Live From Mars was active July 1996-December 1997.
WEBCHAT WITH JACK FARMER
Weekly WebChats offer an opportunity for your students to virtually meet the people on the front lines of the Mars exploration adventure. Teachers have reported that the chats really enliven students' enthusiasm. This week we feature the issue of life on Mars. Wednesday, November 20 from 8-9 AM Pacific (11AM - noon Eastern) Jack Farmer is an exobiologist, so he is interested in the search for life outside of Earth. His background is in paleontology (fossils) and geology (rocks). To get in on this fun, point your Web browser to http://passporttoknowledge.com/lfm/events/interact.html and follow the links to the chat room for experts. If you plan to participate in this event, please RSVP to Andrea by sending a brief email note to firstname.lastname@example.org telling her which sessions you plan to join. This RSVP is very important, since it will allow us to ensure that the chatroom does not become too crowded. To best prepare, please have your students read the biography of Jack before the WebChat session: http://passporttoknowledge.com/lfm/team/farmer.html
CHALLENGE QUESTION #4: WINDSTORMS ON MARS
Recently we asked: Sometimes, the winds on Mars can blow at hundreds of miles per hour and kick up giant dust storms that blanket the entire planet. Yet, if you stood on the surface of Mars at one of these times, you would probably not be blown over. Why? ANSWER from Bill Gutsch: Martian winds can be swift but the Martian air is so thin that it packs very little punch. In more scientific terms, this means that there wouldn't be nearly as many air molecules striking you per second in a Martian wind storm as there would be in a similar storm on Earth. Far fewer molecules translates into much less pressure (force per square inch) pushing against your body. Such "thin winds" can still create giant dust storms, however, because the Martian surface dust is very, very fine and so can easily be lifted into the Martian sky. A listing of the students who submitted answers to this Challenge Question will appear on the LFM Web site shortly.
Last week we asked: The largest crater on the larger of the two Martian moons, Phobos, is named Stickney. Ms. Stickney was not an astronomer but she played a critical role in the discovery of the Martian moons. Who was Ms. Stickney and why did she have this prominent surface feature named after her? ANSWER from Bill Gutsch: The two moons of Mars were discovered by astronomer Asaph Hall at the US Naval Observatory in 1877. According to the story, after many nights of searching for satellites that might be in orbit around Mars, Hall was ready to give up. His wife, however, encouraged him to give it "one more try." That night, Hall found Deimos and Phobos, the two Martian moons. In honor of her encouragement, without which Hall might not have made his discovery, astronomers in the 1970s decided to name the largest crater on Phobos "Stickney" -- Mrs. Hall's maiden name. A listing of the students who submitted answers to this Challenge Question will appear on the LFM Web site shortly.
Here is our last puzzler: The Mars Global Surveyor (MGS) took off in November and is scheduled to arrive at Mars between Sept. 11 and Sept. 22, 1997. The Mars Pathfinder (MPF) takes off sometime in December. No matter when it leaves, it is scheduled to arrive on July 4, 1997. Why does the Pathfinder get to Mars earlier, even though it leaves later. And how can the Pathfinder have an exact arrival date even though its liftoff date may vary? You are invited to send original student answers to us. We will list the names of these folks online and token prizes will be given out to a small number of the students with the best answers. Send your answers to Jan Wee at email@example.com. Please include the words "CHALLENGE QUESTION" in the subject of the email.
Last week we announced an email service to answer student questions about Mars and the missions there. See Updates message LFM #9 or http://passporttoknowledge.com/lfm/ask/question.html for more details. Many people are sending in good questions, and we are happy about that. But many teachers are also demonstrating that they aren't too good about following directions (a trait shared with students, me and the rest of humanity). But please try extra hard in this case; otherwise, the entire question-amswering system will bog down. We requested: If you or your class have several questions which are unrelated, we ask that you please send each unrelated question in a separate email message rather than as one message with many different questions. While this may be inconvenient, it is important because it will help us to keep track of the questions and ensure that no question remains unanswered. Messages that do not follow this request will be unnecessarily delayed as we go through the extra step of splitting up the messages ourselves. Instead of sending one email with these questions: Would it be possible to drill deep enough to find drinkable water on Mars? What do the scientists at NASA plan on doing with the life forms, if they find any? Does Mars have seasons like Earth? Please send three separate emails with one question per message. If you are sending so many questions that this becomes very burdensome, consider doing more work in class to decide on the most important questions and narrowing the number which you send to NASA.
By now, most folks probably know that the Russian Mars-96 mission ended in disaster. After a successful liftoff on Saturday, the booster rocket on the fourth stage failed to ignite. This booster was to have sent the Mars-96 spacecraft on its way towards Mars. Instead, the spacecraft remained in an Earth orbit and tumbled into the Pacific Ocean between Easter Island and the Chilean coast early Monday at 4:32 AM Moscow Time (Sunday in the US). The responsible specialists are analyzing all available data in order to define the reason for the failed insertion burn. They will share this information as it becomes available. This is very sad news indeed for everybody interested in new discoveries about Mars. More information about the failure is available: http://cnn.com/TECH/9611/16/russia.mars.update/
[Editor's note: Guy Beutelschies is a test director for the Mars Pathfinder project. He leads a team that tests the spacecraft to make sure everything works. Here he describes his activities in September] FIXING LITTLE PROBLEMS ON PATHFINDER AND MUD VOLLEYBALL Guy Beutelschies - http://passporttoknowledge.com/lfm/team/beutelschies.html Week of September 2, 1996 We finished up our tests on the equipment underneath the thermal enclosure. One of the activities was to install a fresh silver zinc battery. This was a potentially dangerous operation because the battery is very powerful. If someone accidentally touched the pins on the power connector, it would release enough current to injure or even kill them. This is similar to touching a live wire in your house without the protection of fuses or circuit breakers. We also tested the telecommunications equipment. This is used to receive commands and send down data from the spacecraft after we launch. A bunch of us went out on Friday night and ended up at a restaurant that had Karaoke singing. If you've never heard a bunch of engineers singing, you're lucky. We went water-skiing the next day. Week of September 9 The mechanics put the thermal enclosure back on and mounted the high-gain antenna and the camera on top of it. We then started our tests to make sure that those devices work as expected. The high-gain antenna actually moves to point at Earth. We moved it through its entire range of motion to see if it would hit any part of the lander. Turned out it did! One of the engineers did not take into account how far a particular screw head came out from a nearby bracket. The antenna would have just grazed the top of the screw, which would have messed up the pointing. We did a quick analysis on the screw and determined that we could remove a small amount of material from it without affecting how it holds the bracket in place. So we got a file and filed down the screw just enough so the antenna would not hit it. Another test we did was to make sure that when we pointed the camera and the antenna, they actually pointed to where we specified. To do that we sent commands to point them in a certain direction and then used a set of instruments called theodolites. These are basically small telescopes that give very accurate information about where they are pointed. They are often used by surveyors that you see out on the city streets. We pointed the theodolites at several points on the lander to determine a reference coordinate system. We then pointed the theodolites at several marks on the surface of the antenna, which told us where the antenna was pointed relative to the rest of the lander. We will use this information to make sure that the antenna points at Earth when the lander is sitting on Mars. We repeated this procedure on the camera so that we know exactly where the camera is pointing relative to the commands we gave it. This information will be used to determine where objects (like rocks) inside an image are located in relation to the lander. The rover people are very interested in this information because they plan on using those pictures to tell the rover where interesting rocks are located and how to get to them. The mechanics then connected the petals to the lander. That allowed us to run tests on the equipment located on the petals. The first test was to shine light on the solar arrays to make sure that they were hooked up correctly. We made sure that they were indeed providing power to the rest of the lander. We then put the opaque covers back on to make sure that the lander did not turn on when we weren't expecting it. Another test we ran was to verify the atmospheric structures instrument mast. This mast lies flat against the petal on the way to Mars and then pops up once we are on the surface. It has temperature sensors to tell us what the temperature is at points from right next to the ground up to about four feet above the ground. It also has a wind sensor on the top of it to tell us wind speed and direction. The atmospheric structures instrument also has a pressure sensor located on the base petal. This will track the pressure changes like a barometer to see how it changes during the day. We also verified that the radar altimeter was working correctly. This device is used as we are descending through the atmosphere to tell us when we are about to hit the ground. It signals the airbags to inflate to cushion our landing. Part of our week was taken up by hurricane preparations. Hurricane Fran was heading right toward us so we made plans to evacuate. The hurricane turned north and missed us at the last minute. That weekend, a couple of us played in a mud volleyball tournament in a nearby town to benefit the March of Dimes. They basically dug several pits and filled them with water, which soon turned into mud. We didn't win. Week of September 16 We were now ready to close the petals so that we can install the airbags. Before we did this, we wanted to do a full inspection to make sure that everything was ready. We even called down experts from the Jet Propulsion Laboratory to help us. We all went into the cleanroom and stood around the lander, looking at each piece of it very closely. We found a few wires on the bridle (which connects the lander to the backshell) were too close to part of the lander structure. We were worried that during launch these wires could be broken by rubbing against that structure. This is bad because those wires carry the signal to fire the retro-rockets, which slow us down right before we hit the surface. We spent a couple of days rerouting those wires. We got to see a shuttle launch. It was at 4:00 in the morning so we had to get up real early. It was worth it, though. The ground rumbled and the sky lit up like it was day. Several of us went on a charity 5K run for cancer research in Orlando, which is about an hour from Kennedy Space Center. It was raining so we didn't break any records. We also tried surfing over the weekend. The waves were too weak for any long rides but it was fun anyway. Week of September 23 The mechanical team installed the airbags, which took most of the week. All the electrical team had to do was to open and close the petals whenever the mechanics asked. This gave us a chance to test out the actuators used to move the petals, and the airbag retraction actuators, which are used to pull the airbags close to the lander after they are deflated. We went on another 5K run, this time right at Kennedy Space Center. The race was run right on the runway that the shuttle lands on. Luckily, no shuttles landed during the race.
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