From The "JPL Universe"
October 15, 1999
Mars Polar Lander ApproachesIn December, JPL's next Mars adventure will begin Polar Lander Approaches
By Mark Whalen
Members of the Mars '98 operations team who worked on Mars Climate Orbiter are now gearing up for the upcoming landing of Mars Polar Lander on Dec. 3.
JPL Director Dr. Edward Stone and Mars Surveyor Operations Project Manager Richard Cook discussed with Universe the preparations under way for the mission.
Q: Dr. Stone, following the loss of Mars Climate Orbiter, what do you believe is the most important thing for employees to keep in mind?
Stone: The primary objective for the Laboratory now is not to look back, but to focus on Dec. 3. That's the key. All of our energies need to be focused on whatever needs to be done to assure a successful landing for Mars Polar Lander.
Q: As landing day approaches, how is the morale of the Mars team?
Cook: Obviously, the team was extremely disappointed by the loss of the orbiter. Yet, in a sense, having Mars Polar Lander coming up in less than two months is really the best thing for them. Everybody is moving on as rapidly as they can and focusing on what needs to be done.
Q: Can the loss of the orbiter in some way help the team ensure success on the lander mission?
Cook: Yes. We're using this opportunity to take a bottoms-up look at the risks we're taking and make sure we're doing all the right things. It allows us to see that everything really does work. Personally, I'm optimistic because I know the caliber of the people working on the flight team. To a person, they are committed to ensuring the success of Mars Polar Lander. I'm also extremely proud of the way they are handling adversity while staying focused on MPL.
Q: Review teams within JPL and from NASA are probing the causes of the loss of Climate Orbiter. How can their findings be used to help Polar Lander?
Cook: These reviews should help us identify process improvements that we can immediately apply to help the lander mission. We had already identified some improvements, but additional recommendations from the boards should be very helpful. One change that we are making is to improve our quality assurance, to make it as sound and as all-encompassing as possible. We are also increasing the fidelity of our operations testing to exercise more contingency paths. We are going back and taking a look at what we call an end-to-end risk tree or failure tree, and see where we might have holes. So we're updating our assessment of risk. We've also brought in other external organizations to help us with our processes and to provide us with another double-check.
Q: How are these external organizations helping you with Polar Lander?
Cook: A particularly good example is a team from Langley Research Center, which is helping us go over all the simulations we've done to validate the lander's entry, descent and landing system. They are uniquely qualified to do this work and will help us to verify all of the atmospheric entry and terminal guidance simulations that are performed.
Q: So the checks that are going on are not just in reaction to Climate Orbiter's loss?
Stone: Most of these activities are, in fact, not in reaction to the orbiter. We'll know very shortly what the orbiter's problems were, but we are not limiting what's being done to just addressing those issues.
Cook: I can say right now that the specific problem that led to the loss of Climate Orbiter-one team providing thruster activity information in imperial units with another using the metric system-will not occur with the lander. We're already done assessing that.
Stone: That isn't the main issue, however; the main issue is the process that should have recognized that situation. But rather than just focus on that process, we're taking a second look at all the processes, all of the critical elements and the hard parts of landing on Mars.
Q: Can you address recent concerns about the state of the lander mission, particularly a potential problem with the spacecraft's flight aeroshell?
Cook: This is a good opportunity to put some of those rumors to bed. During final inspections at Kennedy Space Center before launch, a very small pinhole was detected in the substrate, the structural backing behind the aeroshell. At the time, there was no real concern about it. But since the launch in January, some on the project suggested we make sure it's not a problem.
So just last week, we completed a set of tests using what's called an arc jet-like a giant blowtorch-at Ames Research Center, which effectively tests the heating environment we expect for the spacecraft's entry to Mars. The tests were completed with that small pinhole, and everything looked fine-the aeroshell worked exactly as planned.
Q: What is the plan for direct-to-Earth communication with the lander and the use of Mars Global Surveyor as a relay?
Cook: The Deep Space 2 mission, which will last for about about a week, will rely solely on Mars Global Surveyor for Earth communication. So for the first week or so of the lander mission, we will primarily depend on the lander for direct-to-Earth communication. After that, we'll be able to use Mars Global Surveyor for the relay of the lander data.
We will soon do end-to-end validation testing of our engineering unit copy of the Mars relay hardware at Lockheed Martin. We did that before launch, but we think it's useful to repeat those tests.
We've sharpened our pencils about how we might use direct-to-Earth; it would only extend the amount of time it will take to do things at the beginning of the mission. We're probably not going to get color panoramas within the first couple of days, like Pathfinder did; it will probably take three or four days this time. But we will get enough data to do a really successful science mission.
Q: Dr. Stone, do you feel that the reviews and extra attention to detail on Polar Lander will help lead to a successful mission?
Stone: I'm confident that we will have a successful landing, and the processes and additional checks we're going through will help us make sure we've got it exactly right. Our internal activities already in place are looking at all the critical areas, and the JPL review team led by John Casani, as well as the external NASA review team, will make independent assessments of what can be done to assure a safe landing on Mars.
Q: On another subject, Galileo's flyby of Jupiter's moon Io this week has given JPL another shot in the arm, hasn't it?
Stone: Yes. The successful Io flyby is a very important milestone. The team did a tremendous job in recovering the spacecraft from "safe mode," identifying the problem with the computer's memory and restoring the sequence, all during the day of encounter. It's a testimony to the skill the Laboratory has in dealing with complicated missions in difficult environments.
Learning from the occasional setback is critical to honing those skills in the new era of going often, landing and bringing samples back.
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