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UPDATE # 39 - June 19, 1997

PART 1: June 20 & 23: Rebroadcast of LFM Program
PART 2: July WebChat Schedule
PART 3: Journal Update #1: Preparing for the (Un)Expected
PART 4: Journal Update #2: Off to a Running Start
PART 5: Mars Pathfinder Weekly Status
PART 6: Subscribing & Unsubscribing: How to do it!


June 20: Live From Mars Program I "Countdown"
(rebroadcast of live performance), Level: Grades 5-12, 57:30
"Countdown" introduces a new series of "Passport to Knowledge" electronic
field trips. Live From Mars Program I takes students behind closed doors
at Cape Canaveral to see NASA's Pathfinder spacecraft close-up, just days
before its successful early December launch, and invites students and
teachers to follow Pathfinder and Mars Global Surveyor online via the
Internet and with hands-on discovery activities throughout the next two
school years.

NOTE: On June 20 the 2:00 p.m. broadcast will be preempted by the STS 94
Mission Overview/Crew News Conference.

June 23: Live From Mars Program II: "Cruising Between the Planets"
Level: Grades K-12, 60:00
Behind the scenes at NASA's Jet Propulsion Lab, lead center for planetary
exploration. How rocket fuel, momentum, gravity and ingenuity get
spacecraft from Earth to Mars. Mars Pathfinder's and Global Surveyor's
progress to date. Portraits of the men and women who control the missions.
Building and testing the robotic rover, Sojourner. Highlights of hands-on
student activities including the LFM Planet Explorer Toolkit, the Egg Drop
Challenge, and Red Rover, Red Rover.

Note: The NASA TV satellite coordinates are:
GE-2, Transponder 9C at 85 degrees West longitude, vertical polarization,
with a frequency of 3880 MHz, and audio of 6.8 MHz.

Broadcast times: 2-3 p.m., 5-6 p.m., 8-9 p.m., 11 p.m.-12 am, 2-3 am.
All times Eastern. NASA TV may preempt scheduled programming for live
agency events.


WebChats will resume with Bridget Landry on either July 1 or 2 (TBD in
next couple of days). Bridget is the deputy uplink systems engineer, which
means she teaches computers on the ground to speak the same language as
the Pathfinder spacecraft. In other words, she takes very complex, but
general computer programs and makes them understand all the commands that
the Mars Pathfinder knows. Bridget will bring us up to date on all the
pre-landing activities the spacecraft is going through.

Join us again on Tuesday, July 8 for a post-landing WebChat with Jeff
Plescia, from Pathfinder headquarters at the Jet Propulsion Laboratory in
Pasadena, California. Jeff will answer all of your questions about touch
down on the surface of Mars and the daily routines of the lander and
rover. Jeff is a Mars research scientist whose primary interest is
planetary geology. He was an investigator on the Viking mission to Mars in
the 1970s and is anxious to compare past Viking images of the surface of
Mars with new images from Pathfinder.

***The time of this WebChat remains open at the moment. We are looking to
you to tell us when your best time is on July 8. Please let us know by
sending a note to: sandy@quest.arc.nasa.gov***

Be sure to check out the following URL for final details on dates and
times: http://quest.arc.nasa.gov/mars/events/interact.html


Preparing for the (Un)Expected

[Editors note: Greg Wilson is a planetary geologist at NASA Ames Research
Center's Planetary Aeolian Laboratory in Mountain View, California. He is
responsible for conducting geologic research in the Mars and Venus wind
tunnels, and also supports Mars Pathfinder.]

Greg Wilson
June 17, 1997

For the last couple of months we've been busy simulating our activities on
the surface of Mars as we expect they'll occur on July 4. These
simulations are called Operational Readiness Tests, or ORTs. We are also
preparing for other scenarios such as what happens if the battery goes out
or what happens if we only have a low-gain antenna mission like on
Galileo? Each one of these scenarios requires different sequences, which
are operations we write and upload to the computer on the spacecraft. This
is all done at the Jet Propulsion Laboratory in the "sandbox" where we'll
run for five days, working out all of our operational kinks and looking
for mistakes in our sequences.

We just completed ORT 7, our nominal mission, which assumes that we land
correctly and all our systems are functional. If we have a nominal mission
it's going to be really spectacular--the images, the data, the rover

The spacecraft will land at roughly 10 a.m. PST on July 4. We will get a
few pings from the spacecraft as it goes through its air-bag retraction
and opening. We're expecting to receive only 50% of the pings just based
upon them not appearing or not getting them at the tracking stations
correctly. But we will get the first low-gain antenna downlink at roughly
2 p.m., PST, with the first high-gain downlink at 4 p.m. From roughly
5:30-6:00 p.m., PST we will have our second press conference of the day,
but our first with images. We'll have the first press conference at 3 p.m.
where we will have a lot of the deceleration profiles as Pathfinder enters
the atmosphere.

One of the toughest things for everyone on the team is the conversion
between Pacific Standard Time to Universal Time to SCLK (spacecraft clock
time). We also have SCET (spacecraft event time) and Mars Local Solar
Time. So depending upon how you want to plan your activity in terms of
time, you need to understand how all of those are interconnected. On July
4, 10 PST is roughly 3 a.m. Mars Local Time. 

The other thing we need to work through is our own time schedules. You
see, if the spacecraft lands at 10 a.m., we'll need to be at work by about
9 a.m. But our operations and our downlink continue until 11 p.m. that
night. And then there'll be data analysis taking place through the next
morning. Then at 8 a.m. that morning we'll need to have our sequences
ready to go to the spacecraft for the following day. So basically,
operations will be running 24 hours a day!!! The hard part is we have to
get some sleep, but we'll want to be up all 24 hours!!! Each one of those
tasks--downlink, analysis, planning for the next day--we'll want to be
involved in! I think I can do a couple of days straight before I fall a

The engineers will be working 12-hours shifts, but they may cut that down
because experience at JPL has shown that if something goes wrong and a
person has to spend 14-16 hours solving a problem, they're going to
mentally collapse. The managing of our time is one of the harder things to
do and that's why we do these ORTs and we actually run them like they are
official landings in terms of working through the night.

We've completed the last ORT, which we lovingly refer to as "the landed
mission" or ORT 8. So now I'm going on vacation, as are a lot of other
Mars folks. But whatever weaknesses were revealed last week in terms
of--did you have your programs up and running to analyze the data
correctly; do you have all the pretty pictures you want for the press
conferences--we'll spend the next couple of weeks cleaning up our act and
trying to fix some of the anomolies that we encountered this time and
hopefully no new ones spring up during the mission.

So, it's pretty much business as usual right now. The engineers will be
doing a Trajectory Correction Maneuver either this week or next. Come July
1, operations begin in full swing: they'll be tracking the spacecraft
two-way, 24 hours a day and really refining the landing parabola.


Off to a Running Start

[Editors note: David Mittman is one of several flight engineers on the
Mars Pathfinder project. Flight engineers are responsible for the
day-to-day operations of the Mars Pathfinder lander and the rover. Davids
areas of specialization are in planning the spacecraft's
activities, and in sending commands to the spacecraft.]

David Mittman
Friday, June 13, 1997

10:30 AM (PDT) -- Well, it has been a very busy week! We're approaching
the end of what we call an ORT, an Operational Readiness Test. This is the
seventh and most realistic ORT that we've had so far in the mission. It is
our dress rehearsal for the actual landing that will take place on July 4.
(What do you wear to a martian landing? Green?) 

During the test we don't use the actual spacecraft, but instead we use
very accurate simulators. In preparation for the test, some of our
engineers locked themselves in our "sand-box" (this is the area where we
have martian-like sand and working simulators for both the lander and
rover), and rearranged the rocks and sand so that we would be "surprised"
by what we discovered when we "landed" on Mars. No one else is allowed to
see the sand-box during the test. Just like school! No peeking! 

On our first test day on Mars, we were able to accomplish everything that
we had planned. We drove the rover off the lander and onto the surrounding
sand, deployed our camera and took many pictures, and released our weather
mast to take wind and temperature measurements. The rover was able to take
its first 10-hour measurement of the composition of our test material.

My job during the test was to plan the activities that are to take place
on the day after we land, our second day on Mars. Actually, we've already
planned what's going to happen for the first several days, but once we
land on Mars, we'll probably have to change a few of our scheduled
activities. Since just about everything went properly on the first day,
there wasn't that much to replan for the second day. Still, there was a
lot to do.

My mission planning shift started on Wednesday at 9:30 PM. I didn't get to
leave until about 12 hours later! During that time we moved around some
science observations, adding some and removing others. Since the mission
planners work when it's nighttime on Mars, we don't get to stay around and
watch the activities take place during the Martian day. We have to sleep

Since I'm also one of six Mars Pathfinder flight controllers, I have to
worry about the real spacecraft, not just the test lander and rover in our
sand-box. We are now monitoring the spacecraft around-the-clock as it
approaches Mars; landing is just 20 days and 22 hours away! This week I've
had five flight control shifts, each from about 7:00 PM to 11:00 PM. In
fact, the only night that I didn't have a flight control shift was
Wednesday night, and you know what I was doing then!

It has been a very busy week on "Mars" as well as in space!

Mars Pathfinder Weekly Status Report

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

13 June 1997

The spacecraft remains in good health and is currently about 160 million
kilometers from Earth (10 million km from Mars). The total flight time
since launch is now 190 days, and we have 21 days until Mars arrival.

The Operations Team completed the final Operational Readiness Test in
preparation for Entry, Descent, and Landing (EDL) and surface operations.
This test simulated activities from two days before landing through two
days after landing and was very successful.

Major activities completed during this ORT included a simulated Trajectory
Correction Maneuver (TCM)-5, a nominal EDL, a series of simulated press
conferences for Sol 1 & Sol 2, a successful rover deployment of Sol-1, and
extended rover traverses over the course of the following two days.

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