PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Mars Pathfinder Mission Status
October 22, 1997
      The Mars Pathfinder operations team is continuing its efforts to reestablish communications with the Pathfinder lander. Although they are experiencing communications difficulties, the team is confident that the spacecraft is still operating on the surface of Mars, according to Mission Manager Richard Cook. The last time they were able to send a command to the Pathfinder lander instructing it to transmit a signal back to Earth was on Sol 93, which was Tuesday, October 7, at 7:21 a.m. Pacific Daylight Time.

      Team members suspect that the spacecraft may not be receiving commands from Earth properly because the lander's hardware has become much colder than normal. In regular operations, when the lander's transmitter is turned on, spacecraft hardware warms up sufficiently to operate normally. Since the transmitter has not been on for several days, engineers suspect that temperatures within the lander are considerably colder than normal. Predicted internal temperatures drop to as low as -50 C (-58 F) in the early morning and only rise to about -30 C (-22 F) in the late afternoon. These temperatures are about 20 C (38 F) colder than the coldest previous operational temperatures.

      The lower temperatures cause the spacecraft radio hardware to operate outside the range of radio frequencies that ground controllers have used in the past. During the past three weeks the operations team has been transmitting to the spacecraft at a lower frequency and sweeping through a wider frequency range, a technique that has been used on other missions to attempt to cause the spacecraft receiver to lock on to the transmitted signal. Once ground controllers finish this, they send commands instructing the lander to turn on its transmitter and send a signal back to Earth.

      To be certain that they investigate all possibilities, team members are also consulting with experts knowledgeable about the radio and other key elements of the spacecraft. They have identified some new scenarios that are being pursued to regain communications. These recommendations include doing more testing of the engineering model hardware in the laboratory to better understand how the spacecraft might be behaving. Another recommendation has suggested shifting and increasing the range of frequencies being swept through much more than previously attempted.

      According to Project Manager Brian Muirhead, the possibility exists that an unrecoverable problem may have occurred. Team members expected that, once the lander's onboard battery died, cold and thermal cycling could result in a failure of some other element of Pathfinder and thereby end the mission. "However, the team will continue to do everything possible to reestablish communications until all options have been exhausted," Muirhead said. The mission has already exceeded all of its goals in terms of spacecraft lifetime and data return.

      The science team, meanwhile, continues to process and analyze the large volume of data sent back by Pathfinder's lander and rover. Further science products are planned and new results will continue to be presented as they develop.

      The team will continue its daily uplink sessions with Mars Pathfinder. Daily audio updates are available by calling (800) 391-6654.

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