PART 1: Galileo fact of the day
PART 2: Recollections of a great day
PART 3: Thinking about contingency plans
PART 4: Lots of people and a radio interview avoided
PART 5: Faster and faster

Galileo's planetary flybys have allowed the spacecraft to speed up,
at the expense of the planet slowing down slightly. How much were
Venus and the Earth slowed by Galileo's gravity assists? In a billion
years, Venus will be 1.6 inches behind where it would have been in
its orbital path if Galileo hadn't interfered. The Earth will be 5.2
inches behind (a 2.9 inch lag from the first Earth gravity assist, and
the other 2.3 inches from the second assist). 

December 11, 1995
I'm writing this a few days after the fact, but boy what
a great day last Thursday, the 7th was! Everyone on the
flight team and at JPL is happy and relieved that all
went well!

I was so nervous while waiting for confirmation that the
probe that we dropped into Jupiter's atmosphere was
working fine. The signal came about 6 minutes later
than I had been expecting, so I was getting very
fearful that something had gone wrong. When the
confirmation finally came through, I was nearly in
tears from the joy of knowing that we had done it!
(So was our project management!)

I was in our Von Karman auditorium to hear the confirmation
since I had volunteered to help with the press. That
was the best place to be! When the signal came through,
everyone cheered and hugged each other! The press started
snapping pictures of all of us cheering and later came
up to interview some of us!

Later on that evening, we got the signal that the big
engines aboard Galileo started firing right on time!
That was a relief too since if they didn't work
right, we would have become a flyby mission instead of
an orbiting mission! And again, 49 minutes later, the
engines stopped, right on time. Of course, I had all
the confidence in the engine firing, we seem to do that
very well here!

We've started to get some data back from the probe. I
haven't heard any rumors about it yet. They have to
look at it and get ready for the press conference on the
19th. I can't wait to find out what interesting things
they have found! It's so great to finally be in orbit
around Jupiter getting real Jupiter data!

Week of November 27, 1995
Thanksgiving was a good break from the pressure. Not only did we 
get the holiday itself, but we had planned on working Saturday and 
Sunday on TCM-28 and a tweak of it (a TCM is a trajectory 
correction maneuver, and to tweak it means to change it after it was 
sent to the spacecraft to refine it). The project decided that the 
spacecraft was close enough to the target not to try and correct it, 
and canceled the maneuver.

But, there is more than enough work to keep us busy, thank you. We 
gave a final approval for the three background science sequences 
which will operate during the arrival time period. These sequences 
are responsible for the recording of the Fields and Particles 
information as we pass through the Io torus. We begin uplinking them 
(sending them to the spacecraft) on Thursday.

We've also been doing more work on "contingency plans." These are 
plans that are prepared to solve specific problems that might 
happen. It's always better to have foreseen a difficulty, and figured 
out what steps might be taken to solve it *before* you get hit with 
the problem. That way, you can fix the problem quickly, and not 
waste time trying to find a solution right when the spacecraft is 
about to do something critical. The difficulty with this process is 
that there isn't a defined stopping point; you can put an infinite 
amount of work into thinking of possible problems and what should 
be done in each case. So, judgments have to be continually made 
about whether a possible problem is likely enough to justify the 
work. Some of the contingencies we've been thinking about involve 
the tape recorder that we've been having trouble with. Others involve 
what to do in the case that our main engine doesn't perform exactly 
as designed. 

With only a week to go, I'm really excited. It's hard to sleep at night. 
Frequently I get stuck thinking about a possible problem, and I have 
to just give up, go downstairs and write out what I'm thinking about 
so I know I won't forget it in the morning. Even doing that I can't 
always get back to sleep, but sometimes it works. I know what will 
work, and that is a successful Probe Relay and Jupiter Orbit 
Insertion.

December 6
This morning there was a big traffic jam coming in to work. JPL is 
on a dead end street and there isn't that much parking, so for a while 
I thought I was going to have to walk in from miles away. I know it's 
going to get worse. Tomorrow is going to be a zoo. There will be 
something like 600 VIP's and 800 other guests, so I guess I'd better 
get here early. 

Yesterday I was asked by Jan to do a live phone-in radio show, from 
5:00 to 6:00pm , right during the press conference. But I want to see 
the press conference. I've been so focused on the concerns of my own 
instruments that I haven't had much time since I've been here to 
understand other science that the project is doing. It's a forest and 
trees problem. This is my chance to understand it along with 
everybody else. Besides, I'd be way too nervous to answer questions 
about the whole mission for a large radio audience! I asked Jan to 
get Steve Edberg to do it. Steve knows way more than I do and he's 
used to doing these sorts of things. Steve said yes, so I'm off the 
hook, thank God.

November 27, 1995
Since the Mauna Kea observing (on Hawaii's Big Island), things seem 
to have taken on a rapid pace whose toll on me I'm trying to slow 
down. I can't believe that we have so little time to spend on 
preparing for the data before it comes in!

Jose Luis and my colleague on the Galileo Photopolarimeter-
Radiometer (PPR) experiment, Terry Martin, made another trip to the 
NASA Infrared Telescope Facility at Mauna Kea. Despite some bad 
weather conditions, they did well, working only on NSFCAM, the 
near-infrared camera which is mostly sensitive to sunlight 
reflected from Jupiter's clouds (rather than to planetary heat from 
the interior of the planet itself).

While they were there on Nov. 17-21, I tried to get some of their 
files at JPL and look them over to make comments and suggestions. 
One of those nights just didn't work out well. I had a breathless call 
from my wife on Nov. 21, saying she had to take the kids to the piano 
lesson in the car I intended to use (we took both cars in - she's been 
visiting her mother at the hospital each morning). The other one had 
a flat tire! Oh, this was NOT what I needed at all. By the time I 
finished getting the Previa re-wheeled, it was quite dark and I was 
working by flashlight. I don't think I've changed a tire for more than 
20 years; it would feel good to know that I can still do it alone, if it 
were not for the fact that my arms were totally sore and almost 2 
hours went down the tube! I got the tire repaired (where a large nail 
was plainly visible in the puncture) the next day at a store within a 
short shuttle ride from JPL. But when I waited for the shuttle at the 
end of the day, it was 20 min late - there was a fire in a building a 
block away from the tire store. It took another 50 min. to get there 
and get out, where my mother was waiting at home along with my 
wife and kids. All were impatiently wondering what took me so long; 
they wanted to take Linda's father out for supper and it was getting 
late for a Wednesday night before Thanksgiving (when absolutely no 
one cooks dinner at home who's cooking the next day). My mother was 
visiting for Thanksgiving.

Friday night, Padma Yanamandra-Fisher, another colleague in our 
group, was at the IRTF to get images of Saturn just after the rings 
crossed through the plane of solar illumination. She wanted to see 
how fast the newly lit sides of the ring particles would heat up. 
Although she was working through clouds, she did manage to get a 
few good 5-micron images of Jupiter with NSFCAM. At this 
wavelength, we are looking at thermal (heat) radiation from Jupiter, 
not reflected sunlight, because sunlight is so weak at this long 
wavelength. I've been tracking Jupiter's appearance at this 
wavelength, because it's sensitive to temperatures at Jupiter's 
cloud tops.

Padma's data represent almost undoubtedly our last look at Jupiter 
at 5 microns without a polypropylene solar protective cover which 
we'll use in early December. The cover will severely restrict the 
type of data we can get at 5 microns: it won't let much of it pass 
through, and it won't let ANY of the reflected sunlight at shorter 
wavelengths through. I had a phone call from Bob Joseph, the IRTF 
Director, explaining why he decided NOT to allow us to use a new 
configuration for the screen which would have let more of Jupiter's 
light through - it would have been at the forward part of the 
telescope and possibly could have ripped apart in the wind, with 
disastrous results for the instruments it was supposed to be 
protecting.

I spent a little time at JPL on Saturday morning, mostly before my 
family woke up, going over the data from the observing runs and 
trying to map them onto a mercator (cylindrical) disk projection, and 
THEN trying to move them forward in time to see what they might 
look like at the longitude of the Probe entry site. I found that there 
is still a bit of uncertainty as to whether the area is clearer or 
cloudier than "typical" regions in other places at this latitude and 
elsewhere on the planet. I also discovered that there were some 
places where the data didn't make sense, and I have to try to see 
whether there are mistakes in the way I processed the data.

This morning, while the kids and my mother and I were at church, 
Linda left for Kitt Peak - an observatory just outside Tucson, 
Arizona, where she'll make laboratory spectroscopy observations of 
gases. She will get back on Wednesday night, and I'll fly out on 
Thursday morning for the final stretch of observations before Probe 
entry.

November 29     On the eve of a great adventure.
I worked a bit more with the images, and Jose Luis - now back from 
the IRTF - did some work on image reconstruction: trying to recover 
what the image would have looked like in the absence of atmospheric 
blurring (called "seeing"). I can make the features line up near the 
Probe entry site if they all move along with a speed of 103 - 115 
meters per second (222 - 248 mph-- that's relative to the deeper 
layers of the atmosphere). Projecting this forward to Dec. 7, I get 
the sense that the Probe will enter just south of a large clear area 
in the atmosphere where thermal (heat) radiation just beams out at 
a wavelength of 5 microns (a pretty clear area in Jupiter's 
spectrum): they are called 5-micron hot spots. But there is still 
some uncertainty about this "Jovian weather report."

I worked with Bob Carlson, the Galileo Near-Infrared Mapping 
Spectrometer (NIMS) Principal Investigator, Padma, Terry and Jose 
Luis to coordinate what we might do from JPL's own observatory at 
Table Mountain in the mountains to the northeast of JPL. They'll go 
up to Table Mountain Observatory (TMO, for short) on Thursday to see 
what could work. We have the plans all set for the observing run at 
the IRTF, with the major uncertainty being whether the near-
infrared camera, NSFCAM, which is very sensitive at 5 microns will 
do worse than MIRAC (for Middle InfraRed Array Camera) at the same 
wavelength. MIRAC is less sensitive and produces smaller images, 
not letting us resolve much less than 1000 km on Jupiter. However, 
it is easier not to overexpose - one of our major problems with the 
sensitive NSFCAM. Jay Goguen from JPL and John Spencer from 
Lowell Observatory want to observe Io to support the particle and 
field experiments which will be operating through the Io flyby to 
characterize the status of Io's volcanoes which might or might not 
be erupting. That's a big IF, but Jay and John want 3 40-minute 
observing sessions out of our total observing allocation of 6 hours, 
verging on 1/3 of the available time; I was unhappy about that, 
thinking that 30 min would be much better. We may compromise at 
35 min, but I'm still a bit distressed.

There are more ground-based Jupiter observations in the works. Dave 
Crisp will go up to Mount Wilson on Friday and be shown the 
horizontal Snow solar telescope, not being used much lately, to see 
whether that would work well with a JPL visual/near-infrared 
camera. In the meantime, our colleague Sanjay Limaye at the 
University of Wisconsin is at the Swedish Solar telescope at La 
Palma starting to churn out Jupiter images as soon as their weather 
turns better. I also find that Pic-du-Midi Observatory in the French 
Pyrenees has a World Wide Web site showing some really quite 
remarkable images, given that Jupiter is so close to the sun!

Then the usual things rose up, the swarm of little things that are 
making life busy - get the forms filled for a student part-time 
worker, see if the latest model comparisons with the Net Flux 
Radiometer team are coming together right, seeing that the models 
for laboratory experiments modeling absorption between hydrogen 
(the dominant gas in Jupiter's atmosphere) and ammonia (the 
horrible smelling window cleaning chemical, and a major absorber of 
radiation in Jupiter's atmosphere) are being fit correctly. Added to 
this, the fact that my wife is away: get the kids to a piano lesson 
(it's MY turn THIS week!) at 4:30 and then grab some great American 
McDonald's food - :(  - and run to a barber's appointment by 6:45 
through rush hour traffic, get my son to FINISH the book report due, 
my daughter to remember how to spell "harvest" and "family" for 
Friday's spelling test, get him awake on Wednesday morning and out 
to a special early morning class at 7:15 AM (!), then pick him up with 
enough time to finish homework and go to a Cub Scout meeting 
tonight. Linda came home by 8 PM ! (Yay!) Now she can whip out those 
peanut-butter-and-jelly sandwiches by 8 AM... Tell her about the 
arrangements and requirements for the next 7 days, give the kids 7 
kisses and hugs before they're in bed (I'll have left for an early 
morning plane by the time they wake up!). Now finish this journal, 
pack Christmas cards to fill out on the airplane, see whether Terry 
Martin really would like to go out on the next observing run (Jan. 1 - 
3, missing the New Years Holiday), and answer a mailing I got from 
Al Seiff - the Principal Investigator for the Galileo Probe 
Atmospheric Structure Experiment (which will measure pressures 
and temperatures and gravity as the Probe descends in the 
atmosphere).

Oh, and I quell my disappointment at a FAX I received from Nigel 
Henbest of the UK, Pioneer Productions, making a documentary for 
the U.S. Cable Channel "Discovery" on the events surrounding the 
Shoemaker-Levy 9 collision with Jupiter. They filmed me for 2 or 
more hours in August in my office, but their message was 
essentially that I was left on the editing room floor because of time 
constraints. Well, that's show biz!.  :)