Spacecraft lander on Mars.

Artist's concept of Mars Polar Lander on the surface of Mars. Credit: NASA/Jet Propulsion Laboratory-Caltech

Fast Facts: Mars Polar Lander / Deep Space 2

Mars Polar Lander and Deep Space 2 were to make the first in depth exploration of the carbon dioxide ice cap on the Martian south pole, but the lander and both Deep Space 2 impact probes were lost after an unsucccessful landing.

  • A mishap investigation found a sensor malfunction caused Polar Lander's engines to cut off too soon. All three probes crashed on the surface.
  • The Deep Space 2 probes were nicknamed Amundsen and Scott after the famed human explorers who led expeditions to Earth's South Pole.
  • The Phoenix lander, which arrived on Mars in 2008, eventually completed most of Mars Polar Lander's objectives.
Nation United States of America (USA)
Objective(s) Mars Landing
Spacecraft MPL / DS2
Spacecraft Mass 1,270 pounds total, including 639 pounds Lander (576 kilograms / 290 kilograms)
Mission Design and Management NASA / Jet Propulsion Laborary
Launch Vehicle Delta 7425-9.5 (no. D265)
Launch Date and Time Cape Canaveral Air Force Station, Fla. / Launch Complex 17B
Scientific Instruments 1. Stereo Surface Imager (SSI)
2. Robotic Arm (RA)
3. Meteorology Package (MET)
4. Thermal and Evolved has Analyzer (TEGA)
5. Robotic Arm Camera (RAC)
6. Mars Descent Imager (MARDI)
7. Light Detection and Ranging Instrument (LIDAR)
8. Mars Microphone

Key Dates

Jan. 3, 1999 | 20:21:10 UT: Launch

Dec. 3, 1999: Mars Arrival

Dec. 16, 1999: Missions Declared Lost


The Mars Polar Lander (MPL) was one of NASA’s Mars Surveyor missions that called for a series of small, low-cost spacecraft for sustained exploration of Mars.

MPL’s primary goal was to deploy a lander and two penetrators, known as Deep Space 2, on the surface of Mars to extend our knowledge of the planet’s past and present water resources.

The objective was to explore the never-before studied carbon dioxide ice cap, about 620 miles (1,000 kilometers) from the south pole. The mission also called for recording meteorological conditions, analyzing samples of polar deposits, and taking multispectral images.

MPL was to have performed its mission simultaneously with that of the Mars Climate Orbiter, which would have acted as a communications relay during its surface operations.

MPL itself comprised a bus section (for power, propulsion, and communications during the outbound voyage) and a 639-pound (290-kilogram) lander that was 3.5 feet (1.06 meters) tall.

The lander was equipped with a 6.6 foot-long (2 meter-long) remote arm to dig into the terrain and to investigate the properties of Martian soil (using the thermal and evolved gas analyzer).

The spacecraft was scheduled to arrive at Mars on Dec. 3, 1999, to enter the atmosphere, and then, about 10 minutes before landing, it was supposed to jettison its cruise stage and solar panels and then release the two Deep Space 2 microprobes, each weighing about 8 pounds (3.572 kilograms).

Unlike Mars Pathfinder, MPL was scheduled to make a completely controlled landing using retro-rockets all the way to the surface. Landing was scheduled for 21:03 UT Dec. 3, 1999, with two-way communications planned to begin 20 minutes later.

The two Deep Space 2 microprobes (renamed Amundsen and Scott on Nov. 15, 1999), meanwhile, would impact the ground at a speed of about 655 feet per second (200 meters per second) about 50–85 seconds before the lander and about 62 miles (100 kilometers) away.

Each penetrator was designed to obtain a small sample of subsurface soil using an electric drill for analysis. The microprobes’ mission was expected to last about 36 hours while the lander mission would continue until March 1, 2000.

Mars Polar Lander successfully left Earth on a Mars transfer trajectory Jan. 3, 1999. During its traverse to Mars, the spacecraft was stowed inside an aeroshell capsule. The vehicle approached Mars in early December in apparently good health.

Last contact with the vehicle was at 20:02 UT Dec. 3, 1999, as the spacecraft slewed to entry attitude. Traveling at about 4 miles per second (6.9 kilometers per second), the capsule entered the Martian atmosphere about eight minutes later.

Controllers expected to re-establish contact 24 minutes after landing (scheduled for 20:14 UT) but no signal was received.

With no communications for more than two weeks, on Dec. 16, 1999, NASA used the Mars Global Surveyor orbiting Mars to look for signs of the lander on the Martian surface, but the search proved fruitless. On Jan. 17, 2000, NASA finally terminated all attempts to establish contact with the lost lander.

An independent investigation into the failure, whose results were released publicly March 28, 2000, indicated that the most probable cause of the failure was the generation of spurious signals when the lander’s legs deployed during the descent. These signals falsely indicated that the spacecraft had touched down on Mars when in fact it was still descending. The main engines prematurely shut down, and the lander fell to the Martian surface.

The demise of MPL undoubtedly set back NASA’s Mars exploration program and also meant the effective end of NASA’s “Faster, Better, Cheaper” initiative for low-cost highly innovative missions.

The Phoenix lander, which arrived on Mars in 2008, subsequently accomplished most of the original Mars Polar Lander’s objectives.

MPL carried a CD-ROM with the names of 1 million children from around the world as part of the “Send Your Name to Mars” program formulated to foster interest in space exploration among young people.


Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.

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