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Radar Imaging Reconnaissance Satellite

By © Charles P. Vick 2005-7 All Rights Reserved

Lacrosse satellites use synthetic aperture radar as their prime imaging instrument. It is able to see through cloud cover and its gaze also has some ability to penetrate soil. The name Lacrosse is used to refer to all of these orbital spycraft, while there is another name, Onyx, which is sometimes used to refer to the three newer units. Five Lacrosse spacecraft have been launched, and three were in orbit as of 2015. The existence of the Lacrosse terrestrial radar imaging reconnaissance satellites, operated by the US National Reconnaissance Office (NRO), was not officially confirmed for a long time, its existence was declassified only in 2008.

Lacrosse - is now variously called Vega and Onyx. It is in its third and fourth generation IE once designed to fly on shuttle then Titan-4A and 4B but now EELV which involved some structural design changes for launch support of its composite graphite epoxies pipe structures of the spacecraft more easily accomplished than on the Advanced Crystal, Misty revisions. NRO is the lead design detail specification control office while Lockheed Martin is the lead on this spacecraft systems integration. The spacecraft is about 14-14.5 feet in diameter inside its 66 foot long Titan-4shroud with a solar wing span on the order of 150 feet. Its design length of about 42.5 feet and it weighs in at 31,972 lbs mass with a five year plus design life.


Despite its many advances, the ADVANCED CRYSTAL suffers the shortcoming common to all photographic intelligence satellite, the inability to see through clouds. With much of the Soviet Union and other areas of interest frequently covered with clouds, this has always posed a problem for intelligence collection. However, in the past, this problem was primarily one of directing the satellite's coverage toward cloud-free areas, and awaiting improved visibility in cloudy regions. While this procedure may have been adequate for peace-time operations, it is clearly inadequate for war-time target acquisition.


Radar Imaging Spacecraft Launches

LV Vehicle Date   Life Apogee Perigee Incl.
STS-27 Lacrosse-1 2, Dec. 1988     426.28 408.26 57.0
T-4A Lacrosse-2 8, March 1991 USA-69   420.00 417.58 68.0
T-4A Lacrosse-3 24 Oct. 1997 USA-133        
T-4A Lacrosse-4 17 Aug. 2000 USA-152        
T-4B Lacrosse-5 USA-182          

Delta-4 heavy EELV


LACROSSE / ONYX Spacecraft Design

LACROSS was originally designed to be flown on shuttle and used a larger composite graphite epoxy frame with STS-27 Shuttle Trunnion attachment points for the payload bay. Later when LACROSSE was transferred to the Titan-4A booster it had the outer Shuttle support composite graphite epoxy frame cut down eliminating the STS Shuttle adaptation. This is the configuration that has been displayed by the NRO and Lockheed Martin Inc. The initial design for LACROSSE apparently used a deployable white gold open mesh imaging radar antenna with phased array feed. At some point the single semi circular dish was replaced by two white gold semi ellipsoidal open mesh dishes. The radiators are aligned across the top of the Lacrosse spacecraft to shed heat from the instruments and power systems. Subsequent designs may have added a deployable upper rear radiator panel series. The initial solar arrays design had a total span of about 150 feet The 150 foot solar arrays (Ref. AW&ST, 12/12/88 p. 26, 9/30/96 p.34, Ref. The New York Times, 12/13/1988, p.C9) may be Lockheed produced (Ref. Lockheed Missile & Space Company Solar Arrays –Fact sheets 10-85) but also appear to be Hughes 601 class panels based on open Hughes or TRW (Ref. TRW Inc. Photovoltaic Solar Arrays 1991, TRW Inc. Photovoltaic Solar Arrays 1997) solar array vendor documents. It also apparently carries one TDRS up down link communication dish for data management and perhaps one direct down link dish. It carries other mission packages for passive store dump SIGINT and its related COMINT in all probability along with other navigation and thermal control systems, CGM’s, attitude control. The spacecraft of course carries multiple earth, horizon and sun sensors of Lockheed also based on vendor documents (Ref. Lockheed Missile & Space Company Fact Sheet, Earth/Horizon Sensors1-90) and communications antenna of either Harris or like the TDRS, TRW dish perhaps for satellite to satellite and up, down links. Lacrosse is a nuclear war, laser, and battle hardened spacecraft to the extent possible. The spacecraft carries in addition one auxiliary earth imaging IR payload instrument of some kind also in addition to its Harris Corp. (Air Force Magazine, Aerospace World, 3/1986, p. 28) primary gimbals mounted imaging phased array radar deployable dish which is resistant to interference. The open mesh dish was designed to prevent earth or space based interference of its imaging radar that is not possible with flat plate imaging radars.

 ONYX Generational Design Changes Based on Ground Based Imagery Suggestion

 Though the initial earth based images of the ONYX spacecraft in orbit, by John Locker [john@satcom.freeserve.co.uk], are not absolutely clear they are clear enough to pick up on some new features not seen before in this series of spacecraft. The spacecraft radiators on more recent models may have been revised into a single array extending out the top back of the spacecraft at about a 45 degree angle. The solar array on more recent models may have been revised into two solar arrays shortened with the ends of the array have fold out array giving a dumb bill cross section ional appearance. The spacecraft may now use two SAR radar array dishes made of white gold meshes instead of the original one white gold mesh array dish.


A typical radar (Radio Detection and Ranging) measures the strength and round-trip time of the microwave signals that are emitted by a radar antenna and reflected off a distant surface or object. The radar antenna alternately transmits and receives pulses at particular microwave wavelengths (in the range 1 cm to 1 m, which corresponds to a frequency range of about 300 MHz to 30 GHz) and polarizations (waves polarized in a single vertical or horizontal plane).

For an imaging radar system, about 1500 high-power pulses per second are transmitted toward the target or imaging area, with each pulse having a pulse duration (pulse width) of typically 10-50 microseconds (us). The pulse normally covers a small band of frequencies, centered on the frequency selected for the radar. At the Earth's surface, the energy in the radar pulse is scattered in all directions, with some reflected back toward the antenna. This backscatter returns to the radar as a weaker radar echo and is received by the antenna in a specific polarization (horizontal or vertical, not necessarily the same as the transmitted pulse). Given that the radar pulse travels at the speed of light, it is relatively straightforward to use the measured time for the roundtrip of a particular pulse to calculate the distance or range to the reflecting object.

The chosen pulse bandwidth determines the resolution in the range (cross-track) direction. Higher bandwidth means finer resolution in this dimension. The length of the radar antenna determines the resolution in the azimuth (along-track) direction of the image: the longer the antenna, the finer the resolution in this dimension.

Synthetic Aperture Radar (SAR) refers to a technique used to synthesize a very long antenna by combining signals (echoes) received by the radar as it moves along its flight track. Aperture means the opening used to collect the reflected energy that is used to form an image. In the case of a camera, this would be the shutter opening; for radar it is the antenna. A synthetic aperture is constructed by moving a real aperture or antenna through a series of positions along the flight track.

As the radar moves, a pulse is transmitted at each position; the return echoes pass through the receiver and are recorded in an 'echo store.' Because the radar is moving relative to the ground, the returned echoes are Doppler-shifted (negatively as the radar approaches a target; positively as it moves away). Comparing the Doppler-shifted frequencies to a reference frequency allows many returned signals to be "focused" on a single point, effectively increasing the length of the antenna that is imaging that particular point. This focusing operation, commonly known as SAR processing, is now done digitally on fast computer systems. The trick in SAR processing is to correctly match the variation in Doppler frequency for each point in the image: this requires very precise knowledge of the relative motion between the platform and the imaged objects (which is the cause of the Doppler variation in the first place).

Synthetic aperture radar is now a mature technique used to generate radar images in which fine detail can be resolved. SARs provide unique capabilities as an imaging tool. Because they provide their own illumination (the radar pulses), they can image at any time of day or night, regardless of sun illumination. And because the radar wavelengths are much longer than those of visible or infrared light, SARs can also "see" through cloudy and dusty conditions that visible and infrared instruments cannot.

Radar images are composed of many dots, or picture elements. Each pixel (picture element) in the radar image represents the radar backscatter for that area on the ground: darker areas in the image represent low backscatter, brighter areas represent high backscatter. Bright features mean that a large fraction of the radar energy was reflected back to the radar, while dark features imply that very little energy was reflected.

Backscatter for a target area at a particular wavelength will vary for a variety of conditions: size of the scatterers in the target area, moisture content of the target area, polarization of the pulses, and observation angles. Backscatter will also differ when different wavelengths are used. Backscatter is also sensitive to the target's electrical properties, including water content. Wetter objects will appear bright, and drier targets will appear dark. The exception to this is a smooth body of water, which will act as a flat surface and reflect incoming pulses away from a target; these bodies will appear dark.

Backscatter will also vary depending on the use of different polarization. Some SARs can transmit pulses in either horizontal (H) or vertical (V) polarization and receive in either H or V, with the resultant combinations of HH (Horizontal transmit, Horizontal receive), VV, HV, or VH. Additionally, some SARs can measure the phase of the incoming pulse (one wavelength = 2pi in phase) and therefore measure the phase difference (in degrees) in the return of the HH and VV signals.

Track angle will affect backscatter from very linear features: urban areas, fences, rows of crops, ocean waves, fault lines. The angle of the radar wave at the Earth's surface (called the incidence angle) will also cause a variation in the backscatter: low incidence angles (perpendicular to the surface) will result in high backscatter; backscatter will decrease with increasing incidence angles.

A space-based imaging radar can see through clouds, and utilization of synthetic aperture radar (SAR) techniques can potentially provide images with a resolution that approaches that of photographic reconnaissance satellites. A project to develop such a satellite was initiated in late 1976 by then-Director of Central Intelligence George Bush. This effort led to the successful test of the Indigo prototype imaging radar satellite in January 1982. Although the decision to proceed with an operational system was very controversial, development of the Lacrosse system was approved in 1983.

The distinguishing features of the design of the Lacrosse satellite include a very large radar antenna, and solar panels to provide electrical power for the radar transmitter. Reportedly, the solar arrays have a wingspan of almost 50 meters, which suggests that the power available to the radar could be in the range of 10 to 20 kilowatts, as much as ten times greater than that of any previously flown space-based radar.

It is difficult to assess the resolution that could be achieved by this radar in the absence of more detailed design information, but in principle the resolution might be expected to be better than one meter. While this is far short of the 10 centimeter resolution achievable with photographic means, it would certainly be adequate for the identification and tracking of major military units such as tanks or missile transporter vehicles. However, this high resolution would come at the expense of broad coverage, and would be achievable over an area of only a few tens of kilometers square. Thus the Lacrosse probably utilizes a variety of radar scanning modes, some providing high resolution images of small areas, and other modes offering lower resolution images of areas several hundred kilometers square. The processing of this data would require extensive computational power, requiring the transmission to ground stations of potentially several hundred mega-bits of data per second.

Lacrosse 1 (1988-106B 19671) USA 69 was launched on 2 December 1988 by the STS-27 Space Shuttle mission. The spacecraft entered an orbit with an inclination of 57 degrees, with an perigee of 680 kilometers and an apogee of 690 kilometers, and had not maneuvered significantly since launch.

Lacrosse 2 (1991- A) USA 133 was launched from Vandenberg AFB CA on a Titan-4 on 08 March 1991 . Through mid-2005 Lacrossee-2 was thirteen years old, still in orbit, and apparently still at least somewhat functional. It made a small orbit adjustment maneuver in March 2005.

Lacrosse 3 (1997- A) USA 152 was launched from Vandenberg AFB CA on a Titan-4 in the Fall of 1997, replacing Lacrosse 1.

The standard Lacrosse constellation consists of two satellites, one in a 57 deg inclination orbit; the other in a 68 deg orbit. USA 133 and USA 152 are still fairly young compared to their predecessors; however, the statistical sample is tiny. USA 69 continued in orbit, apparently in an extended mission, following the launch of USA 152. The Lacrosse’s seem to be living up to the Aviation Week and Space Technology report of 1988 Nov 07, pg. 25, that "the technology involved is highly advanced, involving a multitude of sensors designed for an especially long life." Though the sample is small, the first two Lacrosse’s do seem to have achieved fairly long lives.

What is Imaging Radar ?

by Tony Freeman, Jet Propulsion Laboratory An imaging radar works very like a flash camera in that it provides its own light to illuminate an area on the ground and take a snapshot picture, but at radio wavelengths. The length of the radar antenna determines the resolution in the azimuth (along-track) direction of the image: the longer the antenna, the finer the resolution in this dimension. Synthetic Aperture Radar (SAR) refers to a technique used to synthesize a very long antenna by combining signals (echoes) received by the radar as it moves along its flight track. Aperture means the opening used to collect the reflected energy that is used to form an image. In the case of a camera, this would be the shutter opening; for radar it is the antenna. A synthetic aperture is constructed by moving a real aperture or antenna through a series of positions along the flight track.

Launch Cost

 Titan-4A Launch cost ($100-$150 Million, old estimate mid 1990’s), $350 - $450 million per booster-satellite (Ref. FAA - (Ref. AIAA, International Reference Guide To Space Launch Systems 1999, p. 449)), IUS stage for the DSP satellite $432 million verses Centaur stage for the SIGINT satellites $433 million combination each for Titan-4A, 4B. (Ref. AIAA, International Reference Guide To Space Launch Systems, 1999, p. 450) ($361 – million for Titan-3B booster with no upper stage (Ref. AW&ST, May 31, 1999, pp. 34-35.) for the Advanced Crystal, Misty-Follow-on Advanced Crystal and Lacrosse/Onyx radar satellites (Ref. AW&ST, May 31, 1999, pp. 34-35.).


 According to AW&ST, (Original Lacrosse spacecraft cost $500 million plus (Ref. AW&ST, 12/12/88 p. 26, 9/30/96 p.34,) lacrosse cost on the order of $700 - 750 million to over $1 billion plus each spacecraft (AW&ST, 9/1/97 p. 22, 03/30/98, p. 18) and the total launch cost of about ($1,400,000,000.00 - $1,461,000,000.00 billion on Titan-4B, $1,202,000,000 billion on EELV) for booster and spacecraft (and $361 – million for Titan-3B booster with no upper stage) for the Advanced Crystal launch and Lacrosse/Onyx radar satellites, and EELV cost about $102 million.


 Lacrosse-5 launched on the last Titan-4B launched from CCAFS, cost $411 million plus (Ref. SpaceflightNow.com April 7, 2005 launched 04-29-05) indicating that the cost of Lacrosse-5 is perhaps $1,000,000,000.00 - $1,051,000,000.00 billion total including $361 million dollars for the Titan-4B launch for a total cost of $1,411,000.000.00 billion dollars or $411 million for the launch plus $1,000,000,000.00 - $1,051,000,000.00 billion for the satellite equals $1,411,000,000.00 - $1,462,000,000.00 total cost.



 Lockheed Martin was believed to be building the sixth Lacrosse radar imaging spacecraft in the series to bridge the gap between it and the Future Imagery Architecture radar spacecraft of Boeing believed to be more advanced in development possible nearing completion and flight testing. This and several other kinds of existing spacecraft are being built to bridge the FIA gap if scheduling development issues arise as they already have occurred. The FIA photo imagining systems have already had the photo imaging spacecraft prime contractor changed from Boeing to Lockheed Martin creating considerable delay in that program.

Former CIA analyst Allen Thomson has compiled and analyzed the shots captured by Russia’s Altay Optical Laser center somewhat between 2005 and 2010. “The [released] images contain enough information (range, angular scale) to perform a bit of technical intelligence (i.e., sophomore high school trigonometry) on the radar antenna size, which is a significant parameter affecting capability,” Thomson said. “The images themselves seem to be mostly just a curiosity,” he supposed. “But perhaps they underscore the growing visibility and the corresponding vulnerability of US space-based assets.” Thomson however supposed that it might be a way “to respond to our [their] space advantage”, citing Gil Klinger, a defense intelligence official, who testified at a 2014 House Armed Services Committee hearing on US national security space activities. Klinger then said that the US asymmetrical advantage in space "also creates asymmetrical vulnerabilities”.

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Page last modified: 03-07-2016 20:07:19 ZULU