PART 1: Welcome to Online from Jupiter 97
PART 2: What are Field Journals?
PART 3: Spotting Corrupted Computer Files - - Just Another Day
PART 4: The Spacecraft is ok. It was just a Coronal Mass Ejection
PART 5: This Week on Galileo, 2/10 - 2/16
PART 6: Subscribing/Unsubscribing: How to do it

Welcome to the project that will give you and your students a direct line to the people involved with Galileo and provide you with information and resources to integrate the spacecraft into your studies. If you are new to this project, welcome - - please keep reading for more information. If you participated in the original OFJ project, conducted during the 1995-96 school year, welcome back. We hope you find this sequel as useful and enjoyable as the first project.

Over the next two months, you'll be sent a unique perspective on NASA's Galileo mission to Jupiter. Through this maillist, you'll receive frequent journals from the members of the Galileo team. These behind- -the-scenes reports will provide insights into the day-to-day work required to support this mission as it continues to provide information from the Jovian system.

Online from Jupiter 97 includes a website housing Field Journals, biographies of new and existing Galileo team members, an image gallery, student activities, resources for teachers, and more. The website is at http://quest.arc.nasa.gov/galileo and is being updated as we write.

OFJ97 will provide special opportunities for K-12 teachers, students and others who are interested. Some resources that are provided include an imaging lesson to show students how scientists analyze images from the spacecraft, and activities related to Europa. Europa is one of the moons of Jupiter and we have two activites available involving it. The first involves students designing a spacecraft to travel to Europa and test for life and the second involves whether or not life actually exists. We are also providing teaching resources, forums for student-student and teacher-teacher interaction, and a forum for students to email questions to Galileo experts and receive answers.

You'll receive an updates-jup message like this approximately once per week.

For those unfamiliar with the Galileo mission, here is a brief introduction: Launched in 1989, the Galileo spacecraft arrived at Jupiter on December 7, 1995, and fired its main engine for 49 minutes for a successful orbit capture around Jupiter. On the same day, Galileo's atmospheric probe plunged into Jupiter's atmosphere, and relayed information on the structure and composition of the solar system's largest planet. The spacecraft's orbiter is now orbiting the giant planet, studying Jupiter and its moons (encountering one moon during each orbit), and returning a steady stream of images and scientific data.

For more information on Galileo and the probe, visit:

The Galileo homepage at http://www.jpl.nasa.gov/galileo
The Galileo Probe homepage at http://ccf.arc.nasa.gov/galileo_probe

The OFJ97 team is interested in your ideas, problems, compliments and thoughts about this project. Please send them to Chris Tanski, ctanski@mail.arc.nasa.gov

If you wish to stop receiving these updates, please:

Send email to:
listmanager@quest.arc.nasa.gov

Place the next line of text in the body of your email:
unsubscribe updates-jup

We hope you find Online from Jupiter 97 to be an exciting and informative resource.

Dr. Jo Pitesky							Chris Tanski
Galileo Mission Planning Office			NASA K-12 Internet Initiative

The story below by Laura Barnard is an example of an OFJ97 Field Journal. The intent of these journals is to show the diversity of real tasks involved in the science of Jupiter, and give snippets of the life of Galileo team members. A sentence or two will be included as background to help orient you toward the story that follows. Also, almost all authors have their biographies (with more background) on our Web site - - the story will include pointers to these bios to make it easier to connect to the richer backgrounds.

Still, reading some of these journals will feel like coming in during the middle of a play, and being forced to leave before it's over. Galileo has been in orbit around Jupiter for over a year now, and its mission will continue after the end of OFJ '97. The journal entries, consequently, might not have the full background that folks are looking and hoping for. We'll try to share what we know about why these folks do what they do, but it definitely won't always have a neat start, middle and end.

Remember, too, that if you have questions about something that you read in a journal, you can always submit them!

Hopefully, these Field Journals will still be useful and interesting!

-OFJ97 Project Team

This is a really active week for me. We have the Project Science Group (PSG) meeting and workshops going on. The Project Science Group is made up of international colleagues that decide what science we are going to do based on the resources and timing of events. They have these two to three day meeting twice a year so that everyone can be in the same room and work together. It also gives the science coordinators a chance to talk to their primary investigators about the science plans that they are creating. Naturally, there is always last minute stuff to put together for their presentations. Yesterday I worked on the graphics that they are presenting today, and tonight I need to put them on-line to our internal website for the science team. I attended the morning sessions (which were mostly about our upcoming ninth orbit, which will last about 90 days--far longer than most of our orbits) because they were talking about schedules and sequences that I will be working on in the near future.

For the rest of the day I worked on archiving our "uplink" planning materials. "Uplink" refers to what we send up to the spacecraft ("downlink" is what the spacecraft sends back to us). There is a lot of work that goes into figuring out what exactly will be sent up to Galileo, and we want to make sure that all of that work is preserved. Archiving is a large task that requires three or more types of software and different types of hardware. While the project is active we keep current copies of information and sequences that are commanded to the spacecraft on our UNIX computer system. When the project ends the files will be transferred to the NASA archives that are accessible by the public. While we were creating a new piece for the archive we noticed that the file sizes were not big enough. Sure enough the files were corrupted! I had to redo several sequences that were already archived and it will take me the rest of the week to correct it. Perhaps it will even take longer depending on the state of the damage. At least we found out *now* that information was missing--it would have been much harder to restore the lost portions years later.

I am just back from my 15-minute lope that takes me on the horse trails around two of JPL's boundaries. I use this time alone at the end of the day to reflect on the events of the day. I usually also remember two or three more things to finish up before I can go home.

On the trail I looked up at the glow where the sun had been. It was the sun that changed almost everything I worked on today. It started with a voice on the network from the station in the California desert that was tracking the Galileo spacecraft. The voice was calling our mission controller whose area is three floors below my eighth floor office. The station operator at Goldstone said her equipment had "lost lock" on the signal coming down from Galileo and she had been unable to reacquire it after several attempts. My attention perked up.

In my role as the telecommunications systems engineer on the Galileo flight team, I make it my responsibility to know how the spacecraft is communicating with the earth. Besides my personal computer, I have an engineering workstation on which I can display various measurements about the two radio links with Galileo. These are the "uplink" (the signal that we send from earth up to Galileo that is received by the spacecraft) and the "downlink" (the signal that Galileo sends us that is received by the tracking station). Besides my telephone, I also have this voice communications assembly to hear the station operators at the three Deep Space Network sites in Australia, Spain, and California.

Before long, the mission controller called me and asked if I was following the situation. At that point, we didn't know why the station couldn't decode the downlink. Perhaps something had happened at the spacecraft to change the signal. Or there could be some problem with the station receiver software. But, most likely, the problem was with the sun. Since Galileo's position in the sky right now is still quite near the sun, the sun's radio emissions sometimes interfere with the spacecraft's radio signal. Several days this week, the stations in California and Australia had trouble receiving Galileo's signal. Most of the data matched what we expected if the sun was interfering. Some didn't. And there was the fact that a new version of the receiver software was installed at the Australian station just before the "track" on Tuesday (February 4th). That day, we lost 47 frames (over three hours) of digital data. If all was well, we shouldn't have lost any.

When the mission controller asked for my help to diagnose the problem today, I called up a graph showing what's known as receiver phase error data. Radio waves, when they are undisturbed and easy to receive, can be likened to the waves in a calm ocean, having regular peaks and troughs. If you are in a boat when the ocean is disturbed by a storm, the surface builds up into higher peaks and deeper troughs. Not only that, the spacing between the wave peaks, and even the direction the peaks travel in, become irregular. In the same way as the boat and its passengers sense a stormy ocean, the phase error measurement gives an indication of how irregular the radio waves have become. It thus tells me how disturbed or difficult it s going to be to receive the downlink.

On my workstation screen, I could see large phase errors beginning about the time the station could no longer decode the signal. It surely looked like solar interference. I had e-mailed Richard Woo, a solar radio scientist at JPL, last night. Richard was just one of the people I worked with during the week, each with his or her own area of expertise. One member of the receiver development team, Robert Kahn, faxed me plots of the difference in phase of the signals received at California and Australia at the same time. This was a clue. Another member, Sue Finley, brought over plots of data of the signal processed through an algorithm; she said it looked similar to other times the downlink experienced solar scintillation.

Wade Mayo and Ray Piereson, members of my Telecom Unit, queried the project data base to produce statistics about the decoding process. Each set of statistics is a block of words (such as "bit rate", "signal level", and "number of corrections") along with numbers (such as "20", for 20 bits per second, and "-168 decibels" for a signal level.) Each block of words and numbers applies to one frame of data. Remember, we lost 47 frames (and successfully decoded 3 frames) on February 4.

The statistics baffled us. The information didn't match previous solar effects. Because not all of our information was consistent, we still didn't have a clear cut idea what was causing the problem. Even if the equipment on board the spacecraft was OK, we were worried that this problem could continue or occur again, causing us to lose still more data. Each scientist whose experiment depends on receiving particular data would be upset if the lost frames happened to contain THAT data.

The possibility of an equipment problem on the spacecraft always worries me the most, puts that feeling of dread in the pit of my stomach. All of us on the flight team tend our spacecraft with great care. We feel bad enough when anything causes science data to be lost. It can be devastating when an "anomaly" occurs, when some part of the spacecraft breaks down, threatening the mission. I would feel quite uneasy until the station could get the data in "lock" again. And I wouldn't really feel released until we were more certain of the problem's cause.

I am an engineer. But I need to describe a little more science here. Radio waves and light waves are of the same electromagnetic nature. It's just that radio waves are much longer than light in wavelength. Have you ever looked at another person through the clear but shimmering air above a hot fire? The person's figure you see is distorted by the shimmering. Even without smoke you can't make out details as well as through clear air. Now imagine that instead of looking at another person, you had a large mirror on the other side of the fire and were looking at yourself. Your image, passing through the disturbed air region twice, would look that much more distorted. It's the same with our radio waves when they pass close by the sun on their way from the spacecraft near by Jupiter. Charged particles, the "solar wind" flowing outward from the sun, create an effect on radio waves much like the heat from a fire disturbs the air above it. The effect is intensified if we send an uplink to the spacecraft, and the spacecraft "reflects" the distorted signal back as the downlink.

It so happens we were sending an uplink this morning. The mission controller and I agreed that we should turn the uplink off. That way, we would receive a signal that had passed near the sun just once. It takes a radio wave over 50 minutes to travel one way from the earth to Jupiter now. We would have to wait twice that long to see if our idea worked. I began to feel some relief when my phase plot showed a large decrease at the expected time. And the relief was still greater when the voice from Australia announced they had "Reed-Solomon decoder successful." We knew then for certain the spacecraft was OK.

My phone rang this afternoon just as the sun was setting. It was solar radio scientist Richard Woo, apologizing for not getting back to me sooner, but he too had had a very busy day. He said that there had been a very large mass ejection from the outer portions of the sun (the corona) late on Monday (February 3). Traveling at 1000 kilometers per second, it would take this huge blob of hot plasma 9 hours to intercept the path between the earth and the spacecraft, where it would create havoc with our radio signal. The time of the coronal mass ejection (CME, as he called it) matched when we lost our data. Bingo!

Richard Woo told me there is a site on the World Wide Web [the URL of the home page is http://lasco-www.nrl.navy.mil/lasco.html, and click on "movies"] where you can watch a movie of the "Feb 3 CME". Oh, dear! I have to get some viewing software into my computer before I can do that.

My phone rang again just as I started this journal page. Richard Woo again. Though he had people waiting for him, he wanted me to know he had confirmed that there had been a "great" CME today. "Maybe great for solar scientists," I mutter, "but not so great for Galileo telemetry or the people who depend on it." Richard is excited by these events. He is coming in this weekend to correlate its timing with Galileo radio signal data type called doppler. I gave him the time the California station lost the Galileo data signal. We'll tie the loose ends up early next week. I stopped by the office of the Galileo mission director, the second-in-charge, to tell him of the CME. He said he will sleep better this weekend knowing we understand the data loss.

Now I'm going ride my motorbike the nine miles home to Sierra Madre. I expect to sleep well tonight also. Sunday, my wife Barbara and I plan to go to a movie, "Hamlet", that's playing in Pasadena. She said it's four hours long. I have to decide if I'm going to take my beeper, the one I have as a member of Galileo's anomaly resolution team. Yes, I decide, I will wear the beeper, but I'll put it on "vibrate" mode.

I wonder what new telecom problems I will work on in the new week.

This week is the final week for data playback from Galileo's previous encounter with Europa. This can only mean one thing! It is time for another satellite encounter. At the end of this week, on the evening of February 16 (PST), Galileo will start executing the sequence of commands required to perform another encounter with Europa, the second of three scheduled during the orbital tour.

In the final scramble for data from the previous encounter, the playback plans for this week include a variety of data from many different observations. Some of the data returned during this week will again be used to fill in gaps caused by solar conjunction. Other portions will expand on partial data sets already return in earlier weeks. New data sets complete the plans for this week.

Europa data includes high resolution observations of dark material and regions with maculas as well as observations taken to map Europa at a global level. High resolution fields and particles data from Galileo's flyby of Europa are also returned this week. These data will be used to understand the interaction between Europa and Jupiter's magnetosphere.

Io observations are returned containing data used to monitor volcanic activity while others will be used to understand what happens on the surface of Io as it moves in and out of sunlight as occurs when sunlight is blocked from getting to Io by Jupiter. Observations of Jupiter continue to include data describing the "hot spots" in Jupiter's atmosphere. Playback plans are rounded off by including observations of Jupiter's main ring, and the minor satellites Amalthea and Thebe.

Preparations continue this week to prepare for Galileo's next encounter. Early in the week, the spacecraft will perform an turn designed to keep it pointed toward earth. These attitude maintenance turns are required periodically as the spacecraft and the earth drift relative to each other in the sky. The first set of commands for the next encounter will be sent to the spacecraft this week. This set of commands will control Galileo's activity from February 16 through the end of February 20. A second set of commands will be sent to the spacecraft before February 20 to control the spacecraft through the end of the encounter (February 22). Optical navigation images will continue to be taken this week. These images will aid navigators in determining how well the spacecraft is following the desired path through Jupiter's system. This type of information will be used to plan the next orbit trim maneuver.