SPACE SHUTTLE COLUMBIA RETURNS.

Byline: Charles F. Bostwick Staff Writer

Space shuttle Columbia on Saturday made its third return to Air Force Plant 42, where it was rolled out in 1979.

Bolted piggyback atop a NASA Boeing 747, Columbia made two passes over parts of Palmdale and Lancaster before coming in for a smooth touchdown at 10:19 a.m., following a two-day flight from Kennedy Space Center in Florida.

``It put on quite a show,'' Boeing spokeswoman Lynne Van Trieste said.

The nation's oldest orbiter is back in Palmdale for approximately $70 million worth of inspections, maintenance and modifications, which will keep more than 350 Boeing technicians and engineers employed for about 10 months.

Veteran of 26 flights into space, Columbia will be largely disassembled inside the huge assembly building where all five shuttles - including the ill-fated Challenger - were put together in the 1970s and 1980s.

Workers will examine structural components for fatigue, corrosion or broken rivets or welds. They also will inspect more than 100 miles of wiring, following the discovery of a wiring problem during the STS-93 mission, and apply abrasion protection where necessary, Boeing and NASA officials said.

The Columbia won't look much different when it comes out, but it will have undergone nearly 80 modifications. The modifications include better protection for its radiators against space debris, upgrades to its thermal protection, weight reductions and a multifunction electronic display system or ``glass cockpit.''

The ``glass cockpit,'' similar to those used in the latest airliners, consists of touch-screen electronic panels to replace the orbiter's 1970s video screens and mechanical gauges. Last year, Atlantis became the first shuttle to get the new displays.

Columbia will also get additional wire harnesses and connectors that will let Kennedy workers install a docking device if NASA officials decide to use it to supply the International Space Station.

Columbia's next flight is scheduled for December 2000.

Columbia had originally been expected to reach Palmdale on Friday afternoon. But the shuttle instead spent Friday night at Whiteman Air Force Base in Missouri after its departure from Florida was delayed by bad weather.

To work on Columbia, Boeing recalled more than 150 workers who had been laid off following the completion of inspections and modifications in September 1998 to Atlantis. Boeing was able to keep on more employees than usual between shuttles by transferring in work from other plants, Van Trieste said.

``The merger with Boeing has been a really good thing for us,'' Van Trieste said.

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2 Photos

Photo: (1--Color in AV only) Space shuttle Columbia, ferried atop a NASA 747 from Kennedy Space Center in Florida, returns to Air Force Plant 42, where it was assembled in 1979.

(2--Ran in AV only) Riding piggyback aboard a 747, the space shuttle Columbia approaches a special gantry.

Charles F. Bostwick/Staff Photographer