Former Astronaut on NASA Risk Assessment
LIANE HANSEN, host:
The astronauts aboard the Space Shuttle Discovery today used a computer simulator to practice landing in preparation for their planned return to Earth tomorrow. As Discovery's crew members complete their 13-day mission, the National Aeronautics & Space Administration is wrapping up a time when the words `risk assessment' have become virtually a daily part of media briefings and other public utterances by NASA officials. Space flight is dangerous, just as exploration has been dangerous since the earliest days when humans sought to learn what existed beyond the horizon. At times, with complex calculations, statistics are presented by NASA as a measure for deciding whether to go ahead with a mission that is inherently risky.
Former astronaut Thomas D. Jones knows the risk. From 1994 to 2001, Jones flew on four space shuttle missions, including one to the International Space Station. He spent a total of more than 52 days in space, including three space walks. His book, "Skywalking: An Astronaut's Memoir," will be published this winter. In the book he examines the complex process of deciding when it is safe enough to send human beings into space. Thomas Jones visited our studios late last week and explained some of the calculations used by NASA engineers.
Mr. THOMAS D. JONES (Author, "Skywalking: An Astronaut's Memoir"): They look at the probabilistic risk assessment, it's called, where they actually crank out the odds of each part failing on a shuttle and try to compile those statistics into some global number that tells you the risk for the entire flight. We know that most of the risk is associated with launch. There is another associated with re-entry. And then there is, surprisingly, a substantial risk still associated with being in orbit, where you might be smacked by space debris, for example. So those three phases of the flight wind up in one big number.
HANSEN: The mission of Discovery, too, has carried with it a large public relations burden for NASA because it's the first flight since the Columbia disaster. Have you ever known any non-flight-related factors to influence decisions?
Mr. JONES: I have not. In my 11 years as an astronaut, everything was couched in terms of what we know, how the numbers shake out and whether or not people were comfortable with the idea that it was safe to fly this next mission. And I can tell you from my own experience that the managers stood down our shuttle launch when they had an unsolved problem that they still had to grapple with. There was no rush to launch on a certain date, and there was no headlong attempt to minimize problems. It was always get them out on the table. I think NASA did go off track, though, leading up to the Columbia accident, and they were facing a lot of missions ahead of them for the space station's assembly and I think that schedule fever was a component in launching the shuttle in the 2003 time frame.
HANSEN: What about this flight, do you think?
Mr. JONES: There's a point at which any manager in the space program has to decide how much effort is enough to ensure safety vs. how much more resources will have to be expended to get an incremental improvement in safety. And they don't have an unlimited budget and they don't have a limitless amount of time, so there comes a point at which you have to say, `We've discovered the cause of Columbia's loss, we've fixed that to everyone's satisfaction,' and then we go forward knowing that we can't make the system perfect. As I said before, it can never be improved by even a factor of 10. That's a job for the next human-carrying spacecraft to come along from the US. And I think in the case of this mission of Discovery, everyone was comfortable with where the risk numbers fell and they were ready to go. Turns out that they didn't have all the problems solved, in fact.
HANSEN: Some former astronauts and original NASA officials have criticized recently the risk-assessment process at NASA. They say like back in the 1960s it was accepted that space flight was dangerous. No calculation could ultimately determine whether to go forward. America wanted to get on the moon. People's lives would have to be put at risk. But still, accepting that space flight is very risky, do you think that NASA has become maybe too risk averse for effective manned space exploration?
Mr. JONES: They're going to have to find a way to roll in their risk calculations without getting caught up in minutiae. There are things that happened on this mission that the press really latched on to: the gap filler sticking out, the fact that we had great video of the belly of the shuttle and saw the little pieces flying off. It turns out only one was really a serious concern, and it is a serious concern and it remains unsolved: the big chunk of foam that came off the tank two minutes into the flight.
But you can't get wrapped up in everything that's interesting and treat it as if it's a potentially catastrophic problem. You have to sort those things out quickly and then move on and devote your limited resources to those. And if NASA can't get the space shuttle to fly for four more years, the US is in a big hole in terms of human space flight because there's nothing to replace it coming along for about five more years.
HANSEN: In the '60s, some of the astronauts were famous for being impatient with ground engineers, other officials, for delays before a launch. Are those same kinds of tensions commonplace in NASA today?
Mr. JONES: Oh, there's the human side of being an astronaut and that is when you're on top of the rocket and you've prepared for years to get there, you don't want anything to step into the way. And so there's a tendency in the cockpit--I can remember this myself in--on Columbia in 1996 when we had a potentially very dangerous hydrogen leak in the aft engine compartment. We thought, `Oh, don't scrub for this. You know, let's get on with it.' Well, the right call was to take a look at it for a few minutes and the engineers decided that it was safe to proceed and we launched a few minutes later, much to our relief. And you--we have to leave that to the engineers on the ground. They have to make the call, and the astronauts are merely bystanders at that point. We get to pray and we get to bias it according to our wishes, but we only hope that that doesn't interfere with the dry, you know, methodical analysis that's required.
HANSEN: On this program, you know, we have a tendency to quiz people. We actually have a little quiz for you. NASA really seems addicted to initializations and acronyms and we really don't think everybody can remember them all. But we want to test your memory. Would you mind playing the game with us?
Mr. JONES: OK.
HANSEN: OK, what's EWA?
Mr. JONES: EWA. I know an EVA.
HANSEN & Mr. JONES: (In unison) ...vehicular activity.
Mr. JONES: OK. And then EWA?
Mr. JONES: Don't know.
HANSEN: I'll give it to you. Emittance wash applicator.
Mr. JONES: That's one of the tile repair techniques they tried.
HANSEN: Oh, it is?
Mr. JONES: Yeah.
HANSEN: It's not like the squirter for windshield wiper fluid or something like that?
Mr. JONES: Oh, no.
HANSEN: Oh. MECO. Is that Meco or M-E-C-O?
Mr. JONES: MECO's fine. That's the main engine cut-off when the shuttle's engines turn off and you're in orbit.
HANSEN: SAFER, and I don't know if it's SAFER or S-A-F-E-R.
Mr. JONES: No, SAFER. We try to phoneticize these things so they're easier to remember. Simplified aid for EVA rescue, and that's the little cold gas jet pack that snaps to the bottom of your space suit backpack. In case you fall off the space station and don't listen to your mom's instructions, you can fly back with the little thrusters on that jet pack.
HANSEN: Thomas Jones flew on four space shuttle missions during his career as an astronaut. And his book, "Skywalking: An Astronaut's Memoir," will be published this winter.
Thanks a lot for coming in.
Mr. JONES: You're welcome. Glad to be here.
HANSEN: It's 18 minutes past the hour.