PART 1: July WebChat Schedule
JULY WEBCHAT SCHEDULE
Tuesday, July 1, 2 p.m., Pacific, Bridget Landry 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. Tuesday, July 8, 9 a.m., Pacific, Jeff Plescia 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. Jeff will answer all of your questions about touchdown on the surface of Mars and the daily routines of the lander and rover. Tuesday, July 15, 7 a.m., Pacific, Peter Thomas Peter, a research scientist at Cornell University, studies pictures of other planets and satellites sent back by spacecraft. His particular interest is in Mars and how the wind shapes the surface by moving sand and dust, sometimes in global storms, and how the polar caps have affected Mars' geology and climate. Peter will fill us in on the current climate on Mars. Tuesday, July 22, 9 a.m., Pacific, Jack Farmer Jack is an exopaleontologist--a searcher for fossils on other worlds. His most important contribution to the Pathfinder mission to date was to recommend the landing site at the mouth of Ares Vallis (a large outflow channel). While it is unlikely that Pathfinder will discover fossil remains of ancient life forms, it may allow us to determine if the right kinds of rocks are present, that is, rocks of sedimentary origin that could harbor a microfossil record. Due to the large number of anticipated participants, it is necessary for you to register for WebChats in order to participate. All you need to do is RSVP to firstname.lastname@example.org no less than 24 hours in advance in order to reserve a space for yourself. You will receive confirmation of your registration and a password to enter the chat room.
MARS TEAM JOURNAL UPDATE #1
How to Write a Pathfinder Sequence [Editors note: David Mittman wears three hats: one as a flight engineer where he is responsible for the day-to-day operations of the Mars Pathfinder lander and the rover. As a mission planner, he tries to balance the requests of the various scientists and engineers who want the lander and rover to perform specific tasks. As a flight controller, David talks with the people in California, Spain and Australia who operate the Jet Propulsion Laboratory's Deep Space Net.] David Mittman June 23, 1997 3:15 AM -- Argh. Isn't Monday bad enough without getting up at three o'clock in the morning? I showered in the dark so as not to wake up the kids, got dressed and went off to work. (By shaving the previous night I figure that I got about 10 extra minutes of sleep!) Today I am a flight controller instead of a mission planner (see my previous journal entry). And while it's early morning here at the Jet Propulsion Laboratory in Pasadena, California, it's mid-morning in Madrid, Spain, where Deep Space Station 65 is located. Lucky Spaniards...eating lunch while I attempt to drink my first cup of coffee of the day. And what a day! Today's activities are likely to be worth getting up early for! Today we collect together all the work we've been doing over the last several months and send it all to the Mars Pathfinder flight computer. All the flight engineers have been developing "sequences" -- collection of commands executed in order by the spacecraft -- in preparation for landing. Our sequences have been tested using a test spacecraft located in our lab and during the many Operational Readiness Tests (ORTs) we've had over the last few months. These sequences have gone through many reviews and revisions (some sequences have been changed as many as 20 times as we've learned more about how to operate Mars Pathfinder). If you were a flight engineer, this is what you would see if you were writing a Mars Pathfinder sequence: 1997-186T10:02:51 IMP_CCD_HEATER("OFF") 1997-186T10:03:21 STORE_IMP() 1997-186T10:08:35 IMP_CAMERA_POWER("OFF") There, you've just turned off the Mars Pathfinder camera for the night. Thanks! Of course, the Mars Pathfinder flight computer can't read English, so we have computer programs translate these sequences of commands into something like this: C5A0 A572 0870 0000 A5C0 77A0 7003 A5C0 AB7A 7801 0000 Once the sequences are in a form that the Mars Pathfinder flight computer can understand, they need to be stored onboard in the spacecraft's memory. To get them to the spacecraft, we transmit them through space from Earth to the spacecraft. That's my job today, transmitting almost 300 different sequences to the spacecraft using the Deep Space Network's 34-meter antenna in Madrid, Spain. Traveling at the speed of light, each sequence takes 9 minutes and 40 seconds to arrive at the spacecraft. If you'd like to see where I work, take a look. I'm located just out of the picture off the bottom of the image. I'll let you know how it goes. I'm on duty until 2:30 PM today... 2:30 PM -- I'm about to go home for the day after a day of sending sequences to the spacecraft. A communications equipment failure here at JPL left us without spacecraft data for about 40 minutes but overall the sequence loading went well. Hopefully, technical glitches won't create these lengthy data outages on Landing Day!
MARS TEAM JOURNAL UPDATE #2
Thanks to Everyone! [Editors note: Bridget Landry is the Pathfinder deputy uplink systems engineer. She takes very complex, but general computer programs and makes them understand all the commands that the Mars Pathfinder knows.] Bridget Landry June 23, 1997 Walking around the floor today, rereading all the good wishes we have posted everywhere, I'm struck again by the support that has been offered so freely by so many. From the sheets signed by the Mars Global Surveyor personnel wishing us a "nominal day" for our launch, to the huge poster from the Galileo team, everyone at JPL has been positive and upbeat. But it doesn't stop there--letters from school children to their congress critters asking for more support for the space program, the "Martian Driver's License" sent to our rover drivers by one class, the enormous rocket with students' pictures and a "piece of Mars" for it to land on, the advice, the good luck wished to us by children, students, and people from all over--it's been overwhelming. I just hope that when that first picture comes down from Mars next Friday, everyone who has written, drawn, sculpted, or otherwise conveyed their support for our team understands that they have been a part of it; not just in taxes paid, but in the emotional energy, the reaching out, the curiosity, the drive to know more. Yes, spacecraft require money to be built, but they also need people--those cheering and watching no less than those with the wrenches and those at the keyboards. Knowing how much everyone believes in us and is pulling for our success really brings out the best in us. Thanks so much!
MARS TEAM JOURNAL UPDATE #3
Making a List, Checking it Twice... Bridget Landry June 22, 1997 In reading over my last journal entry, I realize how much has changed. We've done two more tests, both of which went quite well. Many of the sequences we will use in the first few days on Mars are done, tested and onboard the spacecraft. We're now pulling a "Santa Claus"--we're making lists and checking them twice, tweaking sequences, making sure that all the "that's a good idea; we'll do that right after this test" things actually get done and tested. We're putting finishing touches on procedures: lists of what a particular job entails on a very detailed and step-by-step level. Not everything we'd like to do is done; moreover, not everything will get done. However, all the important things, the necessary things, the critical things WILL get done. In all my years in the theater, there was never a time when I didn't want *one more* rehearsal. I've only rarely had a costume completely finished the first time I wore it. And I always mean to go back and clean up the code I write, to make it cleaner, faster, easier for someone to read and understand. But there is only so much time and money and energy--you do the things that matter most, until it's "good enough." Striving for perfection is a good and worthwhile effort. Perfectionism, expecting to actually attain perfection, can kill you. The trick, of course, is in determining where that distinction lies. That's where experience--your own, and that of folks who have done it before--comes in, helping you to prioritize.
MARS TEAM JOURNAL UPDATE #4
Getting Ready for the Big Day! [Editors note: Mark Adler is the Mars Exploration Program architect. What this means is that he spends a lot of time talking with scientists to understand in detail what the scientific goals of Mars exploration should be. In addition, he talks with spacecraft engineers to understand what's possible and with the technologists to hear what may be possible in the future. And finally, he chats with managers to understand what these things will cost, and what resources will be available, or what resources may become available in the future.] Mark Adler June 21, 1997 During the week of July 4, I will be one of many people interfacing with the media for the Mars Exploration Office. My job will be to help shelter the people who are actually operating the spacecraft from having to do a lot of media interaction so that they can continue to operate the spacecraft! I'm preparing for this role by trying to get a much deeper understanding of the Pathfinder mission, what's going to happen when and why, especially at the times we're not getting data back to tell us what's going on. For example, there will be a long period of time between when Pathfinder lands on Mars and when we'll get pictures back. People will want to know what's happening. I'll be able to tell them things like the panels should be coming down, the airbags are being sucked under or the high-gain antenna is setting up. Between 10 a.m., when Pathfinder lands on Mars, and 2 p.m. when we expect to receive the lander's first signals, I'll have to describe what operations the lander is going through because no spacecraft data will be received during those four hours. Around 2 p.m., which is sunrise at the landing site, if everything's working, we should get some signal back from the lander that says, "I'm here and ready to go!" Then, sometime after 4 p.m. the first pictures begin to arrive. Of course, this is all assuming that everything goes as planned! It rarely does. So, people here at the Jet Propulsion Laboratory are very busy rehearsing post-landing procedures. There are all kinds of contingencies and possibilities and events that are being rehearsed for possible different failures: what the lander team would do in a certain situation, how they would do it, what information they would get and how they would respond to it. The team is busy planning for all possible challenges. Team members are definitely excited but I wonder if they have had time to really think about the significance of what's going on. There are rehearsals 24 hours a day. A guy was in my office yesterday saying that he had been here 16 hours and fortunately his job was over because two hours before Pathfinder "landed" in the rehearsal. After the "test" landing his job was finished as he was responsible for the entry analysis and the aerodynamics of the landing. As far as what I'll be doing to help the Pathfinder team, I'll be prepared to assist with the media as early as July 2 until about July 5. I think I should set up a cot in my office because I have a feeling I'm going to be very busy. JPL is preparing to accommodate 19 microwave trucks, which will beam data back to their satellites for transmission to where ever in the country or the world the broadcast is destined. There will also be a lot of media as well as the public in downtown Pasadena at PlanetFest. Sponsored by The Planetary Society, PlanetFest is going to have a very large, multi-TV screen panel showing what's going on all the time. If I had to summarize the feeling here at JPL, it's a combination of excitement, anticipation and stark terror. :-) Obviously, excitement about landing on Mars for the first time in over 20 years. Anticipation about what we might learn, since every time we've sent a new spacecraft to Mars in the past, our view of the planet has changed. And lastly, stark terror of significant failure in a very ambitious mission that is both trying a new way to land on Mars and operating the very first wheeled robot to ever be sent to Mars. There is always risk in sending our robot agents alone out into the dark expanses of space and the vast uncharted surfaces of other worlds. But if it all works, and we think it will, then all of Earth will share with us the wonder of exploring a new world.
Mars Pathfinder Mission Status Report
[Editor's note: This press release was prepared by the Public Information Office at the Jet Propulsion Laboratory.] June 26, 1997 Mars Pathfinder, now eight days away from landing on the surface of Mars, performed the last of its scheduled trajectory correction maneuvers at 10 a.m. Pacific Daylight Time on Wednesday, June 25. The correction maneuver was performed in two phases occurring 45 minutes apart. The first burn, lasting just 1.6 seconds, involved firing four thruster engines on one side of the vehicle. The second burn lasted 2.2 seconds and involved firing two thrusters closest to the heat shield. The combined effect of both burns changed Pathfinder's velocity by 0.018 meters per second (0.04 miles per hour), which places the spacecraft on target for a July 4 landing in an ancient flood basin called Ares Vallis. Pathfinder is scheduled to land at 10:07 a.m. PDT (in Earth-received time). The one-way light time from Mars to Earth is 10 minutes, 35 seconds, so in actuality, Pathfinder lands at 9:57 a.m. PDT. If necessary, a fifth trajectory correction maneuver may be performed just before Pathfinder hits the upper atmosphere of Mars. The maneuver would be carried out either 12 hours or six hours before Pathfinder reaches the atmosphere at 10 a.m. PDT in Earth-received time. The flight team will make a decision to proceed with the final correction maneuver the evening before landing. A final health check of the spacecraft and rover was performed on June 20. All spacecraft systems, including science instruments and the critical radar altimeter, remain in excellent health from the last check about six months ago. The rover received a "wake up" call, woke up on command from the lander, then accepted a software upgrade. Flight controllers next loaded the 370 command sequences that will be required by Pathfinder to carry out its surface operations mission. The spacecraft is now ready to begin its entry, descent and landing phase. It will be commanded into that mode at 1:42 p.m. PDT on June 30 by an onboard sequence. Mars Pathfinder is currently about 180 million kilometers (111 million miles) from Earth and about 3.5 million kilometers (2.2 million miles) from Mars. After 202 days in flight, the spacecraft is traveling at about 18,000 kilometers per hour (12,000 miles per hour) with respect to Mars.
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