Ask the Crew: STS-99

To: Mission Specialist Gerhard Thiele

Question: Can you see the Moon, planets and stars or just the Earth?

Thiele: Of course, we can see a bright Moon, the planets and the stars.

To: Mission Specialist Gerhard Thiele

Question: Are the radar beams reflected by water and snow?

Thiele: Yes, especially if the snow is wet.

From: Harold Floyd, Las Vegas, Nevada
To: Mission Specialist Janice Voss

Question: Is the mast oscillating, or is it just an anomaly of the video feed?

From: Donald, Ottawa, Ontario, Canada, age 40
To: Mission Specialist Janice Voss

Question: Does the oscillation of the mast affect the quality of the images?

Voss: The oscillation is real. It comes from our desire to keep the antenna very closely pointed at a place on the Earth. We have small jets on the space shuttle that fire to keep the antenna very precisely pointed. When they fire, they cause the mast to move just a little bit. It's just a few inches. It doesn't affect the quality of the images because we have a second system onboard that is actually a star tracker, but it's pointed at some lights on the outboard antenna. It can see that motion, and when we take all of the data at the end of the flight, we subtract that motion out of the image because we have the system recording. So it is real motion, but it won't affect the quality of our images.

From: Richard Nelson, Maynard, Massachussets, age 27
To: Mission Specialist Janice Voss

Question: I am a licensed land surveyor in Massachusetts, and I was curious about the accuracy of the final product that will be produced by your radar topography. What will the contour interval be, and will the results be available to the U.S. public?

Voss: The map that we are producing is just the data itself. How it's distributed, in terms of contour maps or other kinds of elevation data, is up to the individuals using it. The contour interval will be up to the organization that publishes that map, which won't be the Jet Propulsion Lab. The vertical accuracy of the map is about 10 meters or 30 feet relative and 16 meters or 50 feet absolute. The contour, of course, will be closer than that, but how close will depend on the people making the maps and not inherent in the data that we're producing. It will be available to the general public. They're still negotiating exactly how that's going to be distributed and in what formats and what accuracy, but it will be available to the general public in the US.

From: Daniel Rassoulpour, Vienna, Austria, age 25
To: Mission Specialist Janice Voss

Question: Why is the radar mast so long? Is it to reduce reflections from the orbiter?

Voss: The mast is about 200 feet long, and it sticks out the side of the shuttle quite a ways. It's not to reduce reflections from the orbiter, rather to give you sort of a stereo image effect. Not exactly stereo, but conceptually, if you think of how a stereo image works. If your eyes are close together, you don't have as much of an ability to do depth of field as if your eyes were very far apart. So the longer the mast, the better accuracy we get on our depth of field or our height measurements. For this particular flight, this was the longest mast we could make that we could safely fly from the shuttle in terms of weight and controllability, and it was long enough to produce the map that we wanted.

From: Tracy Hartshorne, Prince George, British Columbia, Canada, age 23
To: Pilot Dom Gorie

Question: How much time does each team have for on-task time, and how much time do you have to check out Earth from your spectacular perch?

Gorie: Red and blue shift each are working for 12 hours at a time. When we are on shift, we are all three up on the flight deck, and we're taking care of shuttle systems as well as the payload. We generally have two people looking at the data takes that are going on and one person looking at the orbiter systems. During the 12 remaining hours of the day, we spend eight hours sleeping, and there are two hours on either side of that sleep period where we can do general housekeeping and general kind of maintenance on the shuttle.

There's plenty of time that we get to spend looking outside that you asked about, and we've taken some great pictures already. There have been a lot of clouds in Europe and the United States early this week, but we've been fortunate to see some great places already.

From: Darren Ewing, Great Falls, Virginia, age 29
To: Pilot Dom Gorie

Question: How complex are the battery problems that the mapping crew is dealing with? How did they prepare for a scenario like this?

Gorie: Well, I think Darren is asking about the questions we were talking [about] on the radio yesterday [regarding] our 70-milimeter hand-held cameras. The data backs on those, because of our delayed launch time, have run out in a couple cases. With that, we've been forced to pull out some little hand voice recorders. As we take the pictures, we talk into the recorders and tell the mission time and the location that we've taken those pictures of. The batteries having run low makes the data back modules on the cameras unable to record the mission time. That's very important for reconstruction after the flight, to see where these pictures are coming from because it might not be so evident at first glance, and it saves a lot of time and effort.

From: Tome Bogdanov, Skopje, Macedonia, age 32
To: Pilot Dom Gorie

Question: (1.) How many sunrises and sunsets have you seen? (2.) Do you believe that humans will go to Mars? (3.) What do you need to do to become an astronaut?

Gorie: The answers are provided in German.

From: Germany
To: Mission Specialist Gerhard Thiele

Question: (1.) How many sunrises and sunsets have you seen? (2.) Do you believe that humans will go to Mars? (3.) What do you need to do to become an astronaut?

Thiele: The answers are provided in German.

From: Germany
To: Mission Specialist Gerhard Thiele

Question: (1.) How do you sleep in space? (2.) How do you wash and brush your teeth? (3.) What do you eat?

Thiele: The answers are provided in German.