NASA apparently plans its first Ares flight test a year from today.
The April 2009 flight will be the first of four test fights for the rocket’s first stage, derived from the current space shuttle’s solid-rocket boosters. In particular, NASA hopes the flight will validate measures it is now undertaking to quell an anticipated vibration issue in the booster system, which could pose problems down the line for the survivability of later variants of the rocket.
The flight will also demonstrate the abilities of the first-stage flight control systems to keep the “single stick” rocket on course, without the benefit of control fin surfaces.
For the first test flight, NASA will use a four-segment booster, topped with an empty fifth segment. Replicas of an Ares 1 second stage, Orion space capsule and launch abort system rocket will ride up top. The dummy segments will feature correct exterior detailing for aerodynamics testing, and will weigh about the same as their real-life counterparts.
“It’s made to look a lot like the Ares 1 vehicle, but it’s a very different animal,” said NASA lead ground operations engineer Tassos Abadiotakis. “We’re also going to get some aerodynamics data, some thermal data — just the basic rocketry laws to make sure what we’re proposing to go fly for Ares 1 actually is going to perform as advertised.”
OK, so, if it’s “a very different animal,” how is it going to validate the real animal? I thought that the concern with the vibration was the fact that they’ve never flown a five-segment booster, and don’t know what its resonant modes will be. I don’t see how flying an four-segment booster with an empty casing on top resolves those concerns in any way. Why can’t they fly a five-segment booster? Presumably because it won’t be far enough along in development to allow a test flight a year from now.
And will the upper stage be just a dummy mass, or will it be active? I thought that the Ares was supposed to get roll control from the upper stage, since it has no way of doing it with the booster (as the article points out, it has no fins, and even if it did, they’d be useless once it left the atmosphere). The first stage can control pitch and yaw through gimbaling, but absent some kind of control jets on the circumference, there’s no way for it to control roll on its own.
So, just what is it that this test is supposed to accomplish? Other, of course, than getting something on the pad and flying it to maintain program momentum at a time that a new administration is coming in and considering what to do with it?
[Update on Thursday morning]
I’ve gotten more than one private email from program insiders that this is a political stunt, not a useful engineering test.