Spaceflight Now: Space Station/STS-98

Wiring checks delay shuttle Atlantis launch to February

Posted: January 15, 2001, at 1725 GMT
Updated at 0010 GMT

Space shuttle Atlantis sits atop pad 39A awaiting its mission to carry the U.S. Destiny laboratory module to the international space station. Photo: NASA
On the eve of shuttle Atlantis' countdown to launch Friday, NASA managers today instead ordered engineers to haul the spacecraft back to the Vehicle Assembly Building for work to test suspect wiring in the ship's booster separation system.

The unplanned tests will delay Atlantis' launch on a critical space station assembly mission between two and three weeks -- to around Feb. 6, officials say -- a disappointing start for NASA's ambitious 2001 launch campaign. But failure of the pyrotechnic system that allows the shuttle's two solid-fuel boosters to separate two minutes after liftoff would be catastrophic.

And even though Atlantis' boosters were inspected and given a clean bill of health after a suspect cable was replaced last month, recently discovered problems with four other cables in NASA's parts inventory forced agency managers to order additional inspections and tests.

Atlantis' five-member crew, meanwhile -- commander Kenneth Cockrell, pilot Mark Polansky, flight engineer Marsha Ivins and spacewalkers Thomas Jones and Robert Curbeam -- was scheduled to fly to Florida late today for the start of the shuttle's countdown early Tuesday.

But the astronauts delayed their departure from Houston while NASA managers reviewed the booster cabling issue during a later-afternoon teleconference. The flight was cancelled when the launch delay was announced.

The decision came less than two weeks before the 15th anniversary of the Jan. 28, 1986, Challenger disaster.

Challenger was destroyed by a different sort of booster failure and while today's decision was based on a strictly technical assessment, the approaching anniversary serves to refocus attention on NASA's oft-stated "safety first" approach to space flight.

The wiring concern will force Atlantis to be rolled back to the Vehicle Assembly Building. Photo: NASA
In this case, even though there is nothing known to be wrong with Atlantis, shuttle program manager Ronald Dittemore decided to err on the side of caution and ordered a delay.

The postponement is likely to extend the voyage of the Expedition One crew aboard the international space station by a few extra days. The planned March 1 launch of Discovery to bring the three-man crew home will probably slip as a ripple effect from Atlantis' delay.

The preliminary schedule calls for Atlantis' payload -- the $1.38 billion Destiny laboratory module -- to be removed from the shuttle's cargo bay Thursday and mounted in the launch pad's protective payload changeout room.

The shuttle itself will be hauled back to the Vehicle Assembly Building on Friday.

Engineers will not need to "destack" Atlantis, its external tank and boosters to test the suspect booster separation cables. If all goes well, the shuttle will be moved back to pad 39A Jan. 25.

Under this scenario, the STS-98 countdown would begin Feb. 3 for a launch attempt as early as Feb. 6. But that assumes the tests go smoothly and no additional problems surface.

NASA originally planned to move Atlantis to the pad in mid December for a launch on Jan. 18. But the move was held up after engineers discovered problems with booster separation hardware used in the late November launch of shuttle Endeavour.

One of two pyrotechnic circuits in Endeavour's left-side booster attachment strut failed to fire. The other circuit worked normally and the booster separated as planned.

But booster separation is a critical event -- the shuttle would be destroyed if even one strut failed to separate properly -- and NASA managers ordered X-ray inspections of Atlantis' booster wiring to make sure its separation system was healthy and fully redundant.

File image of solid rocket booster separation. Photo: NASA TV/Spaceflight Now
One cable with a slightly frayed outer jacket was replaced, Atlantis was given a clean bill of health and the shuttle was moved to the launch pad Jan. 3, nearly three weeks later than originally planned.

Taking holiday downtime into account, the launch only slipped one day, to Jan. 19.

In the meantime, engineers continued to assess the wear and tear on the cables while carrying out additional tests on other hardware in the shuttle inventory to characterize electrical conductivity and overall performance.

Over the past week, engineers discovered problems in four separation system cables making up part of the shuttle inventory.

At least one of the cables in question passed a post-flight X-ray examination, sources said, but exhibited intermittent continuity, or electrical transmission, during a so-called "wiggle test" that simulates launch vibrations.

Engineers plan to perform similar wiggle tests on Atlantis' boosters to make sure continuity is solid.

Shuttle rollout panorama

As space shuttle Atlantis rolled atop Kennedy Space Center's launch pad 39A on January 3, Spaceflight Now was there to capture this 360-degree panorama.
  VIEW (329k QuickTime file)

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