Key Officials Not Told of Safety Questions : Some Thiokol Engineers Insisted Till End That Liftoff Be Delayed

At least three key NASA officials were not informed before the launching of the space shuttle Challenger that “a number” of engineers still wanted to postpone the mission for fear that cold weather could cause catastrophic malfunctions of the spacecraft’s booster rockets, the chairman of a presidential commission investigating the disaster said Wednesday.

In a statement, William P. Rogers said commissioners learned last Friday, “in very active questioning” of witnesses in a closed hearing in Florida, that space agency officials and engineers from Morton Thiokol Inc., manufacturer of the rocket suspected of causing the Challenger explosion, never came to complete agreement about the safety of the launching.

Rogers’ statement, along with interviews with several sources close to the investigation, yielded a description of the prelaunching discussions between NASA and Morton Thiokol engineers that differed dramatically from the impression created by NASA officials in public testimony.

Sources described several hours of sometimes anguished debate on the eve of the Jan. 28 launching and said that not all of Morton Thiokol’s rocket engineers--including its key representative at the Kennedy Space Center--were convinced that liftoff should proceed.

“The commission,” Rogers noted, “learned that, although a telefax (a document transmitted by telephone) was later received from Thiokol indicating approval of the launch, a number of engineers at Thiokol still strongly urged against the launch.”

“It was further learned that at least three key NASA officials had not been notified and did not know of the recommendation of Thiokol not to launch, or the events leading up to Thiokol’s change of mind as reflected in the telefax,” he said.

Commission sources said that the three National Aeronautics and Space Administration officials to whom Rogers referred were mem bers of a team at the Kennedy Space Center that gave the ultimate approval to send the spacecraft and its crew of seven aloft. They included Jesse W. Moore, head of NASA’s shuttle program, and Arnold Aldrich, manager of the shuttle system. Sources said it is believed that the third official was Robert Sieck, NASA’s director of flight operations.

A member of the commission said the panel was “surprised” that the engineers’ concerns had not been forwarded to the top rungs of the command chain, and he said it was “definitely not NASA procedure.”

Subtle Pressure

The sources said that nearly all Morton Thiokol engineers initially were in agreement that the launching should be postponed, and they indicated that the firm’s written consent to proceed with the launching was issued hours later--but only after subtle pressure was applied by the space agency officials.

These sources said that NASA officials had questioned a mass of data presented by the rocket engineers in their attempt to persuade the space agency to hold off on the mission.

“Not all the Morton Thiokol people changed their mind,” said one source close to the commission. “It was like they said: ‘I’m not going to approve of this. If you want an approval, you’ll have to go over my head.’ ”

Ranking NASA officials have told the commission and Congress that Morton Thiokol representatives at one point did “suggest” postponement, citing concerns about the performance of booster rocket seals in low temperatures.

Company’s Consent Cited

However, they have refused to discuss the length or tenor of prelaunching discussions and have always taken pains to note that, ultimately, the rocket company did sign a written consent form.

The prelaunching discussions centered on evidence presented by Thiokol that cold temperatures can affect the ability of rubber rings in joints along the multi-sectional rocket to form a complete seal.

According to sources, a series of meetings between NASA officials and Thiokol engineers began at about 8 p.m. on the eve of the launching, with a conference call among Thiokol representatives in Alabama and Utah and NASA and company officials at the Kennedy Space Center.

The meetings continued until shortly before midnight.

“The whole presentation for a couple of hours was that Morton Thiokol was very concerned about the temperatures,” a source said.

Wanted Warmer Conditions

“The official position of the management team prior to the recess was: ‘We recommend you not launch,’ ” the source said. “. . . The way they put it was that they would recommend, based on the data they had at that time, to launch at warmer conditions than we were having.”

Commission member David C. Acheson, in an interview, noted: “The NASA people felt the data was too slender, that there were not sufficient tests and that the results didn’t point one way or another.”

Overnight temperatures were forecast to be in the mid-20s, with a launching-time temperature of barely over freezing. In fact, it was 38 degrees at liftoff--13 degrees lower than the previous coldest launching temperature.

Thiokol engineers presented data illustrating their concern that abnormally cold weather on the launching pad would decrease the O-rings’ resiliency and prevent them from setting properly in the rocket joints during the first crucial seconds of ignition.

If the seals failed, rocket propellant burning at nearly 6,000 degrees could escape through the joints in the rocket and heat the shuttle’s huge external fuel tank to the point of explosion.

Earlier Seal Failures

In previous flights, primary O-rings had shown evidence of erosion and charring, and in two cases the rings appeared to have been penetrated by an initial blast from inside the rocket during ignition. But, in all cases, the secondary seal had held.

NASA and the commission have released photographs that indicate a rupture of the right solid rocket booster near a seal.

In the midst of the prelaunching discussion, NASA officials told Thiokol representatives that they would not proceed against the advice of a contractor, and they asked for Thiokol’s recommendation in writing. The Utah representatives asked for a recess to meet and consider the request.

Thirty minutes later, Thiokol reversed its opposition to launching and telefaxed back its recommendation in writing to proceed. Acheson said what happened in that 30-minute recess in Utah will become part of the investigation.

While the company representatives met in Utah, Thiokol’s chief representative at Cape Canaveral, Fla., Allan McDonald, had kept arguing against a launching, sources said.

“McDonald asked them, ‘Why would you want to go ahead if there is the slightest element of doubt, why would you want to push it?’ ” one source said. “In their minds, they (NASA officials) said there wasn’t any element of doubt. In their opinion, the arithmetic and the data presented didn’t support the position that it wouldn’t work.”

Engineer Never Wavered

Efforts to reach McDonald on Wednesday were unsuccessful. He was quoted in other reports as having never wavered in his belief that the flight should be postponed. A source said McDonald had the power to sign the consent form and only after he refused was one transmitted from Thiokol representatives in Utah.

When asked if the NASA officials tried to pressure Thiokol into recommending that the launching proceed, the source said: “There are all kinds of pressure. Sometimes you take a stick and beat a kid, sometimes you holler a lot, and sometimes you just frown a lot. There was no spanking or hollering, but there were a lot of frowns. There was indirect pressure.”

Thiokol officers at corporate headquarters in Chicago did not return phone calls Wednesday.