Mars Polar Lander
Mars Polar Lander — a NASA lander launched on 3 January 1999 to set down on the layered terrain near the south pole of Mars, record its weather, and dig into the soil for water ice and other volatiles. Its last signal came on 3 December 1999 as it turned to enter the atmosphere, and it was never heard from again. The review board traced the probable cause to its software, which took the jolt of the landing legs unfolding for touchdown and shut the engines off about 40 m above the ground. It has never been found. (It is drawn at its target landing site, 76° S, 165° E.)
Key facts
Mission & specifications
Mission
- Operator
- NASA / JPL
- Launched
- January 3, 1999
- Status
- Lost
Trajectory
- Distance from the Sun
- 1.58 AU
- Computed from the cached position
- Distance from Earth
- 1.53 AU
- Computed from cached positions
- Distance from Mars
- 1,125,151 km
- Computed from cached positions
Mission
Mars Polar Lander, built by Lockheed Martin Astronautics, was the lander of NASA's Mars Surveyor '98. It was launched on a Delta II 7425 from Cape Canaveral on 3 January 1999 at 20:21 UTC, carrying the two Deep Space 2 probes on its cruise stage. It was to land on the layered terrain near the south pole of Mars, at 76° S, 195° W (165° E), record the weather, dig trenches with a robotic arm, and analyse the soil for water, carbon dioxide and other volatiles. On 3 December 1999 its last signal arrived at 20:02 UTC as it turned to its entry attitude; its landing signal was expected on Earth at about 20:14 UTC. Nothing was heard, and the search went on until 17 January 2000. Faint signals picked up by Stanford University's radio dish were later traced to the receiver itself. NASA's Special Review Board found the probable cause to be the software's vulnerability to transient signals: the jolt of the landing legs unfolding could be read as touchdown, and the descent engines would then shut down about 40 m above the ground, so that it struck at about 22 m/s. With no telemetry from the descent, the board said other failures cannot positively be ruled out. In May 2005 the team running Mars Global Surveyor's camera published a possible sighting of the lander and its parachute; after new images, on 17 October 2005 it published "Mars Polar Lander NOT Found": the parachute was the lit slope of a small hill and the lander a noisy pixel. Later searches with Mars Reconnaissance Orbiter's HiRISE camera have found nothing either.
- 1999Mars Polar Lander launches toward Mars on a Delta II rocketLaunch
With the two Deep Space 2 probes on its cruise stage.
Its last signal comes as it turns to enter the atmosphere; it has never been found.
Images
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