BEHIND THE SCENES AT JPL

Over the next week, surrounding Pathfinder's landing on Mars, we
will bring you a series of special reports. These special reports will
provide a glimpse behind the scenes at the Jet Propulsion Lab as the
excitement of the Pathfinder mission unfolds.

Look for these stories in your email box via this updates-lfm list.
The first should be coming within a few hours. As well, the stories
will be available at the top of the Live From Mars web site
(http://passporttoknowledge.com/lfm); we hope that some of these
web issues will also be illustrated with pictures from JPL.

Stay tuned....it promises to be an eventful week for all of us.

LIVE TELEVISION PROGRAMS COMING

Don't forget that July 6 and July 9 bring two new Live From Mars
television broadcasts. Each show is two hours long (from 2:00 - 4:00
p.m., Eastern); the programs will originate from NASA JPL-Pasadena,CA,
the American Museum of Natural History-New York, and museums and
science centers around the country. More information can be found at
http://passporttoknowledge.com/lfm/teachers/tg/program3

The telecasts can be found on some local PBS stations and via
satellite. The remainder of this section will provide additional
details.

The easiest route to seeing the broadcast is likely to be via your
local PBS station. However, many stations will carry the programs
on tape delay or not at all. Please consult your local listings for the
PBS programming options in your area.

Using a satellite dish, three different options exist.

NASA-TV plans to air the programs but these transmissions can be
preempted by updates on the Space Shuttle/Pathfinder missions
and other factors. NASA-TV is found on GE-2, Transponder 9C at 85
degrees West longitude, vertical polarization, with a frequency of
3880 MHz, and Audio 6.8 MHz.

A backup plan is in place utilizing another GE-2 transponder not
subject to preemption. Tune to GE-2, C-Band, 85 degrees West,
Transponder (channel) 21, vertical polarity, frequency of 4120 MHz,
and Audio 6.2 & 6.8.

Finally, the main PBS satellite will also carry the programs.
Although the first program (July 6) will be carried live, the second
program will be delayed and broadcast on July 10 from 11:00 a.m.
to 1:00 p.m., Eastern. The specifications for this transmission are:
Telstar 402 R, 7 Lower, 89 degrees West, Frequency 11895 Vertical,
6.2 & 6.8 Audio.

TELEVISION ON THE INTERNET

Besides the options listed above, the television shows will also be
carried in various formats over the Internet. Although these options
do not provide broadcast-quality reception, they do provide an option
for those otherwise unable to receive the programming. The
following page lists more details about the Internet options:
http://passporttoknowledge.com/lfm/video/online7-6.html

Audio and video of the broadcasts will be available via
CU-SeeMe at http://space.rice.edu/hmns/dlt/videosched.html#next
RealAudio at http://www.cotf.edu/program/live/touchdown/

Audio only will be available using Real Audio. The details will be
provided immediately before the broadcasts at
http://www.cotf.edu/program/live/touchdown/

In addition, if the programs are carried on NASA-TV (assuming
they aren't preempted), they'll be available over the MBONE. See
the MBONE scheduling program (SDR) for details.

MARS TEAM JOURNAL UPDATE #1

Anticipating Pathfinder's First Weather Report

[Editor's note: Jim Murphy is a scientist who develops numerical computer
models of the Martian atmosphere. These computer models are very
similar to the computer models used for forecasting weather here on
Earth.]

Jim Murphy
June 18, 1997

I've been very busy working on completing the software
that's needed to convert the signals from our wind sensor
instrument, onboard the Pathfinder spacecraft, to wind
speed and wind direction.

The wind sensor sits on top of a mast about 3 feet (1 meter)
tall. The mast is currently laying down and will hopefully
pop up after Pathfinder lands. The first measurement should
be completed by about 2 p.m. Pacific, July 4, while the mast
is still laying down. We'll take this measurement just to
make sure things are working. Eight hours after we land the
mast should spring to an upright position and we'll start
measuring winds about 3 feet above the ground.

We expect to receive the first real wind information between
6 and 7 p.m., Pacific, July 4. What we expect to find at the
Pathfinder site is based on what Viking Lander saw during a
similar season at a nearby location (Pathfinder's site is about
1000 km (600 miles) from where Viking landed): winds on
the order of 5 - 8 miles per hour. We're not worried about
dust storms because it's the middle of summer on Mars and
the climate suggests that there are not big dust storms during
this time. [Editor's note: Soon after Jim wrote this, the Hubble
Space Telescope observed a dust storm on Mars. Therefore the
possibility of a storm may not be as remote as Jim suggests.]

Our wind sensor has six wires that are spaced around a
cylinder about the size of a spool of thread. Each of those
wires will get hot when we turn the electricity on. With wind
blowing past the cylinder, some of the wires are going to be
in front of it, as it sees the wind, and some will be behind it.
The wires in front of the cylinder will get cooler than the
wires behind it because the wires in front will have a faster
wind going by. By measuring how hot and cold the wires
are, we will get some indication of the wind speed. And by
figuring out which wires are hot and which ones are not as
hot, we'll get an indication of wind direction.

Our main science sampling will occur about every half hour
when we will get about 3 minutes worth of measurements.
We'll turn the sensor on for 3 minutes, collect information
and then switch it off. Thirty minutes later the process will
be repeated. Each day we'll get 51 three-minute samples.

Just because we know the temperature range on Mars, that
doesn't immediately tell us what the wind speed is. We did
some testing in a wind tunnel here at Ames (run by Greg
Wilson) where we turned our instrument on at different
wind speeds under conditions that were Mars-like, e.g. very
low pressures. We were able to do the calibration in which
we knew the wind speed and the temperature, so we were
able to make a relationship between the temperature of the
wires and the speed of the wind.

The data we got in the tunnel aren't perfect because, as
you've probably experienced, things never go quite the way
you plan them. So we also did our calculations on a piece of
paper and that told us what the approximate temperatures
should be. We're now going back and redoing those
calculations to make sure that we have consistency between
what we can calculate using our hand calculator and a piece
of paper and a pencil and the temperatures we saw in the
wind tunnel. After that it's just a matter of finding a
straightforward way of taking the temperature and
converting it to wind speed. If we did measurements at 3
meters per second, and at 5, 10, 20, 35 and 50 meters per
second, we could draw a curve through those points on our
plot. We can then try to fit a mathematical equation to them.
So rather than using our eyes to look at every temperature
and then go to our curve and pick out what the wind speed
is, we can use some math to spit out the corresponding wind
speed.

The wind-speed data will allow us to see what the winds are
at a third location on Mars compared to what the Viking
landers collected 20 years ago. We'll also be able to compare
different weather processes: cold fronts and warm fronts as
they move through an area, winds that flow up and down
valleys, which we saw happening at the Viking Lander 1
site. We'll also be able to tell if things are different on Mars:
if there's less dust in the atmosphere as some of the recent
observations suggest, and how that affects the weather.
We're interested to see if the wind blows strong enough at
the site to lift dust off the ground. We know there's dust in
the atmosphere and we know there are various sites where
dust rises. What we also want to know, is this specific site
one of them?

While Viking measured wind, temperature and pressure, it
only measured the wind and temperature at single points
above the surface. On Pathfinder the wind sensor sits on top
of a 3-foot-tall mast from which three wind socks hang.
Pathfinder will give us new information about how wind
speed changes the closer it gets to the surface. The mast also
houses three thermal-couples, or temperature-measuring
instruments hung at three different heights. From this
information we will learn how heat is transferred from the
surface vents and also how energy or momentum are
transferred from the atmosphere to the surface. Because the
surface tends to drag on the atmosphere it tends to provide
most of the heat input to the atmosphere.

Understanding the climate and the weather on Mars is an
absolute must before humans can land there. This is easily
accomplished by taking measurements at several different
locations. If a spaceship landed on Earth and measured
temperatures in San Francisco, it wouldn't be an accurate
representation of Earth's weather. It's the same on Mars.
With Pathfinder, we'll soon have three points of data
collection rather than two, so we'll have increased our
knowledge by 50 percent!

We'll receive our first Mars temperature measurement on
July 4 at 7 a.m. My guess is that it'll be 190 degrees Kelvin,
which is about -110 or -120 F. By about 10 a.m.
temperatures will start to rise to 205-210 Kelvin. The
temperature should peak around 1:30 or 2 p.m. at about 250
Kelvin. Then the temperature will start to drop fairly rapidly
so that by 6 p.m. it'll be down to 220 Kelvin (-60 degrees
F).

There is a much larger daily temperature range on Mars than
we see on Earth. Think about it this way: If you put a small
amount of water in a pot on the stove it heats up quickly.
The small amount of water is Mars' atmosphere. If you put a
lot of water in the pot it takes longer to heat up because there
is more water, which is Earth's atmosphere.

I'm really excited about being one of the first people to look
at the data and to realize that things are working and that we
are actually getting a glimpse of what's happening on Mars.
I actually got to see the wind sensor instrument on the
spacecraft. I didn't touch it, but it was within 12 inches of
me. What's really going to be exciting is when the rover
drives off the lander and turns around to take a picture of the
spacecraft.

MARS TEAM JOURNAL UPDATE #2

Ready or Not, Here They Come!

[Editor's note: Matt Wallace is one of two people who coordinates the
operations of the Mars Pathfinder rover. First he must help the
rover get off of the lander. Then he will send sets of instructions
to the rover about where to go, what experiments to do, and which
rocks to investigate each day. This may last for many weeks.]

Matt Wallace
June 24, 1997

We just finished a couple of sets of operational readiness
tests. We had a full-up test about a week-and-a-half ago,
where we had all the participating scientists and all the
operations engineers come to JPL where we went through
four days of operational testing, simulating the first four
days on Mars. It was really exciting! We have a sandbox
here that simulates the Martian environment, and hardware
that looks and acts just like our flight hardware. We have a
rover that's really a flight spare, so it's very high fidelity.
We did a lot of really good testing, which included waking
up the rover and letting it go through its self-assessment and
health checks and making an assessment from the lander
images to determine if it was safe to deploy the ramps. Once
we made that assessment we deployed the ramps and the
rover stood up and locked into an upright position. We took
a few more pictures to make sure the ramps unfurled and
then the rover traversed down the ramps onto the surface of
Mars. This test went better than any of the tests we've done
so far. This really was a good experience!

Pathfinder lands on Mars at about 10 a.m. local time on July
4. We get our first transmission session at about 2 p.m. on
the low-gain antenna (rather than the high-gain), so our
downlink period will be rather slow. But during that
session, which lasts about 50 minutes, we'll get information
from the rover. It'll wake up when it's commanded by the
lander and it'll go through a self-assessment and transmit the
data to the lander, which in turn will relay it back to us
during that session. Somewhere around 2:45 p.m. we'll see
the first rover telemetry data.

We'll have a bit of a wait before we can turn around and
send our first set of instructions because the lander will have
to go through a few of its operations. Shortly after landing it
will do a sun search with the camera so it can figure out its
orientation and point the high-gain antenna. That will take
about three hours. Sometime around 4 p.m. we will receive
our first high-gain session and will activate a sequence to
stand the rover up.

There is a whole list of things we have to look at before
we'll tell the rover to egress down the ramp. First we'll look
at the tilt of the ramp to make sure it's not too steep for the
rover to drive down. Then we'll look to make sure the ramp
isn't twisted because if it is, the rover could fall off the
sides. We'll check to make sure the airbag material has
properly retracted. If it puffs up and gets up around the sides
of the ramp, there's a potential for the rover's wheels to
snag on material while egressing down the ramp. We'll have
to look for rocks that may impinge on the ramp and cause it
to twist. We'll look for rocks down at the base of the ramp
to make sure that once the rover actually gets down to the
surface, it can go somewhere! The rover can traverse over
small rocks, lower than the height of its wheels, which is
about 8 cm. Once the rocks get much than that they become
hazards rather than obstacles.

During our first week on mars, we intend for the rover to
stay very close to the lander, just because we'll have a better
idea of the obstacles in the terrain of the lander images and
the area directly around the lander. I think we're going to
find that there are a lot of very interesting rocks and soils
within just a couple of meters. If the mission lasts several
months there's a possibility that we'll traverse outside the
visual range of the lander.

The rover carries three experiments: a spectrometer, a dust
experiment and a wheel-abrasion experiment. The primary
instrument is the spectrometer, which is mounted on the
rover's back. We'll use it to determine the elemental
composition of the soil and the rocks by putting the
spectrometer down on the soil and the rocks. The dust
experiment sits on top of our solar panel where there is a
small sensor with a coverglass that can be moved back and
forth to determine how much dust is building up.

The wheel-abrasion experiment is on the rover's right,
middle wheel. There is a strip of metal that contains different
coatings and metals. We're going to turn that wheel while
holding all of the others in a fixed position. We can turn that
wheel and look at the way in which the metal coatings
abrade. This will give us an indication of the roughness and
granularity of the soil and sand.

Another whole set of experiments we're going to do is the
soil mechanics experiment. It's similar to the wheel-abrasion
test, but slightly different in that we'll turn the rover's front
and rear brake wheels one at a time, a number of
revolutions, while holding the other wheels fixed. This will
dig a wheel down into the soil and by looking at that hole,
geologists and scientists can determine a lot about the
internal coefficient of friction and cohesion. It's an
interesting way to use the rover's hardware to get good
science data!

The rover will not specifically look for life on Mars. The
Mars Pathfinder program was designed before the Mars
meteorite rock was found, so it was not specifically
designed to look for life. But it will tell us quite a bit about
the geology and the effects that water may have had on the
planet. It will also tell us a lot about the elemental
composition of the soil and the rocks and whether or not
those conditions were actually conducive to life at some
point in Mars' history.

The rover's primary mission will last seven days, but if we
go seven days there's a good chance we'll last at least 30
days, which is the primary mission span of the lander. The
30 days are limited by the lander battery. The rover's
seven-day primary mission is a function of the thermal cycle
and the unknown effects of thermal cycling on the rover. It
gets extremely cold on Mars--down to -120 C at night and as
high as 20 C during the day. That's a pretty big swing!
There's a possibility that the mission will continue longer
than 30 days. It will definitely go on as long as the hardware
survives. We've even got some long-range plans out to a
year!

THE SCHEDULE ON LANDING DAY

On July 4 NASA's Mars Pathfinder spacecraft and its Sojourner
rover will enter the Martian atmosphere. If all goes well, the craft
will survive the entry and landing and be able to right itself. The
flower-like lander will then open its petals. Several hours later, the
Sojourner rover will be deployed. Here's a schedule of the day's
activities:

Time (PDT)        Event

07:00        JPL press briefing
08:45        JPL landing commentary begins
09:51        Mars atmosphere entry
09:53        Parachute deployment
09:55        Landing
10:01-11:01  Receive first indication of a successful landing
13:55        Receive first engineering and atmospheric entry
             data from lander
15:30        JPL press briefing
16:35-17:30  Receive first images of surface from lander
18:00        Release of the first color panorama image of the surface
21:00        Rover deployment
23:00        JPL press briefing

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