The two probes were to be separated from the cruise stage of the Mars Polar Lander by mechanical pyros. The probes had no active control or propulsion systems, but they were designed to passively orient themselves during free fall with the forebody front forward. On impact, the aeroshell would shatter, and the forebody would separate from the aft body and would penetrate to 0.3 to 1 meter below the surface depending on the surface material. The impacts were planned to occur about 15 to 20 seconds before the Mars Polar Lander touchdown on December 3. Light travel time from Mars at that point was approximately 14 minutes. However, no signals were received from the probes after landing or over the following days. The reason for the probes' failure is not known.

After landing commands would be sent from Earth via the MGS, soil experiments would begin in which the small drill would be deployed. The drill would bring approximately 0.1 gram of sample into the water experiment sample cup inside the forebody, where it was to be examined for the presence of ice. The sample would then be heated and measurements would be made of the amount of water vapor released at each stage. The temperature sensor in the forebody was designed to measure thermal properties of the Martian soil. A Sun detector on the aft body was to be used to verify that the aft body remained on the surface after landing. Data would be stored onboard and would then be transmitted to the Mars Global Surveyor spacecraft and relayed to Earth. The total cost of development of the Deep Space 2 probes was $29.2 million.

Questions to think about:

• These were the first drill probes to be sent to Mars. NASA even sent two to be redundant! What plan might you have for replicating this experiment on a future mission?
• Think of three possible causes for the loss of these spacecraft combined with or independent of the Mars Polar Lander.
• What do you think were the most important lessons to come out of the loss of the Mars Climate Orbiter, Mars Polar Lander and the Deep Space 2 missions?

Future Missions: Introduction