COUNTDOWN TO DISASTER : Challenger’s Last Flight : 1. LIFTOFF : ‘Challenger, Go at Throttle Up’

America avoided disaster in space through 52 manned missions spanning 25 years. Then it happened. Perhaps the day was inevitable, but few were prepared. Now, as a search for answers--and for understanding--rises from deep within the national psyche, The Times presents this special report.

There comes an instant when all the noise and pressure turns to calm, when the shaking suddenly ceases and the ride gets smooth.

The twin rocket boosters that have punched a path into the heavens have dropped away, and the sky is jet black. Gravity no longer tugs.

This is space.

Four aboard the space shuttle Challenger had already known this instant, and their three colleagues were eager to find it out.

One of the newcomers was a Concord, N.H., social studies teacher who carried into the adventure her grandmother’s watch and her son’s stuffed frog.

By her own description, she would be America’s first “ordinary person” to go up, the common man’s emissary into the ether of the right stuff. To her, and to a confident nation, it was the ultimate field trip.

At 73 seconds into the flight, the spellbinding instant--this burst into orbital serenity--was less than six minutes away. They were riding a shaft of fire to get there.

Computers guided and throttled the ascent. Rockets gulped fuel. Roger. Go.

Then the explosion.

“Obviously, a major malfunction,” was the delayed response from the NASA flight narrator.

His voice was restrained in the familiar space program monotone. It seemed too controlled for the calamity obvious on millions of televisions in millions of living rooms:

“We have no downlink. We have a report from the flight dynamics officer that the vehicle has exploded. The flight director confirms that.”

So there it was, disaster in space, the fiery horror of failure. Surely, they were all dead, the teacher, the commander, the pilot, the laser physicist, the three engineers.

America, first to the moon, would be left to scavenge for debris, to grieve and console, to question plans and purposes in the trembling aftermath of a fireball in the Florida sky.

“Sometimes when we reach for the stars, we fall short,” President Reagan said in a eulogy three days later. “But we must pick ourselves up again and press on despite the pain.”

That is the inclination. Space is the next frontier, and this is a country forged from the frontier spirit. Since 1961, when President John F. Kennedy pledged victory in what was then called the “space race,” the nation has spent $117 billion on skyward exploration.

But there is now another dreadful price tag affixed to the national pride. The videotape rolls and the images repeat. Experts are quick to remind that too much has been taken for granted, that the space shuttle is the most complex flying machine ever built. It is fueled by propellants mightier than anything but a nuclear bomb.

Harnessing these tempests of hell seems to inevitably invite the demons of tragedy. Instead of a burst into serenity, Challenger’s crew met with a cataclysm that now demands national introspection as well as the frantic search for clues.

It may be months, if ever, before the precise error is pinned down. But the broader causes are found in more than the nip of a frosty morning or the simple math of the odds.

In the last 12 days, it has become clear that the complete story of the shuttle’s countdown to disaster stretches back more than 15 years to a chain of dollar-saving compromises. Design and operating procedures were tailored with the bottom line in mind.

What remains uncertain is if any of those compromises directly affected Challenger. Was the mistake in an engineer’s miscalculation? In a manufacturer’s defect? In the lack of inspection? In a ground crew shortcut?

“Where We’ve Been, Where We’re Going,” the 37-year-old teacher and mother of two, Sharon Christa McAuliffe, had planned to call one of the lessons she would teach from space.

She was an energetic, confident woman with a bounce in her step. Once, she had been urged to go to law school, as her husband had. She preferred the challenge of Room 305 at Concord High.

If a trip into space was an unusual breather from the classroom, she had reason to be confident in the safety of the 12-story orbiter. NASA’s four shuttles--Atlantis, Discovery, Columbia and Challenger--had flown 24 missions and landings had been almost perfect. The space agency had not suffered a fatal accident since three Apollo astronauts perished in a 1967 launch-pad fire.

McAuliffe was riding a winner as she sat in the vehicle’s mid-deck. To her left was Ellison Shoji Onizuka, 39, grandson of Japanese immigrants and a father of two. An aerospace engineer who had already experienced one shuttle flight, he was also the crew’s devoted quipster. Among many tasks, he was to film Halley’s comet with a hand-held camera.

To McAuliffe’s right was Gregory Jarvis, 41, an engineer who lived with his wife in Hermosa Beach and had patiently waited for a shuttle seat during two years of postponements. He was to experiment with the effects of weightlessness on board.

For more than three hours they had waited inside Challenger. Conversation was minimal, the mood all business.

Outside, the orbiter had already come to tenuous life. Cryogenic hydrogen and oxygen was being pumped into the huge external tank. The liquid mix was so cold that a steaming vapor cloud lifted from launch pad 39B. The tank seemed to groan as its aluminum skin contracted from the cold of the fuel.

But inside there was only expectation--and the urge to walk about, which was impossible. The crew members were flat on their backs, strapped into seats pitched at a 90-degree angle to the ground. The astronauts’ weight pressed against their buttocks and spines.

The chairs were cold steel and the padding was thin. Straps and buckles were cinched snugly against their light-blue flight suits. Safety belts crossed their chests. Another belt came up between their legs, another around their waists.

The crew had actually practiced this waiting. McAuliffe compared it to spending hours with your feet up on a bed while wearing a motorcycle helmet. The legs went to sleep.

In the meantime, Challenger’s machinery was busy, even if the five men and two women were not. The computers checked the flight instruments, a mechanical doctor taking its own pulse.

Mission commander Francis R. (Dick) Scobee, 46, studied the flight plan, occasionally staring through the front window of the flight deck. It had been nearly two years since his first shuttle mission, and he had remarked that he would give “absolutely anything” to again experience the thrilling lurch and growl of liftoff.

The countdown ticked closer. Just minutes before launch, Scobee, like the others, placed the airtight plastic face plate of his helmet over his eyes.

Beside him was Michael John Smith, 40, a handsome and athletic one-time Navy test pilot. A father of two, he had yet to pilot a shuttle. Like the commander, he was a Vietnam veteran.

By now, the crew was breathing pure oxygen. Their eyes glanced at panels that held 600 displays and nearly 2,000 switches and circuits.

With 25 seconds to go, the on-board computers did the final checks. The slightest glitch would still mean an aborted mission.

“T minus 10-9-8. . . .”

Behind the commander and pilot sat Judith Arlene Resnik, 36, and Ronald Erwin McNair, 35. They completed a crew that was a hearty spoonful from the American melting pot.

Resnik, an electrical engineer, was a Jew from Akron, Ohio, and a math whiz who also played classical piano. McNair, the laser physicist, was the product of segregated South Carolina schools. He had become the second black into space in 1984.

Six seconds until liftoff, Challenger’s main engines ignited. One, two, three, they fired. Inside, they sounded like jet engines--the whoosh of air and the hum of power. The shuttle jolted more than a foot sideways.

In a tower that flanks the launch pad, water shot from 16 nozzles that sit atop flame deflectors. Thousands of gallons splashed into a depression at the pad’s base, stifling some of the roar and rattle. Without it, acoustic shock waves would damage Challenger before it leaped free.

“T minus 3-2-1. . . .”

Finally, at 11:38.03 EST, Challenger’s two solid-fuel rockets burst into life. They were 149 feet long and 12 feet in diameter, the largest solid fuel rockets ever built.

They are filled with a propellant of powdered aluminum the consistency of a hard eraser. They look like giant Roman candles.

Pressurized exhaust gases spat from the boosters’ exit cones with a combined thrust of nearly 3 million pounds--enough power to light up much of the East Coast.

The noise was a roar. It was not uncomfortable to the ears of the crew but it was still an unforgettable thunder. It would only get louder until the fuel burned into oblivion and the rocket casings were cast free.

With the noise came feverish vibrations, the trembling that astronaut Sally Ride once called a Disneyland “E ticket,” in reference to the park’s premier rides, and others liken to being strapped to a paint shaker.

A slow boost toward space began. The crew members felt the surge of power beneath them, but the lift was smooth, something like a fast elevator. Challenger cleared the service tower in seven seconds.

Quickly, the shuttle rolled into a high arc above the Atlantic, turning gently on its back, suspended beneath the external tank.

“Houston, we have roll program,” Scobee reported 16 seconds into the flight.

“Roger, roll Challenger,” routinely answered Richard Covey of Mission Control in Houston.

Acceleration jammed the crew members back into their chairs. Three Gs--or three times the force of Earth’s gravity--pulled at their skin. Their limbs felt heavy.

By then, there was no safe way to call it quits. They were at the mercy of the boosters. The shuttle was off on a ride until the rockets guzzled the fuel.

Out the front window there was only the brilliant blue of sky, soon to fade into blackness. Out the sides, the horizon sharpened into the sea in one direction, land in the other.

The instrument panels registered temperatures, flow rates, cabin pressure, trajectory. The shuttle appeared as a blip on a screen, the computers predicting its trajectory. The crew could watch Challenger’s course, on beam all the way.

At 35 seconds, just as planned, the throttle was cut back to 65% of full power. This prevented the force of rushing air from overstressing Challenger’s wings and tail. Speed had increased to 2,257 feet per second--seven football fields in the blink of an eye.

“Three engines running normally,” NASA reported. “Three good fuel cells. Three good APUs (auxiliary power units) . . . altitude 4.3 nautical miles. Down-range distance three nautical miles.”

The roar built. Sometimes it sounded like a clanging. Sometimes it was a strange twang like the bending of sheet metal.

“Challenger, go at throttle up,” Covey said at 52 seconds into the flight.

This was not a command. It meant that Challenger had passed that part of the atmosphere where the dynamic pressure was greatest. Its engines had automatically returned to full thrust, or “throttle up.” All systems were “go,” or OK.

“Roger, go with throttle up,” Scobee responded.

All was routine.

Relentlessly, it seemed, Challenger approached that blissful instant. Relentlessly, it lunged toward the serenity of space.

THE LAUNCH

There had been problems from the beginning of Challenger’s 10th flight. Origianlly set for Jan. 22, the launch was delayed by weather problems and finally by a troublesome bolt on a hatch door. On the night before launch, temperatures at Cape Canaveral dropped to 27 degrees and icicles were scraped from the launch pad. But when the Challenger’s five engines fired on the morning or Jan. 28, the space shuttle lifted serenely. It seemed a perfect launch. THE EXPLOSION

At 11 seconds into the flight, right on time, the shuttle rolled on its back. About 48 seconds later, the problem began. A small “unusual plume” erupted from the shuttle’s right booster rocket. It grew rapidly, blowtorching the liquid fuel tank, Cmdr. Francis R. (Dick) Scobee, oblivious, signaled that the main engines had throttled up to full power. The shuttle disappeared in an orange fireball. THE RECOVERY

Debris rained down into the Atlantic, a relatively shallow area about 18 miles off Cape Canaveral. Coast Guard and NASA retrieval efforts using submarines and divers were hampered by strong northerly currents, but about 12 tons of debris was recovered by week’s end. Among the larger pieces were chunks of the orbiter’s fuselage and possibly a section of a booster rockert casing. Recovery ships, using sonar, located 17 additional objects on a sea floor littered with the remains of rockets lost over 25 years of launches at the Cape. Staff for Special Report on Challenger’s Last Flight A team of 41 reporters, photographers, artists and editors produced this special section, called Challenger’s Last Flight: Countdown to Disaster.

Reporters: Maura Dolan, Bob Drogin, Lee Dye, Josh Getlin, Peter H. King, Kim Murphy and David Treadwell at the Kennedy Space Center, Fla.; Don Irwin and Michael Wines in Washington; Rudy Abramson in Huntsville, Ala.; Bob Baker and Eric Malnic in New Orleans; Miles Corwin, Paul Jacobs and J. Michael Kennedy in Houston; Scott Kraft in Brigham City, Utah, and Barry Bearak, Robert Jones, Thomas H. Maugh II, William C. Rempel, Kevin Roderick and Ralph Vartabedian in Los Angeles.

Photographers: Larry Davis, Marsha Traeger and Carol Bernson.

Researchers: Doug Conner in Los Angeles and Wendy Leopold in Chicago.

Project Director: Gaylord Shaw in Los Angeles.

Editors: Edwin Chen, James Hill, Tim Rutten and Roger Smith.

News Editor: Terry Schwadron.

Copy Editors: Roger Julin, Ann Herold, Jim Houston, Rebekah Lane.

Art director: Tom Trapnell.

Artists: Michael Hall, Patricia Mitchell and David Puckett.