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DARPA history ...

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« on: July 26, 2010, 08:28:44 pm »

Part 2 of 2 ...

The TRANSIT program proved to be an example of the benefit of having an R&D organization like ARPA outside of the services; a benefit that the DoD has reaped time and time again since the founding of ARPA. In the TRANSIT example, because the DoD responsibility for space programs lay outside of the Navy in 1958, APL brought the proposal to ARPA, where in October 1958 it was quickly approved and funded for all the pieces of a demonstration system including the construction of a demonstration satellite, tracking/orbit update stations, launch systems, and the development of ground navigation equipment/receivers. . Within just months of the Sputnik launch, APL had been able to fully develop the concept for the proposed satellite navigation system. The benefits of this solution, especially for submarines, as compared to other forms of navigation were overwhelming. The polar orbits of the satellites allowed worldwide coverage of the system, Since the measurements of angles or directions are not required, simple omni-directional antennas can be used (very useful on a pitching ship and with a submarine that only has to expose a small antenna at appropriate times). As the method uses radio frequencies, the solution is all-weather. Now a submarine in the open ocean could in any conditions and with minimal exposure, determine its location worldwide within 200 m. Almost by accident, APL had found the solution to the problem of determining missile launch coordinates on a moving platform.
The first successful TRANSIT launch was in April 1960 (TRANSIT 1B), just 18 months after project approval and demonstrated the feasibility of satellite navigation. Just as other early ARPA programs, TRANSIT had secondary demonstration goals. The Able-Star second stage demonstrated for the first time an engine restart in space. Also, TRANSIT 1B tested the first magnetic torquer devise used for satellite attitude control and a solar attitude detector. Future versions of TRANSIT demonstrated for the first time gravity-gradient stabilization, allowing a directional antenna for transmitting its signal, greatly decreasing on-board power requirements. Another side benefit of the TRANSIT program was greatly improved scientific knowledge of the earth’s gravitational field through the large data set provided by the TRANSIT satellites and tracking stations. This geodesy knowledge was the fundamental limiting factor to position calculations as slight changes in the earth’s gravitational field would slightly alter the satellites orbit. By 1965, the gravity model had become sufficiently accurate to reduce the positional
22 a different operating principle than the current GPS navigation system
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accuracy of TRANSIT to less than 400 m, the requirement set for POLARIS. 23 By 1968, the TRANSIT system was declared fully operation by the Navy and had already begun to be used for civilian applications. The system remained in active service until 1996 when the current GPS system became fully operational.
VELA HOTEL
“Each of the Parties to this Treaty undertakes to prohibit, to prevent, and not to carry out any nuclear weapon test explosion, or any other nuclear explosion … in the atmosphere; beyond its limits, including outer space; or under water, including territorial waters or high seas” – Limited Test Ban Treaty of 1963
During the second ever very large thermonuclear test at Bikini Atoll in March of 1954, poor prediction of the fallout pattern from such a large explosion led to the unintentional exposure of hundreds of Marshall Island natives to high, but non-lethal, levels of radiation. The ironically named Fortunate Dragon, a Japanese fishing boat, was in the area and also received very high doses of radiation which proved to be fatal for its captain. This “Bravo” nuclear fallout accident focused international attention on nuclear testing and spurred President Eisenhower to consider proposing a nuclear test ban as a solution to the fallout issue and possible slow down the arms race.24 By 1957, the issue had been given to the Presidential Science Advisory Committee (PSAC) to consider both the implications for a nuclear testing ban and methods in order to verify such a treaty. The latter effort was, in part25
In a continuation of presidentially directed programs, Eisenhower assigned ARPA in the summer of 1959 the task of developing the technologies necessary for the detection of nuclear tests, what would become Project VELA (Vela means watchman in Spanish). This program would examine technologies for detection space and atmospheric tests by satellites (VELA , undertaken by the High Altitude Detection panel (the Panofsky panel) of PSAC, which recommended that a satellite system be employed to detect atmospheric or space nuclear tests as part of a verification system for a possible nuclear test ban treaty.
23 Reed, p. 3-7
24 York, p. 117
25 Reed, 11-1. Separate panels were assigned to examine parts of the testing ban, such as underground (the Berkner Panel).
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HOTEL) or by ground-based system (VELA SIERRA) and for underground test by large seismic arrays (VELA UNIFORM).
By September, ARPA had already planned for the required launchers for VELA HOTEL and had assigned Los Alamos and Sandia the responsibility for designing the satellite system and execution of the effort to the Air Force. The goal of the program was to develop a satellite system that would be able to detect a minimum 10 kiloton nuclear explosion taking place on the surface of the Earth from as far away as 160 million kilometers. By 1963, the first of the satellites were ready for launch, and just in time. In April, 1963 the UK, US, and USSR signed the Limited Test Ban Treaty (banning atmospheric and space testing of nuclear weapons), which went into effect on October 10 of that year. Just 7 days later, the first pair (of six) of VELA satellites was launched on top of an Altas-Agena rocket and placed in 115,000 km circular orbit, beyond the outer Van Allen belt and nearly a quarter of the way to the moon - higher than any military satellite had been placed before. Spaced 180 degrees apart from each other and at an altitude that could examine a complete hemisphere, this first pair quickly established a verification method for the new treaty. It is noteworthy that the second pair of VELA satellites detected the Chinese Lop Nor test in 1964, quickly demonstrating their capability and utility.26
VELA 5 Satellite. A Presidential directed effort, the ARPA VELA HOTEL satellites, part of the larger VELA program, provided the United States with the means to detect atmospheric and space nuclear detonations, a key verification capability in support of the Limited Test Ban Treaty.
(downloaded form http://imagine.gsfc.nasa.gov/Images/vela5b/vela5b_5sm.gif )
26 Magnuson, S., “History of DARPA in Space”, 50 Years of Bridging the Gap, 2008, p. 114
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Under the ARPA program, 6 pairs of VELA satellites were eventually placed into orbit from 1963 through 1970. The first two pair included neutron and gamma ray detectors, designed by Los Alamos and Sandia to measure the characteristics of a nuclear explosion in space. As has been true of many ARPA programs throughout its history, science and equipment that has first been developed and tested for military purposes has the unintended consequence of vastly improving or creating a new area of science. In the case of the VELA HOTEL satellites, the gamma ray detectors that were developed to detect a nuclear test in space kick started the field of gamma ray astronomy,
27 key in the identification of supernovae and measurements of the early universe just after the Big Bang. On the third pair of spacecraft, launched in 1965, an optical instrument, called a bhangmeter, was added to provide a separate modality to identifying and verifying atmospheric tests. The bhangmeter, developed by Los Alamos for this purpose, measured the double flash signature that is characteristic of an atmospheric nuclear detonation. The utility of the bhangmeter in the third pair was limited by the satellite’s spin stabilization. But by 1967, the fourth pair was gravity gradient stabilized (earth-oriented), which greatly improved their capability. The last two pair (1970) also included an electromagnetic pulse detector, even further increasing the data sets necessary to reduce false positives.28
The VELA program was completely transferred to the Air Force in 1970 after the launch of the last pair. Since July 1983, the GPS satellite network has carried the nuclear test detection equipment, including X-ray, bhangmeter, and EMP detectors, and in September 1984, the VELA satellites were shut down
29. However, during the time that the VELA HOTEL satellites were operational, it is believed they did not miss a single nuclear event that they were in a position to observe, providing the verification capability necessary to support the Limited Test Ban Treaty.30 Even more importantly, the known capability of the US to detect atmospheric nuclear tests, and through the VELA UNIFORM program underground tests, has been a disincentive to aspiring nuclear powers to attempt to test nuclear weapons in secrecy.
ARPA’s Role in Launch Vehicle Development
27 York, p. 220
28 Reed, 11-6
29 Reed, 11-7
30 Argo, Harold, “Satellite Verification of Arms Control Agreements”, Arms Control Verification, Pergamon Press, 1985, p. 292
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In June 1958, the National Security Council invited ARPA to present its plans for developing launch vehicles. ARPA still had complete control over the US space program, but plans had already begun for a civilian agency, NASA, to take over the civilian aspect of the program. However, in that meeting, ARPA personnel set the ground work for the much of the launch architecture that would be used by NASA in reaching the moon and exploring the other planets – the use of clusters of engines for large launch vehicles (used in the Saturn series) and hydrogen-oxygen upper stages (Centaur)
31.
Centaur
“CENTAUR was “the” rocket by which NASA would conduct extensive earth orbit missions, lunar investigations, and planetary studies. Aside from military missions assigned to CENTAUR, which were to be considerable, NASA planned to launch one operational CENTAUR every month for a period extending well into the 1970’s and beyond.”32
The advantages of using LH2/LOX as a rocket propellant had been recognized even by early rocket pioneers. However, working with and designing for cryogenic liquids could not be adequately overcome – producing, handling, and storing LH2/LOX on the rocket proved to be too difficult for the engineering solutions of the time. During the early 1950’s, though, the Atomic Energy Commission (AEC) had produced major advances in large-scale hydrogen generators and storage systems for its work in thermonuclear devices33
Before ARPA’s creation, Convair had proposed to the Air Force that it develop a LH2 upper stage for its Altas booster using the same thin-skinned, pressurized structure technology. Pratt & Whitney was also proposing using its experience in LH2 propulsion to develop an upper . Additionally, during the mid-1950’s, the Air Force, under contract to Lockheed, was pursuing a supersonic surveillance aircraft, SUNTAN, using LH2 as its fuel. Pratt & Whitney was subcontracted to Lockheed as the propulsion lead, and successfully demonstrated that LH2 could be used in a turbojet engine. The new found industrial capability to produce, handle and utilizing in a propulsive device re-energized the interest in LH2/LOX as a solution to high-energy launch systems.
31 Sloop, J., “Liquid Hydrogen as a Propulsion Fuel”, NASA SP 4404, NASA historical series, 1978, p. 223
32 “History of CENTAUR”, NASA Lewis Research Center, undated, p. 2
33 Reed, p. 4-2
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stage. ARPA combined the proposals and in August, 1958 funded through the Air Force a joint Convair-Pratt effort to develop a LH2/LOX upper stage for the Atlas booster, the Centaur.
Although the program was quickly transferred to NASA in October, 1958, the Centaur was already on a path for success. The program was the first to demonstrate the cooling of the nozzle with cryogenic fuel, the pumping and control of these fuels in zero gravity, and that thin-skinned metal structures could survive cryogenic embitterment. Also, as Centaur was intended as an upper stage, the program demonstrated engine restart and precision navigation, both necessary to achieve accurate orbits. All of these advances would be used in later launch systems, including the Saturn family and the Space Shuttle. The final version of Centaur has an operational proven Isp of over 444 sec (the Atlas booster, which uses RP-1 as fuel, achieves approximately 353 sec), underlining the vision of the ARPA judgment in LH2/LOX technology and its teaming of Convair and Pratt. When mated to and Atlas booster, the Centaur is capable of placing 4 tons in LEO, 2 tons in GEO, and 1 ton to escape velocity34. As stated by a Glenn Research Center history, Centaur is simply “America's Workhorse in Space”35.
The Atlas Centaur launch system. ARPA funded the development of the LH2/LOX Centaur upper stage, as a high performance stage necessary to lift heavy payloads. Combined with the Atlas and Titan boosters, Centaur was the upper stage for launches of probes to Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune. Centaur continues to serve as the Untied States’ most powerful upper stage.
(downloaded from http://exploration.grc.nasa.gov/education/rocket/gallery/atlas/AtlasCentaur.jpg )
34 Reed, 4-5
35 http://www.nasa.gov/centers/glenn/about/history/centaur.html, downloaded 6/8/08
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Saturn
“But why, some say, the moon? Why choose this as our goal? And they may well ask why climb the highest mountain? Why, 35 years ago, fly the Atlantic? Why does Rice play Texas? We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win.” President John F. Kennedy, Rice University, 1962
Although President Kennedy provided the vision and drive behind the space program, and the moon shot in particular, to the nation as a whole, it was decisions and a time-saving suggestion that were made during that short period that ARPA controlled the US space program that jumpstarted the US booster program to be in a position to meet the challenge. Von Braun’s group at ABMA had been working on a concept for a large booster since early 1957 – work that received a big push after the launch of Sputnik. Their concept, a major feature of ABMA’s “National Integrated Missile and Space Development Program”, proposed to speed the development of a large booster by ganging a cluster of existing missiles together and using a to-be-developed Rocketdyne E-1 engine burning RP-1/LOX. After being given the space mission at its formation in February 1958, ARPA pickup up on the concept and made a critical suggestion, recommending substituting eight existing Thor/Jupiter S-3D engines for the still-to-be-developed E-1, saving $60 million and two years in development time. With this change, ARPA provided funding of $92.5 million in August of 1958 to get the Juno V (soon to be changed to SATURN) project started36
36 Reed, p. 5-2 . ARPA continued its funding support through ground testing and the study of launch facilities – right up until the booster development was transferred to NASA.
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Saturn 1b launching the Apollo 7 spacecraft. The Saturn family of launch systems was derived from the Juno (Jupiter-C) rocket developed by the Army Ballistic Missile Agency, funded by ARPA, and then transferred to NASA upon its creation.
(downloaded from http://exploration.grc.nasa.gov/education/rocket/gallery/atlas/Saturn1b.jpg )
The ARPA/ABMA first stage was successfully launched in October 1961 as part of the SATURN C-1 configuration. NASA used 10 SATURN C-1 launchers, which also included CENTAUR LH2/LOX engines on the second and third stage, to test APOLLO procedures and equipment. The follow-on SATURN B-1, which used the same first stage and CENTAUR engines for the third, was used to test APOLLO systems and engines and demonstrate docking maneuvers right through 1966 when the SATURN V test flight began37. Although the final SATURN V configuration differed from these early models, it was the early support of ARPA for the cluster concept, the suggestion of using existing engines during early development, and the technology demonstration of LH2/LOX engines in the CENTUAR program, that accelerated the US space program in its quest to beat President Kennedy’s deadline and land a man on the moon by the end of the 1960’s.
A New Mission
ARPA’s control of the US civil space program was short-lived. Formed in February 1958 to accelerate the US space effort, it would be nearly completely out of the business in the civil effort by November 1959. It was clear even during the creation of ARPA that President Eisenhower and Senate Majority Leader Johnson desired for a civilian agency to pursue the
37 Ibid, p. 5-6
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space race. Although it took a little longer to pass the Space Act legislation (the authority already existed for the Secretary of Defense to create a new defense agency), by July 1958 NASA had been formed and by fall most of the civilian space effort had been transfer from ARPA to the new agency, including the Saturn and Centaur rocket development and the TIROS weather satellite program.
There was pressure on the military space side as well. The services had never fully accepted that a separate agency was needed for the military space program and noted that even at its peak ARPA had returned 80 percent of its programs back to the Air Force to manage38
Just 21 months after its creation as the central space agency for the United States, most the ARPA portfolio of program, and much of its budget, had been transferred to other entities. It would have to find a new mission, not the last time a major portion of the agency would be split off to form a new agency. It should be noted that many of the efforts that ARPA handled during its short period of control of the US space program were concepts that were already in existence – ARPA established some order and the funding necessary. However, in losing existing, established technology programs to the services ARPA found its mission – to push the beyond the capabilities of today and bridge the gap to the future. . Defense Secretary McElroy saw the issue the same way and on September 18, 1959 made the Air Force the executive agent for space, transferring the communication and early warning satellite programs to it.
DARPA in Space: the 80’s and 90’s
Although the years in the twentieth century following the early 1960’s did not see frenetic space activity at DARPA, important programs and progress were non the less made. Significant DARPA space programs during the 1980’s included the Global Low Orbiting Message Relay (GLOMR), manufactured by Defense Systems Inc, now a part of Orbital Sciences Corporation. GLOMR was a store and forward system designed to relay data from remote earth based sensors. A small, basketball sized 52 kg polyhedron, it was originally to be launched from Shuttle mission STS-51B, but a battery issue forced a delay. It was eventually launched on mission STS-61A on October 30, 1985 and released into orbit 2 days later (this was the second use of the Shuttle “Get-Away-Special”,or GAS payload approach). It re-entered the earth’s atmosphere 14 months later. A noteworthy bit of data: the price tag on the satellite was a mere $1M – ushering in the idea of a “cheapsat”39
38 Magnuson, p. 112 . GLOMR was a “back to the future” program
39 Data from http://msl.jpl.nasa.gov/QuickLooks/glomrQL.html
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of sorts for DARPA, as it was the second store and forward relay satellite launched – SCORE being the first.
Significantly DARPA contributed to the development of what today may be considered the workhorses of small satellite launch – the Taurus and Pegasus launch vehicles built by Orbital Sciences. Both vehicles relied on similar solid rocket boosters. Taurus, a ground launched system was designed to be rapidly integrated and erected at a simply launch site. Pegasus was inspired by the idea that an air-launched system would provide enhanced flexibility as it steered clear of range impediments (in addition its performance was enhanced because of increased efficiencies at higher altitudes).
DARPA’s space activity in the 1980’s and 1990’s does appear at first glance to have been dwarfed by that which took place soon after Sputnik. But what is too overlooked is how other DARPA efforts in this time frame were integrated with newer space systems (with an ARPA/DARPA heritage) to provide unmatched advantage for the warfighter in the field during the last decade of the twentieth century. Satellite relayed UAV imagery, GPS guided munitions, and fully networked satellite communications for command and control are examples.
DARPA’s Space Mission Enters the Next Millenium
"If the US is to avoid a 'space Pearl Harbor,' it needs to take seriously the possibility of an attack on US space systems … The US is more dependent on space than any other nation. Yet the threat to the US and its allies in and from space does not command the attention it merits," Space Commission Report, 2001
Thanks in part to the effort of early ARPA satellite and rocket pioneers, by 2000 space played a vital and enabling role in the nation’s global military strategy and tactics, and just as importantly was paramount to the American economy and safety of its citizens. Global communications, GPS, accurate weather forecasting, and freedom through knowledge of the adversary were all now possible because of space technology. But, with this capability came vulnerability. Vulnerability not only in the form of catastrophic attack as made explicitly by the 2001 Space Commission, but vulnerability also in the form of technological surprise (like that of Sputnik) and the potential to fall behind in the technical supremacy needed to maintain a warfighting advantage. It was in this light that during his assignment to DARPA in mid-2001 that Dr. Anthony Tether was given the basic directive by then Secretary Donald Rumsfeld to get DARPA back into space (Rumsfeld of course headed the 2001 Space Commission which had published its findings early that year). Tether focused DARPA’s space activities into major focus areas, among them being Space Protection, Space Situational Awareness, and Access and Infrastructure.
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Two of the most dramatic programs that aimed to support the Access and Infrastructure domain are Falcon and Orbital Express. The Falcon program is “designed to vastly improve the U.S. capability to promptly reach orbit”40
No other DARPA program in the recent past may have more profound impact on the future of space access and infrastructure than Orbital Express. Orbital Express was conceived in the late 1990s as a demonstration of autonomous robotic servicing and refueling of spacecraft. The Hubble repair missions conducted by Space Shuttle crews have demonstrated the undeniable value of satellite servicing. As in the case of Hubble, too often spacecraft that have required enormous resources to build and launch fail within weeks of placement on orbit. Likewise, as technologies rapidly evolve in the post-information age, the ability to replace outdated sensors and computers onboard otherwise healthy satellites can bring increased utility to their users. Orbital Express was created with these thoughts in mind, but with the knowledge that human spaceflight repair missions – although very valuable – are very costly as well. By creating an autonomous capability for repair, costs could be vastly reduced and mission turnaround time could be decreased. When considering Orbital Express, its developers evaluated historical space programs and concluded that a key life limiting factor for many satellites is its store of propellant, used to provide for maneuvering and station-keeping. The amount of propellant available is limited by launch vehicle and spacecraft constraints on mass and volume. By allowing a means to refuel on-orbit, satellites' operational lifetimes could be increased, or they could be allowed to maneuver more frequently. Other life limiting elements include onboard batteries and computers, which can degrade (in the case of the former) or become obsolescent (in the case of the latter). . This activity includes development of new hypersonic test vehicles that could bridge the gap between space and the atmosphere inhabited by aircraft. Falcon also focused efforts to develop new low-cost launch vehicles, including the SpaceX Falcon 1 launch vehicle. The initial first two tests were sponsored by DARPA, with the second launch successfully getting to space and providing important data for continued develop of this vehicle that could potentially open new markets to space users.
40 2007 DARPA Strategic Plan
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In 2000, the Boeing Company's Phantom Works was awarded a contract to develop the Orbital Express system. Phantom Works designed and built the autonomous servicer, ASTRO (Autonomous Space Transfer and Robotic Orbiter), while the client (servicee) spacecraft, NextSat was built by Ball Aerospace. ASTRO, which weighed in at 1000 kg (carrying propellant both for itself and NextSat), used two optical cameras, a laser rangefinder, a NASA-designed laser ranging and client pose determination system, and an infrared camera for rendezvous, proximity operations, and docking of NextSat. The smaller 225 kg (dry) NextSat was fitted only with targets and retro-reflectors to assist ASTRO's sensors. A special docking mechanism allowed reliable mating of the two spacecraft, even at off-nominal docking angles. A fluid transfer mechanism was developed to pump or pressure-feed hydrazine propellant from one vehicle to the other. A purpose-built robotic arm allowed for the berthing of NextSat and the removal and replacement of modular flight computers and batteries.
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An in-orbit view of NextSat from ASTRO during DARPA’s Orbital Express Mission.Launch of the Orbital Express took place on 8 March 2007 from Cape Canaveral. Over the next 135 days, the mission conducted 14 refueling operations, demonstrated six battery transfers and a flight computer changeout, and performed seven discrete autonomous rendezvous and docking operations from separation distances of as much as 400 km. Each operation would begin with ASTRO and NextSat in the mated configuration. ASTRO would then fire its thrusters and retreat along a preset trajectory to a target separation distance, then return and dock.
With Orbital Express, DARPA offered a new way of thinking about the design and operation of future space systems: not only can serviceable satellites offer unmatched capabilities, they also provide decision makers and warfighters with the ability to change or modify these capabilities at any time in their lifecycle, as well as the ability to continue to perform the intended mission despite changes to the operating environment. These are the respective definitions of flexibility and robustness. Flexibility and robustness will be critical in a future filled with uncertain threats, uncertain technological development timeliness, uncertain budgets, and uncertain performance.
Closing Thoughts
It was a simple beep from Sputnik that surprised a nation and spurred the creation of a radically innovative agency called ARPA. Now DARPA, the legacy of the agency in space is incredible. The roots of vital communication, weather, sensing, and navigation spacecraft are found at DARPA. Today new roots are being planted that may yield yet again unparalleled space capabilities. The events of the future are difficult to predict. DARPA has no crystal ball. But DARPA will remain committed to preventing the United States from being surprised by the future. As in the past, DARPA in fact will continue to harness the genius of innovative people to create technologies that will change and indeed shape the future.

http://www.darpa.mil/Docs/DARPASpaceHistoryFinal.pdf
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