Who's Who at NASA

NTB: What were some of your other big technical challenges with ALHAT?

Reisse: The Doppler altimeter is essentially an entirely new technology that’s been developed here at Langley. It’s a package that in many ways simulates radar Doppler systems, which are used on some of the Mars landers to determine how they are approaching the surface. The accuracy that we can determine distance and velocity is the order of 100 times better than the radar. We can determine velocities down to the order of centimeters per seconds, and altitudes of the centimeter range. That’s one technology that’s probably state-of-the-art at this point.

NTB: Can you walk us through how ALHAT has been tested, and how well that test worked out?

Reisse: We’ve had a series of flight tests, most of which have been to demonstrate the instruments and how well they work. We’ve had a series of helicopter flights, culminating in a flight this past December. We’ve had a couple flights on a plane, and in the last flight we attempted to integrate all the various components. We had all the instruments melded on the bottom of Langley’s HUEY helicopters, and we flew them over a prepared target area at Kennedy Space Center. It was prepared just for us. It had craters, rocks, and various other things that the sensor could detect. We flew a series of flights over two weeks in December, and that data is being analyzed. We didn’t try to guide the helicopter; that’ll come next. So we had all the sensors working together. They all integrated in with the computer systems that were doing the job of generating the maps and providing input to our internal guidance system. The helicopter was still controlled by pilots.

NTB: So what’s next? More tests?

Reisse: What’s next is to work with the Morpheus vehicle out at Johnson Space Center. That’s what they call a vertical testbed. It’s an autonomous rocket that will lift off all by itself and navigate using the ALHAT guidance computer to the landing area. All of the ALHAT sensors will be involved, and all of the computer systems will work. Hopefully we’ll test the whole system and be able to take off, guide to the right area, and determine the safe area to land.

NTB: What is exciting to you about this technology? What do you see as the possibilities?

Reisse: The possibilities are 1) to be able to go anywhere, any place, any time. Our original charter [encouraged us] to be able to go to the moon: anywhere, any place, any time — and put down either a human being or an intelligent spacecraft to do anything that it needs to do. We built the idea of the technology such that it could go to what we call the “back” of the moon, or where it’s dark and not illuminated. The places that Apollo went, and various other landers have gone, have usually been fairly benign. One of the more interesting places to go is the south pole of the Moon, where there’s potential for water supplies in the craters. That’s a particularly rocky, not very benign, area to try to land. It opens up more possibilities for exploration by other humans or robots.

NTB: Is it true for asteroids as well?

Reisse: Yes, one of the problems with asteroids is that we probably will never be able to really map them very accurately before we get to them.

NTB: How can these technologies carry over to other industries? Can helicopters use these?

Reisse: With helicopters, the technology for the Doppler system would really be able to give you, in nasty conditions, access to how fast you’re moving relative to the ground, as well as your altitude and attitude relative to the ground on a continuous basis, from say two kilometers to the surface. This would be advantageous for instruments that have to navigate in not very good conditions, such as rain or fog. ALHAT does have applications with helicopters, particularly in terms of navigation in non-ideal conditions.

NTB: What is your specific work with ALHAT?

Reisse: I basically deal with the project management at Johnson, in terms of coordinating our work with the rest of the team. The project is based at Johnson Space Center, and we also have contributing work done at Jet Propulsion Laboratory (JPL). So it’s a multicenter project. That’s part of my job. The other part is to manage the team here to get the work done on time, and get our sensors out to where they have to be when they have to be there.

NTB: What is your favorite part of the job?

Reisse: I have worked on a lunar mission in the past and believe that we as a nation and as a people need to be exploring, as well as we can, the solar system and beyond. I think that’s the primary reason I asked to be on the job, because it’s exciting and it may add to the capability of us exploring the solar system.

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