PART 1: Galileo fact of the day
PART 2: Web chats scheduled for Thursdays
PART 3: Press conference to announce early Galileo Probe results
PART 4: Even propulsion folks do outreach
PART 5: Sequence test preparation plays Grinch
PART 6: Mission (Number 1) accomplished

How many people have worked on Galileo? Nobody knows for
sure, but it's been estimated that roughly 10,000 people have
worked directly on Galileo since the Project's start in 1977.
That's excluding people associated with the Space Shuttle and
the Inertial Upper Stage booster

I'm hoping to reinstitute a regularly scheduled chat time.
For now, I plan to loiter in our WebChat area on Thursdays
from 3:00-4:30PM Pacific time (starting today January 18).
The address is http://quest.arc.nasa.gov/galileo/webchat/chat.html

My goal is to gather some feedback from folks about this project
or to address some of your concerns. I'm particularly interested in
chatting with teachers who may have used some of this material
with their classes, but everybody is invited. Please try to join me if 
you can. Thanks, Marc

Scientists analyzing data returned by NASA's Galileo
atmospheric probe into Jupiter will unveil early scientific
discoveries during a news briefing at 1 p.m. EST on Monday,
Jan. 22, at NASA's Ames Research Center, Mountain View, CA.

Project scientists and principal investigators will
present results from the probe's six instruments based on
their initial looks at data collected Dec. 7 during the
probe's fiery 57-minute descent through the giant gas
planet's upper atmosphere.  New animation portraying this
event also will be available.

Originally scheduled for Dec. 19, 1995, this briefing
was postponed by the government-wide furlough.

The briefing will be carried live on NASA Television via
Spacenet 2 Transponder 5, Channel 9, at 69 degrees West
longitude.  The frequency is at 3880.0 megahertz, audio at
6.8 megahertz.

NASA Television is also available over the Internet.  Xerox PARC
broadcasts this signal (both video and audio) over the MBONE.

The programming is also available through CU-SeeMe from
the following sites:

In the US, video reflectors are:
   139.88.27.43 at the NASA Lewis Research Center
   139.169.165.25 at the NASA Johnson Space Center
   128.158.1.154 at the NASA Marshall Space Flight Center
   131.123.5.1 at Kent State University
   128.2.230.10 at Carnegie-Mellon University
   129.186.112.242 at Iowa State University

In Europe, the video reflector are:
   158.36.33.5 at /stfold Regional College in Norway
   130.235.128.100 at Lund University in Sweden
   147.94.38.2 at Ecole Superieure de Mecanique de Marseille in France

In Asia, the video reflectors are:
   140.129.142.49 at Tung Nan Junior College of Technology, Taipei, Taiwan
   164.78.252.4 at Singapore Polytechnic, Singapore

January 9, 1995
Happy New Year, everyone! And what a happy 1996 it is, with the
orbiter safely tucked in Jupiter orbit and with some high-priority
probe data on the Earth (though not released due to the government
furlough). There is not much I can write about arrival day that could
possibly do justice to the tremendous joy I felt at orbit insertion.
I can tell you, though, that as one of the people responsible for the
propulsion system, including the main engine and thus orbit insertion,
I was quite antsy following the successful lock onto the probe signal
after 3 pm on arrival day (following my initial whooping and
hollering). Ironically, this success put more pressure on us to at
least have a safe ATTEMPT to get into orbit, since now we knew that
there was most likely probe data on the orbiter to be played back to
Earth! In other words, suddenly the stakes for avoiding a
catastrophic failure while attempting orbit insertion were much, much
higher. Luckily, I had only had 3 hours to deal with such
ruminations!

I purposely chose a high visibility spot in the mission control area for
the Jupiter Orbit Insertion (JOI) burn, being kind of a "TV ham." I
actually had a vested interest in doing so--my parents, sister and
brother-in-law and some of my high school teachers were watching the
events unfold (live via satellite link) from the Kansas Cosmosphere, in
Hutchinson, Kansas, near Wichita. In November, I had done an article
with the Wichita Eagle, a daily newspaper with a circulation of 250,000.

The local TV news picked up on the story and my family became local
celebrities around Wichita, with newspaper and television interviews
after the successful completion of JOI! Apparently, fifteen minutes of
fame can be contagious. Between Christmas and New Year's, I did a
follow-up article with the newspaper while home visiting my family.

This so-called "public outreach" is becoming a more important part of
our business at JPL, which suits me just fine. There is nothing I enjoy
more than conveying the excitement of this place and our missions to the
general public. I recently joined the JPL Speaker's Bureau, a volunteer
organization here that sends members out to schools, rotary clubs, etc.
to brief the public on how we spend their tax dollars here, nestled up
against the towering San Gabriel mountains. As you might imagine, there
is a strong desire to hear more about the Galileo mission in the general
public right now, so the Speaker's Bureau was very glad to have me
aboard. I can't wait for my first assignment!

Of course, work continues as well (there doesn't seem to be much
time to celebrate in this biz). Some of my recent pursuits include
doing a quick look at the JOI data to make sure that the propulsion
system seems leak-tight with respect to helium (the pressurant),
nitrogen tetroxide (the oxidizer), and monomethylhydrazine (the fuel);
starting to plan the proper usage of the main engine for the perijove
raise maneuver in mid-March, which raises the spacecraft's orbit above
the harshest radiation surrounding Jupiter for subsequent closest
approaches to the planet; and helping select an alternate duty cycle
(the on-time and wait-time for engine firing) for the spin-rate change
burns around the perijove raise maneuver. After this maneuver, there
is currently no planned subsequent usage of the 400-N engine (although,
perhaps the main engine will be needed at the end-of-mission to go back
to Io, if that turns out to be feasible). Also, after the perijove
raise maneuver, we will have used nearly 90% of the total propellant
on-board Galileo.

It has been a stupendous last few months, and I look forward to
sharing with you in the excitement of the unique science results that
will be astounding us in the coming months and years. Thank you for
your support and interest in the Galileo mission, and, to quote the
Kansas state motto, "Ad Astera Per Aspera!" (To the stars through
difficulties)

December 20, 1995
I cancelled my Christmas vacation today! I will fly up on Christmas 
day, and fly back again that night. Mom will hate it, but this year I 
just can't do it. Even my brother is working, so I know I'm not the 
only one.

Sometimes when you work for a living, Christmas vacation just 
doesn't come at a good time for the job. For us on Galileo, the 
schedule has been squeezed and squeezed until there is no room left 
to postpone things. For example when we had the problem with the 
tape recorder, everybody on Galileo had to drop what they were doing 
in order to work on all the tape recorder issues, and put other things 
aside for "later." But the deadline for Galileo's first flyby of 
Jupiter's moon Ganymede cannot be postponed. The spacecraft is 
going by Ganymede in June whether we are ready or not. There is no 
more room for doing things "later."

We are trying to test one of our spacecraft computer sequences (the 
testing is done on equipment here on lab, not on the spacecraft 
itself). This is the first time that we've tried running the test with 
all the instruments "on." The test was supposed to be in December, 
right around arrival day. That wouldn't have interfered with 
Christmas vacation at all. But one of the engineers who we *had* to 
have present during the test had to help with another test on the 
tape recorder at the same time, and that couldn't be rescheduled. So 
the sequence test was postponed until Jan 8.

Now normally the testbed engineers like to get the sequence of 
commands 2 weeks early, so that they can "massage" it and make 
sure it is correct. That would mean that we would need have the 
commands to be tested ready on Christmas Day! (That meant we were 
sure to have a "slip" of at least one day!)

We have already found problems which have to be fixed before the 
computer sequence will run, even before getting the test started. 
One of my instrument's commands was not working properly. My 
instrument engineer fixed it. The computer software engineer fixed 
his portion. But the SEQGEN writers cannot be ready on time.

SEQGEN, which stands for SEQuence GENerator, is like a giant 
complex spellchecker for the sequence of commands that are written 
by people like me. Galileo is a very complicated spacecraft, and the 
commands that run it are also very complicated. It's easy to make a 
mistake that would mean a command wouldn't work (for example, not 
allowing enough time for the command to do everything it has to do). 
Plus all of the other science teams and the engineering people are 
also putting in *their* commands, which means that one instrument 
might try to do something during a time when the spacecraft can't 
handle that much activity. SEQGEN catches all of these possible 
mistakes before they can be sent on to the spacecraft where they 
could do serious damage. Then you clean up your mistakes and send 
the sequence back for another run through SEQGEN until SEQGEN says 
that you've passed inspection.

My instrument engineer fixed the portion of our instrument's 
software that didn't work. That means that our commands are now 
different from what SEQGEN expects to see. If I run the test 
sequence through SEQGEN, it will tell me there are errors, when they 
are not really there, but it will also not give me the "OK" on my 
sequence. A new version of SEQGEN was supposed to be ready in time 
for the test, but it won't be. It's like one of those machines that 
automatically grade tests; I KNOW that the answer key has been 
changed to something new, but SEQGEN doesn't know it yet.

So I have to bypass SEQGEN, and grade this exam by hand. I have to 
write the subcommands, by hand, that SEQGEN would generate if 
SEQGEN could read my sequence. This will be very complicated and 
will take a couple of days to do. (Since I work half-time on Galileo, 
it will actually take me more than a couple of days). Then I have to 
make sure I did not make a mistake -- and since I can't use SEQGEN 
to catch my mistakes, this will be harder than usual. My instrument 
engineer back at the University of Iowa will help me by reviewing 
what I do. That'll probably be a day or two after Christmas. Then we 
have to give the new sequence to the testbed engineers so they can 
make sure it will work properly. They really want to have it the day 
after Christmas (they aren't taking Christmas off either). If they 
make any changes, my instrument engineer at the University of Iowa 
and I have to review them and make sure we agree.

They are supposed to generate the "bits and bytes" version -- the 
actual 1's and 0's that would get sent to the testbed -- on or about 
Jan 3, 1996. We will also begin doing some preliminary testing on 
the 3, 4, and 5th. So I have to be here to review the sequence as it 
comes out from the various teams. (I still haven't reviewed the final 
product that the sequence team helped us put together! - yiiipes, 
naughty me. This is what I get for going away for a week to work on 
other things). Then, since I'm new at this testbed stuff, I have to 
learn how to read the data that the testbed will send to us, etc. 
AAAAck. And I still have to finish my paper and deliver pages for my 
Windows project. This is why I have to cancel my Christmas 
vacation. I'm not sure I can explain all this to my mother, though.

December 13, 1995
It has taken me almost a week to get my feelings about the Jupiter
arrival events sorted out. After having worked for over 18 years
(my entire career at JPL) on Galileo, it has taken a while for it
to sink in that the spacecraft is actually in orbit at Jupiter.
Over the past 18 years, I have designed and evaluated a tremendous
number of interplanetary trajectories for Galileo -- so many that
I don't think I could even estimate the number (hundreds?, thousands?).
There were launch dates as early as 1982 and as late as 1989, and
the Jupiter arrival dates ranged from 1985 through 1995 and beyond.
So many trajectories! Now it's over; the interplanetary phase of
the Galileo mission is completed.

I feel relief  and a tremendous sense of satisfaction that Probe
relay and Jupiter Orbit Insertion have been completed successfully.
To think that I was fortunate enough to be able to participate in
getting Galileo to Jupiter is like a dream come true. Perhaps the
most exciting moment of last Thursday was the instant that the
Jupiter Orbit Insertion burn ended. Galileo was in orbit -- a new
artificial satellite of Jupiter! But this is just a new beginning.
The Galileo orbital tour of the Jovian system has now started.