UPDATE # 24 - March 13, 1997
PART 1: Upcoming WebChats
PART 2: Get Out and Observe Mars
PART 3: Headbone Derby Contest
PART 4: "Saturday" Means Nothing to a Spacecraft
PART 5: Pathfinder Mission Status
PART 6: Global Surveyor Flight Status
PART 7: Subscribing & Unsubscribing: How to
- Wednesday, March 19, from 10-11 a.m., PDT, Pieter Kallemeyn, Jet
Propulsion Laboratory, Pasadena, CA
- Tuesday, March 25, from 9-10 a.m., PDT, Ted Roush, Ames Research
Center, Moffett Field, CA
PIETER KALLEMEYN is one of three navigators for the Mars
Pathfinder, the 900-kg unmanned spacecraft whose final destination
is more than 150 million miles away. Pieter and the other navigators
are responsible for determining where the spacecraft is, predicting
where it will go in the near future, and determining the means to
correct the path in order for it to reach the surface of Mars.
TED ROUSH is a planetary scientist who studies the composition of
solid surfaces throughout the solar system. He is interested in the
minerals and rock types found on the surfaces of rocky bodies and
the various ices found on the surfaces of icy bodies. His work
includes telescopic and spacecraft observations, laboratory work
and computer calculations. He use telescopes located on Earth and on
spacecraft to measure the sunlight that is reflected from the
surfaces of objects in the solar system.
Read more about Pieter and Ted by going to their biographies at:
Please join us! RSVP to Andrea by sending a brief Email note to
email@example.com. This RSVP is very important, as it will
allow us to ensure that the chatroom does not become too crowded.
GET OUT AND OBSERVE MARS!
March is a great month for viewing Mars. For information on: how to
observe; using the Mars map; and locating albedo features, polar caps
and clouds go to http://www.skypub.com/whatsup/mars97.html
To see the latest telescopic images of Mars go to the Marswatch
archive page at: http://mpfwww.jpl.nasa.gov/mpf/marswatch_images.html
Most of the folks observing Mars through their telescopes are
reporting that there is a lot of cloud activity around the high peaks
and that the north polar cap is shrinking as summer comes to the
northern hemisphere. A few localized dust storms have been spotted
by observers and the Hubble Space Telescope (HST).
HST has been photographing the red planet from September '96
through January '97. Color composites of the images can be seen at:
HEADBONE DERBY CONTEST
The Headbone Derby is a fun, effective curricular tool designed to
help teachers and students use the World Wide Web constructively.
In particular, the Headbone Derby teaches children how to locate
information on the Web by using effective techniques and tools. The
derby is designed for teams of 4th - 8th graders, though previous
derbies have been played with great success by kids all the way
from 1st through 12th grades.
The derby first engages kids by presenting them with an entertaining
story in comic-strip form. At the end of each episode, players are
tasked to find a specific piece of information, and are given the
tools and support to find this information by searching the Web.
(Players are welcome to use conventional sources such as
dictionaries and encyclopedias as well.)
Beyond helping with research skills, the derby meets many
curricular requirements by exercising kids' reading comprehension
skills and expanding their knowledge of various subject areas. In the
spring derby "Mystery on Mars," students will learn about astronomy,
geography, geology, history, mathematics and general science.
Furthermore, the puzzles are varied in nature to employ verbal,
visual and analytical styles of thinking.
The story line for "Mystery on Mars" takes place on the planet Mars.
Fourteen-year-old sci-fi heroine Isabelle LeGrande and her sidekick,
Augustus T. Robot, have traveled to the red planet for a much-needed
vacation. No sooner do they arrive when Auggie finds all his data on
Mars erased from his built-in hard drive. Who could be behind this?
Is some other form of life lurking nearby?
Kids will have to dig up critical information about Mars to further
the plot and resolve the mystery of life on Mars. In the process they
will peruse a wide range of educational Web sites including
university astronomy sites, museums, history sites and NASA.
Participation in the derby is free. The contest runs from March 16
until May 21 and you can register and participate anytime up to the
end. Prizes will be awarded May 23 and include a laptop computer for
the teacher of the winning team..
Get involved by webbing over to http://derby.headbone.com
"SATURDAY" MEANS NOTHING TO A SPACECRAFT
by David Mittman
[Editor's note: David is a flight engineer on the Mars Pathfinder
project. His expertise is in planning the spacecraft's activities and
in sending commands to the spacecraft. These two areas are known
as mission planning and flight control. David works at the Jet
Propulsion Laboratory (JPL) in Pasadena, California.]
Saturday, February 22, 1997
08:30 PST -- It's Saturday morning and I've just kissed the wife and
kids good-bye for the morning. It's off to work! Today I get to do the
flight controller part of my job. I haven't had flight control duty for
about three weeks now because we are no longer tracking Mars
Pathfinder 24 hours a day. Since the spacecraft is behaving so well,
we no longer need to monitor it around the clock. So, although
Saturday duty is not great, at least I get to work during the daylight
hours. During around-the-clock monitoring, we all had some pretty
rough shifts, for instance, 11:15 p.m. to 7:30 a.m. for four days in a
Today we expect to hear from the spacecraft that all is well. No one
has been listening to it since Thursday morning. If all is well, we
will command the spacecraft to perform what's called an HRS Pump
Cycle. Some explanation: There are two pumps that move freon (a
coolant similar to that used in household air-conditioners) through
the spacecraft, picking up heat inside the lander and dumping it
outside the cruise stage. Usually we only use one of the pumps.
To make sure the second, or backup pump remains in good working
condition we are required to periodically switch it on for an hour.
After turning on the second pump, the thermal control analysts
watch the temperatures inside the lander for a small but noticeable
drop...about one degree Celsius. If the temperature drops and the
power analysts report that the pump is drawing the right amount of
power, then we can assume that the pump is in good working order.
The backup pump is then turned off until the next pump cycle
activity or until the first pump fails.
As flight controller, I have to be at the JPL Mars Pathfinder Project
Operations Control Center before everyone else in order to set up the
communications link with the spacecraft. Actually, what I really do
is tell the engineers at the Deep Space Network (DSN) some key
information and they make sure that the antennas are set up
properly. Today's tracking pass will use the 34-meter antenna at
Madrid, Spain. If there is a problem with the communications link, I
can help them figure it out. If there seem to be no problems with
either the spacecraft or the DSN antennas, then the JPL staff get to
go home and leave the communications link unattended for the rest
of the eight-hour shift. If a problem occurs, we'll all get paged and
have to come back to work. I'm glad about unattended operations
today because tomorrow is my son's fourth birthday party and I have
to go home to help set up the house.
12:00 PST -- Well, everything went very nicely and the JPL staff is
going to an unattended operations mode. I'll secure our spacecraft
commanding workstation, make sure that the spacecraft data are
still flowing smoothly to our database here at JPL and go home!
Tuesday, March 4, 1997
22:00 PST -- It's 10 o'clock in the evening and I'm just getting in to
work to set up for another flight controller duty shift. There seems
to be a problem with our spacecraft command computer as I can't
communicate with another computer located one floor above me.
Wednesday, March 5, 1997
01:00 PST -- The 34-meter DSN antenna in Canberra, Australia is up
and running, sending information about Mars Pathfinder's health to
JPL. At JPL, however, the problems continue. It's after midnight
(now it's Wednesday morning), and not only can't I send commands to
the spacecraft, I can't see the data that are coming our way from
Australia. The data seem to make it to our data control center
upstairs, but I'm not seeing it. It looks like we have a broken
connection of some kind between our project control room and the
data control room one floor up. Since this kind of problem is not my
area of expertise, I'll wake up some of our computer network experts
to help diagnose the problem.
02:00 PST -- Well I've awakened two of my coworkers at home and
we've found the problem. A computer device called a "router" has
died, taking out our communications link with our data control
center upstairs. Our network expert is coming in to fix the problem.
For now, there is nothing to do but go home and get some sleep. If
needed, we can always have our data control team replay the data to
us at a later time.
PATHFINDER MISSION STATUS
The spacecraft is currently about 37 million kilometers from Earth
and continues to function as expected. The total travel distance
covered since launch is 248 million kilometers, which means that
the spacecraft has reached the halfway point to Mars. A set of Entry,
Descent, and Landing communications tests were started this week
using the spacecraft and the Deep Space Network Galileo Telemetry
recorders at Goldstone. These tests are meant to simulate the open
loop strategy that we intend to use during entry to record
significant events. The first test was successfully completed on
March 3, and three additional tests will be performed during the next
The project completed Surface Operational Readiness Test #3 on
March 7-8. This test was the first formal operations test after
launch and was designed to test the nominal Sol 1 and 2 sequences.
Although there were a few start-up problems, the test was
generally successful. All elements of the project worked well
together to complete the critical Sol 1 operations and replan Sol 2.
The Rover Operations Team performed remote field testing on
Monday and Tuesday. With the SIM Rover at Amboy Crater, the
Operations Team ran four Martian sol sequences from JPL. The
sequences included navigation and traverse activities, and science
and technology experiments. The Pathfinder Science Team also
participated in the testing.
GLOBAL SURVEYOR FLIGHT STATUS
[Editor's note: This status report was prepared by the Office of the
Flight Operations Manager, Mars Surveyor Operations Project, NASA
Jet Propulsion Laboratory.]
Friday, 7 March 1997
On Monday, the onboard command sequence controlling Surveyor
executed a test called the "Solar Array Feather." During the several-
hour test, the solar arrays were rotated back and forth several
times in a similar fashion to the motion that a person makes when
rotating the wrist joint.
This activity was performed for the benefit of the Magnetometer
science team. The test simulated the rotation of the solar arrays
that will occur as the arrays automatically track the Sun during
Mars mapping operations. Because the Magnetometer sensors sit at
the end of the solar arrays, the data collected from the test will
allow the science team to determine the effect of the solar array
rotation on the quality of their data.
On Tuesday, the flight team loaded new parameters to Surveyor's
attitude control software. These parameters deal with the
performance of the star scanner that controls the spacecraft's
ability to point at targets in space. With this parameter update, the
spacecraft will be able to point its science instruments at objects
with better accuracy than previously possible.
Later on Tuesday, the Ka-band communications team accomplished a
major milestone in their experiment. Over a several hour time
period, an antenna at the Goldstone tracking station recorded data
transmitted simultaneously from Surveyor's X-band and Ka-band
transmitters. Normally, the spacecraft utilizes the 25-Watt, X-band
transmitter for communicating with the Earth. The main difference
between the two signals is that the 1-Watt, Ka-band transmitter
operates at a frequency near 32 gigaHertz versus 8 gigaHertz for X-
An analysis of the experiment indicated that no disagreements
existed between the X-band and Ka-band data for all 12 million data
bits observed on Tuesday. This positive result marks the first
verified data transmission by an interplanetary spacecraft using a
Ka-band signal. The result affirms a long-held belief that the use of
Ka-band signals can allow a spacecraft to transmit information at
faster data rates with transmitters that consume much less power.
After a mission-elapsed time of 120 days from launch, Surveyor is
36.46 million kilometers from the Earth, 76.39 million kilometers
from Mars, and is moving in an orbit around the Sun with a velocity
of 27.23 kilometers per second. This orbit will intercept Mars on
September 12, 1997. The spacecraft is currently executing the C5
command sequence and all systems continue to be in excellent
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