NASA - National Aeronautics and Space Administration

Tiffany Nail: Joining me now is NASA launch manager Omar Baez. Thank you, Omar, for joining us today on NASA Direct.

Omar Baez: Thanks, Tiffany.

Nail: We're all looking forward to getting DART off the ground. Omar, you've participated in many launches. How does this mission differ from past ones?

Baez: Tiffany, this mission differs from past ones in that every satellite we launch is a little bit different and the DART space vehicle is just one of those that provides us with a different opportunity, a different mode of operating. A very interesting way of doing this is that we only have very few launch opportunities a week or per month, and that is because of the rendezvous aspect of this mission and the requirements to make a rendezvous inside of 24 hours. So this one is interesting in that aspect.

Nail: Omar, take us through final phases of vehicle preparations and launch.

Baez: Very good. If you would roll the tape with the Pegasus processing, please. This is the Pegasus in the 15-55 facility where we integrate the stages together, do all the testing, mate the stages and prepare the rocket before it goes out to the launch pad. Right here, what you're seeing is stage three, or stage one and stage two being mated. They're looking for all the proper clearances between the boxes, the electronic boxes and the ordnance device inside of the structures there. What you're seeing here is the DART space vehicle to the left, and it's being brought over, being hoisted over, and going to be mated to the third stage of the Pegasus. This is all done in the horizontal position, which is the way all Pegasus are put together. This is a little bit different than you'd see in some of our other launch vehicles where the rocket and satellite are stacked vertically. And this is what you're seeing here. The two halves that you're seeing here are the fairing, and this is what protects the satellite from the wind, obviously, as you're taking off and as it's flying through space, provides it a nice, clean environment and the air dynamic heat that the rocket does see as it's flying through the atmosphere. During the second stage flight, this fairing will separate into the two halves you see here, and it'll expose the DART space vehicle, and shortly after that, after the third-stage burn, we're able to separate. What you're seeing here is a convoy out to the runway to a place we call the hot pad. This is a tarmac just down from where the landing strip is, where we're going to take off this coming Tuesday. And what we're doing is, this is the L-1011, the orbital carrier airplane that you're seeing the underbelly of, and it's very interesting, you see it on jacks, no somebody didn't steal the tires off of it. We're trying to tuck the Pegasus space vehicle up under it, into the recesses of this specially modified L-1011. This is what you're seeing here. This is the wing, or the wing of the Pegasus. This trailer will slowly lift the Pegasus and the DART space vehicle up under the L-1011, as you see there.

Nail: Thanks, Omar. And now we have some questions from our viewers. Our first question comes from Gregor from Slovenia. What are the reasons for using the Pegasus XL instead of the Delta 2 rocket?

Baez: Gregor, the reasons we use the Pegasus XL instead of the Delta 2 rocket are size and weight limitations, or requirements that this mission was initially set to have. The size requirements are such that the Delta rocket is not necessary for this type of launch and it would be overkill, and that's the reason why we use the Pegasus. The Pegasus is an adequate vehicle to encapsulate the DART space vehicle and it gets it to its proper orbit at the right price.

Nail: Marc from Bowie, Md.: For the viewers that will be watching this mission on NASA TV, will they be able to see live shots of the L-1011 taking off from Vandenberg?

Baez: The viewers will be able to see live shots. I believe it will be played on NASA Select and on the webcast as you're seeing here. We also have available a chase airplane, an F-18 aircraft with a camera on-board that's going to be following it up to the launch point and during the drop and launch.

Nail: We have a few questions from Mrs. Glackman's class at Merion School. Our first question is: At what altitude will DART deploy? Or, when will Pegasus separate from the L-1011?

Baez: Our altitude for the Pegasus drop or separation from the L-1011 is at 39,000 feet, so we're roughly 8 miles up in the air.

Nail: How do you keep the rocket from crashing into the L-1011?

Baez: That's a good question. If you looked at some of the processing shots we showed before, there's these hooks that are under the L-1011 and they hook into the top of the wing box, where the wing on the Pegasus is, and this is an attach point, it's hydraulically operated, and at the right time we release those hooks which keep the Pegasus stable under the L-1011, we drop them and release the DART vehicle, and after 5 seconds is when we'll actually light or ignite the stage on the Pegasus, and by that time we'll have adequate separation from the L-1011 and they won't crash into each other.

Nail: When the Pegasus is separated from the L-1011, how fast is it going?

Baez: The Pegasus is going to be traveling at the same speed that the carrier aircraft is traveled, which is at about 600 miles per hour.

Nail: We have a next batch of questions coming from KSC employees. What happens onboard the L-1011 between runway liftoff and the launch of the Pegasus?

Baez: What we're doing is, we're turning on power to the rocket. We're making sure that we're getting all the proper air conditioning into the fairing, making sure that the electronic boxes are not getting too cold or too hot. We're turning on the avionics package, the guidance package, the way that this rocket steers, actually. We're turning on the brain of this machine and getting it ready for flight.

Nail: How will NASA track the Pegasus as it flies into space?

Baez: The Pegasus and the L-1011 both have GPS packages and navigation packages that are constantly feeding telemetry to us back here on Earth, and we have also range assets that are tracking it via radar, and also telemetry links that are telling us where exactly as a point of reference in space the vehicle is at.

Nail: Do astronauts fly the plane that drops the rocket?

Baez: Astronauts don't fly the plane that flies the rocket, but I tell you, there's three folks on board: Bill Weaver, the commander, Don Moore, the pilot, and Bob Taylor, the flight engineer, who are the real right stuff. They've got some extensive flying experience. If you've read the book The Right Stuff or seen the movie, these are the real, live guys that do this. They're just phenomenal and they don't have the fame to go along with what you hear an astronaut might have, but these are certainly the top pilots there are.

Nail: Our last question is: Since the launch occurs at 40,000, how does the weather affect the mission?

Baez: The launch or drop at 40,000 feet really doesn't affect us much as far as weather. All the weather really gets us when we're on the ground, and the constraints are really heavy for us to get up if it's raining or if there's thunder or if there's standing water on the runway, or actually clouds and thunderstorms in the flight path. That's the type of weather that would most likely affect us on the day of launch. At 40,000 feet, we're usually over any kind of weather that would affect us. The only thing that could possibly impede the launch would be turbulence at that altitude.

Nail: Thank you, Omar, for joining us today. Good luck with the launch.