high sensitivity. Such sensitivity helps the telescope detect and track the very small, very faint objects zipping across the wide-angle view of space.

Ultimately, the new telescope aims to find more of the space objects in the geosynchronous region of space around the Earth's equator. That would allow the Pentagon to better keep track of collision dangers for its satellites – at least until the expensive spacecraft get better shields.

Space Based Radar

Space Based Radar

During the Discoverer II program, a DoD program that ended in 2000, prime contractors and payload suppliers were funded by the United States Government to study the use of radars in space. The planned successor program, SBR, will fund the development and production of an operational radar reconnaissance satellite system.

In response to the FY01 DoD Authorization Conference Report, the National Security Space Architect is led a multi-service, multi-agency effort to develop an SBR Roadmap, to bring together requirements for both the DoD and national users. As part of the Roadmap development, the Air Force was heavily involved in an analysis of alternatives that will allow the DoD leadership to make SBR decisions in concert with decisions being made on other intelligence, surveillance and reconnaissance systems.

Space-Based Radar was a new major defense acquisition program in 2001 delegated by the Secretary of Defense to the Air Force. The Directorate of Developmental Planning at the Space and Missile Systems Center, Los Angeles Air Force Base, CA led this joint program with principle participation from Electronic Systems Center in Bedford, MA, the National Reconnaissance Office (NRO), U.S. Army, and U.S. Navy. The main objective of the SBR program is to field, beginning in 2008, a space borne capability for theater commanders to track moving targets. The focus in 2002 and 2003 includes requirements development (led by Air Force Space Command), technology risk reduction, concept exploration, and cost feasibility.

The 2001 Multi-Theater Target Tracking Capability (MT3C) Mission Needs Statement (MNS) establishes the requirement for continuous multi-theater surveillance, identification, tracking, and targeting of ground-moving targets. In June 2001, the Under Secretary of Defense for Acquisitions, Technology, and Logistics (USD(AT&L)) directed an accelerated acquisition program to leverage technology from the cancelled Discoverer II technology demonstration program and provide a capability satisfying the MT3C MNS no later than FY10. The Office of the Secretary of Defense (OSD) Acquisition Memorandum (AM) directive dated 30 November 2001 initiated SBR as an ACAT ID program. As a result, the SBR program was established with the purpose to develop and implement a space-based capability to provide surface Moving Target Indications (MTI), Synthetic Aperture Radar (SAR) imaging, and High Resolution Terrain Information (HRTI) mapping to national decision makers and joint/coalition forces deployed worldwide.

The Space Based Radar Program is administered by Air Force Space Command, Space and Missile Systems Center (AFSPC/SMC) and the National Reconnaissance Office (NRO), in coordination with the Services and the National Imagery and Mapping Agency (NIMA).

The SBR Joint Program Office (JPO) at Space and Missile Systems Center will be beginning the process of awarding a concept development contract that will allow development of the system through the Increment 1. The acquisition strategy is to conduct a best value, progressive ompetition / down-selection. The source selection will result in the award of one or possibly two contracts with performance through System Design Review (SDR) plus six months.

In February 2002 Space and Missile Center (SMC), the National Reconnaissance Office (NRO) and Air Force Research Laboratory (AFRL) announced a Space Based Radar On-Board Processing (OBP) Broad Agency Announcement (BAA) as supplemented and applicable to Program Research and Development Agreement (PRDA) soliciting research proposals from private industry, educational institutions, and nonprofit organizations for research. The purpose of this PRDA was to design and demonstrate a prototype OBP Architecture that can meet the tactical user near real time needs of Ground Moving Target Indication (GMTI), Synthetic Aperture Radar (SAR), and Digital Terrain Elevation Data (DTED). The OBP development must be affordable and capable of being transitional to the evolving SBR baseline with a planned Initial Launch Capability (ILC) in 2010. Proposed technology development must be demonstrated in 2004 or 2005 at TRL-5 as a minimum. Proposals to the PRDA shall identify key interface parameters such as data rate, power requirements, word length, speed, storage capacity, buffer requirements, number of ports (channels), redundancy, interchangeability, etc. Processor and Mass Data Storage (MDS) size, weight, power, cost and radiation tolerance are key parameters and will be factors in determining contract award(s). Output data shall be compressed for communications downlink capability. Output data and communications interface capability and parameters shall be proposed. Note that the MDS and downlink capabilities shall also support raw wideband data downlink to CONUS. All OBP algorithms shall be documented as well as all OBP features that would allow on-orbit algorithm modification. For the purpose of this PRDA, the Government considers the OBP to include MDS, Back End Processor (BEP) and interface elements (at the beamformer/pulse compression interface). The BEP shall provide algorithm capability for sub-band combining to create either GMTI detections or SAR image data. OBP system proposed concepts that incorporate a complete FEP (distinct from current payload designs and including A/D, channelizers and beamformer) with a BEP shall provide justification as to how this enhances performance, cost parameters, and the SBR mission. Output data shall be compressed for communications downlink capability, if appropriate. Output data and communications interface capability and parameters shall be proposed. Note that the MDS and downlink capabilities shall also support raw data (post-FEP) downlink to CONUS.

Several significant efforts were underway in 2002. These include the System Concept Analysis task order executed via the Engineering, Analysis, Design and Development (EADDII) contract (awarded in December 2002) the ongoing SBR On-Board-Processor (OBP) and the Electronically Scanned Array (ESA) contracted activities that are planned to continue through 2003. Results of this effort may influence the design of the SBR Concept of Operations, OBP design, ESA design, and system design.

On March 19, 2003 Harris Corporation (NYSE:HRS) announced that it is one of three companies awarded three-year contracts by the U.S. Air Force to develop and demonstrate a prototype radar payload for Space-Based Radar. The initial value of the contract is $8.6 million, with options that could bring it to $88 million over the three-year period of the prototype program. The final payload design, development, production and support program for all SBR spacecraft could reach $1 billion by 2013 for the winning company, which will be selected at the conclusion of the prototype phase. Under terms of the contract with the U.S. Air Force Space and Missile Systems Center (SMC) and the National Reconnaissance Office (NRO) Joint Program Office, Harris will lead the three-year study of SBR's radar payload. The Harris SBR radar payload concept includes state-of-the-art On-board Processing (OBP) technology and a large Electronically Scanned Array (ESA) that will enable each spacecraft to collect and process large amounts of data and imagery in near real-time.

On 17 September 2003 the Space and Missiles System Center announced plans to release Request for Proposal No. FA8820-04-R-0001 between the 1st and 31st of November 2003 for the Space Based Radar (SBR) Concept Development effort. SBR is an ACAT 1D program currently entering Acquisition Phase A as defined in NSS 03-01.

As of early 2003 the formal RFP was to be issued in October 2003 by the SBR Joint Program Office (JPO) at Space and Missile Systems Center. Proposals were due 45 days later with an anticipated contract award date in March 2004. If one contract was awarded, the contract will be a cost-plus award fee arrangement. If two contracts are awarded, the contract will be a cost-plus fixed fee arrangement. The launch vehicle, launch vehicle integration, spacecraft operations, spacecraft ground station, telemetry and data dissemination, and ground beacons, if required, will be provided. The contractor is expected to provide experiment plans and proposed mission CONOPS, data analysis to verify performance, and command and control software for spacecraft operation. The demonstration will include a partially populated array (mass simulation as required). A one year "on orbit" test, evaluation, and extrapolation is planned, with structural constituent equations and FEM verification to provide a statistically significant beam-pointing and transmit calibration & compensation variances.

At the development milestone of SDR, the Government will request a Call for Improvement (CFI) proposal. This CFI will be used to conduct and evaluate a progressive down-selection intended to identify the single contractor offering the superior (best value) design approach to continue the development and manufacture of the SBR system. It is anticipated that only those contractors participating in the preceding phase will be capable of successfully competing for the next phase contract awards, although other offerors will not be precluded from consideration at the down-selection decision point.

The contractors will be required to submit a priced proposal for the first phase of this effort through SDR plus six months, and evidence of affordability of the total system. This will allow the Government to judge best value through SDR and judge the affordability of the system. While the Government intends to down-select at the System Design Review (SDR), we reserve the right not to, and either extend the parallel development effort to a future down-selection milestone or to proceed with a full and open competition if that approach is determined to be in the Government?s best interest.

On 21 October 2003 Raytheon Company was awarded a $37.4 million cost-plus-fixed-fee contract to define, analyze, design and demonstrate a Space-Based Radar (SBR) pre-prototype payload consisting of an electronic scanned array and an on-board processing component. The Air Force's Space and Missile Systems Center, Los Angeles Air Force Base, Calif., is the contracting agency. The developmental payload will be designed to meet the tactical/national user near real-time data needs for ground moving target indication (GMTI), synthetic aperture radar (SAR) and digital terrain elevation data.

In October 2003 SAIC's Space, Air and Information Group announced a contract award to support the U.S. Air Force's Space and Missile Systems Center (SMC) in the development of the Space-Based Radar (SBR), an important national defense program. Under the terms of the agreement, SAIC will be the lead System Engineering and Integration (SE&I) contractor for this effort. This delivery order contract has a base value of $4.6 million, with the potential of eight option years valued at a total of $139.4 million. For the SBR SE&I program, SAIC will implement and execute systems engineering and integration processes and oversee the delivery of systems engineering products necessary for effective execution of the SBR program and oversight of SBR system developers. SAIC also will lead the integration of the surface, air and space components of the nation's ISR system-of-systems. Members of the SAIC-led team include Lockheed-Martin Corp., headquartered in Bethesda, Md.; ARINC, based in Annapolis, Md.; Veridian Engineering, based in Arlington, Va.; TASC, Inc., based in Chantilly, Va.; and Titan Corp., headquartered in San Diego, Calif.

The FY2004 budget request for the Space Based Radar was $274 million. The FY2004 DOD authorization bill (H.R. 1588/S. 1050) approved the requested funding and directed DOD to assess the contribution SBR could make to missile defense. In the FY2004 DOD appropriations act (P.L. 108-87), Congress cut SBR by $100 million.

SBR was in the initial phase of development, and passed its first Key Decision Point A (KDP-A) to enter Phase A (the Study Phase) in July 2003. The purpose of the Study Phase is to develop concepts and architectures to a sufficient level of maturity to enter the KDP-B Design Phase, expected in FY04. The Study Phase will consist of further concept definition, concept of operations and requirements development, risk reduction, and initial planning to develop a test and evaluation strategy prior to KDP-B. After KDP-B, the program is expected to enter a system pre-acquisition period lasting through a planned KDP-C at the end of FY07, when system acquisition activities will begin.

The 2004 program invested in technology and concept definition activities to include but not limited to up-front, in-depth system engineering, risk reduction activities. Continue Technology Risk Reduction activities on Electronically Scanned Array (ESA) and on-board processing efforts that included end-to-end payload test beds and prototype development of high-risk signal processing algorithms, expanded tactical integration effort that includes interface identification and definition, support an Advanced Concept Technology Demonstration (ACTD) and on-orbit demonstrations. Additional near term efforts include technology risk reduction demonstrations as well as, system-of-systems engineering activities, wargames and experiments, and Modeling & Simulation (M&S) capability, to include access to operational C4ISR systems for enhanced data expoitation.

In April 2004, both Lockheed Martin and Northrop Grumman were awarded $220 Million SBR study contracts. They were selected as phase “A” or concept development prime contractors. Each of them selected several subcontractors to join them as part of their teams. During phase A, each contractor developed concepts for the system which that can best satisfy the government’s draft requirements.

Although DOD had taken positive steps to strengthen the involvement of senior leaders within DOD and the intelligence community in setting requirements, as of mid-2004 SBR's concept of operations [CONOPS] had not been approved and signed by requirements boards for either of the two partners. Without documentation and formal approval, it was unclear who will be held accountable for setting requirements or how disagreements among SBR's partners will be resolved when DOD moves SBR into ensuing phases of acquisition.

During the Discoverer II program, a DoD program that ended in 2000, prime contractors and payload suppliers were funded by the United States Government to study the use of radars in space. The planned successor program, SBR, will fund the development and production of an operational radar reconnaissance satellite system.

In response to the FY01 DoD Authorization Conference Report, the National Security Space Architect is led a multi-service, multi-agency effort to develop an SBR Roadmap, to bring together requirements for both the DoD and national users. As part of the Roadmap development, the Air Force was heavily involved in an analysis of alternatives that will allow the DoD leadership to make SBR decisions in concert with decisions being made on other intelligence, surveillance and reconnaissance systems.

Space-Based Radar is a new major defense acquisition program in 2001 delegated by the Secretary of Defense to the Air Force. The Directorate of Developmental Planning at the Space and Missile Systems Center, Los Angeles Air Force Base, CA led this joint program with principle participation from Electronic Systems Center in Bedford, MA, the National Reconnaissance Office (NRO), U.S. Army, and U.S. Navy. The main objective of the SBR program is to field, beginning in 2008, a space borne capability for theater commanders to track moving targets. The focus in 2002 and 2003 includes requirements development (led by Air Force Space Command), technology risk reduction, concept exploration, and cost feasibility.

Although DOD had taken positive steps to strengthen the involvement of senior leaders within DOD and the intelligence community in setting requirements, as of mid-2004 SBR's concept of operations [CONOPS] had not been approved and signed by requirements boards for either of the two partners. Without documentation and formal approval, it was unclear who will be held accountable for setting requirements or how disagreements among SBR's partners will be resolved when DOD moves SBR into ensuing phases of acquisition.

The U.S. Air Force announced 23 May 2005 that Lockheed Martin had been selected to continue development of the Innovative Space Based Radar Antenna Technology, known as ISAT. The contract, valued at $19.5 million, is for the next phase of the Defense Advanced Research Project Agency's (DARPA) ISAT project, administrated by the Air Force Research Laboratory (AFRL). Lockheed Martin will continue development of the ISAT Flight Demonstration Experiment design over the next 14 months, which will take it to the Critical Design Review (CDR) maturity level. Following the CDR, DARPA and the Air Force plan to select a contractor to build and deploy a scale version of the antenna for a one-year proof of technology experiment in low earth orbit.

The FY 2005 Appropriations Bill reduced the President's Budget from $327M to $75M, and redirected the Air Force's development efforts "towards technologies and concepts that would lead to program costs far lower than currently conceived" and "breakthroughs that fundamentally change the cost-benefit equation for a space based radar system."

To address Congressional concerns and to arrive at a technically feasible solution, the Air Force placed increased emphasis on innovation and affordability on the SR concept exploration efforts. This emphasis has resulted in significant changes to the SR program. While continuing to be dual-use to meet Department of Defense (DoD) and IC needs, the SR is focused on smaller constellations of high performance, more affordable satellites. This move to smaller, more affordable constellations was driven by the realization that it is ultimately unaffordable for a single system to provide global continuous target tracking capability. The resulting more affordable system concepts remain highly effective by leveraging advanced technologies and increased levels of horizontal integration with other ISR platforms, national infrastructure and DoD weapon systems.

Air Force and OSD leadership will further address Congressional concerns through an on orbit demonstration that will validate Space Radar costs and technology maturity. The program will also shift focus towards payload maturation, a robust technology risk reduction and system-of-systems engineering program, and a structured revalidation of requirements. In addition, leadership commissioned an Independent Technology Assessment to look at alternative technologies to reduce cost and improve utility.

The 2006 program focused on overall program affordability by stressing innovation through program risk reduction and technology maturation. The program will leverage National Reconnaissance Office (NRO), National Geospatial-Intelligence Agency (NGA), Defense Advanced Research Projects Agency (DARPA), and Air Force Research Laboratory (AFRL) activities to ensure both DoD and Intelligence Community requirements are satisfied in the baseline SR effort. In addition, an on orbit demonstration will be developed to validate Space Radar costs and technology maturity.

The Air Force leads the SR Joint Program Office (JPO) with the National Reconnaissance Office (NRO) and National Geospatial- Intelligence Agency (NGA) as the principal partners with other Service, DoD, and Intelligence Community participation. The SR JPO awarded two contracts for Concept Definition and plans to select a single contractor after KDP-B.

As of 2005 Space Radar was intended to provide synthetic aperture radar mapping and surface moving target indication capabilities in all weather conditions. The first operational spacecraft would be launched beginning about 2015, with plans calling for a constellation of nine satellites.

As of 2004 DoD had estimated total life-cycle costs for a nine satellite Space Radar constellation of $34 billion, including the ground segment. The 2006 FYDP and Congressional Budget Office [CBO] long-term projection include $19 billion through 2024 for the space segment of Space Radar. CBO assumed that starting in 2023, the constellation would be reconstituted or possibly increased. The CBO projection used a cost for each Space Radar satellite of $500 million, based on a potential weight of 7,000 pounds at $70,000 per pound. 

SPACEX - Space Exploration Technologies Corporation

Space Exploration Technologies Corp. (SpaceX) is an American space transport company founded by PayPal co-founder Elon Musk. It has developed the Falcon 1 and Falcon 9 rockets, both of which are built with a goal of being reusable launch vehicles. SpaceX is also developing the Dragon spacecraft to be carried to orbit by Falcon 9 launch vehicles. SpaceX designs, tests and fabricates the majority of their components in-house, including the Merlin, Kestrel, and Draco rocket engines. In December 2010, SpaceX became the first private company to successfully launch, orbit and recover a spacecraft (a Dragon) 

In an era when most technology based products follow a path of ever-increasing capability and reliability while simultaneously reducing costs, launch vehicles today are little changed from those of 40 years ago. SpaceX aims to change this paradigm by developing a family of launch vehicles which will ultimately reduce the cost and increase the reliability of space access by a factor of ten. Coupled with the newly emerging market for private and commercial space transport, this new model will re-ignite humanity's efforts to explore and develop Space.

Our company is based on the philosophy that simplicity, low-cost, and reliability can go hand in hand. By eliminating the traditional layers of management, internally, and sub-contractors, externally, we reduce our costs while speeding decision making and delivery. Likewise, by keeping the vast majority of manufacturing in house, we reduce our costs, keep tighter control of quality, and ensure a tight feedback loop between the design and manufacturing teams. And by focusing on simple, proven designs with a primary focus on reliability, we reduce the costs associated with complex systems operating at the margin.

Established in 2002 by Elon Musk , the founder of PayPal and the Zip2 Corporation, SpaceX has already developed two brand new launch vehicles, established an impressive launch manifest, and been awarded COTS funding by NASA to demonstrate delivery and return of cargo to the International Space Station. Supported by this order book and Mr. Musk's substantial resources, SpaceX is on an extremely sound financial footing as we move towards volume commercial launches.

Although drawing upon a rich history of prior launch vehicle and engine programs, SpaceX is privately developing the Dragon crew and cargo capsule and the Falcon family of rockets from the ground up, including main and upper stage engines, the cryogenic tank structure, avionics, guidance & control software and ground support equipment.

With the Falcon 1, Falcon 9 and Falcon Heavy launch vehicles, SpaceX is able to offer a full spectrum of light, medium and heavy lift launch capabilities to our customers. We are able to deliver spacecraft into any inclination and altitude, from low Earth orbit to geosynchronous orbit to planetary missions. The Falcon 9 and Falcon Heavy are the only US launch vehicles with true engine out reliability. They are also designed such that all stages are reusable, making them the world's first fully reusable launch vehicles. And our Dragon crew and cargo capsule, currently under development, will revolutionize access to space by providing efficient and reliable transport of crew and cargo to the ISS and other LEO destinations.

Our design and manufacturing facilities are located near the Los Angeles International airport, leveraging the deep and rich aerospace talent pool available in Southern California . Our extensive propulsion and structural test facilities are located in Central Texas. We currently have launch complexes available in Vandenberg and Kwajalein Island , and in April 2007 we were granted use of and began developing Space Launch Complex 40 at Cape Canaveral.

Falcon Heavy’s first stage will be made up of three nine-engine cores, which are used as the first stage of the SpaceX Falcon 9 launch vehicle. It will be powered by SpaceX’s upgraded Merlin engines currently being tested at the SpaceX rocket development facility in McGregor, Texas. SpaceX has already designed the Falcon 9 first stage to support the additional loads of this configuration, and with common structures and engines for both Falcon 9 and Falcon Heavy, development and operation of the Falcon Heavy will be highly cost-effective.

	FALCON HEAVY
Mass to LEO (200 km, 28.5 deg):	53,000 kg (117,000 lb)
Overall Length:	69.2 m (227 ft)
Width (body):	3.6 m (12 ft) x 11.6 m (38 ft)
Width (fairing):	5.2 m (17 ft)
Mass on liftoff:	1,400,000 kg (3,100,000 lb)
Thrust on liftoff:	17 MN (3,800,000 lbf)

HIGH RELIABILITY AND HIGH PERFORMANCE

The Falcon Heavy is designed for extreme reliability and can tolerate the failure of several engines and still complete its mission. As on commercial airliners, protective shells surround each engine to contain a worst-case situation such as fire or a chamber rupture, and prevent it from affecting the other engines and stages. A disabled engine is automatically shut down, and the remaining engines operate slightly longer to compensate for the loss without detriment to the mission.

Falcon Heavy will be the first rocket in history to feature propellant cross-feed from the side boosters to the center core. Propellant cross-feeding leaves the center core still carrying the majority of its propellant after the side boosters separate. This gives Falcon Heavy performance comparable to that of a three-stage rocket, even though only the single Merlin engine on the upper stage requires ignition after lift-off, further improving both reliability and payload performance. Should cross-feed not be required for lower mass missions, it can be easily turned off.

Anticipating potential astronaut transport needs, Falcon Heavy is also designed to meet NASA human rating standards. Falcon Heavy is designed to higher structural safety margins of 40% above flight loads, rather than the 25% level of other rockets, and triple redundant avionics. Despite being designed to higher structural margins than other rockets, the Falcon Heavy side booster stages have a mass ratio (full vs. empty) above 30, better than any launcher in history. By comparison, the Delta IV side boosters have a mass ratio of about 10.

SAVING THE USA $1B ANNUALLY

If allowed to compete, SpaceX can help the Department of Defense save at least one billion dollars annually in space launch services, while providing a truly independent family of vehicles to help assure access to space.

The Falcon Heavy is classified as an Evolved Expendable Launch Vehicle (EELV). The EELV program was established by the United States Air Force to launch satellites into orbit more economically. The program was intended to both secure access to space for the Department of Defense and other United States government payloads and lower costs by at least 25%, and with a goal of 50%.

Unfortunately, primarily due to lack of competition, costs have actually escalated–increasing by over 30% for FY 2012 alone. The total cost of the current program now exceeds $2.7B, with over $1B paid to a single provider just to sustain the program. That is one billion dollars per year, whether they launch or not.

Falcon Heavy with more than twice the payload but less than one third the cost of a Delta IV Heavy, will provide much needed relief to government and commercial budgets. This year, even as the Department of Defense budget was cut, the EELV launch program, which includes the Delta IV, still saw a thirty percent increase.

The 2012 Air Force budget includes $1.74B for four launches, an average of $435M per launch. With Falcon Heavy priced at $80-125M per launch SpaceX has the potential to provide the US government significant value. In addition, the medium-lift Falcon 9 could support a number of medium-lift Air Force launches at only $50-60M per launch, if SpaceX were allowed to compete for this business.

Microwave Satellite Communication.

                                                 Satellite Microwave

A communication satellite can be seen as a microwave repeater in space. It is equipped with a number of devices called transponders, each of which listens to some portion of the electromagnetic spectrum, amplifies an incoming signal (the uplink), and re-broadcasts it at another frequency (the downlink). Geostationary satellites are placed in orbit above the equator at a height and speed that enables them to maintain a position above a specific location on the earth’s surface. The antenna used to receive signals from these satellites can thus be mounted in a fixed position.

The Astra 1H geostationary satellite

The downlink signal can be relatively narrowly focused (a spot-beam), or may cover a substantial fraction of the earth’s surface. The area covered by the signal is called its footprint. The size of the satellite dish required to receive a signal from a satellite depends on its location within the footprint (see below).

The footprint for the Astra 1G and 1H geostationary satellites

Although signals travel between earth stations and satellites travel at the speed of light (circa 3x10⁸ kilometres per second), the distances involved introduce substantial delays (typically 250-300 milliseconds). Satellites are also inherently broadcast media - very useful for some applications, but necessitating the use of encryption if security is an issue.

Low earth orbit (LEO) satellites are only visible for a short period. For this reason, large numbers of these satellites are required to implement a satellite communication system. When one satellite passes from view, another one replaces it. Satellite networks (or constellations) can provide worldwide telecommunication services using hand-held devices that communicate directly with the satellites.

Iridium is a constellation of 66 low earth orbit communication satellites

In the Iridium system, the satellites are positioned at a height of 750 kilometres in circular polar orbits, and are arranged in north-south necklaces, with one satellite every 32 degrees of latitude. Each satellite completes one orbit every 100 minutes, and six such necklaces are sufficient to provide coverage of the entire earth. The uplink and downlink frequencies used make it possible to communicate with a satellite using a small battery powered device equipped with an omni-directional antenna. Messages are received by one satellite and then relayed from one satellite to another around the world until the message can be transmitted to the destination mobile device (or via an Irridum gateway if the call is being routed via the public switched telephone network). The user simply requires line-of site between their antenna and one of the Iridium satellites. 

Modulation Microwave Communication

1, With the explosive growth of information flows, the current to the carrier's space satellite microwave communications technology gradually exposed the weaknesses of its own, that as the communication data rates have increased, as traditional means of microwave began to close to its maximum transfer rate bottleneck theory. In this context, it is natural to look to transfer to the laser signal with the optical communications, laser communications expect to rely on high data transfer rate to solve the problem.



Satellite optical communication is a new means of space communication. Use of artificial earth satellites as relay stations transmit laser signal can be achieved between multiple spacecraft and between spacecraft and earth station communications. The high transfer rate, high security and reliability, confidentiality and strong, terminal devices are small, light weight, low power consumption perseverance attracted national experts to explore the [1-4]. Space laser communication system in the structure should have an interface with the microwave communications. There is no one country has established space laser communication link, and therefore the satellite microwave communication and optical communications, few studies of mutual conversion process. In the field of optical communication has been a breakthrough, the successful realization of the satellite - terrestrial, satellite - satellite optical communication between tests in recent years is expected to enter the practical application [5-6]. Therefore, the space optical communications and microwave communications interconnection is a problem to be solved.



2, laser inter-satellite links Laser inter-satellite links include synchronous satellite communication link between, synchronous orbit and low orbit satellite communication link between China and LEO satellite communications links between satellites and ground stations and communication between link.



Based on consideration of the space environment, satellite and ground-based microwave link can only. Therefore, in order to meet the demanding star power, volume and complexity of the request, must study the satellite communications and microwave communications polish the mutual conversion technology. In addition, the existing satellite network using microwave technology, in order for satellite optical communication to optimize their effectiveness, the need to address the traditional satellite communications and satellite communications, optical networking technology, therefore, necessary to conduct in space optical communications and microwave communications interchangeable.



3, satellite communications and microwave communications optical conversion method

For most satellites, it is both microwave and optical communication link conversion node, is also a satellite routing optical network switching nodes. On the one hand, when the node up / down link, the satellite must complete the microwave / optical and optical / microwave interchangeable. On the other hand, routing is determined by the middle of the satellite onboard processors, according to the dynamic routing table lookup to complete, so that the packet needs to go through complex demultiplexing, demodulation process and routing the exchange of such treatment.



The relay satellite and the LEO satellite (GEO-LEO) relay link between the laser, the need to send back to the ground to LEO LEO high-speed data initially modulated laser communication terminals to the relay satellite complicated by the GEO laser communication terminal for receiving, processing obtained by the regeneration of the baseband demodulation signal, then microwave for QPSK modulation, the frequency to Ka-band, Ka-band satellite ground line via the link sent to ground stations. LEO sent to the first floor to the low-speed data, the spread spectrum, BPSK modulated, the ground line from the Ka-band satellite link sent to the relay satellite, GEO received baseband demodulation signal regeneration processing, enter the GEO optical laser communication terminals prepared and sent to LEO laser communication terminal. This microwave communication and optical communication method exists mutual conversion process complex, cumbersome equipment and network delay to increase the volume and other shortcomings, can not meet the requirements of the satellite payload.