[Live from Earth and Mars]

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Jim Tillman
Pathfinder Mission Operations
Jet Propulsion Laboratory
Pasadena Calif.

Updated Saturday, Oct 4, 1997
Events in reverse chronological order

Mission Status, Sol 93, 8 October "The Mars Pathfinder operations team reestablished communications with the lander on Sol 92 of the mission, after four days of silence from the spacecraft. The team received a transmission from the spacecraft's main transmitter. The signal was detected using the Madrid, Spain 34-meter antenna."

"No data was received, but receipt of a spacecraft signal indicates that the lander is operational and the battery is off- line. Meanwhile, the rover, which is programmed to begin a contingency sequence when it has not heard from the lander for five days, started that activity on Sol 90. In this mode of operation, the rover is instructed to return to the lander and begin circling it."

"The Mars Pathfinder operations team will repeat commands tomorrow night, on Sol 93, to verify two-way communications with the lander's main transmitter and attempt to return engineering data on the health of the lander and rover. If successful, that information would be returned the following day, on Sol 94 of the mission."

Operational problems; Sept 27 through Oct 3, Sol 90: Since Sept. 27, no data have been received due to operational problems. However, short transmissions of a carrier, (a signal from the transmitter, without and information modulating the carrier) have been received in response to project engineering staff efforts. It is thought that the initial problem was caused by battery failure during night time operations, an expected event. (Since Sol 30, the remaining capacity of the battery has been carefully allocated to obtain night time meteorology and other measurements.) These efforts are reported on the Pathfinder home page .

Autumn: 13 September, Sol 70 on Mars is the equivalent season to autumn on Earth. On Mars, the seasons are identified in degrees of aerocentric longitude, Ls, ranging from 0° to 360°. Spring is Ls= 0°, Summer Ls= 90°, Autumn, Ls= 180°, and Winter, Ls=270°(or 0°). After mid autumn, (Ls 210°), similar to Earth, weather fronts become stronger, as described in the section on atmospheric pressure. By clicking on the Viking Atmospheric Pressure plot, this seasonally increasing frontal activity is seen easiest at the high latitude, VL2, site where it is strongest, but also can be observed at the VL1 low latitides, in clear years when data are available. During dusty years like the first VL1 year, the frontal activity is suppressed, while in clearer years 2 and 3, they are seen as occassional blue or green "spikes" until winter. The missing data of years 2 and 3, make it impossible to clearly describe the buildup of Martian frontal activity at low latitudes during fall. However, the general season to season variability in the northern hemisphere is similar to Earth's, due to the similar inclination of their axes of rotation.

Tuesday August, 12, Sol 39 We are catching up on meteorology processing, which was interrupted by JPL data base problems, a change in the mode of operations that required major changes in our procedures, illness, and too much success. The large total data volume, complicated by data base problems, severely impacted our software and procedures, causing errors and excessive processing time. These have been alleviated by revising key components.

Between Sol 30 and 35 meteorology data collection has been revised in conjunction with the new mode of operation, dictated by battery preservation. The flight team used two Sols to carefully charge the battery, maximizing its remaining life. The science team decided to end almost all night operations except for meteorology every fifth Sol. On the other four Sols, the lander and computer are operated only on solar power, waking when there is adequate solar power, taking data during the day, and shutting down in the afternoon, after transmission of the Sols data. When it shuts down, all data in the RAM, primary, memory are lost. The afternoon cutoff time depends on the relative positions of Earth and Mars and the availability of an appropriate Deep Space Network station during the time the solar power is adequate to operate the computer, instruments, receiver and transmitter.

Because of these operational constraints, for four of every five Sols, data will only be acquired during morning and afternoon. Current plans are for meteorology to be acquired continuously every fifth Sol throughout the Sol. Sample intervals of 4, or at times, 1, second are used. The new operations no longer generate baseline data, so we had to modify our software and procedures to create baseline data from these longer data sets. This new, continuous sampling scenario has already resulted in capturing dust devil like structures; they have yet to be observed in the images.

Wednesday July 30, Sol 26. Data received over the past few Sols will be displayed, as soon as a software processing bug, related to the volume of data acquired, is resolved. They will be incorporated as soon as possible, along with a new display.

Friday, July 25; Sol 21. A complete Sols worth of data has been received and gaps in the past few Sols will be filled in as data on board the spacecraft are downlinked to Earth again.

Thursday, July 24; Sol 20. The past two downlink opportunities have not relayed all of the meteorology data that were taken and stored on the spacecraft due to communication problems between Earth and Mars, such as rainfall over the Canberra site. The missing data are stored on board and will be received in the next several Sols. A meteorology sequence is being prepared which will sample continuously throughout Sol 25, Tuesday 29 July, while Hubble is observing Mars.

Although Martian weather is similar to Earths, prior to direct observations is was considered simpler than Earths since it is too cold for liquid water, oceans, and the complex interactions between rain, snow, clouds and liquid water. Martian local and global dust storms introduce their own complexity and provide a laboratory for studying the effects of dust on atmospheric circulations. Looking at the daily temperature cycle, one might consider that the weather is dull and monotonous. Since this is slightly after mid summer in the sub tropics, and Martian weather somewhat resembles terrestrial weather, the repetitive diurnal temperature cycle is not surprising. Around early fall, the winds will increase and become much more variable during winter, unless there is a great dust storm; these storms begin in early fall in some but not other years. Finally, the weather is not always dull at this season since a global atmospheric oscillation mode was generally observed by Viking Lander 1 for 20 to 30 Sols centered on Pathfinders first Sol. This will be discussed in more detail in associated pages using the Viking atmospheric pressure observations.

Tuesday, July 22; Sol 18. Nominal communications resumed after the problems of the prior Sols. The software patch was completed, nominal full meteorology sampling restarted, and more frequent, longer sampling begun. Mission operations should become smoother as the single Sol, (and even hour to hour), activities and responses required to land and operate Sojourner in its initially unfamiliar environment, are replaced by operations planned over longer terms due greater knowledge of the environment and spacecraft operating parameters.

Wind socks and Meteorology Instrument observations are being compared. Especially interesting are Sojourner movies and the "Presidential" Panorama found at one of these sites. Dust is uniformly depositing on Sojourner's Materials Adherence experiment. and depositing on the Magnetics Experiment supported by the IMP camera.

Sunday, July 20; Sol 16. Most of the uplink and downlink communications with Pathfinder were lost, although it appears to be functioning normally from engineering data. The software patch was not completely uplinked and its status will be verified at the next opportunity.

Saturday, July 19; Sol 15. Communications problems caused the last half of this Sol's meteorology data not to be relayed to Earth this morning. The data are stored in memory on the spacecraft and expected to be relayed tomorrow. Data acquisition should return to nominal full coverage since the software patch to fix the computer resets is also scheduled to be uplinked and activated tomorrow.

Sols 3 through 6 produced almost complete meteorological sampling. Between Sol 7 and now, Sol 13, July 16, 1997, there have been several "lander computer resets". Testing in the engineering test bed July 15 and 16, generated resets due to an interaction between the meteorology sampling and the lander software. The problem has been found, fixed, and is undergoing testing. Revisions will be uplinked to the lander and it is anticipated that meteorological sampling will go from partial to full on Saturday. Until that time, meteorology sequences will not run during most of the daylight hours on Mars to preclude impacts on the other operations.

Sun evening, July 6; We are awaiting NASA's rescheduled press announcement by the meteorology team to release the new temperature data or 11 AM Monday, which ever occurs first.

The view is a geologists dream, with rocks of all sizes, large hills in the distance, tantalizingly too far for Sojourner, but a goal for a 2001 rover!

First meteorology data has been received and is being processed. Fri July 4 15:25:48 PDT 1997

Rover is nominal.

The rolling time might be compatible with light night time winds, which is consistent with flat terrain. Viking Lander 1 had readily observable "drainage winds" due to cool air sliding down the south west side of the Chryse Basin in the late night and early morning: these were first described by J. Tillman of the Viking Meteorology Science Team. Winds at the Pathfinder site should be less than at Lander 1, as calculated by Prof. Moti Segal, Iowa State using a Martian meso scale meteorological model.

Entry Descent and Landing Critical data:

Petals fully open
Air bags should be fully retracted by info from the motors.

Tilt is 2.35 Degrees
Solar array power is nominal.

The receiver has locked on signal, power is within 0.1 db of predicted!

Pathfinder is sitting on the surface of Mars, on its base petal, air bags retracted! about 11:35

We just passed the point where air bag retraction should have happened at 11:15. No signal has been received nor was one necessarily expected.

On July 4, Pathfinder sent a signal that it landed successfully on the surface of Mars. The air bag retraction and lander deployment will proceed and communication will resume later. This and the following key events, resulted in cheers, tears and hugs throughout Mission Operations.