One element of the ISTD program is Warfighter -1. In the fall of 1995, Phillips Laboratory completed its mission concept definition of a broad-area coverage, Hyperspectral Imager (HSI) demonstration, to support resolution AFSPC mission area deficiencies. Prior to this, the Laboratory also finalized a memorandum of agreement with NASA to use a Multispectral Imager (MSI) to be flown on NASA's Clark spacecraft. Clark would transmit imaging data to a mobile ground station. Phillips Laboratory procured through NASA this specially equipped satellite communications van from Wolf Coach, headquarters in Auburn, Massachusetts, in late 1995. The purpose of this space demonstration is to determine the feasibility of MSI data when downlinked to a commercially oriented mobile van.
Launch Vehicle: OSC Taurus
Satellite Weight: 360 kg
Scheduled Launch Date: Mid FY00
Hyperspectral Payload Lifetime: 3 Yr Life/ 5 Yr Goal
Sensor Characteristics:
Hyperspectral Focal Plane Characteristics
Array Array Band Operating Size Type Spacing Temp
Vis 40 x 640 Si 11.4nm 257 K NIR 80 x 640 HgCdTe 11.4nm 257 K SWIR 80 x 640 HgCdTe 11.4nm 195 K MWIR 80 x 640 HgCdTe 25 nm 90 K
Hyperpectral Band Characteristics
Band Wavelength Range (µm) #Bands
Vis 0.45-0.905 40 NIR 0.83-1.74 80 SWIR 1.58-2.49 80 MWIR 3.00-5.00 80
Commercial Band Characteristics
Pan 0.45-0.675 1 MS1 0.485±.007 1 MS2 0.565±.007 1 MS3 0.660±.008 1 MS4 0.830±.009 1
One of several focused, small satellite missions under development by NASA's
Mission to Planet Earth enterprise, Lewis featured remote-sensing instruments
designed to split up the spectrum of light energy reflected by Earth's land sur-
faces into as many as 384 distinct bands. In addition, Lewis carried the Ultra-
violet Cosmic Background astrophysics instrument built by the University of
California at Berkeley. The satellite was built by TRW Space & Electronics
Group, Redondo Beach, CA, for launch aboard a Lockheed Martin Launch Vehicle,
under NASA's Small Spacecraft Technology Initiative.
Outfitted with advanced technology Earth-imaging instruments and subsystems in-
tended to push the state-of-the-art in scientific and commercial remote sensing,
NASA's Lewis satellite was launched from Vandenberg Air Force
Base, CA. at 11:51 PM PDT (0651 UT) on 23 August 1997 [schedule slipped from late 1996]. The planned orbit was a circular 523 km Sun-synchronous, 97.4 degree inclination, 10:30 AM equator ascending with a 7 day revisit interval. The spacecraft entered a flat spin in
orbit that resulted in a loss of solar power and a fatal battery
discharge. Contact with the spacecraft was lost on Aug. 26, and it then
re- entered the atmosphere and was destroyed on Sept. 28. Lewis failed last fall due to a
combination of a technically flawed attitude-control system design and
inadequate monitoring of the spacecraft during its crucial early
operations phase
The primary payload on Lewis consisted of two complementary hyperspectral imaging
radiometers. The 384-band Hyperspectral Imager instrument built by TRW covers
the spectral range from .4 microns to 2.5 microns. It was based on a convention-
al airborne spectroradiometer design integrated with new advanced technology
components, making it the first high-resolution hyperspectral imager to be flown
in space. The Hyperspectral Imager could resolve objects on the ground as small as
16 feet (five meters) in its panchromatic band and 100 feet (30 meters) in its
hyperspectral bands.
The companion hyperspectral instrument on Lewis was called the Linear Etalon
Imaging Spectral Array. Built by NASA's Goddard Space Flight Center, Greenbelt,
MD, it could "see" the Earth in 256 bands with 1,000-foot (300-meter) resolution,
in the spectral region from 1.0 to 2.5 microns. The Array's fundamentally new
technology provided data in the same spectral bands as the Hyperspectral Imager
while offering "factors-of-ten" reductions in size, cost and design complexity.
The Hyperspectral Imager and the Linear Etalon Imaging Spectral Array accomplish theoretically equivalent measurements using different approaches. The
Imager takes a snapshot of a narrow "one-dimensional" stripe of the Earth and
separates the incoming optical signal into its component spectral bands for a
concurrent spectral observation. It then uses the motion of the spacecraft over
its ground track to build up the spatial image through successive snapshots.
Conversely, the new approach enabled by the Array technology involves a "two-
dimensional" snapshot of 256 adjacent stripes of the image, with each stripe
viewed in a different spectral band. Using the motion of the spacecraft over
the ground track, the Linear Etalon Imaging Spectral Array then takes 256 successive snapshots, thus building up the complete spectral signature of each of
the image stripes.
SSTI Characteristics
| Size: | 59 in. hex x 80 in. |
| Weight: | 385.6 kg (850 lbs) |
| Electrical Power: | 370 W |
| Attitude Control: | 3-axis stabilized; zero momentum bias |
| Propulsion: | Eight 1-lbf hydrazine thrusters |
| Telemetry: | S-band (GSTDN-compatible) |
| Instruments: 178.86 lbs (81.3 kg) |
|
| Technology Demonstrations (partial list): |
|
| Launch Vehicle: | LMLV-1 |
| Operational Orbit: | 523 km, sun synchronous (282.7 nm) |
| Design Life: | 3 years (minimum); 5 years (goal) |
| Reliability: | 0.83 at 5 years |
Originally scheduled for mid-1996, Clark's schedule soon slipped to no sooner than late 1997, and then to March 1998. Problems with availability of Lockheed Martin's new Athena rocket pushed the launch date back until August 1998. In December 1997 an independent advisory team from Goddard recommended that Clark be terminated, since the delay and associated costs probably would push the program above the 15% cost-growth threshold for termination. In February 1998 NASA terminated the Clark Earth science mission due to mission costs, launch schedule delays, and concerns over the on-orbit capabilities the mission might provide. NASA had invested approximately $55 million in Clark. The Agency expects to recover some assets of the mission, such as some spacecraft payloads, components and subsystems which may be used on other NASA projects.
Its primary sensors included panchromatic 3-meter resolution, multispectral 3 bands 15-meter resolution, Off Nadir capability. The key to this was a Mobile Ground Station to real time downlink the imagery in theater. The LLV-1 version of the Lockheed Launch Vehicle family would have launched the 633-pound satellite satellite from Space Launch Complex-6 at Vandenberg Air Force Base, CA, into in a 318-mile, Sun-synchronous, 97.4-degree near-polar orbit.
The Clark spacecraft contract was awarded to CTA, Inc., Rockville, MD, under a $51 million contract for NASA's new Small Spacecraft Technology Initiative. Subcontractors include EarthWatch, providing a 3-meter panchromatic and 15-meter
resolution sensor with appropriate SSR data storage, and Lockheed-Martin, supplying additional subsystems. Odetics is supplying the 160-Mb/s flight-model solid-state
recorder (SSR) to EarthWatch Incorporated for the Clark Mission. The EarthWatch flight-model SSR has a capacity of 16 Gb, weighs less than 12 pounds, and consumes
only 13 watts of power during simultaneous recording and playback. CTA won the original contract for Clark, but ran into problems on the program before it sold out to Orbital , and those problems continued under the new management.
SCHEDULED LAUNCH DATE
CANCELLED February 1998
DATA AVAILABILITY
60 Days After Launch
DATA ACCESS
Stennis Space Center Mission Data Management Center via the Internet
INSTRUMENTS
206.58 lb. (93.9 kg)
SPACECRAFT BUS (DRY) 377.52 lbs (171.6 kg)
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Maintained by Robert Sherman
Originally created by John Pike
Updated Thursday, January 14, 1999 10:22:14 AM