GOLETA, California - Like a giant sequoia growing from a tiny seed, Space Shuttle Endeavour will sprout from its narrow cargo bay a 200-foot (60-meter) mast, just hours into its 11-day mission to map the world.

"This will turn out to be the longest rigid structure ever deployed in space," said Ed Caro, the mission's chief engineer at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

The massive graphite-epoxy and titanium mast forms the nexus of the Shuttle Radar Topography Mission, separating the two radar antennas used in the project.

Strong, lightweight and stowable, the $8 million mast is also as stable as a surgeon's hands.

Its tip sways less than an inch (2.5 centimeters) when flying in space, allowing for the radar to map with a high degree of accuracy. Heat it to 150 degrees Fahrenheit (66 degrees Celsius) or cool it to minus 76 degrees Fahrenheit (minus 60 degrees Celsius), and the mast will vary in length by less than 0.12 inches (3 millimeters).

"If people want to deploy something from here to there - and keep it there - this is what they are going to be looking at," said David Messner, vice president of engineering for mast-maker AEC-Able Engineering Co. Inc. (AEC)

Working in seaside Goleta, just north of Santa Barbara, California, AEC's 97 employees are about as casual as aerospace types come. Surfboards lurk in most offices and the conference rooms all bear names of local wave-catching hotspots, including Rincon, Jalama and El Capitan. And while bunny suits are still de rigueur in the clean room, it's strictly shorts underneath.

The company has built NASA masts and booms for years, including specimens that flew, or are flying on Galileo, Cassini, Mars Pathfinder and Lunar Prospector. It is now building the twin petal-like solar panels for the 2001 Mars lander, as well as masts that will support the solar arrays on the International Space Station.

A first among its peers, engineers named their latest - and longest yet - creation "ADAM," or Able Deployable Articulated Mast.

The mast deploys and retracts - don't say "collapses," AEC engineers warn - into a canister nestled tightly in the shuttle's bay.

Pulled out of the canister by a four-threaded, motor-driven rotating nut when activated from inside the shuttle by the astronauts, the mast unfurls all of its 87 bays in a swift 20 minutes.

"That is probably going to be the most spectacular part of the mission," Caro said of the mast's rollout - and roll-in.

As each bay emerges from the canister, it locks into place, forming a skeletal rectangular box.

"It's clever and it's fairly simple," Messner said, "but mostly clever."

The 605-pound (275-kilogram) mast also carries a shiny web of utility lines, including 440 pounds (200 kilograms) of coaxial and fiber-optic cables, copper wire and a single thruster gas line.

"That was the trickiest part of the program," said William Spink, the ADAM project manager at AEC, about threading and folding the cables origami-like through the mast. "It took technicians coming in after many sleepless nights saying, 'I have an idea.'"

But when stacked, cables and all, the mast fills a space just 56 inches (142 centimeters) wide, or about 2 percent of its deployed length.

That's like folding all of Los Angeles Lakers Center Shaquille O'Neal's 7-foot-1-inch (216-centimeter) frame into a box 2 inches (5 centimeters) high. Or shrinking the 128-foot (38-meter) mainmast on Capt. James Cook's bark Endeavour, the shuttle's 18th-century namesake, into a 3-foot (1-meter) stump.

Engineers at AEC said they have tested deploying and retracting the mast 35 times. "It's just turn on the motors," said Dave Gross, AEC technical director, of deploying the mast.

Should the motor drive fail in space, the astronauts can perform a spacewalk to crank it out with the help of an electric drill, or by hand if need be.

If successful, the SRTM mission may not be the last hurrah for ADAM, however. "We're already talking to JPL about a re-fly," Messner said.