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UPDATE # 7 - November 2, 1996

PART 1: Correction on Mars atmosphere
PART 2: Upcoming WebChat with Bob Haberle
PART 3: Challenge Question #2: Unimpressive canyon
PART 4: Challenge Question #3: Moons of Mars
PART 5: A Mars rover in the backyard
PART 6: Software to draw the ground means some weird hours


CORRECTION ON MARS ATMOSPHERE

In Challenge Question #1, we mistakenly wrote:
"Mars' atmospheric pressure is estimated at 0.005% that of Earth's."

In fact, the correct number to use is 0.6% (we slipped a few decimal
places). Fortunately, Donna Shirley caught the mistake and let us know. If
you don't recognize Donna's name, you should. She is the leader for the
overall Mars Program at the Jet Propulsion Laboratory (JPL). So if anybody
knows the correct number, it is Donna. My apologies for the error.



UPCOMING WEBCHAT WITH BOB HABERLE
Bob Haberle is a Mars atmosphere scientist who works on Mars Global
Surveyor. His job is to analyze the data that comes back from the
spacecraft and to try to develop models that match this data. Also, NASA
asks Bob to work on future spacecraft.

Bob will be available in the Live From Mars chatroom this coming Tuesday,
November 5 from 9-10AM Pacific (noon-1PM Eastern).

To virtually meet Bob, point your Web browser to
http://quest.arc.nasa.gov/mars/events/interact.html
and follow the links
to the chat room for experts. If you plan to participate in this event,
please RSVP to Andrea by sending a brief email note to
andream@quest.arc.nasa.gov.
This RSVP is very important, since it will allow us to ensure that the
chatroom does not become too crowded.

To best prepare, please have your students read Bob's biography before the
WebChat session. It is at 
http://quest.arc.nasa.gov/mars/team/haberle.html

      
      
CHALLENGE QUESTION #2: UNIMPRESSIVE CANYON

Last week we asked:
The Valles Marineris is much larger and deeper than the Grand Canyon in
Arizona. Yet, if you stood at the rim of the Valles Marineris, it probably
wouldn't seem as impressive to the eye. Why?

ANSWER from Bill Gutsch:
While the Valles Marineris is big, deep and wide, Mars is a much smaller
planet than Earth. This means that on Mars, the horizon curves out of the
way much closer to you than it does on Earth. The result is that
differences in surface feature elevations are not as impressive. On Earth,
for example, you can stand at the North or South Rim of the Grand Canyon
and see the whole breath of the canyon -- all the way over to the opposite
rim. In places, however, the Valles Marineris is over 100 miles from rim
to rim. This is so great compared with Mars' tiny size that if you stood
on one rim of the Valles Marineris, you wouldn't be able to see the other
rim because it would be out of sight over the horizon ! So therefore, it
wouldn't seem as impressive to the eye.

A listing of the students who submitted answers to this Challenge Question
will appear on the LFM Web site shortly.


CHALLENGE QUESTION #3: MOONS OF MARS

Here is a new puzzler for this week:

Mars has two moons: Deimos and Phobos. If you stood on the surface of Mars
and looked up into the night sky, you would see Deimos slowly travel from
east to west across the sky while Phobos would be slowly traveling from
west to east. In other words, the two Martian moons travel in opposite
directions across the Martian sky. Yet both moons actually orbit Mars in
the same direction.

Explain this apparent paradox.

You are invited to send original student answers to us. We will list the
names of these folks online and token prizes will be given out to a small
number of the students with the best answers. Send your answers to Jan Wee
at jwee@mail.arc.nasa.gov. Please include the words "CHALLENGE
QUESTION" in the subject of the email.


[Editor's note: Mansel is a chemistry teacher at Tuba City High School in Arizona. NASA is testing a Mars rover near his school. Mansel is helping local students get plugged into the NASA activities.]

A MARS ROVER IN THE BACKYARD
Mansel Nelson

October 25, 1996
The Marsokhod rover is a six-wheeled robotic platform designed by Russian
scientists for exploring the surface of Mars. The Marsokhod is presently
on loan to NASA Ames to test the rover's capability to carry
out remote field science in a Mars-like terrain. The test site is on the
Navajo Reservation (near Tuba city) in northern Arizona, which provides a
diverse geological terrain that will challenge the rover's scientific
capabilities. The field test is being carried out under the supervision of
Navajo tribal leaders.

The test will be conducted using telepresence from NASA Ames in Mt.View,
CA . Telepresence means that the robot is controlled remotely; pictures of
what the rover sees are sent to NASA Ames, and engineers at NASA Ames
send back commands to the rover, telling it what to do. This simulates
what would happen if the rover were really on Mars.

Also, remote links will be established to more than a half-dozen schools
on
the Navajo Reservation. Classrooms will be directly linked to the rover by
satellite through the Ames Command Center. This will afford the
opportunity for students to command the rover, and to participate in the
analysis of data collected at the field site by the rover's science
instruments.
The demonstration will be conducted in so-called "lunar mode", which will
provide students an opportunity to drive the rover in real time using
computer command protocols. Enhanced color stereo imaging will provide
three-dimensional viewing of the terrain to achieve telepresence.

Imaging which also will be used to construct virtual terrain models in the
computer to use in planning autonomous traverses. "Autonomous" means
self-governing, so in this mode, the Marsokhod makes some decisions about
how to proceed on its own (through sophisticated computer programs). This
will help to simulate "Mars mode" operations which involve time delays in
sending and receiving command signals because of the great distance
separating the Earth and Mars. At Ames, student participants will also be
able to command the rover and help plan traverses to achieve science
objectives identified by the rover team.

Just to give you a flavor of the activities going on here in Tuba City, I
am including a calendar of events:

Oct 28-29, All Day - NASA Filming at the Rover Test Site
The Tuba City Unified School District filming crew will be allowed
on the test site.

Oct 29, 10:00 am to 1:00 pm - Dry Run Rover Control Activity
        Greyhills Academy High School (L122) - Gary Kmett / Steve
Showalter
        Monument Valley High School - Neil Browne
        Hopi High School - Phil Lair
        Shiprock High School - Rick Nussbaum
All sites are required to participate in the Dry Run in order to
maintain their position in the Rover Control activity. We will also
want to test communications, both email and voice. At the
Greyhills Tuba City site, representatives of all the schools using the
Greyhills Site are encouraged to participate in the dry run (1:00 pm).

31 Oct 96, 12:30 pm - Orientation to Rover test site
All student engineers and JROTC security will receive an orientation to
the Rover test.

31 Oct 96, 12:30 pm - Ames Headquarters Visit
One student from Greyhills Academy High School and one student from
Tuba City High School will travel to Ames Headquarters.

1 Nov 96, All Day - Media Day
The Tuba City Unified School District filming crew will be allowed on the
test site. NASA will be transmitting footage all day. Selected TCHS and
GAHS students will be on site. Two students from Tuba City will
participate in the Rover Control activity from the Ames Headquarters.

1 Nov 96, 10:00 am to 2:00 pm - Rover Control Activity
        Greyhills Academy High School (L122) - Gary Kmett / Steve
Showalter
        Monument Valley High School - Neil Browne
        Hopi High School - Phil Lair
        Shiprock High School - Rick Nussbaum
All sites must be ready 10 minutes prior to their assigned time or they
will lose their time slot. All lost time slots will revert to students at
the Greyhills Tuba City site for control.

etc, etc......

[Editor's note: the testing is scheduled through November 12. Mansel has
indicated that he'll keep us informed of what the NASA engineers are up
to]


[Editor's note: Geb Thomas is a software engineer who works on the Marsokhod rover described above. Geb's biography is not yet available online]

SOFTWARE TO DRAW THE GROUND MEANS SOME WEIRD HOURS
Geb Thomas

October 9, 1996
It's 5:00 a.m. I've come in early today to find out why my computer
program is not working.

The program compares the pictures from the two cameras on our mobile
robot and tries to figure out how far away everything is. People do
the same thing, they just might not realize it. Because their eyes
are on either side of their nose, each eye gets a slightly different
view of the world. Our brains compare the views to figure out how far
away everything is.

I need to fix this bug soon. (Bugs are errors in a computer program.
They are called that because when computers had lots of mechanical
parts, an insect could fall die inside the machine and make the
programs fail.) We are going to put this robot in the desert in a few
weeks and everything needs to be working.

Everyone on the team is working very hard. I know some people who prefer
to work late, instead of early like me, sometimes staying here until 2
a.m. In fact I've seen my boss getting ready to go home when I've come in
at 5. Everyone is excited to see if the projects they have been working on
for the last year will perform as expected. Many of these ideas have
never been tried before, others are new to the person who worked on them
for this project.

My job is to create computer graphics so the people at NASA will be able
to drive the robot in the desert. I will use my program to build a
computer model of the ground around the robot. The model will look like
a crinkled piece of paper. The robot's driver will be able to look at the
crinkled paper and decide which is the safest way to travel. I will use
the computer to paint the picture from the cameras onto the paper. This
will make it easier to tell the difference between rocks and sand hills.

Well, back to work.
Wish me luck.
Geb



      

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