NAIL: Launch Service Program Launch Director Chuck Dovale joins us to talk about the Pegasus rocket preparation for flight.
Welcome to NASA webcast, Chuck. DOVALE: Thanks, Tiffany. It's great to be here.
NAIL: Chuck, you take us through the rocket processing flow tape and address how the Pegasus differs from other NASA rockets?
DOVALE: Sure. If we could have the tape start. OK, this is a view of the aft end of the Pegasus in its vehicle assembly building.
The technicians are working on the aft skirt, torqueing it down. The aft skirt holds the fins, as you see being installed there.
The fins are responsible for controlling the Pegasus launch vehicle during the first-stage burn. Here's a shot of the stages being mated.
This is the third stage and the second stage coming together. This operation occurred between Jan. 10 and 19 of this year.
These are Orbital technicians and engineers you see in the photos, and it's taken about 100 or so Orbital and NASA personnel
to process the Pegasus launch vehicle and ST5 spacecraft for launch.
Here's a shot of the payload support structure and the three payloads for ST5.
It's being mated to the third stage of the Pegasus. Again, this took place in the third week of January.
Here's a technician going through black-light inspections, as the fairing, the protective shroud is being installed around the spacecraft.
This protects the spacecraft during atmospheric conditions as the launch vehicle's burning.
It's in a clean room in Building 1555 on North Vandenberg. This helps keep their cleanliness levels to the proper level for ST5.
Here's the second half of the fairing coming in. It's coming into the clean room.
It'll be cleaned and verified to a class 100,000 clean room. It's very important that we keep the instruments for ST5 clean.
Technicians performing an alcohol wipe.
Here's a shot of the L-1011 on the flight line, as it awaits the Pegasus launch vehicle to be rolled out.
Pegasus was rolled out last Friday. You can see quite inclement weather, but there was enough break in the clouds for
us to get the Pegasus out to the flight line and mate it with the L-1011. The L-1011 is jacked up so the Pegasus
will fit underneath it, and in doing so, the rudder has to be removed so it would fit under that.
The rudder is subsequently mated to the Pegasus afterwards, and then aligned.
The combined systems test follows to make sure that the mating procedure was done correctly,
and that both electrically and mechanically, the L-1011 and the Pegasus are operating satisfactory.
And now we're back. I can tell you, so far the technicians are finishing their work today, and other than some weather
issues that we have, all technical issues have been resolved, and we've got a review in the morning just to check on the weather.
Right now, it's not very favorable, but we'll see what the, what the morning brings. As far as the countdown,
it's a four-and-a-half-hour count, and technicians and the team will come to the control center about 1:30 in the morning.
We're targeting a 6:02 drop. The plane and the aircraft will take off 58 minutes prior to that and go to its preprogrammed
racetrack conditions and hopefully drop Pegasus and ST5 on time at 6:02.
NAIL: Chuck, we have a couple questions for you from our viewers. DOVALE: OK.
NAIL: Our first question comes from Mark from Bowie: How fast does the Pegasus travel after it drops from the L-1011?
DOVALE: Good question, Mark. The L-1011 is traveling at 39,000 feet at about 500 miles an hour.
It drops Pegasus and Pegasus goes into a freefall for about five seconds before the first stage ignites.
The first stage will burn for about 77 seconds, and at that point, it's going about 5,700 miles an hour.
Second stage will light and burn, third stage the same. At the end of third-stage cutoff,
the vehicle is going 19,500 miles an hour. Just to put that further in perspective, that's about 5 miles per second.
NAIL: Our last question is from Ikaika from Laupahoehoe: What kind of fuel is used to power the engines of the Pegasus?
DOVALE: OK. The, the Pegasus motors are all solid-motor propellants, as opposed to liquid. If you've seen the space shuttle
launch before, the space shuttle main engines are liquid but the two twin solid rocket boosters along the sides are solids and there's
quite a bit of difference in how they burn. If you've, if you look at the shuttle main engines, the liquid main engines,
they burn very cleanly, kind of like a blue smoke and flame. The solids are completely different. The solids are bound
in a rubber compound. The fuel is bound in a rubber compound, and it actually burns quite dirty;
it's like a burning old tire. So, you see that grey, billowy smoke. And another difference in solid motor propellants as opposed to
liquid is once you ignite them, they burn until they burn out. There's no way of shutting them off,
unlike a liquid propellant that you can shut down an engine. So that's the main difference.
NAIL: Well, thanks for joining us today, Chuck, and good luck on launch day. DOVALE: Thank you. Thanks for having me.