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Gravity Probe B Webcast: Delta II Rocket and Launch Processing Q&A
 
Question and Answer Board

Rich from Elk Grove, Illinois
What specific procedures and precautions were done with handling of the GPB because of the delicate nature of the equipment while assembling the rocket?
As you can imagine, the spacecraft is designed to survive launch, which is a pretty violent atmosphere. So that is the most significant event it's going to see. But we also have to take precautions for what it will see during handling. Like was shown in the video, we use soft dry bands, protective slings and that type of apparatus.

We also take great care in the contamination side of things. As you can imagine, GP-B, with its gyroscopes and telescope, is very sensitive to contamination. So we were very clean, things were bagged and double-bagged, and people who were working on it wore clean-room type garb, or "bunny suits" as we call them, so those were ways we took great pains to ensure the GP-B spacecraft was processed correctly.
Marc from Bowie, Maryland
After the Delta II Rocket clears the SLC-2, will viewers be able to see the cameras facing forward and aft?
Another good question. Let me show you a Delta rocket here. We do have two cameras facing forward on this mission and they are predominantly to capture the spacecraft separation as it's separating from the vehicle. So the cameras are approximately in this area looking forward, and as the rocket's going downrange and the fairing halves open up, then we can look forward and hopefully see the deployment of the solar arrays and also the separation of the spacecraft from the launch vehicle.
Adam from Toledo
If you lose power to the Delta Rocket, or lose engines in the middle of flight, is it possible to recover the spacecraft?
Well unfortunately, and I certainly hope this is the only time I'm talking about this subject, the way this and all other expendable launch vehicles are designed, a pre-programmed trajectory is loaded into the launch vehicle. Now it can deviate from this trajectory to a great degree.

However, if we were to suffer a significant event like an engine failure or a premature shutdown, we would not have enough performance to maintain that trajectory and unfortunately, the vehicle and spacecraft would splash down in the ocean. There aren't any plans at this time to recover them.
Chelle from Disneyland
When the Delta rockets release the booster rockets, are first three ejected and then the remaining six or are they released three at a time?
Another good question. Let me get my rocket here. As we’ve seen before, there are nine solids on the bottom of the first stage. We light six at launch and they burn for about 60 seconds. The other three will light after the first six burn out, and will carry the six for a period of time in order to avoid some oil platforms that we have off the coast.

Once we feel that we are clear of the oil platforms, we separate three of them and then one second later, we separate three more. Then the third set that is flying will continue to burn for about one more minute and then we'll separate those.

We do it in sets of threes to avoid contact with each other.
Terry P. from San Diego
What water source cools the the pad at take off?
We do have a water deluge system at the complex. This is to suppress any vibration and acoustics or sound levels that might occur during launch. We want to dampen those levels so they don't bounce off the ground and the launch pad and come back and harm the vehicle. So that's what we have, it comes on a few minutes before launch and you will see the water deck flushed.