Space Shuttle Atlantis Still Blocked From Liftoff; Launch Set For Jan. 24 Is Unlikely; Feb 2-7 Window Would Be Next; Liftoff Likely Later In February
Space Shuttle Endeavour Launch To Be Delayed Beyond Earlier-Scheduled Feb. 14 Target
Troublesome Atlantis Electrical Link Removed; Replacement Of Problem-Filled Tank Gear Set
NASA leaders think they have figured out the enigmatic, infuriating sensor data problems that have kept Space Shuttle Atlantis sitting idle on Launch Pad 39A at Kennedy Space Center (KSC) for more than a month past its original launch date for the STS-122 Mission to the International Space Station (ISS).
That problem has forced repeated delays in the Atlantis flight originally set for Dec. 6.
Meanwhile, the next flight, of Space Shuttle Endeavour on the STS-123 Mission to the ISS, has been postponed because of those repeated launch delays in the Atlantis mission.
Putting first things first, NASA won’t set a new date for the Endeavour flight until the Atlantis problems are resolved, and they have been a tough challenge. (Please see Space & Missile Defense Report, Wednesday, Dec. 19, 2007.)
Just when Atlantis lifts off is uncertain. NASA set a new launch date of Jan. 24 for the Atlantis blastoff, but the shuttle is unlikely to fly then unless everything goes perfectly, and a window of Feb. 2 – 7 is problematical because a Russian Progress spacecraft is slated to lift off for the space station Feb. 7. NASA doesn’t wish to have a Progress freighter at the ISS at the same time that a space shuttle is arriving.
That was the picture painted by John Shannon, deputy space shuttle program manager, in a lengthy phone call to several space journalists after a 2.5-hour meeting of senior NASA officials to scope out the Atlantis situation.
A Critical Time
"The next week to 10 days is very important" in determining the timing of future space shuttle launches, Shannon said.
While he and other NASA leaders have been unfailingly optimistic about the future of the space shuttle program and the chances of the shuttles finishing their assigned task, what is clear to observers is that the Atlantis launch delays further compress an already tight flight schedule, in which construction of the space station must be completed by the Sept. 30, 2010, mandated retirement of the space shuttle fleet.
Only the shuttles have the size and power to hoist huge structural components into orbit to build the space station, which now is a bit more than half complete.
Some members of Congress are pressing to extend the shuttle flights program beyond that deadline, both to ensure completion of the space station and to perform missions that at present are canceled for lack of cargo space on the remaining shuttle flights. Expensive experiments otherwise will sit uselessly on Earth. As well, extending shuttle flights, and accelerating the first manned missions of the next-generation U.S. spacecraft Orion-Ares, would cut or eliminate a half-decade gap when the American space flight program would cease to exist. (Please see Space & Missile Defense Report, Wednesday, Dec. 19, 2007.)
Shuttles have been flying for roughly a quarter century, and the aging vehicles are complex machines.
A total of years of planned shuttle flying time has been eliminated as one problem after another occurred: for example, two decades ago, Space Shuttle Challenger exploded seconds after liftoff when solid rocket booster O-ring seals failed in cold weather. In 2003, a piece of foam insulation broke free from the external fuel tank of Space Shuttle Columbia, punching a hole in heat shielding on the leading edge of an orbiter vehicle wing, so that searing hot gases of reentry caused structural failure. Both Challenger and Columbia, and their crews, were lost, and it took scientists, engineers and others years after each accident to determine what went wrong and how to fix it.
Then there were other, lesser problems that thankfully didn’t lead to fatalities, but which did force delays in scheduled shuttle flights.
Perhaps no shuttle has been so afflicted with such delays as the star-crossed Atlantis.
It almost was hit by lightning and then narrowly avoided an encounter with a hurricane before one flight. Earlier last year, Atlantis was sitting on the launch pad when a rogue thunderstorm swept in, slashing hail onto the Atlantis external fuel tank that forced repair of an enormous number of dings in the tank foam insulation.
The Latest Problem
Then, in the fall, things appeared to go much better, with a blissfully smooth countdown toward a scheduled Dec. 6 Atlantis launch, when the latest glitch struck: malfunctions and wrong readings appeared in data from three of four low-fuel-level warning sensors in the portion of the Atlantis external fuel tank holding super-cold liquid hydrogen fuel.
This is important in averting yet another disaster, because if space shuttle engines continue to run after a fuel tank has gone empty, a catastrophic explosion could occur. The fuel gauges for that reason are called engine cut off, or ECO, sensors.
While at first suspicion centered on the sensors about 10 feet from the bottom of the tank, the real culprit may lie in wiring and connectors feeding data from the sensors to the orbiter vehicle, specifically in a pass-through connector assembly that takes sensor data from inside the tank, through the tank wall to the outside.
To resolve the problem, NASA and contractor technicians worked at the launch pad to remove the external portion of the pass-through connector to be sent for tests at Marshall Space Flight Center at Huntsville, Ala., first to see whether a test in cryogenic conditions will permit experts to replicate the sensor data glitch, and then to see whether a fix of soldering connecting pins in place will solve the faulty sensor data problem. Marshall has facilities that can replicate the super-cold cryogenic conditions that the sensor line connectors would encounter in flight. All of this will take about two weeks, Shannon said.
No Anomalies Seen
As well, NASA and contractor experts working at the launch pad inspected the other half of the connector, still in place inside the tank, that feeds fuel sensor data to the outside, Shannon said. That inspection of the internal connector showed "no anomalies," he reported.
Another move will be to provide some slack in wiring leading to connectors, so if they contract in the stunningly cold cryo temperatures, they won’t pull on the electrical pass-through connector gear.
Technicians also will install new external connector gear, with the soldering fix, on the Atlantis tank by Thursday. If it turns out the problem has been correctly diagnosed, and tests also show that the soldering fix works, that would mean Atlantis is good to go, barring other, unforeseen problems.
On the other hand, if that fix doesn’t solve the problems, it could cost some time. "We are taking some schedule risk" here, Shannon said.
Even if all goes well, these moves take time. "If things break our way," and all goes well, then Jan. 24 would be the earliest date to launch Atlantis, so KSC crews were told to protect for a Jan. 24 launch date, Shannon said.
Endeavour Mission Postponed
Since crews normally require five weeks between shuttle launches to clean up from the first one and prepare for the second one, and there are but three weeks from Jan. 24 to Feb. 14, that means the Endeavour flight on the STS-123 Mission has been postponed.
For Endeavour, there would be "no way to launch on Feb. 14," given that Atlantis will launch no earlier than Jan. 24, Shannon said.
If Atlantis doesn’t fly on Jan. 24, a "much more likely" launch during Feb. 2 – 7 would be a possibility, if "everything goes about as we expected," Shannon added. At the meeting Thursday, there was no discussion of moving Atlantis from the launch pad back to the Vehicle Assembly Building, he said.
However, there is a Russian Progress cargo ship slated to launch Feb. 7, and that might force NASA to delay any Atlantis liftoff until some later time next month. "We won’t dock a shuttle if a Progress is docked there," said Mike Suffredini, ISS manager. The Russians "need to stick to that [Feb. 7 launch] date."
Shannon also termed the Progress launch "a hard constraint," not wishing to delay that supply ship mission.
In all this, of course, there always is the notoriously fickle Florida weather that can mandate a postponement of even the smoothest space shuttle launch countdown.
To help speed any eventual Endeavour launch, NASA gave KSC crews permission to prepare to perform the same pass-through connector fixes on its external fuel tank that are being performed on the Atlantis EFT, with removal of foam insulation and a cover over the connectors on the Endeavour EFT.
When the Endeavour mission will begin still is uncertain. "Once we have a good launch date for this mission" of Atlantis, then NASA leaders can kick off a discussion of a new launch date for Endeavour, Shannon said.
Asked why so many shuttles have been able to fly missions when, apparently, there was a possibility of this sensor-data-line flaw in tank connectors, Shannon said he is unsure. NASA will check whether something might have changed: a new technician installing connectors, a different way of installing them, or the like.
When it finally gets off the launch pad, Atlantis will take the Columbus European Space Agency laboratory, a room-sized addition, into orbit for attachment to the space station.
The lab will provide scientists around the world the ability to conduct a variety of life, physical and materials science experiments.
The Atlantis crew going up to space consists of Commander Steve Frick, Pilot Alan Poindexter, mission specialists Leland Melvin, Rex Walheim, Stanley Love and European Space Agency astronauts Hans Schlegel, from Germany, and Leopold Eyharts, from France.
Coming back to Earth, Atlantis will bring back home astronaut Dan Tani, who has been at the space station since October. During his time in space, Tani’s mother died in a highway accident at a railroad train crossing, and he missed her funeral as he circled the Earth, 250 miles from the ground. He is eager to rejoin his family and help console them.
The Atlantis and Endeavour flights will be followed by four other space shuttle launches, for six in all this year.
That would be double the number of shuttles that NASA got off the ground last year. However, to be sure, NASA got the three 2007 shuttle launches up in less than six months, so that pace would indicate that six launches in a full year would be possible.