The Third Ilan Ramon Annual International Space Conference

Transcription

1 Israel Ministry of Science Culture & Sport The Fisher Brothers Inst. For Air & Space Strategic Studies The Third Ilan Ramon Annual International Space Conference January 30-31, 2008 Publication No. 39 May 2008 THE FISHER INST. FOR AIR AND SPACE STRATEGIC STUDIES FOUNDED BY THE ISRAELI AIR FORCE ASSOCIATION P.O.B 303, Herzlia, Israel Tel: Fax:

2 Roving Mars Ms Nagine Cox, JPL, NASA The human exploration program is obviously focused on the space station and on the space shuttle, while the other part of what NASA does is the robotic exploration of the solar system. The Jet Propulsion Laboratory in California used to be an Army facility from the 1930 s on, and in 1958 when NASA was formed, JPL was given the charter of robotic exploration of the solar system to complement what the astronauts are doing. So now any time you hear about a robotic mission it falls into four main phases and three of those are in support of human exploration. The first phase is when you pick a body like Jupiter and you send a fly- by mission, which is when a robotic spacecraft just goes by very quickly, and you get a quick glance at the planet. Phase two is an orbiter mission - we have a spacecraft orbiting Saturn right now, the Cassini has been there for a number of years. That gives you a chance to see the planet on a long term basis. Phase three is in-situ or sample return - that means you go up close, you either land on it like the rovers do, or you bring back a sample. All of those are in support of human exploration which you do after you send the robots. Mars has a special interest for us since humans have gazed at for many years, but also as a possible destination for future exploration. The robotic probes basically focus on following the water. Water is necessary for life as we know it, so our exploration focuses on where in the solar system might be the evidence of past water. The Earth and Mars are at their closest every twenty six months so we try to send missions in those time periods, try to visit on a regular basis, so we might have an orbiter lander was a remarkable year to send a spacecraft to Mars because the Earth and Mars were closer together than they had been in thousands of years so everybody wanted to go. The Japanese were sending a mission, the Europeans, the British were sending a lander and the United States was also going to send a mission. But the problem we had in December 1999 was that both American robotic missions to Mars failed. That was Mars Climate Orbiter and Mars Polar Lander. We did not know then why Mars prolander failed, but we knew that we needed to build

3 up a spacecraft in time to get it to launch in So we went back to a method that had worked in We had last landed on Mars in the 1970 s, then went back in 1997 with Mars Pathfinder and that was the first time we sent a rover, so this time we said, let's use the same method of landing since it worked before, only this time we will send a bigger rover. The objective of the Mars rover was to find out if there had ever been liquid water on Mars in the past. We set a robotic geologist - the rovers have large-scale cameras that help us get a view of where we are. The scientists say, oh look, there s an interesting rock, and we drive over with our wheels and then just like the arm described on the space shuttle, we have a robotic arm on the rovers, with a shoulder, elbow, and wrist. A rock abrasion tool or 'the rat' lets us look beneath the surface of the dust on top of the rocks, so we can actually tell what s underneath. We are solar powered and we communicate with the Earth through this high gain antenna or other antennas. We take the rover, we fold it out, put it inside this lander. The lander goes inside the back shell and the heat shield that attaches to the cruise stage, which is how we get to Mars. Developing this vehicle in three years was very complicated. From an engineering perspective, we had to do a lot of things for the first time, even though we thought we could use what we had used in 1997 because our vehicle was heavier this time, so we needed larger parachutes, larger air bags. Due to these complications we split up the team into a group focused on getting us to Mars, another group focused on entering and landing and then the team actually building the rover, and when you are trying to do something this complicated, it really helps to develop the hardware as soon as you can, in order do as much testing as possible. We worked for three years, got the rovers built, they were called Spirit and Opportunity. Spirit had its final driving test at the Kennedy Space Center and I remember that day, I was standing off to the side during this test, and we were all aware that this was the last time that Spirit s wheels would move on the Earth. Next time will be on Mars. Like any proud parents we took family photos and then we shifted them off to the Cape and got them ready to go. We launched them both in the summer of 2003 and then off we went for our seven months flight to Mars. This was actually a very busy time because we had two rovers on the way to Mars, while we were still finishing our preparations for entry and landing, in fact we were still riding some other flight software to get us there in time, as we needed every bit of time before landing on the surface and we also had the larger solar flare on record while we were flying to Mars, so we had to recover the spacecraft from the impacts of that radiation. Where were we going to land? The rovers are solar powered which meant we could only land in the equatorial region, and I should say that when we started up we thought we were building one rover. But about

4 six months into the project we got a call from NASA headquarters saying how about building two? We said okay and started working on it right away. We had the Opportunity to land in two different places on Mars and asked the scientists to pick two places where one could go and possibly be able to prove that there had been liquid water. This was a multi-year process. First the scientists would say: oh how about here? And the engineers would say that s like the Grand Canyon, no, no, how about here? Those are mountains no, no, the engineers wanted to go someplace safe and the scientists wanted to go someplace interesting - eventually we settled on Gusav Crater because you know the engineers wanted a place without a lot of slopes, air bag killer rocks, wind. We were looking for a place where the spacecraft could land safely. We picked the craters because we thought there might be a channel that might have water running into the crater and then Maredian Plonium where we found hematite from orbit. Hematite is a mineral that on Earth forms in the presence of liquid water. It s used in women's jewelry, it s like a grey silver stone and we thought that if we saw that from orbit, it will be a very good place to send the rovers. For our landing approach we would use a heat shield and a back shell, parachutes and air bags so the air bags cushion the rover on its landing. It takes six minutes to get from the top of the Martian atmosphere down to the surface. The CNN called it the six minutes of terror. We would enter the Martian atmosphere at about fifteen thousand kilometers per hour. We would spend the first four minutes slowing down just based on drag and that would slow us down to about fifteen hundred kilometers per hour, then the parachutes would slow us down further and at that point we can deploy the air bag and see the rover inside it. So now the air bags are deployed we fire the retro rockets to slow us down even further, cut the bridle and then let the rovers fall the rest of the way and bounce. These are not small bounces. These are five- storey high bounces and each of the rovers bounced over twenty five times; at that point we still could not communicate with the rovers, so we had to go through some more autonomous activities before we could talk to them, we had to deflate the air bags, unfold the lander and the rover then deploy the mast and the high gain antenna. At this point the rover is finally powered positive, firmly stable and able to communicate. The "six minutes of terror were over, the ground was back on the loop, and in those seven days we could stand up the rover and deploy it. This transpired on January 3rd 2004, a day I will never forget. We were kind of already tired from having worked so hard for the last three years to get the rovers ready and launched, and there was a lot of pressure on that day. President Bush had been planning to announce the plan to go back to the moon and Mars at the anniversary of the Kitty Hawk flights. But he decided to wait until after our landing to see if we were successful, while the British mission that was supposed to land on Mars just a week earlier had failed, and we were also very aware of the Columbia loss a year earlier

5 and how important this day was for the space program. What was happening on Mars that day was to be relayed to us through tones, not full telemetry. We got the tone that the parachute had deployed, that the bridle had lowered, that we found the ground and that the air bags had inflated, that the retro rockets had fired, the bridle had cut and the rover was bouncing and then we got silence for five minutes. Ten minutes pass and I am sitting in the control room with my colleagues thinking about all of the things you didn t have time to test. Fifteen minutes pass. Two thirds of the robotic missions to Mars fail. You can do everything right, everything that you can think of and still have a bad day on Mars. But that day everything went great. We were thrilled to get the images and then to just see the first image come down from Mars. It did not feel like a robotic mission, it felt like we were seeing Mars through our own eyes, through the eyes of the rover we had built. I was literally screaming Mars, Mars, Mars, everybody was screaming. We were so thrilled and in the days that followed I felt like the whole world was with us, this was our new neighborhood on Mars and this time we brought wheels, so the scientists were urging let s go here, let s go there, and when we saw these hills in the distance we knew immediately what we should do. We knew that those hills should be named in honor of our colleagues who did not return from their mission of exploration one of them is Ramon Hill. We wanted to bring a part of them with us so we left the rover and then we actually had six wheels on Mars, and then we set up our robotic arm to make our first contact with a rock on Mars and we got silence. Spirit had had a significant anomaly. It was actually in critical condition. We did not hear from the rover for a number of days. But JPL and NASA have over forty years of experience in figuring out how to help a spacecraft when it s in critical condition. Meanwhile we had another rover on the way to Mars at the moment, and as we have this major problem with one rover the other rover is about to land. It took us a while to figure out what was happening with Spirit, we regained contact and once we were able to talk to Spirit it went into a two year old mode, we would tell it to go to sleep and it would wake up, we would tell it to wake up and it would go to sleep. Spirit had had a problem with its flash memory but we were able to figure out what the problem was, get it back on track, we had almost full control of the vehicle on the same day that Opportunity was landing. For a short while it seemed we were going to lose the rover right after it landed, but we were able to recover it and get back to the business of landing Opportunity. Just because you landed one rover on Mars doesn t make the second one easier. This was the highest altitude landing ever attempted on Mars and we knew that there had been a global dust storm in December that changed the atmosphere density. Between the two landings we had to change the time when we deploy the parachute on Opportunity. I still can t

6 believe that Opportunity landed right there, in that crater. Just think, what are the odds of this? After all those bounces it got right into the crater. The crater had dug the hole for us, so this is like the Holy Grail of Mars geologist exploration because that rock is from underneath the surface of Mars. You could hear the scientists a few doors down screaming bad rock, bad rock, and bad rock. It was that significant that right off the bow was the very rock that will tell us what was underneath the surface of Mars. We put out the robotic arm and sure enough we started to see these little round nodules, which we were calling blueberries basically because they were minerals that we thought had formed in the presence of water and then the water evaporated away and we were left with these concretions. We finally found a spot which had a lot of blueberries and next to it no blueberries at all. Once we found that spot we could use our spectrometer and look at the blueberries- no-blueberries and actually get a spectrum of what it was made of; then we could tell it was made of hematite, just like we d seen from orbit. After we gathered this and other evidence we could actually tell that there had once been liquid water on Mars. That was what the rovers had come to find out, and within three weeks we had evidence that there was water on Mars. One of the other things we learned from this mission was how to live and work robotically on Mars, meaning we had to be on Mars time. The Martian day is approximately forty minutes longer than the earth day so the rover would wake up at eight a.m. on Mars local solar time everyday. If we wanted to come into work at the same time when the rovers were waking up we had to come in forty minutes later. That created all sorts of interesting aspects to the mission. The two teams were on the opposite sides of Mars and all were working on Mars time, thus we had a very different work schedule that separated us from our colleagues who were working on other missions because during the entire primary mission, which was three months, we were living on Mars time. Spirit was also teaching us how to drive on Mars. This was the first vehicle that was actually able to autonomously drive a good distance on the surface of another planet. Since the rover can drive itself there was an instance where Spirit didn t want to go into that indentation, so it went around. When driving autonomously we can now drive much faster than we used to, but in the beginning we were pretty slow. Spirit was not having much success when trying to find evidence of past water on Mars from the rocks down in the crater. We then decided to head for the hills and see if evidence could be found there. The rovers were designed to last only for three months, for ninety sols, a sol is a Martian day, and we didn t even know if we would make it to the hills because the warranty basically ran out on sol ninety. But we kept going and on sol 135 we made it to the hills and Spirit started to climb up in the hills and as soon as we did we started to see different kinds of rock.

7 Spirit became our first mountain climber on Mars, chugging up to try to get to the top of Husband Hill. Again we didn t know if it would make it but in August of 2005 after driving four and a half kilometers, when the rovers were designed to drive only one kilometer, it had gone four and a half kilometers, and we got to the top of the Columbia hills, Spirit was finding very different types of rocks. It was quite a tall hill and we were definitely seeing that once we were up in the hills Spirit was also finding evidence of silica and other material that had formed in the presence of water. It is very significant that both Spirit and Opportunity on two different sides of Mars found evidence of liquid water in the past. Now we were ready to head out, a chance for the Opportunity crew to drive and get the paddle to the muddle, a very different terrain than before. We got a chance to head out and head over to Endurance crater, and again we didn t know if we would make it all the way to Endurance. It was a much bigger crater and if you could get further down you might get the older rocks; the older the rocks were the further back you looked into Mars history. We had to drive for a while taking pictures, trying to figure out a safe way to go in. We wanted a place where the slopes were not too bad. We were trying to make sure that the rover would stand the tilt that we needed to get down into the crater. We came down into the crater; we d hoped to get down to the dunes but it got real slippery so we ended up leaving the crater from the other side. We were now at about sol 300 so we headed out south from Endurance crater. We got a rare Opportunity to see what had happened to the heat shield after entry when Spirit and Opportunity just has this record of having everything kind of come easily. As we continued to drive south we actually drove right by this meteorite. It turns out that the meteorite matches one that was found on the earth in Antarctica and we were able to determine from the signature on the meteorite that what had happened was that there was an impact on Mars. Part of the impact had fallen back to Mars. The other part of the rock had actually traveled to Earth and ended up landing in Antarctica. This was some amazing find - just as we happened to be driving south we saw the meteorite sitting right out there. We continued our journey trying to get down to Victoria crater. We never thought the rovers might be able to make it and we got stuck. The rover was busy spinning its wheels one day - we would send up commands to the rover in the morning, the rover would wake up saying what am I supposed to do today, look in its memory and say ah, these are my instructions. We would not talk to the rover until the afternoon and then call it up and say Hello, how was your day? and Opportunity would say I drove so far, we said No, you didn t you were spinning your wheels. Then we had to figure out how it had gotten stuck, so we made multiple trips to a home improvement store and bought much sand and dirt to try to figure out, to try to reproduce how Opportunity had gotten stuck so that we could get it unstuck.

8 At that point we continued to drive but we had to drive more carefully, we had gotten our first speeding ticket on Mars so now we drove more slowly. And everywhere we looked we were seeing more and more of this bad rock as this stuff is all over that southern terrain, meaning that what we were actually seeing were pockets of liquid water, maybe not a full lake but it had covered a substantial amount of the terrain and then, as we were driving along we actually encountered a road and we called it The Yellow Brick Road. It is better to drive on the road than off the road, it makes movement faster, and we started driving Opportunity along the road and as far as it would take, so that we did not slip as much. At this point we were actually very close to making it to Victoria crater, and we are now at sol 1300 or about sixteen times past the designed lifetime of the rovers. This was our first image of Victoria crater, a place we never thought Opportunity would manage to get tot, then we got that picture from orbit. I don t think any work got done at JPL the day this picture came down. This Victoria crater is huge. We will probably spend the rest of Opportunity mission exploring the edges of this crater. Actually we are not going deep into the crater at the moment, we are staying down in the bright bend, staying right below the ream because it is obviously a very big crater and if we go in we don t know if we can get back out. The rovers are getting old and we don t know how much longer they ll last. At this point we really have no idea as the mission was supposed to end in 2004 and it s now As they get older we call them our baby-boomer rovers, they start having troubles, and one of Spirit's wheels is stuck so it drives backwards dragging the other wheel, Opportunity's shoulder hurts so the robotic arm isn t working as well. They have now weathered two Martian winters each time we have a winter. Since Spirit is further south of the equator it s harder for it to get enough sunlight in the winter, so again, just like your grandparents who might like sunny places, we try to park the rovers someplace where they ll be safe for the winter. In fact the next winter starts in just a couple of months, so we are trying to position them to get enough sunlight. Opportunity continues to explore the edges of the Victoria crater and the scientists have started to find targets other than Victoria in case the rovers last that long and Spirit has traversed the Columbia Hill so it s made all the way over the hills and is right now where Spirit will spent this next winter, again on a north-facing slope so it would get enough sunlight. We position the rover so that it can stay there all winter and still survive. We have two rovers on Mars, one is a mountain climber and the other explores craters deeper than we ever thought, and both are doing fine. Still, we don t know how long they ll last. I shall conclude by talking about what is happening right now. The Phoenix mission launched this past August and it s the 2007 mission to Mars. It will land in May this upcoming year. It s a lander, not a rover and it will go to

9 the polar regions of Mars, specifically because we found water ice there. It has a scoop which will actually dig underneath the soil, get a sample and then analyze it right there on the spot. Now that the rovers have found evidence of past liquid water, the future mission are focusing on finding out if there is an environment for life, are there organic compounds, was it once habitable? This is the mission that I m working on now; this is the 2009 Mars mission. The next rover to go is much bigger than the current rovers and it will be solar-powered. This rover should last about two Earth years and it will be able to traverse kilometers not just less then a kilometer. We expect to be able to explore a much bigger part of Mars this way. We are picking the landing sites now, so we plan to finalize the landing sites shortly. Each of these missions feeds into the next. The robotic missions are in support of human exploration. We go to scout out the area, to find out what it s like so that when we send people those are precious missions and a little riskier which is why we want to be very careful with where we send the astronauts. Everything we do is in support of human exploration. In memory of our colleagues who did not make it home from their mission. After the Columbia was lost two engineers took the back of our high-gain antenna and on the back they designed a plaque for the Columbia astronauts. The names of all the astronauts are written here, and next to Ilan s name is the Israeli flag. We wanted them to journey with us to Mars and that plaque is now with Spirit wherever it may go. One of my favorite pictures is one taken by the Hubble telescope. If you were to go out tonight and look up at the part of the sky that seems empty and hold your thumb up this is what the Hubble telescope did. We turned the telescope to a part of the sky that we thought was relatively empty and we did a ten day exposure. The image it sent is a galaxy, not a star, a galaxy with billions and billions of stars. We are not even out of the driveway yet in our exploration of space. We ve made our initial forays into the solar system, sometimes the missions work, sometimes they don t, but we are learning how to go back into the solar system. Our voyages of exploration are just beginning. The space programs of the world, the Israeli, the American, the European, the Chinese, the Indian programs, all of these represent hope for the future. Let us voyage together and do this exploration as one people and one world. In response to a question from the audience about analyzing Martian samples in laboratories on Earth, Ms Cox said "We thought a number of times about sending a sample return. At this point we are hoping the discussion will start again about a Mars sample return mission and that means that we are probably looking at about the time that we might send astronaut back to the moon in 2015 to One of the things we are thinking of doing is not sending a mission to Mars in one of these opportunities so we have the

10 financial resources to return a sample, but as we think about a sample return just consider for a minute what that mission will involve. You launch a rocket from the earth, you go to Mars, you leave a spacecraft in orbit and then you land. Once you ve landed you deploy a rover or something to go get rock, you get the rock, come back to the lander, launch from the surface of Mars, this is all robotically done, after the launch from Mars you go back into orbit, then autonomously dock with the spacecraft that s in orbit, transfer rock from one ship to another. Then that orbiter has to leave Mars orbit, come back to earth, enter through the earth atmosphere and safely land. That is a tremendous amount of steps to accomplish robotically so it would be, it will be, a marvelous mission, but it s going to take some time to develop the robotic expertise to do that, which is why we are looking at doing something like that in 2015 or possibly There s a lot of different pieces that have to go together in order to bring back a rock robotically as opposed to having the astronaut just pick it up and bring it back." Another question was if the Phoenix would move at all, and Ms Cox replied "The answer is no, it is a lander specifically, it will not have a lot of time. We didn t sent a rover because it takes time to develop the next rover but also because landing in the north polar regions means this mission is very unlikely to last beyond about three months, the sun will set, there s not going to be enough power, so having a robotic mission that could move around really wouldn t manage to take much advantage of that given the short lifetime we expect Phoenix to have. Phoenix is a stationery lander that will have a robotic arm that will scoop up soil. "