Journey to Mars
Senior Systems Engineer, Robotics Division, Jet Propulsion Laboratory
Author, Sojourner: An Insider’s View of the Mars Pathfinder Mission
The recent landing of the Mars Explorer Rover has turned our attention once again to the Red Planet, and the upcoming landing of a second vehicle will grant us a view of the opposite side of the planet. These missions are just a small part of the many explorations of Mars now underway that may shed light to whether if life could have evolved on Mars. Well, joining us today to give us a glimpse into these Mars missions is Andrew Mishkin. Mr. Mishkin is a senior systems engineer at the Jet Propulsion Laboratory where he has been involved in the development of various robotic vehicles and their subsystems for more than 15 years. He was a key member of the team that designed, developed, and finally operated the Sojouner rover that captured the imaginations of the public during the Mars Pathfinder missions in the summer of 1997. He has recently written a book entitled Sojourner: An Insider’s View of the Mars Pathfinder Mission. Mr. Mishkin is now a part of the Mars Exploration Rover project that has just landed a new rover on Mars and will be landing a second rover in about three weeks. Charles Lee (CL) talks with Andrew Mishkin (AM):
CL: Mr. Mishkin, thank you very much for joining us today.
AM: Thank you very much for having me.
CL: Well, it’s certainly our pleasure and I think most of the public is watching with eager anticipation the journey of the recent Mars Exploration Rover. I’m just curious, what is the latest status of the Rover?
AM: The Spirit Rover is very healthy, we’re really pleased with it and we’re a day from driving it off the lander and onto the actual surface of Mars where we are going to begin our explorations.
CL: I see and why is it taking so long to move the rover off of the platform?
AM: Well, we’re going through all of the checkouts and deployments. So for example, in the last couple days we finally stood the rover up and folded it. It’s been described as reverse origami because the rover is crouched down and has all of its wheels turned in so that it could fit in the lander during the trip to Mars. So now we’ve stood it up, extended the wheels, locked them in place, and now we’re going to be adjusting the orientation of the rover to a safe direction to drive off the lander and onto the surface.
CL: And how do you determine a safe direction for it to go?
AM: We both determine the altitude of the lander, we look at where the airbags are, and we had one airbag that was in our prime dry rock direction that we were unable to get fully retracted out of the way and we were concerned about that possibly snagging one of our solar panels as we drove off. And so, what we’re going to do is turn about 120 degrees off to the right that look safe, get images as we are doing those turns to make sure that it’s clear in that direction. Once we’ve assessed those images, we expect to be driving off.
CL: And how does the terrain look where the rover has landed?
AM: Well, it mostly looks very nice and flat with a number of small rocks. In fact, we never expected it before, we got to Mars this time, but it looks like we will be able to drive a good distance in this terrain and one thing that’s kind of exciting is there is some hills that are about 2 km or so away and it looks like the scientists are interested in heading off in that direction, so we’ll just see how close we get.
CL: So what is it about the Rover that it is trying to do on this journey?
AM: What we’re going to be doing is truly a geology mission to assess, really, a history of rocks and see whether there was a presence of water at this location. Gusev Crater where we’re sitting has been hypothesized to have been a crater lake sometime in Mars’ history and what we’re going to try to do is see whether that hypothesis is correct.
CL: I see and how is the Rover going about doing this?
AM: We’re going to basically drive up and touch rocks. We’re going to put up a number of spectrometers onto targets and assess both the elemental and mineralogical makeup of the rocks. We have what we call the RAT (Rock Abrasion Tool) that we use to scrape off the outer surface of rocks, get past the weathered outer surfaces and to the inside, and we also have a microscopic imager that gives us a close-up view of the structure of the rocks. So, we’ll be applying those and again, these number of spectrometers to get a lot of data for science analysis.
CL: And is this the same sort of mission that the companion ship will also be working on?
AM: Yes. The Opportunity Rover, when it lands on the opposite side of the planet, it will be doing a similar mission. The difference is in the landing site that has been selected, which we often refer to as the hematite site because from orbit, we have been able to tell the presence of grey hematite at this other site and that type of mineral usually forms in the presence of water. We’re going to that site because the minerology would indicate that there was water there at one point while the site we are at now, it’s just looks like based on the feature that it is a crater that has a valley that feeds into that would have been direction for water to flow, that water might have existed there.
CL: How are then these missions different from the Beagle 2 mission?
AM: Beagle 2 is specifically to be a life-finding mission that had a number of instruments on it to assess whether life was currently present but even if it had succeeded, it would have been able to examine the area of soil or rock that was literally within reach of the lander, it would reach out an arm and apply instruments on the surface right next to the lander. The Mars Exploration Rover mission in contrast was designed to cover a significant amount of ground and get to a number of distinct rocks and soil in order to assess a number of different locations.
CL: There’s some logistical issues for communicating with Mars since it’s so far away. How exactly do you compensate for the time lag?
AM: Well, what we do is plan what the rover is going to do, this is in particular once we drive off, for the course of the next Martian day, what we call a sol. And we plan that over the Martian night while the rover is sleeping. We plan where the rover is going to drive and what observations it is going to take and build up an entire set of commands and then we send that up on the morning on Mars when the rover wakes up and it then performs these commands all day long and then sends those back in the afternoon, the results and any images taken, so we can now plan the next day. And so that way we don’t have to worry so much about the time delay that is right now a little over ten minutes in sending a message to Mars.
CL: What were some of the logistical issues with actually building all these instruments in such a small compact device then?
AM: There’s always a number of constraints. One is that you have to keep all of the instruments in an appropriate temperature range. The temperature on Mars can vary by up to a 150 degrees Fahrenheit between day and night, and so we can basically freeze our equipment if we are not careful and so all of this had to be set into what we call a warm electronics box, that’s kind of like a beer cooler, but pretty sophisticated to keep everything warm. And so what happens is that when we are operating over night, when we have warmed up during the day, during our operations and then we shut-down, we slowly cool off overnight, but then by the next morning, we are still within an acceptable temperature and then can start operating again. And so that was one of the challenges was to maintain all of these instruments as healthy. The other was making the entire rover fit into the confines of the lander. That is why it was crouched down and everything was folded up so that it would actually fit, which was a pretty major challenge to make work.
CL: I think the people who have followed the many missions that have gone to Mars have sort of been amazed by the technology with getting an actual rover onto the planet. There have been a number of well-publicized problems with actually landing these things. Is there a particular why getting the rover on Mars is difficult.
AM: Landing on another planet is always difficult. And so the same approach we used for Pathfinder and this mission, which involves basically barrelling in the planet’s atmosphere and being slowed down by an aeroshell and supersonic parachutes, and finally the airbags and being dropped to the surface. All of that is a pretty complex series of things that has to take place and has to work. Even if all of that works perfectly, there could always be a nice sharp pointed rock sticking up that we could bounce on deflate our airbags and result in damage. It’s a very challenging set of things we need to do to land on a planet that is a hundred million miles away.
CL: Well, you’ve written a very fascinating book “Sojourner” which is an insider’s view of the Mars Pathfinder Mission. I’m just curious, why did you decide to chronicle the last rover mission to Mars?
AM: Well, I worked on a number of years on that mission and it was a very exciting mission. And working on the Rover and developing it were high points of my career, having worked on rovers for so many years and it just seemed like a story worth telling based on how many different people were involved at all of the different contributions. We often tend to look at things after the fact and say it was inevitable that it would work and it must have been just straightforward, this concerted effort for a few years, but the reality was that there so many different people whose contributions were essential to making the mission work. I wanted to provide a sense to how many different people are involved and how each one of them is necessary and does something that makes the mission succeed. Without any of them, we wouldn’t have gotten to Mars that time and perhaps might not be trying to get to Mars this time.
CL: What were your most gratifying moments during this Pathfinder Mission?
AM: I think two particular moments. One is just seeing those first images come back. You really see a new place that no one has seen before. Just being there and watching that happen. There’s just nothing like that. The other moments for me is when problems come and I get a chance to dig into them and actually solve something and figure out how to make something work that doesn’t seem to be working that’s off there in Mars and seems too far to fix but we find a way. I find those to be just really special times when I have a chance to use my engineering and problem solving abilities.
CL: Have there ever been any times when you were scared the whole thing would not work out?
AM: Well, whenever a landing is coming up, we all have that feeling in the pit of our stomach about whether it’s going to work or not. There’s no guarantee and no matter how perfect the job is done, there’s still probably a 5 or 10 percent chance that there might be rock in the wrong place. So yeah, that’s one of those places where we kept our fingers crossed and hoped to hear a signal and so far we have.
CL: So whatever happened to Sojourner?
AM: What we think happened on the 83rd day on Mars, the rechargable batteries on the Pathfinder Lander finally went dead in the middle of the night and we think we actually lost our clock so we didn’t really know the time on-board enough to know where to point our antenna to communicate. We were not able to recover from that and in the meantime, the Sojourner rover itself was still functioning but we had no way to communicate with it except except through the lander. And what it would have done after a few days of not getting a signal is it would have said oh well, maybe I’ve gotten too far away from the Lander to communicate and it would have basically driven towards the Lander and gotten very close of it. It wouldn’t have driven up onto the Lander because then it would probably have gotten stuck so it circled the Lander at a range of couple of meters hoping to get a message which never came.
CL: We hope that the Mars Explore Rover won’t suffer such a fate. So, what’s next for the Explorer Rover?
AM: Well, we’ll be driving off, we’ll hope coming up on January 24th, we will be attempting to land the Opportunity Rover and basically go through. The same thing again that we think that landing site will look rather different and may have sand dunes near the rover and be a very different view. We basically got a lot to keep ourselves busy.
CL: All right! Well, I think we will all be watching in eager anticipation on what comes out of these missions. I just want to thank you for joining us today.
AM: Thank you very much.