PART 2: Live Television Programs Coming
PART 3: Television on the Internet
PART 4: Journal Update #1: Anticipating Pathfinder's First Weather Report
PART 5: Journal Update #2: Ready or Not, Here They Come!
PART 6: The Schedule on Landing Day
PART 7: Subscribing & Unsubscribing: How to do it!
BEHIND THE SCENES AT JPL
Over the next week, surrounding Pathfinder's landing on Mars, we will bring you a series of special reports. These special reports will provide a glimpse behind the scenes at the Jet Propulsion Lab as the excitement of the Pathfinder mission unfolds. Look for these stories in your email box via this updates-lfm list. The first should be coming within a few hours. As well, the stories will be available at the top of the Live From Mars web site (http://quest.arc.nasa.gov/mars); we hope that some of these web issues will also be illustrated with pictures from JPL. Stay tuned....it promises to be an eventful week for all of us.
LIVE TELEVISION PROGRAMS COMING
Don't forget that July 6 and July 9 bring two new Live From Mars television broadcasts. Each show is two hours long (from 2:00 - 4:00 p.m., Eastern); the programs will originate from NASA JPL-Pasadena,CA, the American Museum of Natural History-New York, and museums and science centers around the country. More information can be found at http://quest.arc.nasa.gov/mars/teachers/tg/program3 The telecasts can be found on some local PBS stations and via satellite. The remainder of this section will provide additional details. The easiest route to seeing the broadcast is likely to be via your local PBS station. However, many stations will carry the programs on tape delay or not at all. Please consult your local listings for the PBS programming options in your area. Using a satellite dish, three different options exist. NASA-TV plans to air the programs but these transmissions can be preempted by updates on the Space Shuttle/Pathfinder missions and other factors. NASA-TV is found on GE-2, Transponder 9C at 85 degrees West longitude, vertical polarization, with a frequency of 3880 MHz, and Audio 6.8 MHz. A backup plan is in place utilizing another GE-2 transponder not subject to preemption. Tune to GE-2, C-Band, 85 degrees West, Transponder (channel) 21, vertical polarity, frequency of 4120 MHz, and Audio 6.2 & 6.8. Finally, the main PBS satellite will also carry the programs. Although the first program (July 6) will be carried live, the second program will be delayed and broadcast on July 10 from 11:00 a.m. to 1:00 p.m., Eastern. The specifications for this transmission are: Telstar 402 R, 7 Lower, 89 degrees West, Frequency 11895 Vertical, 6.2 & 6.8 Audio.
TELEVISION ON THE INTERNET
Besides the options listed above, the television shows will also be carried in various formats over the Internet. Although these options do not provide broadcast-quality reception, they do provide an option for those otherwise unable to receive the programming. The following page lists more details about the Internet options: http://quest.arc.nasa.gov/mars/video/online7-6.html Audio and video of the broadcasts will be available via CU-SeeMe at http://space.rice.edu/hmns/dlt/videosched.html#next RealAudio at http://www.cotf.edu/program/live/touchdown/ Audio only will be available using Real Audio. The details will be provided immediately before the broadcasts at http://www.cotf.edu/program/live/touchdown/ In addition, if the programs are carried on NASA-TV (assuming they aren't preempted), they'll be available over the MBONE. See the MBONE scheduling program (SDR) for details.
MARS TEAM JOURNAL UPDATE #1
Anticipating Pathfinder's First Weather Report [Editor's note: Jim Murphy is a scientist who develops numerical computer models of the Martian atmosphere. These computer models are very similar to the computer models used for forecasting weather here on Earth.] Jim Murphy June 18, 1997 I've been very busy working on completing the software that's needed to convert the signals from our wind sensor instrument, onboard the Pathfinder spacecraft, to wind speed and wind direction. The wind sensor sits on top of a mast about 3 feet (1 meter) tall. The mast is currently laying down and will hopefully pop up after Pathfinder lands. The first measurement should be completed by about 2 p.m. Pacific, July 4, while the mast is still laying down. We'll take this measurement just to make sure things are working. Eight hours after we land the mast should spring to an upright position and we'll start measuring winds about 3 feet above the ground. We expect to receive the first real wind information between 6 and 7 p.m., Pacific, July 4. What we expect to find at the Pathfinder site is based on what Viking Lander saw during a similar season at a nearby location (Pathfinder's site is about 1000 km (600 miles) from where Viking landed): winds on the order of 5 - 8 miles per hour. We're not worried about dust storms because it's the middle of summer on Mars and the climate suggests that there are not big dust storms during this time. [Editor's note: Soon after Jim wrote this, the Hubble Space Telescope observed a dust storm on Mars. Therefore the possibility of a storm may not be as remote as Jim suggests.] Our wind sensor has six wires that are spaced around a cylinder about the size of a spool of thread. Each of those wires will get hot when we turn the electricity on. With wind blowing past the cylinder, some of the wires are going to be in front of it, as it sees the wind, and some will be behind it. The wires in front of the cylinder will get cooler than the wires behind it because the wires in front will have a faster wind going by. By measuring how hot and cold the wires are, we will get some indication of the wind speed. And by figuring out which wires are hot and which ones are not as hot, we'll get an indication of wind direction. Our main science sampling will occur about every half hour when we will get about 3 minutes worth of measurements. We'll turn the sensor on for 3 minutes, collect information and then switch it off. Thirty minutes later the process will be repeated. Each day we'll get 51 three-minute samples. Just because we know the temperature range on Mars, that doesn't immediately tell us what the wind speed is. We did some testing in a wind tunnel here at Ames (run by Greg Wilson) where we turned our instrument on at different wind speeds under conditions that were Mars-like, e.g. very low pressures. We were able to do the calibration in which we knew the wind speed and the temperature, so we were able to make a relationship between the temperature of the wires and the speed of the wind. The data we got in the tunnel aren't perfect because, as you've probably experienced, things never go quite the way you plan them. So we also did our calculations on a piece of paper and that told us what the approximate temperatures should be. We're now going back and redoing those calculations to make sure that we have consistency between what we can calculate using our hand calculator and a piece of paper and a pencil and the temperatures we saw in the wind tunnel. After that it's just a matter of finding a straightforward way of taking the temperature and converting it to wind speed. If we did measurements at 3 meters per second, and at 5, 10, 20, 35 and 50 meters per second, we could draw a curve through those points on our plot. We can then try to fit a mathematical equation to them. So rather than using our eyes to look at every temperature and then go to our curve and pick out what the wind speed is, we can use some math to spit out the corresponding wind speed. The wind-speed data will allow us to see what the winds are at a third location on Mars compared to what the Viking landers collected 20 years ago. We'll also be able to compare different weather processes: cold fronts and warm fronts as they move through an area, winds that flow up and down valleys, which we saw happening at the Viking Lander 1 site. We'll also be able to tell if things are different on Mars: if there's less dust in the atmosphere as some of the recent observations suggest, and how that affects the weather. We're interested to see if the wind blows strong enough at the site to lift dust off the ground. We know there's dust in the atmosphere and we know there are various sites where dust rises. What we also want to know, is this specific site one of them? While Viking measured wind, temperature and pressure, it only measured the wind and temperature at single points above the surface. On Pathfinder the wind sensor sits on top of a 3-foot-tall mast from which three wind socks hang. Pathfinder will give us new information about how wind speed changes the closer it gets to the surface. The mast also houses three thermal-couples, or temperature-measuring instruments hung at three different heights. From this information we will learn how heat is transferred from the surface vents and also how energy or momentum are transferred from the atmosphere to the surface. Because the surface tends to drag on the atmosphere it tends to provide most of the heat input to the atmosphere. Understanding the climate and the weather on Mars is an absolute must before humans can land there. This is easily accomplished by taking measurements at several different locations. If a spaceship landed on Earth and measured temperatures in San Francisco, it wouldn't be an accurate representation of Earth's weather. It's the same on Mars. With Pathfinder, we'll soon have three points of data collection rather than two, so we'll have increased our knowledge by 50 percent! We'll receive our first Mars temperature measurement on July 4 at 7 a.m. My guess is that it'll be 190 degrees Kelvin, which is about -110 or -120 F. By about 10 a.m. temperatures will start to rise to 205-210 Kelvin. The temperature should peak around 1:30 or 2 p.m. at about 250 Kelvin. Then the temperature will start to drop fairly rapidly so that by 6 p.m. it'll be down to 220 Kelvin (-60 degrees F). There is a much larger daily temperature range on Mars than we see on Earth. Think about it this way: If you put a small amount of water in a pot on the stove it heats up quickly. The small amount of water is Mars' atmosphere. If you put a lot of water in the pot it takes longer to heat up because there is more water, which is Earth's atmosphere. I'm really excited about being one of the first people to look at the data and to realize that things are working and that we are actually getting a glimpse of what's happening on Mars. I actually got to see the wind sensor instrument on the spacecraft. I didn't touch it, but it was within 12 inches of me. What's really going to be exciting is when the rover drives off the lander and turns around to take a picture of the spacecraft.
MARS TEAM JOURNAL UPDATE #2
Ready or Not, Here They Come! [Editor's note: Matt Wallace is one of two people who coordinates the operations of the Mars Pathfinder rover. First he must help the rover get off of the lander. Then he will send sets of instructions to the rover about where to go, what experiments to do, and which rocks to investigate each day. This may last for many weeks.] Matt Wallace June 24, 1997 We just finished a couple of sets of operational readiness tests. We had a full-up test about a week-and-a-half ago, where we had all the participating scientists and all the operations engineers come to JPL where we went through four days of operational testing, simulating the first four days on Mars. It was really exciting! We have a sandbox here that simulates the Martian environment, and hardware that looks and acts just like our flight hardware. We have a rover that's really a flight spare, so it's very high fidelity. We did a lot of really good testing, which included waking up the rover and letting it go through its self-assessment and health checks and making an assessment from the lander images to determine if it was safe to deploy the ramps. Once we made that assessment we deployed the ramps and the rover stood up and locked into an upright position. We took a few more pictures to make sure the ramps unfurled and then the rover traversed down the ramps onto the surface of Mars. This test went better than any of the tests we've done so far. This really was a good experience! Pathfinder lands on Mars at about 10 a.m. local time on July 4. We get our first transmission session at about 2 p.m. on the low-gain antenna (rather than the high-gain), so our downlink period will be rather slow. But during that session, which lasts about 50 minutes, we'll get information from the rover. It'll wake up when it's commanded by the lander and it'll go through a self-assessment and transmit the data to the lander, which in turn will relay it back to us during that session. Somewhere around 2:45 p.m. we'll see the first rover telemetry data. We'll have a bit of a wait before we can turn around and send our first set of instructions because the lander will have to go through a few of its operations. Shortly after landing it will do a sun search with the camera so it can figure out its orientation and point the high-gain antenna. That will take about three hours. Sometime around 4 p.m. we will receive our first high-gain session and will activate a sequence to stand the rover up. There is a whole list of things we have to look at before we'll tell the rover to egress down the ramp. First we'll look at the tilt of the ramp to make sure it's not too steep for the rover to drive down. Then we'll look to make sure the ramp isn't twisted because if it is, the rover could fall off the sides. We'll check to make sure the airbag material has properly retracted. If it puffs up and gets up around the sides of the ramp, there's a potential for the rover's wheels to snag on material while egressing down the ramp. We'll have to look for rocks that may impinge on the ramp and cause it to twist. We'll look for rocks down at the base of the ramp to make sure that once the rover actually gets down to the surface, it can go somewhere! The rover can traverse over small rocks, lower than the height of its wheels, which is about 8 cm. Once the rocks get much than that they become hazards rather than obstacles. During our first week on mars, we intend for the rover to stay very close to the lander, just because we'll have a better idea of the obstacles in the terrain of the lander images and the area directly around the lander. I think we're going to find that there are a lot of very interesting rocks and soils within just a couple of meters. If the mission lasts several months there's a possibility that we'll traverse outside the visual range of the lander. The rover carries three experiments: a spectrometer, a dust experiment and a wheel-abrasion experiment. The primary instrument is the spectrometer, which is mounted on the rover's back. We'll use it to determine the elemental composition of the soil and the rocks by putting the spectrometer down on the soil and the rocks. The dust experiment sits on top of our solar panel where there is a small sensor with a coverglass that can be moved back and forth to determine how much dust is building up. The wheel-abrasion experiment is on the rover's right, middle wheel. There is a strip of metal that contains different coatings and metals. We're going to turn that wheel while holding all of the others in a fixed position. We can turn that wheel and look at the way in which the metal coatings abrade. This will give us an indication of the roughness and granularity of the soil and sand. Another whole set of experiments we're going to do is the soil mechanics experiment. It's similar to the wheel-abrasion test, but slightly different in that we'll turn the rover's front and rear brake wheels one at a time, a number of revolutions, while holding the other wheels fixed. This will dig a wheel down into the soil and by looking at that hole, geologists and scientists can determine a lot about the internal coefficient of friction and cohesion. It's an interesting way to use the rover's hardware to get good science data! The rover will not specifically look for life on Mars. The Mars Pathfinder program was designed before the Mars meteorite rock was found, so it was not specifically designed to look for life. But it will tell us quite a bit about the geology and the effects that water may have had on the planet. It will also tell us a lot about the elemental composition of the soil and the rocks and whether or not those conditions were actually conducive to life at some point in Mars' history. The rover's primary mission will last seven days, but if we go seven days there's a good chance we'll last at least 30 days, which is the primary mission span of the lander. The 30 days are limited by the lander battery. The rover's seven-day primary mission is a function of the thermal cycle and the unknown effects of thermal cycling on the rover. It gets extremely cold on Mars--down to -120 C at night and as high as 20 C during the day. That's a pretty big swing! There's a possibility that the mission will continue longer than 30 days. It will definitely go on as long as the hardware survives. We've even got some long-range plans out to a year!
THE SCHEDULE ON LANDING DAY
On July 4 NASA's Mars Pathfinder spacecraft and its Sojourner rover will enter the Martian atmosphere. If all goes well, the craft will survive the entry and landing and be able to right itself. The flower-like lander will then open its petals. Several hours later, the Sojourner rover will be deployed. Here's a schedule of the day's activities: Time (PDT) Event 07:00 JPL press briefing 08:45 JPL landing commentary begins 09:51 Mars atmosphere entry 09:53 Parachute deployment 09:55 Landing 10:01-11:01 Receive first indication of a successful landing 13:55 Receive first engineering and atmospheric entry data from lander 15:30 JPL press briefing 16:35-17:30 Receive first images of surface from lander 18:00 Release of the first color panorama image of the surface 21:00 Rover deployment 23:00 JPL press briefing
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