Lewis

 1997-044A

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Lewis, built by TRW for NASA's SSTI (Small Spacecraft Technology Initiative) was one of the first Earth remote sensing satellites with combined high spatial and spectral resolution, having 384 spectral channels and a 30-m ground resolution in the 0.4 to 2.5 micron wavelength band. The panchromatic camera had 5-m resolution. The satellite was built by TRW/Redondo Beach and operated by TRW/Chantilly, VA, with NASA HQ having a minimal management oversight role and NASA-Stennis involved in data distribution. Mass is 403 kg full (194 kg bus, 81 kg instrument, 12 kg fuel, 116 kg u/k). Uses LEOStar/STEP bus. Size is a 1.50m hexagon 2.0m tall. The satellite was named after Meriwether Lewis (1774-1809), the American explorer. A companion satellite, Clark, was cancelled in 1998.

After delays caused partly by the failure of the first LMLV, Lewis was launched on 1997 Aug 23 into a 300 km parking orbit. Planned final orbit was 523 x 523 x 97.4. However, three days after launch the attitude control system malfunctioned, using up most of the fuel and leaving the spacecraft's solar panels pointing away from the Sun with the bus spinning at 2 revs per minute. The craft rapidly lost power and fell silent. The investigation determined that a badly designed safemode was initially to blame. A processor switch during launch was the first anomaly, and a solid state recorder failure prevented playback of launch data, complicating interpretation; and the operations team failed to declare a spacecraft emergency and call up additional resources when problems began.

The requalified LMLV was built by LMA/Denver instead of LMSC/Sunnyvale. The payload fairing is 3.9m x 2.0m. Although described as a 2-stage rocket, LMLV-1 really has three stages. Stage 2 cuts out at 190 km altitude and 900 km downrange; the OAM third stage burns from then until 320 km altitude and 12000 km downrange, imparting 620 kNs of impulse and 0.3 km/s of velocity. The LMLV OAM, built by Primex Aerospace and LMA, reached orbit with the satellite.

Lewis
Date	Time	Event	Orbit
1997 Aug 23	0651:01	Launch by LMLV-1	V SLC6
	0652:30	T+1:29 Castor 120 MECO
	0653:26	T+2:25 PLF sep
	0653:31	T+2:30 Orbus 21D burn
	0656:05	T+5:04 Orbus 21D MECO	-340 x 200 x 97?
			-760? x 220? x 97
	0656:06	T+5:05 OAM ignition 16:41
	0712:47	T+21:46 OAM shutdown
	0722:05	T+31:04 OAM sep
			293 x 305 x 97
		B-side processor in control
	1730	SSR telemetry loss
1997 Aug 25	1417	Loss of Earth lock attitude
	1700?	Attitude restored on command in safe mode
	2100	Ops team off duty
1997 Aug 26	0802	Ops team reacquire
	0805	Spacecraft in flat spin
	1017	Commanded thruster firing
	1100?	loss of power
1997 Sep 28	0930		87.53 145 x 159 x 97.53
	1030		87.16 124 x 143 x 97.55
	1129	Reentered

Payload:

• HSI Hyperspectral imager: 30-m resolution, plus 5-m panchromatic band

• UCB Ultraviolet Cosmic Background, Diffuse EUV cosmic background radiometer, UCB

• LEISA Linear Etalon Imaging Spectral Array 256 channel spectrometer, GSFC