Mars Polar Lander

 1999-001A

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The MS 1998 Lander (Mars Polar Lander) is built by Lockheed Martin Astronautics and was launched on 1999 Jan 3 by Delta 7425. It was to land near the south pole at 195W 76S.

in Dec 1999. (the ice-free safe zone is 170 to 230W, 75 to 76S). It is 1.0m wide and 0.5m high. The aeroshell is based on the MPF aeroshell, but the lander uses a Viking-type rocket descent system. Attached to the aeroshell is a cruise stage with solar panels. The lander uses solar arrays for power, and will terminate operations as the winter begins. The Lander has four 22N REM engines used during cruise, using the same 64 kg hydrazine propellant tanks as the descent engines.

Aeroshell ejection is followed by propulsive terminal descent. The MARDI imager, mounted on the lander underside, operates during descent. The SSI imager, used on the surface, is similar to the MPF lander's.

Landing near the south pole is during local spring. MPL will dig a trench and collect soil samples for analysis. It will search for near surface ice and look for evidence of climatic changes: however,nothing was heard from the lander after scheduled Cruise Stage separation. A review board suggested the most likely cause was a design flaw in a touchdown sensor causing the engines to shut of at 40m altitude and impact at 55 kph; however, when the successor Phoenix mission was being ground-tested, it was discovered that the Cruise separation itself probably did not occur. A design error exposed critical parts of the separation system to excessively low temperatures which would have stopped them working. The aeroshell entered the atmosphere with the cruise stage still attached, and the spacecraft was probably destroyed and burnt up during entry.

Estimated impact location was 76.1S 195.3W.

Planned B-plane miss at injection (+60000,-20000) km. Mass injected: 583 kg, with PAM-D 2141 kg full 132 kg empty. 1997 planned injection data: 11.165 km2/s2, RLA DLA =235.35, 0.92. Arival data at 125 km: 143.37 -62.57 az 173.69, fpa -13.25, V 6.91, for landing at 210,-76.

MPL
Date	Time	Event	Orbit
1999 Jan 3	2021:10	Launch Delta 7425	CC LC17B
		T+4:24 MECO
		T+4:32 Stage 1 sep
		T+4:37 Stage 2 burn
		T+4:42 Fairing sep
	2032:32	T+11:22 SECO-1	157 x 246 x 28.4
	2055:21	T+34:11 Stage 2 restart
	2055:40	T+34:30 SECO-2	237 x 770 x 28.4
	2056:33	T+35:23 Stage 2 sep
	2057:10	T+36:00 Stage 3 burn
	2058:38	T+37:28 TECO 293 km 11.434 km/s	0.97 x 1.45 AU
		T+42:10 Yo-yo deploy
	2103:25	T+42:15 Stage 3 sep	185 x -84447 x 28.43
		Deploy solar panels
1999 Jan 4	0543	Pass EL1:4
1999 Jan 8	1548?	Exit Earth sphere 1.5Mkm
1999 Jan 21	1227	TCM-1, 3min 16m/s
1999 Mar 16	1305	TCM-2, 10s, 0.9m/s
1999 Sep 1	1700s	TCM-3, site adjust 2.3m/s
1999 Oct 30	1728	TCM-4 site adjust 12s
1999 Nov 30	1800	TCM-5 0.1m/s 3.5 Mkm from Mars
1999 Dec 1	0615	Enter Mars sphere
1999 Dec 2	0000?	PAM-D enter Mars sphere
1999 Dec 3	1339	TCM-6, 8s
1999 Dec 3		Mars arrival OWLT = 14m
	1949	Transmitter off
		E-7h TCM-5 at 125000 km
	1951:00	E-5min L-10 min Cruise stage sep
	1951:18	DS2 sep
	1955	DS2 entry
	1956	E-0 L-5 Entry 6.91 km/s, 125 km, -13.1 deg
		E+0:33 Hypersonic ops begin
	1958	E+2:30 Parachute deploy 7.3 km
		E+2:37 MARDI imaging begins
		E+2:37 Aeroshell sep
		E+2:39 Landing legs deployed
		E+2:40 Landing radar on
		E+4:00 Radar lock, 2.5 km
	2000	E+4:00 Backshell sep 1.8 km
		E+4:01 Landing engines on
1999 Dec 3	1959	DS2 impact
	2001	Landing
	2000	PAM-D pass at 63000 km
1999 Dec 5	1600?	PAM-D leave Mars sphere
2000 Feb 29		End primary mission

Payload:

• MARDI Mars Descent Imager

• LIDAR Lidar (light detection and ranging) for dust and aerosols, IKI/RKA

• MVACS Mars Volatile and Climate Surveyor

  • SSI Stereo surface imager

  • RA Robotic arm (2m)

  • RAC Robotic arm camera

  • TEGA Thermal and evolved gas analyzer

  • MET Meteorological package