Mars Polar Lander
Frequently Asked Questions

1. When will the lander land on Mars?
2. When will we get the first images?
3. Does the lander use airbags to land like the Mars Pathfinder?
4. Why doesn't the lander use airbags like Pathfinder?
5. Does the lander have a rover?
6. Why doesn't the lander have a rover?
7. Why is the lander going to the Martian south polar region?
8. What are volatiles?
9. Why is the lander going to the Martian south polar region instead of the north?
10. Will the lander be capable of detecting life?
11. Why doesn't the lander have instruments designed to detect life?
12. Will the lander contaminate Mars with life forms from Earth?
13. Has the lander's landing site been chosen?
14. Who decides where the lander will land?
15. What can we expect to see at the landing site?
16. How long will the landed mission last?
17. What determines the length of the landed mission?
18. What are the temperatures that can be expected at the landing site?
19. Is there a chance for an extended mission?

1. When will the lander land on Mars?
The lander will land on Dec 3, 1999 at 12:00 PM Pacific Standard Time (20:00 UTC).

2. When will we get the first images?
We expect to receive the first images from the lander's stereo camera as soon as one hour after landing. A partial panorama of the horizon should be available within a day after landing.

3. Does the lander use airbags to land like the Mars Pathfinder?
No. The lander uses hydrazine thrusters to slow the vehicle's descent during the final 1400 meters above the surface to achieve a soft landing.

4. Why doesn't the lander use airbags like Pathfinder?
The Mars Polar Lander was designed before Mars Pathdinfer's airbag landing system was successfully demonstrated. The MPL landing system is derived from the landing system used by the two Viking landers, which landed successfully on Mars in 1976.

5. Does the lander have a rover?
No.

6. Why doesn't the lander have a rover?
The MVACS integrated payload that NASA selected for MPL lander did not include a rover. Using a rover like the Sojourner rover on Mars Pathfinder for this mission was out of the question because:
(a) The total mass allocated to the lander's integrated payload was 20 kg. For comparison, the total mass of the Sojourner Rover plus its lander-mounted support equipment was over 16 kg. Of this mass, only 0.74 kg was devoted to the Alpha-Proton X-Ray Spectrometer, the rover's only science instrument.
(b) The total cost of the MPL integrated payload was capped at $20 million. The total cost of reflying a copy of the Sojourner rover, as is planned by the Mars Surveyor Program '01 lander mission is comparable.
(c) The scientific goals of the MVACS payload were better served by a robotic arm, whose total mass is approximately 5 kg.

7. Why is the lander going to the Martian south polar region?
The purpose of the MPL mission is to study Mars volatiles and climate. The Martian polar regions are the best places to conduct these studies because the colder conditions at high latitudes increase the probability that the lander will be able to come into contact with volatiles and geologic units such as the polar layered deposits which may contain records of past climate variations on Mars.

8. What are volatiles?
Volatiles are substances that tend to be liquids or gases at room temperature (25 °C). The principal volatiles on Mars are water and carbon dioxide. These volatiles and their dynamic behavior and history are one of the main reasons why Mars is an interesting place to study. They are also an important resource which could be utilized by future human inhabitants.

9. Why is the lander going to the Martian south polar region instead of the north?
The trajectory that will be employed by MPL places a number of constraints on entry geometry which can only be met by a south polar landing for this launch opportunity.

10. Will the lander be capable of detecting life?
No. The lander has no instruments designed to search for living organisms.

11. Why doesn't the lander have instruments designed to detect life?
The Mars polar lander one in a series of Mars Surveyor program missions designed to learn more about Mars' Climate, Resources and Life. The specific scientific focus of this mission is Mars volatiles and climate. Instruments dedicated to searching for life on Mars were part of the scientific payload of the two Viking landers. Future Mars Surveyor Program missions will focus on bringing Martian rock samples back to Earth, which will be analyzed for evidence of past biologic activity.

12. Will the lander contaminate Mars with life forms from Earth?
This is very unlikely. All US space missions are required to meet planetary protection standards, and these standards are particularly stringent for Mars. As a Mars lander with no life detection experiments, the Mars Polar Lander is categorized as a Category IV A mission. This requires that the spacecraft has to be assembled in a class 100,000 clean room, and that contamination control effectiveness must be monitored and demonstrated by periodic microbiological assays.

The spacecraft carried fewer hardy spores at launch than the number of bacteria that might be found in a large glass of water, and many of these will die before the Lander reaches Mars. The planetary protection approach also takes into account the extreme dryness, oxidizing soil, and lower atmospheric pressure of Mars, which will limit any growth by terrestrial organisms. The Mars Polar Lander project has completed the Planetary Protection Plan for the mission detailing how the requirements will be met.

13. Has the lander's landing site been chosen?
Yes. On August 25, NASA held a press conference announcing the final selection for the landing site. The landing site is located at 76S, 195W, and is on the "polar layered deposits" which may have been created by Mars' changing climate. Images from the Mars Orbiter Camera (MOC) and topographic data from the Mars Orbiter Laser Altimeter (MOLA), both aboard the Mars Global Surveyor spacecraft currently at Mars, assisted the team in locating the landing site.

14. Who decides where the lander will land?
NASA Headquarters made the final decision based on inputs from the Mars Surveyor Operations Project and independent assessments from the scientific and engineering communities.

15. What can we expect to see at the landing site?
We are not completely sure. The geologic setting of the MPL landing region in the polar layered deposits quite different from that of the Viking and Pathfinder landers. At scales of 10 km, the available orbiter images of the landing region indicate the presence of smooth topographic undulations which may be visible on the horizon. At 10-meter spatial scales, the available images suggest areas which appear to have etched grooves. Thermal mapping data suggest that the presence of fine-grained dusty material at the surface, with few surface rocks. At this point, anything beyond this is pure speculation.

16. How long will the landed mission last?
The landed mission is scheduled to last for 87 Earth days.

17. What determines the length of the landed mission?
The duration of the landed mission is determined by the lander's ability to function in the changing Martian environment. As on Earth, the Martian polar regions experience significant seasonal variations in environmental conditions. When the lander arrives at Mars during the late southern spring season, the sun will be above the horizon throughout the day. As the southern summer season progresses, the sun will get lower and lower on the horizon, resulting in decreased power output by the lander's solar arrays. Air temperatures get progressively colder as the fall season approaches, requiring the lander use more of its energy to keep warm. As the mission progresses, the lander will spend more and more of its time in its energy-conserving "sleep" mode. Eventually, it will reach the point where it will not have enough energy to collect data or communicate, and the mission will effectively be over.

18. What are the temperatures that can be expected at the landing site?
During peak summer, maximum daily surface temperatures are expected to be -5 °C and minimum daily surface temperatures are expected to be -60 °C. Near the end of the mission, maximum daily surface temperatures are expected to be -30 °C and minimum daily surface temperatures are expected to be -90 °C.

19. Is there a chance for an extended mission?
At the end of the scheduled mission, the lander will be frozen in place for more than one Earth year during the cold and dark southern polar night season. The vehicle was not designed to survive the Martian winter. However, if all goes well, there is a slim chance that the lander will be able to bring itself back to life during the Martian southern spring season in 2001.

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