John Noble Wilford 1986 this is a digital version of an article from The Times Print Archive, before it starts online in 1996. To keep these articles as they appear initially, the Times will not change, edit, or update them. There are occasional copywriting errors or other problems during the digitization process. Please send a report of such issues to archid_feedback @ nytimes. com. Only four weeks after the worst space disaster in history, people have already learned a lot about the events and situations before the Challenger space shuttle exploded. Suspicious factors, cold weather and some obvious human misjudgment seem to be involved. When the puzzle is combined, begin to tell about the role of key engineers and managers in key Shuttle decision-making, the knowledge they have and conceal, and the pressure on them to work and decide to launch a challenger on their last mission -- The mission that will bring the American space industry to an indefinite halt. As public hearings on the disaster resume today, a series of new disclosures may expose other flaws in the space shuttle system and decision-making -- Production process before launch in January. Killed seven people on the challenger. There is no doubt that more questions will be raised about the failure of the right-hand booster rocket. New evidence will be presented that for reasons still mysterious, some serious security issues have not been brought to the attention of the top management of the space agency. But even now, a thrilling story has emerged in interviews with participants and expert observers; In the testimony of the Senate and the presidential inquiry committee, as well as in the videotape and documents published by the National Aeronautics and Space Administration. At Cape Canaveral, the weather in Florida is ominous, and as usual everyone is thinking about the weather, but this time it is cold and rainy. At the Kennedy Space Center in Cape Canaveral, bad weather caused the challenger to launch twice in three days. The advertisement is scheduled to be released on Sunday morning, January. 26. However, just the night before, NASA officials followed the rain forecast and decided not to go on Sunday. Sunday\'s weather proved perfect for launch, but it\'s too late to do anything now. Advertising on Monday, January. On the 27 th, the sky was cloudy, but it was expected to be clear, so the crew boarded the challenger ready to leave. If it weren\'t for a clumsy handle on the hatch of the shuttle, they might have done the same. It took the workers two hours to remove the stuck handle. By then, the stiff wind went through the launch site, forcing- Postponed Until 9: 38 on Tuesday. The wind blew into a cold front. Forecasts released in the medium term In the afternoon, the temperature was cold all night. Officials at NASA and major space shuttle contractors, especially Morton tiokor, worry about the weather. , The manufacturer of the booster rocket, negotiated through the evening. \"When we see the predicted temperature, I know we have to talk about it,\" said Alan J . \" MacDonald, an engineer at Morton tiokor in Cape Town, strongly opposes entering the countdown. A decision must be made around midnight, after which liquid hydrogen and liquid oxygen are pumped into the huge external fuel tank of the shuttle. So many people are on the task. NASA is pressing for 15 flights of four space shuttles in 1986, six more than ever. The launch will be the first from pad 39. B, proving the ability of the extra pad is critical to accelerating the success of the flight plan. It was 25 shuttle flights, a symbolic moment to confirm the safety and reliability of the new shuttle Help calm criticism of the project. To highlight this, the crew members include the first ordinary citizen passenger, the school teacher, srista maluliff. Space agency officials insisted that during the countdown there was no compromise on the safety of the crew. But the delay is the most frustrating. An engineer said, \"No one wants to be the one who says\" no \"to lift off. Mr. advertising MacDonald played a villain. Later in the afternoon the day before the launch, he held an engineer conference call with several NASA officials at the Morton tiokor plant in Cape Town, Utah, near the city of Brigham. It is located at the Marshall Space Flight Center in Huntsville, Alabama. Responsible for the design and performance of the shuttle propulsion system. According to all the accounts, sir. McDonald\'s and other Thiokol engineers advise not to enter the countdown. They are worried about the impact of cold weather on solids Fuel Booster Rocket In a launch in January 1985, the lowest temperature was 53 degrees Fahrenheit. Seals have never been tested below 47 degrees. What is predicted is the temperature during the 20 th century night and the 30 th century launch. The SEAL team has a history of problems. This is a set of synthetic rubber O-rings like giant washers, which are mounted around the rocket housing, designed to fill in the tiny gaps left after the two steel rocket parts are bolted together. In 1982, a year after the shuttle began flying, engineers found that the huge pressure inside the rocket could cause the steel shell to expand and exert a rotating force at the joint, this may peel off the spare seal and void it. March 1983, L. Michael Weeks, deputy assistant space flight administrator in charge of technical issues, signed a waiver to keep the shuttle flight, although in some cases only one O-ring can be expected to contain the propulsion gas. Another problem with seal loss was after last summer. Flight check. At a high- High-level management meeting held at NASA Headquarters in Washington on August The recommendation, Weeks said, is \"analysis of existing data shows that it is safe to continue flying the existing design\", but \"efforts to eliminate seal erosion of solid motors need to continue to accelerate. But Richard C. Cook, a budget analyst at NASA Headquarters, said every time the shuttle takes off, engineers who know about seal erosion hold their breath. \"The Thiokol engineer began to suspect that cold weather would only increase the likelihood that the O-ring seal would fail. It makes the rubber hard to shrink, increasing the possibility of the seal being destroyed. They concluded that the consequences could be disastrous. At the end of the cold with Go- Remember all this, sir. Macdonald continued to oppose the launch, and he made his case when he met with NASA officials, including Lawrence B. The head of NASA\'s solid rocket, Mulloy. Marshall\'s project manager for fuel-boosting rockets and Marshall space shuttle, Stanley reinac. Both Mr. Mulloy and Mr. Leynz is at the Cape. Mr. Moloy said that the conference call with Utah engineers has ended, and it is initially recommended that if the temperature is lower than the temperature at the time of launch on January 1985, do not try to launch. However, at some point later, the meeting between NASA and Thiokol officials in Cape Town was postponed for five months. minute break. The adjournment lasted more than half an hour, and when the meeting resumed, the top Thiokol manager in Utah changed his position for unclear reasons and approved the launch. Joe C. Kilminster, vice president of Utah Corporation, signed Page memo at 11: 45M. It was immediately transmitted to the Cape. The company warned that the O-ring would harden in the cold, so it would take longer to \"sit\" normally \". Jesse W. NASA\'s deputy director, Moore, had to make a final decision to \"go\" the launch, saying he had not received any heated debate. If he knew \'I will definitely ask a lot of questions,\' Moore said. As predicted, the temperature dropped below freezing. At 6 A. M. At 27 degrees, the orange outer box of the shuttle is white, with ice and frost. The technicians who checked the challenger and the launch pad three times that morning reported that they found ice pillars 1 feet to 2 feet long hanging on the water pipes. Arnold D. Aldridge, space shuttle integration manager at Houston Johnson Space Center, said that the only weather issue discussed at the morning meeting was whether the ice would loose when it was lifted off, whether it would damage the soft hot tile, when the shuttle drops into the atmosphere, these hot tiles willMr. Aldrich testified to the presidential commission that the icing conditions for the shuttle\'s operation were \"very limited \". At 9:07 A. M. After the astronauts sat on the challenger because it was cold inside, the ground controllers burst into applause after wearing gloves. Still, the countdown stopped, mainly to wait for the warm-up in the morning and melt some ice. It turned out to be two- Delay an hour The ice team returned to the mat for optical infrared measurements to find dangerous conditions. ( The group\'s visit came at 1: 30 a. m. M. , 7 A. M. and 11 A. M. ) The panel noted readings of 7 and 9 degrees on the right side The manual booster rocket is much lower than the temperature of the left booster. The temperature on the pillar connecting the rocket and the external fuel tank may have dropped to minus 8 degrees Fahrenheit. It was later thought that this could be the effect of wind beating the challenger\'s ultra-cold fuel tank and cooling the rocket. Some experts believe that low temperatures may also be the result of a very cold hydrogen leak in an external fuel tank. Since the group\'s main task is to check the unwanted ice, it is clear that infrared measurements are not taken seriously. These readings may or may be evidence of a real problem, but have not drawn the attention of Mr. High Moore-level managers. Please click on the box to verify that you are not a robot. The email address is invalid. Please re-enter. You must select the newsletter you want to subscribe. View all New York Times newsletters. The crew waited patiently in the challenger\'s cabin. Francis R. (Dick) Mission commander Scobee and Comdr. Michael J. Smith of the Navy sits in front of the controls. The center flight engineer behind them is sitting in the doctor\'s position. Judith A. Lieutenant Resnick. Col. Ellison S. The Air Force\'s Onizuka sits behind Commander Smith. Below, in the middle The rest of the crew are on deck. Ronald E. Gregory B. McNairJarvis and Mrs. McAuliffe. When the countdown is finally restored, at T-minus- 9 minutes, no further delay. The temperature at the pad is 38 degrees. At 6. The three main engines of the challenger ignited quickly in an unprecedented 6 seconds. When the countdown reaches zero, two 149-foot- The high booster rocket connected to both sides of the external fuel tank is firing in unison. Hugh W announced: \"Lift Off\" Countdown commentator Harris \"The launch of the shuttle 25 mission has cleared the tower. \"But less than a second later, in one of the seals or nearby, a black smoke came out in the lower part of the right booster. One of the seals may have caught fire. Burning rocket fuel gives off a bright flame. Whatever it is, NASA\'s engineers just found it in the analysis of launch photography. Smoke spreads and darken, then disappears 12 to 13 seconds after takeoff. Strangely, all the visual signs of trouble are gone. All computer data arriving at task control is normal. Boosters are considered so reliable that they are equipped with very few sensors to monitor possible failures. According to the data, after 40 seconds of flight, just after the main engine was throttled to 65% thrust, the shuttle experienced a stiff, constantly changing wind and responded, maintain the correct trajectory by automatically rotating the booster and the main engine nozzle. In 52 seconds, the three engines began to accelerate to full power. Challenger, come on, Radio Mission Control in Houston. \"Come on, Roger,\" replied the gentleman. The sound is calm Scobee This is the last sentence I heard from the challenger. In 59 seconds, the challenger experienced the maximum dynamic pressure, and when launching the vibration of the rocket, the rising power and wind combined to create a huge pressure on the structure of the shuttle. At about this point in time, a series of ruthless events, neither the ground controllers nor the crew were immediately aware of, leaving the challenger sleepy. A new smoke from the lower side of the right booster. The pressure inside the two boosters that should be equal begins to diverge, and the pressure on the right booster drops sharply, indicating some kind of leakage. At 60. 6 seconds, the right booster squirts the flame. At 66. 17 seconds, bright light appeared on the booster and with fast-burning plume. At 73 seconds, the pressure on the right booster drops further, 24 pounds/square inch lower than the pressure on the other booster. Shortly after the advertisement, at 73. For 175 seconds, a mysterious cloud spreads along the outer fuel tank, followed by flashes and explosions. The last radio data received from the shuttle was 73. The pressure on the main engine suddenly surged in 621 seconds. The high temperature in the fuel pump caused one of the engines to shut down. 18 miles from Cape Canaveral, 10 miles in the blue sky, a fireball swallowed up the challenger. It\'s too late for the crew to do anything if they have any warning, even Radio mission control. The first sign of most flight controllers is that there is any problem when their computer screen flashes intermittently. Stephen Nesbitt, a public affairs official, reported that \"it is clearly a major failure . \" \"We don\'t have a downlink. We got a report from the flight Power officer that the vehicle had exploded. \"It was shocking that its success and the perfect image of the project were broken, and the space agency started its own investigation within hours of the explosion. It was immediately suspected that it was an O-ring fault. The interim review committee, led by Jesse Moore, seized all mission records and flight data, and everyone seemed determined to keep all procedures confidential. Within two days, however, news reports identified the main suspect in the case: the right-hand rocket. According to the New York Times, the pressure reading showed that the rocket began to fail at least 10 seconds before the explosion, and quoted experts as saying that, computers and sensors are not programmed to detect flame rockets burning on the side. Finally, later on Saturday, February. 1, NASA released a new set of photos showing at least 14 seconds before the explosion, the \"unusual\" smoke and flame spewing from the side of the rocket or near the seams. Two days later, with questions about whether NASA was in a position to investigate itself wisely, President Reagan appointed a 13- Independent investigations were conducted by the member committees. The committee is mainly from the scientific, educational and business circles, by William P. Former Secretary of State Rogers is with Neil. Former astronaut Armstrong served as vice chairman. The Supreme inquiry began, and the document required it to take place at the commission\'s first public hearing on February. 6. That pre- Attention to the weather is an important factor in this case. Over the coming weekend, the Times reported on documents NASA warned about O-ring problems a few years ago. A memo written by Richard Cook, the agency\'s budget analyst, points out evidence of previous ring damage and concluded last summer that flight safety was \"due to the potential of the seals The US Presidential Commission responded by asking NASA to produce all records relating to the O-ring issue. These documents were released on February. 12, among other things, it is shown that NASA has abandoned the requirement to prove redundancy in the booster seal. A valid assumption at the time was that the propulsion gas leaked from the right booster, possibly in the area connected to the outer tank at the lower part of the rocket. The hot gas triggered a series of events that caused the propellant to explode in a huge tank. According to reports from Aviation Weekly and space technology, investigators believe that the flames caused by the leak, or the pressure caused by the fire plume, cut off the fixing of the rocket base on the fuel tank. When the booster turns outward, its nose swings, causing the tank to break and causing an explosion. At the subsequent committee hearing, February. 11. The space agency acknowledged that cold temperatures reduced the effectiveness of seals. Advertising, but on a visit to Cape Canaveral later that week, the commission learned about the debate between Thiokol engineers and NASA officials, which intensified the night before the launch. Mr. It is reported that Rogers found that the information about the weather problem was not communicated to the senior officials of the space agency, which is \"pleasing \". On Feb. He made a statement saying the decision NASA\'s manufacturing process could be \"unfair\" and ordered officials involved in the launch decision not to participate in NASA\'s investigation. Last week, the pressure on NASALast appeared to have expanded the scope of the investigation, gained momentum and had an impact on NASA\'s hierarchy. In an interview Thiokol engineer Macdonald revealed that rocket experts were almost unanimously opposed to the launch due to concerns about the cold weather. Officials at NASA and the final Thiokol manager hope to continue the countdown. Meanwhile, Mr. Moore announced that he would step down as head of the space shuttle program earlier than expected, while serving as the remaining director of the Johnson Space Center. Mr. Replaced by Richard H. Moore. In fact, a major general of the Navy and a former astronaut arrived in Cape Town yesterday in charge of the space agency\'s investigation into the Challenger\'s destruction. James M. Bezos, NASA\'s director, is on vacation to crack down on fraud charges unrelated to NASA and is expected to resign soon so the White House can find someone to take full control of the troubled agency. Dr. William R. Graham Jr. Is an agent administrator. The presidential commission, which must report its findings on April, continues to conduct investigations in Washington, Cape Canaveral, Huntsville and Brigham. When the panel resumed its hearing today, Mr. kilminther and As a result of the testimony, McDonald\'s is one of Thiokol\'s officials. For NASA, Mr. Mulloy and Mr. Set to Reinartz appears. So far, many important questions have not been answered. Here are some of the most pressing issues. There is growing evidence that NASA is particularly eager to complete the Challenger mission without delay. In addition to the normal pressure to maintain the schedule, does the shuttle manager try to prove their own ambitious forecast for 15 flights in 1986? Is there political pressure to prove the reliability of the space shuttle? It is not clear why the Thiokol manager vetoed their engineers the night before the release and gave up their work --ahead. Is it true or implied pressure from NASA? Is Thiokol\'s officials concerned that too cautious and clumsy a reputation could jeopardize the company\'s future contractual relationship with NASA? If NASA and the company\'s engineers have determined that the rocket seal needs to be heavily modified, why do they think it is safe to continue flying the space shuttle? Once the presidential commission has determined the exact cause of the explosion, there will still be decisions that affect the country\'s future space. Does the shuttle have to go through such a major redesign that it will not fly again for a year, two years or more? When the space shuttle is grounded, what can be done to maintain the American presence in space? A version of this article appears on page C00001 of the National edition on February 25, 1986, with the title: shuttle crash: where is the clue so far.