Live From Mars was active July 1996-December 1997.

PART 1: Take the Challenge
PART 2: Join in Discovery Channel Chats
PART 3: "Cruising Between the Planets" Broadcast
PART 4: Launching the Planet Explorer Toolkit
PART 5: Team Journal: A Day in the Life of a Gravity Man
PART 6: Global Surveyor Flight Status
PART 7: Pathfinder Mission Status
PART 8: Subscribing & Unsubscribing: How to do it!


Last week, in CQ #2: WHO ARE THEY?, we asked:
In the 19th and 20th centuries two men with almost the same last
name created the exact same titles in two different media. Who
were these men and what did they write and produce?

In 1898 H.G. Wells wrote the 17-chapter novel "The War of the
Worlds." Forty years later, Orson Welles adapted the novel for radio
and on the night before Halloween in 1938, he starred in a radio
drama by the same name. This began the most stunning single
program ever broadcast on radio. It set off a wave of mass hysteria
as Welles described in breathless radio news bulletins and on-the-
scene reports that Martians had invaded New Jersey. Even though CBS
made four announcements during the radio show that it was "only a
play," may listeners did not year them. Panic swept through New
Jersey as people fled their homes and covered their faces with wet
handkerchiefs to protect themselves from the reported poison gases!

A list of answers from all students who submitted them will be
posted on the Live From Mars Web site soon.

With the exception of size, what is the major difference between
Earth and Mars? And, in what way are Earth and Mars most alike?

Bonus Question:
What do we mean when we say that "this feature" may make Earth
unique when compared to other planets (but maybe not the moons) in
our solar system?

You are invited to send original student answers to: Please include the words CHALLENGE
QUESTION in the subject line of your email. The kids' names will be
listed online and token prizes will be given to those will the best

Answers are due within seven full days of Challenge Question
posting. (e.g. If a CQ is posted on April 4, answers are due by
midnight PST on April 11.)


Join Discovery Channel School and NASA's K-12 Quest Project for an
exciting week of WebChats with NASA experts!

During the week of April 7 -11, everyday there will be a two-hour
chat from 11 am-1 pm Pacific and 2-4 pm Eastern.

Topics of the chats will include:
Monday - Today's Missions to Mars
Tuesday - Planning Space Missions
Wednesday - Looking for Life in Space
Thursday - Exploring the Solar System
Friday - Human Survival in Space

Each day, two or three different scientists will share their
experiences and knowledge about these topics.

To join the chats go to:
For curriculum support materials for these programs, see:


April 24: Live From Mars Program 2 "Cruising Between the Planets"
Broadcast live at 13:00-14:00 EST

Join a first-hand account of behind-the-scenes activities at NASA's
Jet Propulsion Laboratory in Pasadena, Calif., the lead center for
planetary exploration. You will see how rocket fuel, momentum,
gravity and ingenuity blast spacecraft from Earth to Mars. Up-to-
date reports on Pathfinder's and Global Surveyor's progress will be
given and you will be meet the men and women who control the
missions and who build and test robots.

A full overview of "Cruising Between the Planets" is available at the
Live From Mars Web site at:

If you are participating in the Launch Phase of the Live From Mars
Planet Explorer Toolkit activity, this notice is for you! The Planetary
Data Input (PDI) Web-based form is now available for classes who
have collected their data and are ready to input/post the
information. The form allows you to conveniently input your data and
submit it via the LFM Web site at:

Even though many classes will be conducting their data collection
during the upcoming week or so, it is not too late to participate!

For more information about the Planet Explorer Toolkit activity, see
the full overview at:
Select "Featured Events," where you will find the Planet Explorer
Toolkit link.


A Day in the Life of a Gravity Man
by Bill Sjogren

[Editor's note: Bill is a senior research scientist at NASA's Jet
Propulsion Laboratory (JPL) in Pasadena, California. His specialty is
determining gravity fields of planetary bodies. Presently, he is the
principal investigator on the Mars Global Surveyor (MGS) Mission for
the gravity experiment.]

March 17, 1997

Today was a very busy day. If you could have spent the day with me,
here is a list of some of the things we would have done together:

1. Evaluated Doppler and ranging data coming from the Surveyor
spacecraft (now in cruise phase), so the data during the orbiting
phase will be high quality for gravity parameter extraction.

Radio tracking of the MGS is done at a frequency of 8,400,000,000
cycles per second. A shift in this frequency is a measure of the
spacecraft speed. It's like a train whistle: When the train is coming
fast toward you, its whistle will have a high pitch; when it is going
away from you, it will have a low pitch. We can measure the speed of
the MGS spacecraft to better than one inch per hour (that's slower
than a snail crawl!) when its moving at a speed of 5400 miles/hour
on its way to Mars.

Presently the spacecraft is rolling around the line toward Earth so
as to keep its attitude correct using its star sensors. However, it is
not precisely rolling about this line for we can see in the radio
tracking data that it is off by 8 millimeters. This must be corrected
by the time we go into orbit about Mars for this effect will greatly
degrade our gravity field determination. I'm in constant
communication with the spacecraft team in Colorado to reduce this
effect and send them plots of the data as evidence that they have a
problem. There is also a problem at the Deep Space Tracking station
in Australia. The ranging data are not being calibrated correctly,
which causes the trajectory computation to be in error and again
this will have its effect on our gravity reduction.

2. Interviewed a new candidate to help program our H.P.
supercomputer, where we will be estimating, simultaneously,
approximately 6000 unknowns with Doppler radio tracking data.

Interviewing candidates for a job takes a lot of time. This is the
procedure I must follow:
- examine college grades (must have a Masters or Doctoral degree)
- review course work
- talk to references and professors
- speak with candidate to see if this person is a good match for the
- fill out all kinds of paperwork that JPL requires
- get signatures for approval from higher management

Following this process takes months to bring someone new onboard!

3. Made viewgraphs for a presentation to MGS Project on a low orbit
that will produce high-resolution gravity observations and new
scientific results.

The best gravity-field observations are obtained when the
spacecraft is at low altitudes. This is because gravity is a direct
measure of acceleration on a particle at a particular location from
it. So the closer the spacecraft is to Mars, the better the variations
in gravity are sensed. Gravity variations tell us something about the
internal (and also surface) mass distribution. Denser materials
beneath the surface will show more gravity, while craters on the
surface will show less gravity.

Immediately after aerobraking the nominal plan is to circularize the
spacecraft's orbit to 400 kilometer altitude. My suggestion to the
MGS Project is to not go to 400 kilometers, but go down to 200
kilometers for two weeks and then go up to 400 kilometers for the
mapping mission. I must convince the project that we will have
excellent science results and that the risks are worth the payoff and
would not cause the mission to fail.


[Editor's note: This status report was prepared by the Office of the
Flight Operations Manager, Mars Surveyor Operations Project, NASA
Jet Propulsion Laboratory.]

March 28, 1997

No major activities occurred onboard the Mars Global Surveyor
spacecraft this week. Meanwhile, at the Jet Propulsion Laboratory in
Pasadena, Surveyor's navigation team has completed their
preliminary assessment of the trajectory correction maneuver that
took place on March 20. This short firing of the spacecraft's main
rocket engine resulted in a velocity change of 3.875 meters per
second and refined Surveyor's flight path to Mars.

Initial analysis provided by the navigation team indicates that the
spacecraft performed the maneuver with an accuracy of greater than
99%. Consequently, the spacecraft is now on a flight path that will
come within 630 kilometers of the Martian surface at the point of
closest approach on September 12. Additional trajectory correction
maneuvers scheduled for April 21 and August 25 will reduce this
approach altitude to 500 and 380 kilometers, respectively.

After a mission-elapsed time of 141 days from launch, Surveyor is
54.12 million kilometers from the Earth, 58..29 million kilometers
from Mars, and is moving in an orbit around the Sun with a velocity
of 25.82 kilometers per second. This orbit will intercept Mars on
September 12, 1997. The spacecraft is currently executing the C6
command sequence, and all systems continue to be in excellent


[Editor's note: This status report was prepared by the Office of the
Flight Operations Manager, Mars Pathfinder Mission, NASA Jet
Propulsion Laboratory.]

March 28, 1997

The spacecraft remains in good health and is currently about 55
million kilometers from Earth. The most significant spacecraft
activity performed this week was to turn the spacecraft to a 5-
degree Earth leading attitude. Regular attitude turns will be required
for the remainder of cruise to keep the spacecraft pointed within 5
degrees of Earth. The propulsion and attitude control subsystems
functioned flawlessly after a seven-week hiatus.

Successfully completed a set of sun recognition tests using the
Prototype IMP at the University of Arizona. These tests have boosted
our confidence that we can successfully perform sun search and
point the High Gain Antenna after landing.

An IMP Science Team meeting was held at the University of Arizona
on March 25, 26. The sequence changes for Sols 1 and 2 were
reviewed. The mission plan for sols 3-5 was discussed and a
scenario for the imaging observations was adopted. Discussions of
image processing plans and data distribution were held and a number
of contentious issues were resolved.


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