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.
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
Tilt is 2.35 Degrees
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.
Radar detected ground all way after activating.
90 Meters from surface fall rate was 62 meters/sec
The deceleration of the first 3 bounces was:
First impact 18.7 G
The maximum atmospheric deceleration was 11.5 G
Second 9.1 G
Third 11.5G
It rolled 94 to 95 seconds
Air bags should be fully retracted by info from the motors.
Solar array power is nominal.