Ares 1-X test rocket being assembled for launch
BY STEPHEN CLARK
Posted: July 9, 2009
NASA moved one step closer to a long-awaited test flight of America's new moon rocket Wednesday night, when engineers hoisted the first piece of the booster atop an Apollo-era launch platform.
But the flight's launch date is anyone's guess.
NASA says the official launch date is August 30, but officials openly anticipate the key test will be put off until at least this fall due to tight schedules and unresolved vibration problems that could doom the launch.
"It just takes time to go do it all, so we're working through it," said Jon Cowart, deputy mission manager at Kennedy Space Center. "If it's going to take longer than our current launch date allows, then that's the way it's going to be."
Technicians started building the 327-foot-tall rocket Wednesday night, as engineers continue extensive analysis to determine if the slender booster can survive the strong shaking produced as it slices through the atmosphere.
The aft assembly of the rocket's first stage rolled to the 525-foot-tall Vehicle Assembly Building from a preparation facility Wednesday. Workers lifted the booster segment, packed with flammable solid propellant, onto a mobile launch platform inside a high bay in the building's northeast corner.
The operation was completed by 6:30 a.m. Thursday morning, according to NASA.
The lower piece of the rocket includes the first stage's aft skirt, nozzle, control systems, and one of four cylinders already loaded with solid fuel.
Officials expect to stack the first stage's other three segments within
the next ten days, according to Cowart.
"At that point, we're going to make a decision whether or not the data is trending in the right direction," Cowart said. "But the data will not be fully complete."
If results show some parts need to fixed, officials may opt to halt stacking before adding the simulated components, officials said.
In the VAB's northwest high bay, workers are putting together ring-like sections of the rocket's forward assembly. The pieces are replicas of the real hardware to be used on the Ares 1 rocket.
Super Stack 1, the lowest of five dummy segments, is undergoing final checks and should be ready to be lifted and bolted atop the rocket around July 24, if engineers can overcome the vibration problems.
First reported last month by the Orlando Sentinel, the violent vibrations could damage the thrust vector control system that steers the rocket during launch. Work platforms built inside the rocket's dummy sections could also shake loose.
The shaking could also damage the flight termination system, or FTS, a critical system Air Force safety officials would use to blow up an errant rocket threatening populated areas near the launch site.
The most intense vibrations appear at launch and beyond about 70 seconds after liftoff, according to NASA.
The Air Force is "very concerned" with the FTS issue, according to Cowart.
"The range are the ones who lay down the rules for the flight termination system," Cowart said. "I can't even remember the last time I saw the range allow a waiver. They're going to want their system to really perform without a doubt because it's the last-ditch thing that keeps the public safe."
Computer models predict how the vibrations could affect the rocket during its two-minute flight.
"You look at that and go, 'Oh, wow, we've got some issues,'" Cowart said.
Similar problems have been encountered during the design of the Ares 1 rocket.
"Obviously, as a rocket is launching, it vibrates quite a bit," Cowart said. "It vibrates in the up and down direction and also the first stage vibrates in and out because of the pressure that's inside of it."
"Plus you're passing through the atmosphere at very high speed and that causes vibrations," Cowart said. "There's the thrust oscillation because you've got a pogo thing going on, where you're pushing at the bottom very hard at this very (large) object, so it's compressing and expanding."
But vibrations on Ares 1-X exceed safety margins of components that were originally designed to fly on the space shuttle.
"Most of the components we're talking about are heritage because we've flown them on shuttle for so many years," Cowart said. "Our initial thinking was our loads would be less than we see on shuttle. In a lot of cases they are, but in some cases they aren't."