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Shuttle managers decide against special fueling test BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: May 4, 2006
Shuttle program manager Wayne Hale ordered engineers to make tentative plans for a tanking test earlier this spring as a way to make sure recently replaced engine cutoff - ECO - sensors would work properly on launch day. The test would not have included any so-called "drag on" instrumentation in the shuttle's aft compartment and its sole purpose would have been to verify the ECO sensors changed state from dry to wet and back again as expected. In the absence of additional instrumentation, no detailed operational insights would be possible. During a weekly program meeting today, the management team unanimously decided not to run the test, officials said, because any major problems with the ECO sensors almost certainly would preclude a launch in the July window anyway and because loading the tank with supercold propellant would subject its foam insulation to unwanted thermal stress. Shuttle tanks are certified for 13 fueling cycles. When a countdown proceeds past the point where the tank is pressurized for launch - part of the plan for the June test - it counts as two cycles. Discovery's launch on the second post-Columbia mission is targeted for July 1. The ECO sensors will be checked, as usual, when the tank is loaded with liquid hydrogen and oxygen on launch day. The ECO sensors are part of a backup system intended to make sure the shuttle's three main engines don't shut down early or run too long. All four hydrogen ECO sensors are required to be operational for launch, but NASA managers could waive that requirement in certain narrowly defined cases depending on whether a given sensor failed in the wet or dry state. But any major ECO sensor problems, whether they occurred June 1 or July 1, almost certainly would rule out a launch before the window closes July 19. The engineering community believes all four sensors currently installed will work properly. Engineers currently plan to move Discovery from its processing hangar to the Vehicle Assembly Building for attachment to the tank and its twin solid-fuel boosters on May 12. Rollout to the launch pad is targeted for May 19. Rollover could be briefly delayed if engineers decide to correct a subtle timing problem with a recently installed jet thruster control assembly. But with the elimination of the tanking test, the Kennedy Space Center launch team has 17 days of contingency time available to handle unexpected problems. The engineering community is still assessing the overall safety of the external tank without foam wind deflectors called protuberance air load - PAL - ramps. The ramps were removed following the loss of foam debris from the hydrogen PAL ramp of the tank used by Discovery during the first post-Columbia mission last July. A final analysis of the tank's ability to withstand aerodynamic buffeting without the ramps in place, based on wind tunnel testing and complex computer modeling, is expected next month.
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MISSION INDEX |
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The flight of Spacelab 3 aboard Challenger in April/May 1985 was a week-long scientific research mission using a laboratory tucked in the shuttle's payload bay. Experiments focused on material and fluid behaviors in weightlessness, plus observations of monkeys in the lab. The crew also watched amazing auroral displays over Earth. This post-flight crew film shows the highlights of STS-51B and includes remarkable views out the shuttle cockpit window during launch showing the Chesapeake Bay, New York City and Cape Cod as Challenger soared up the eastern seaboard.
Discovery launched April 12, 1985 on the STS-51D mission. A U.S. military communications satellite, known as Leasat 3, failed to activate after its deployment from the payload bay. That set the stage for a spacewalk -- the shuttle program's first unplanned EVA -- to attach handcrafted "Flyswatter" objects on the shuttle robotic arm to hit a timing switch on the satellite. The rescue attempt did not succeed. Upon landing at Kennedy Space Center, Discovery blew a tire. The crew, including Senator Jake Garn of Utah, narrate this post-flight film of highlights from the week-long mission.
NASA managers hold this news conference April 28 to give an update on plans for the next space shuttle mission, the ongoing external fuel tank testing and debates over further modifications.
The Boeing Delta 2 rocket carrying the CALIPSO and CloudSat atmospheric research spacecraft lifts off at 3:02 a.m. local time April 28 from Vandenberg Air Force Base, California.
Inside the Vehicle Assembly Building, the external fuel tank for the STS-121 space shuttle mission is hoisted into position for attachment with the twin solid rocket boosters atop a mobile launch platform. The tank, ET-119, will carry the liquid oxygen and liquid hydrogen to feed Discovery's three main engines during launch.
In preparation for space shuttle Discovery's departure from its Orbiter Processing Facility hangar for rollover to the Vehicle Assembly Building and mating with the tank and boosters, the ship's 60-foot long payload bay doors are swung shut.