The Questions Get Tougher

By Ed Magnuson

The painstaking search for the cause of the world's worst space disaster shifted dramatically, and distressingly, in tone last week. After 24 successful space-shuttle flights, the explosion of Challenger and the loss of its seven crew members had been widely viewed as a tragic but virtually inevitable cost of pioneering on the high frontier of space. As it one day must, so it was said, ill fortune had finally overtaken the methodical, ever cautious, technological wizards of the National Aeronautics and Space Administration. Declared President Reagan on that fateful day: "It's all part of the process of exploration and discovery; it's all part of taking a chance and expanding man's horizons."

Across the nation, there was vast public sympathy for NASA's sorrowful officials as they began seeking the accident's cause. "We grieve at NASA," said Jesse Moore, its associate administrator for space flight. "We grieve every day." A presidential commission headed by former Secretary of State William Rogers opened its investigation with a protective attitude toward NASA. Rogers even publicly badgered an internal critic of NASA's safety standards about his competence to criticize. Surely it would eventually be found that, despite NASA's elaborate precautions, some technical aberration had caused the tragedy.

But by last week the atmosphere, and NASA's image, had changed. After declaring that NASA's procedure for deciding whether to launch Challenger "may have been flawed," Rogers demanded that no NASA official involved in that decision take further part in the space agency's own investigation. And word leaked out that Rogers had told the White House he had been "appalled" by the way the launch decision had been made. At a public hearing of the Senate Subcommittee on Science, Technology and Space, South Carolina Senator Ernest Hollings said of the disaster: "At this particular juncture it seems like an avoidable accident rather than an unavoidable one." Later he charged that it was becoming "increasingly apparent that NASA made a high-level, political decision to go ahead with a morning launch of the shuttle, despite strong objections from Morton Thiokol engineers, who said the temperature was far too cold for a safe launch."

Even the authoritative and generally pro-NASA trade journal Aviation Week & Space Technology was critical. While praising the "dedication, high level of effort and in many cases personal sacrifice" of NASA personnel, it charged that "undercurrents reveal a hidebound space agency fraught with lax management oversight, intramural turf battles between headquarters and key field centers and a tendency toward compartmentalized bureaucratic thinking that, in the aftermath of the accident, has generated self-serving responses."

Why the sudden turnabout? In closed meetings the commission had grilled top NASA officials as well as engineers from Morton Thiokol, the company that makes the solid-fuel boosters suspected of triggering the disaster. The commissioners could scarcely believe what they were hearing as they made some startling discoveries: 1) the engineers had adamantly opposed the launch because of the unusually cold weather at Cape Canaveral; 2) on the morning of the tragedy, an infrared temperature-sensing instrument had shown abnormal "cold spots" of 7 degrees and 9 degrees F on the lower part of the right-hand booster; and 3) most unsettling of all, neither of the first two findings had been conveyed to at least three of the highest officials responsible for making the decision to send Challenger aloft.

There was a stunned silence in the commission's closed hearing room at the cape after Robert Sieck, shuttle manager at the Kennedy Space Center, Gene Thomas, the launch director for Challenger at Kennedy, and Arnold Aldrich, manager of space transportation systems at the Johnson Space Center in Houston, all testified that they had never before heard that Thiokol engineers had objected to the launch. Rogers ordered everyone except the commissioners out of the room and declared, "We must advise the President as soon as possible." Explained one commission source: "We did not want the President to be blindsided."

The latest developments focused once again on the unusually frigid Florida temperatures, which had fallen to the mid-20s, accompanied by 35-m.p.h. gusts for hours before Challenger was launched, and on the right booster, which had clearly failed. Less than half a second after booster ignition, just as the shuttle began to lift, first a white and then a black puff of smoke gushed from a joint between two of the 149-ft. rocket's four segments. At 59.8 seconds, high in the sky, flame burst through the booster's steel casing, apparently at the same aft joint. In another 13 seconds, the external tank that fueled the orbiter's three main engines exploded in a catastrophic, fatal fireball.

To most rocket experts, the telltale black smoke meant that right from the start, at least one of the two synthetic rubber O rings that were meant to seal the joint between the rocket's segments had begun to burn. Roughly a quarter-inch thick and 37.5 ft. in circumference, the large O rings rest in grooves at the three joints. Like the washers that prevent faucets from leaking, they are designed to keep the rocket's exhaust gases from escaping through any gaps in the joints. These are especially vulnerable under the immense forces generated at lift-off (the entire shuttle bends momentarily in what engineers call "the twang," and the nearly half-inch-thick steel casing of the boosters balloons slightly above and below each joint). In the Challenger disaster, the exhaust gases had apparently burned through a protective putty (signaled by the white smoke) and jetted past both O rings, presumably because they had not seated properly in their grooves at blast-off.

The potential impact of the cold weather on the O rings was of deep concern to Thiokol engineers on the day before Challenger made its last flight. Some were at Kennedy Space Center, where the shuttle launch had repeatedly been delayed (in part by rain and wind at the cape, as well as by a dust storm at a possible emergency landing site in Africa). Others were at the Thiokol plant in Brigham City, Utah. Also involved in any decision about the booster's reliability in cold weather were officials of the Marshall Space Flight Center in Huntsville, Ala., where the boosters and the orbiter's engines had been developed and tested.

A critical meeting on the problem began at 4:30 p.m. that day in a large conference room in the Kennedy center. Linked by telephone were relevant Thiokol engineers and agency officials at Marshall and Kennedy. While details of this teleconference have not been revealed, a key role was apparently played by Lawrence Mulloy, rocket-booster manager at Huntsville, who was at the cape. The discussion, according to some accounts, was long and heated, and the engineers were unanimous in asking that the Challenger launch be delayed yet again because of the weather.

Their concern centered on the fact that the O rings lose some of their resiliency, and thus their ability to seat tightly in their grooves, when their temperature falls below 50 degrees . (One expert later explained that the resilience of the synthetic rubber declines ever more sharply as its temperature drops below freezing, adding, "It's a pretty steep curve when it gets down in the 15-to-0 degree range.") Challenger should not go, the engineers warned, until the weather warmed to at least the lowest temperature at which a previous shuttle had been launched. That was 51 degrees , on a mission earlier in January.

One Thiokol engineer who vigorously protested any go-ahead for Challenger was Allan McDonald, 48, who was director of Thiokol's solid-fuel rocket project and the company's senior official at the cape. He told the New York Times that he had engaged in "heated exchanges" with NASA officials about the launch when he learned that the temperature of the O rings had fallen to about 30 degrees . His argument, mainly with Mulloy, was a "very prolonged discussion. The engineers in Utah were largely in agreement with me." As the discussion continued into the evening, McDonald refused to sign an official approval to proceed with the launch.

Several reports suggested that Mulloy had insisted that the engineers prove to him that the conditions of the launch would be unsafe, rather than asking them to be certain that everything was right. "He in effect was reversing the whole safety process, demanding to know, 'Where do the launch criteria say we can't launch?' " one commission source contended. According to National Public Radio, Mulloy asked the engineers at one point, "My God, Thiokol, when do you want me to launch, next April?" Repeatedly, Mulloy, and possibly other officials from the Marshall center, asked the engineers to recheck their data opposing the launch. Each time, the conversation broke off, and the engineers re-examined their figures, then resumed the debate still firm in their position.

Finally, Mulloy apparently went over the heads of the engineers, asking Joe Kilminster, Thiokol's vice president for space-booster programs, in Utah to sign the launch go-ahead. He did so shortly before midnight, sending a memo to both the Marshall and Kennedy centers. It concluded that the launch should proceed and argued that the rocket boosters would not be "significantly different" from a 1985 flight, also exposed to overnight chills, even though Kilminster conceded that the Challenger O rings would be 20 degrees colder than on that mission.

Kilminster advanced one argument that had been challenged in previous NASA memos about the long-studied O-ring problem: "If the primary seal does not seat, the secondary seal will seat." NASA had in fact concluded in March 1983 that the stress on the joints during launch could prevent the secondary ring from seating properly and that it was not a reliable backup for the primary . ring. But the agency, seemingly confident from the results of previous flights that the primary rings would not fail, then officially waived its own long- standing requirement that there must always be a backup to provide redundancy for critical shuttle systems. In short, NASA continued to launch missions fully aware that failure of a primary O ring could cause disaster.

Thiokol's McDonald continued to protest the decision. "I argued before, and I argued after," he said. But he was unsuccessful in changing what turned out to be a tragic decision. Challenger would go. (Last week McDonald quit his job in protest at not having been heeded.)

On the morning of the launch, another chance to avoid a disaster was missed. Overnight, icicles had formed on the huge gantry that supports the shuttle on the pad. NASA launch officials, concerned that ice breaking off at launch might damage the fragile tiles on the orbiter's skin, sent "ice teams" to inspect the pad three times: at 5, 6:30 and 11 a.m. Each time, the teams reported that the ice did not really seem to pose a flight hazard. But for reasons not yet explained, at least one of their findings did not reach top launch officials. At the 6:30 inspection, their infrared instrument detected the 7 degrees and 9 degrees cold spots on the skin of the right booster. By contrast, the readings on the left booster were considered normal (19 degrees to 24 degrees ), since the wind chill had been severe. If accurate, the readings on the right booster meant that its O rings, which are not insulated from outside temperatures, were subjected to far greater cold, and thus greater loss of resiliency, than on any previous shuttle flight.

Last week Richard Feynman, a Nobel-prizewinning physicist from Caltech and a member of the presidential commission, was back at the cape trying to determine why those cold readings had developed. As he watched, NASA recalibrated their infrared meter and found that it had been accurate to within .1 degrees . The low readings had been correct.

As Feynman probed further, he was told by NASA that the surface temperature of the external tank, which contains supercold liquid oxygen (-297 degrees ) and hydrogen (-423 degrees ) had not been abnormally cold, casting doubt on a theory that liquid fuel, leaking unnoticed from the tank, had chilled the nearby booster. He also discovered that the wind on the morning of the launch had been blowing across the cold surface of the tank toward the right booster. As one NASA engineer explained, "Even a slight breeze, wafting over the external tank full of those cryogens (supercold fluids) may have been enough to produce lower temperatures on the right-hand solid rocket booster than on the left."

Incredible as it may seem, Shuttle Director Moore also had been one of the officials who were never told of the heated opposition to the launch by Thiokol engineers or the discovery of the booster's cold spots. Asked by the Senate subcommittee what he would have done if he had known about the cold spots, Moore replied, "I would have asked more questions about what the readings indicated." Said Tennessee's Senator Albert Gore Jr.: "The record calls into question the way alarm bells are rung and heard" at NASA.

As the presidential commission continues its work, NASA's ambitious goal of launching 15 shuttle flights this year is bound to come under closer scrutiny. "There seems to have been a speedup policy at NASA," says Jerome Lederer, a former director of the space agency's office of manned flight safety, adding, "There are signs that complacency may have set in, and that is not good for safety." Insisted a NASA engineer: "We are being driven by a launch manifest, not hardware capability or concerns about anything else." NASA has in fact been pushing its contractors for faster delivery of shuttle components, and many of these companies have been pressing their employees into working six-day weeks with heavy overtime. But whether the speedup in any way contributed to the Challenger disaster is not clear.

Finding his agency increasingly on the defensive, NASA's acting administrator William Graham ordered the immediate transfer of Moore to head the Johnson Space Center. Although the move had been in the works before the Challenger disaster, the speedy transfer permitted Graham to bring in a new and wholly untarnished leader for the shuttle program. He is Rear Admiral Richard Truly, 48, who had spent 14 years as a NASA astronaut and whose last duty before leaving the agency in 1983 was to command a flight of the Challenger. Departing from his post as head of the Naval Space Command, Truly vowed last week to "find the cause and fix it," and get NASA "back in business."

While investigators probed the possibility of human error, the search for evidence of the technical failure that caused the Challenger explosion continued off Cape Canaveral. A flotilla of four undersea craft and ten surface ships had located and photographed parts of the right booster, scattered on the ocean floor under about 1,200 ft. of water.

Rough as last week's revelations were on NASA, tougher times may lie ahead. The Rogers commission has scheduled for this week two days of public hearings at which key officials involved in the launch decision, as well as some of the experts who opposed the go-ahead, are expected to testify. Predicted one source close to the commission: "There will be a hanging." That assessment may be too harsh, but clearly the full story of why Challenger and its crew had been sent on a doomed mission remains to be told.

With reporting by Jay Branegan/Washington and Jerry Hannifin/ Cape Canaveral