Mars Pathfinder Update - October 22, 1997

[Ron Baalke <BAALKE@kelvin.jpl.nasa.gov>]

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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