Weekly WebChats offer an opportunity for your students to virtually
meet the people on the front lines of the Mars exploration adventure.
Teachers have reported that the chats really enliven students'
enthusiasm. This week we feature the issue of life on Mars.

Wednesday, November 20 from 8-9 AM Pacific (11AM - noon Eastern)
Jack Farmer is an exobiologist, so he is interested in the search for
life outside of Earth. His background is in paleontology (fossils) and
geology (rocks).

To get in on this fun, point your Web browser to
http://passporttoknowledge.com/lfm/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 telling her which sessions you plan to
join. 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 the biography of
Jack before the WebChat session:
http://passporttoknowledge.com/lfm/team/farmer.html

CHALLENGE QUESTION #4: WINDSTORMS ON MARS

Recently we asked:
Sometimes, the winds on Mars can blow at hundreds of miles per
hour and kick up giant dust storms that blanket the entire planet.
Yet, if you stood on the surface of Mars at one of these times, you
would probably not be blown over.
Why?

ANSWER from Bill Gutsch:
Martian winds can be swift but the Martian air is so thin that it
packs very little punch. In more scientific terms, this means that
there wouldn't be nearly as many air molecules striking you per
second in a Martian wind storm as there would be in a similar
storm on Earth. Far fewer molecules translates into much less
pressure (force per square inch) pushing against your body. Such
"thin winds" can still create giant dust storms, however, because
the Martian surface dust is very, very fine and so can easily be
lifted into the Martian sky.

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

Last week we asked:
The largest crater on the larger of the two Martian moons, Phobos, is
named Stickney. Ms. Stickney was not an astronomer but she played a
critical role in the discovery of the Martian moons. Who was
Ms. Stickney and why did she have this prominent surface feature
named after her?

ANSWER from Bill Gutsch:
The two moons of Mars were discovered by astronomer Asaph
Hall at the US Naval Observatory in 1877. According to the story,
after many nights of searching for satellites that might be in
orbit around Mars, Hall was ready to give up. His wife, however,
encouraged him to give it "one more try." That night, Hall found
Deimos and Phobos, the two Martian moons. In honor of her
encouragement, without which Hall might not have made his
discovery, astronomers in the 1970s decided to name the largest
crater on Phobos "Stickney" -- Mrs. Hall's maiden name.

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

Here is our last puzzler:
The Mars Global Surveyor (MGS) took off in November and is
scheduled to arrive at Mars between Sept. 11 and Sept. 22, 1997.
The Mars Pathfinder (MPF) takes off sometime in December. No
matter when it leaves, it is scheduled to arrive on July 4, 1997.

Why does the Pathfinder get to Mars earlier, even though it leaves
later.

And how can the Pathfinder have an exact arrival date even though
its liftoff date may vary?

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.

Last week we announced an email service to answer student
questions about Mars and the missions there. See Updates message
LFM #9 or http://passporttoknowledge.com/lfm/ask/question.html for more details.

Many people are sending in good questions, and we are happy about
that. But many teachers are also demonstrating that they aren't too
good about following directions (a trait shared with students, me
and the rest of humanity). But please try extra hard in this case;
otherwise, the entire question-amswering system will bog down.

We requested:
   If you or your class have several questions which are unrelated,
   we ask that you please send each unrelated question in a separate
   email message rather than as one message with many different
   questions. While this may be inconvenient, it is important because
   it will help us to keep track of the questions and ensure that no
   question remains unanswered. Messages that do not follow this
   request will be unnecessarily delayed as we go through the extra
   step of splitting up the messages ourselves.

Instead of sending one email with these questions:
   Would it be possible to drill deep enough to find drinkable water
   on Mars?

   What do the scientists at NASA plan on doing with the life forms,
   if they find any?

   Does Mars have seasons like Earth?

Please send three separate emails with one question per message.

If you are sending so many questions that this becomes very
burdensome, consider doing more work in class to decide on the
most important questions and narrowing the number which you
send to NASA.

By now, most folks probably know that the Russian Mars-96 mission
ended in disaster. After a successful liftoff on Saturday, the booster
rocket on the fourth stage failed to ignite. This booster was to have
sent the Mars-96 spacecraft on its way towards Mars. Instead, the
spacecraft remained in an Earth orbit and tumbled into the Pacific
Ocean between Easter Island and the Chilean coast early Monday at
4:32 AM Moscow Time (Sunday in the US).

The responsible specialists are analyzing all available data in order
to define the reason for the failed insertion burn. They will share
this information as it becomes available.

This is very sad news indeed for everybody interested in
new discoveries about Mars.

More information about the failure is available:
http://cnn.com/TECH/9611/16/russia.mars.update/

[Editor's note: Guy Beutelschies is a test director for the Mars
Pathfinder project. He leads a team that tests the spacecraft to
make sure everything works. Here he describes his activities in September]

FIXING LITTLE PROBLEMS ON PATHFINDER AND MUD VOLLEYBALL
Guy Beutelschies - http://passporttoknowledge.com/lfm/team/beutelschies.html
Week of September 2, 1996
We finished up our tests on the equipment underneath the
thermal enclosure. One of the activities was to install a fresh
silver zinc battery. This was a potentially dangerous operation
because the battery is very powerful. If someone accidentally
touched the pins on the power connector, it would release
enough current to injure or even kill them. This is similar to
touching a live wire in your house without the protection of
fuses or circuit breakers. We also tested the telecommunications
equipment. This is used to receive commands and send down
data from the spacecraft after we launch. A bunch of us went
out on Friday night and ended up at a restaurant that had
Karaoke singing. If you've never heard a bunch of engineers
singing, you're lucky. We went water-skiing the next day.

Week of September 9
The mechanics put the thermal enclosure back on and mounted
the high-gain antenna and the camera on top of it. We then
started our tests to make sure that those devices work as
expected. The high-gain antenna actually moves to point at
Earth. We moved it through its entire range of motion to see if
it would hit any part of the lander. Turned out it did! One of the
engineers did not take into account how far a particular screw
head came out from a nearby bracket. The antenna would have
just grazed the top of the screw, which would have messed up
the pointing. We did a quick analysis on the screw and
determined that we could remove a small amount of material
from it without affecting how it holds the bracket in place. So
we got a file and filed down the screw just enough so the
antenna would not hit it.

Another test we did was to make sure that when we pointed the
camera and the antenna, they actually pointed to where we
specified. To do that we sent commands to point them in a
certain direction and then used a set of instruments called
theodolites. These are basically small telescopes that give very
accurate information about where they are pointed. They are
often used by surveyors that you see out on the city streets. We
pointed the theodolites at several points on the lander to
determine a reference coordinate system. We then pointed the
theodolites at several marks on the surface of the antenna,
which told us where the antenna was pointed relative to the rest
of the lander. We will use this information to make sure that the
antenna points at Earth when the lander is sitting on Mars.

We repeated this procedure on the camera so that we know
exactly where the camera is pointing relative to the commands
we gave it. This information will be used to determine where
objects (like rocks) inside an image are located in relation to the
lander. The rover people are very interested in this information
because they plan on using those pictures to tell the rover where
interesting rocks are located and how to get to them.

The mechanics then connected the petals to the lander. That
allowed us to run tests on the equipment located on the petals.
The first test was to shine light on the solar arrays to make sure
that they were hooked up correctly. We made sure that they
were indeed providing power to the rest of the lander. We then
put the opaque covers back on to make sure that the lander did
not turn on when we weren't expecting it.

Another test we ran was to verify the atmospheric structures
instrument mast. This mast lies flat against the petal on the way
to Mars and then pops up once we are on the surface. It has
temperature sensors to tell us what the temperature is at points
from right next to the ground up to about four feet above the
ground. It also has a wind sensor on the top of it to tell us wind
speed and direction. The atmospheric structures instrument also
has a pressure sensor located on the base petal. This will track
the pressure changes like a barometer to see how it changes
during the day.

We also verified that the radar altimeter was working correctly.
This device is used as we are descending through the
atmosphere to tell us when we are about to hit the ground. It
signals the airbags to inflate to cushion our landing.

Part of our week was taken up by hurricane preparations.
Hurricane Fran was heading right toward us so we made plans
to evacuate. The hurricane turned north and missed us at the
last minute.

That weekend, a couple of us played in a mud volleyball
tournament in a nearby town to benefit the March of Dimes.
They basically dug several pits and filled them with water,
which soon turned into mud. We didn't win.

Week of September 16
We were now ready to close the petals so that we can install the
airbags. Before we did this, we wanted to do a full inspection
to make sure that everything was ready. We even called down
experts from the Jet Propulsion Laboratory to help us. We all
went into the cleanroom and stood around the lander, looking at
each piece of it very closely. We found a few wires on the
bridle (which connects the lander to the backshell) were too
close to part of the lander structure. We were worried that
during launch these wires could be broken by rubbing against
that structure. This is bad because those wires carry the signal
to fire the retro-rockets, which slow us down right before we
hit the surface. We spent a couple of days rerouting those
wires.

We got to see a shuttle launch. It was at 4:00 in the morning so
we had to get up real early. It was worth it, though. The
ground rumbled and the sky lit up like it was day.

Several of us went on a charity 5K run for cancer research in
Orlando, which is about an hour from Kennedy Space Center.
It was raining so we didn't break any records. We also tried
surfing over the weekend. The waves were too weak for any
long rides but it was fun anyway.

Week of September 23
The mechanical team installed the airbags, which took most of
the week. All the electrical team had to do was to open and
close the petals whenever the mechanics asked. This gave us a
chance to test out the actuators used to move the petals, and the
airbag retraction actuators, which are used to pull the airbags
close to the lander after they are deflated.

We went on another 5K run, this time right at Kennedy Space
Center. The race was run right on the runway that the shuttle
lands on. Luckily, no shuttles landed during the race.

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