The puffs stopped after a few seconds: the seal got plugged up somehow, temporarily, only to break open again a minute later.
There was some discussion about how much matter came out in the smoke. The puffs of smoke were about six feet long, and a few feet thick. The amount of matter depends on how fine the particles are, and there could always be a big piece of glop inside the smoke cloud, so it’s hard to judge. And because the pictures were taken from the side, it was possible there was more smoke farther around the rocket.
FIGURE 16. Detailed picture, taken from the launch pad, of the “smoke.” (©; NASA.)
To establish a minimum, I assumed a particle size that would produce as much smoke as possible out of a given amount of material. It came out surprisingly small—approximately one cubic inch: if you have a cubic inch of stuff, you can get that much smoke.
We asked for pictures from other launches. We found out later that there had never been any puffs of smoke on any previous flights.
We also heard about the low temperatures before the launch from a man named Charlie Stevenson, who was in charge of the ice crew. He said the temperature had gone down to 22 degrees during the night, but his crew got readings as low as 8 degrees at some places on the launch pad, and they couldn’t understand why.
During the lunch break, a reporter from a local TV station asked me what I thought about the low temperature readings. I said it seemed to me that the liquid hydrogen and oxygen had chilled the 22-degree air even further as it flowed down the big fuel tank onto the rocket booster. For some reason, the reporter thought I had just told him some important, secret information, so he didn’t use my name in his report that evening. Instead, he said, “This explanation comes from a Nobel Prize winner, so it must be right.”
In the afternoon, the telemetering people gave us all kinds of information on the last moments of the shuttle. Hundreds of things had been measured, all of which indicated that everything was working as well as it could under the circumstances: the pressure in the hydrogen tank suddenly fell a few seconds after the flame had been observed; the gyros which steer the shuttle were working perfectly until one had to work harder than the other because there were side forces from the flame shooting out of the side of the booster rocket; the main engines even shut themselves down when the hydrogen tank exploded, because there was a pressure drop in the fuel lines.
That meeting lasted until 7:30 in the evening, so we postponed the tour until Friday and went straight to a dinner set up by Mr. Rogers.
At the dinner I happened to be seated next to Al Keel, who had joined the commission on Monday as its executive officer to help Mr. Rogers organize and run our work. He came to us from the White House—from something called the OMB*—and had a good reputation for doing a fine job at this and that. Mr. Rogers kept saying how lucky we were to get somebody with such high qualifications.
One thing that impressed me, though, was that Dr. Keel had a Ph.D. in aerospace, and had done some post-doc work at Berkeley. When he introduced himself on Monday, he joked that the last “honest work” he had done for a living was some aerodynamics work for the shuttle program ten or twelve years ago. So I felt very comfortable with him.
Well, I haven’t been talking to Dr. Keel for more than five minutes, when he tells me he’s never been so insulted in his life, that he didn’t take this job to be so insulted, and that he doesn’t want to talk to me anymore!
Now, I have a way of not remembering things when I do something dumb or annoying to people, so I forget what I said that put him out. Whatever it was, I thought I was joking, so I was very surprised by his reaction. I had undoubtedly said some boorish, brash, damn-fool thing, which I therefore can’t remember!
Then there was a rather tense period of five or ten minutes, with me apologizing and trying to get a conversation going again. We finally got to talking again, somewhat. We were not big friends, but at least there was peace.
On Friday morning, we had another public meeting, this time to hear people from Thiokol and NASA talk about the night before the launch. Everything came out so slowly: the witness doesn’t really want to tell you everything, so you have to get the answers out by asking exactly the right questions.
Other guys on the commission were completely awake—Mr. Sutter, for instance. “Exactly what were your quality criteria for acceptance under such-and-such and so-and-so?”—he’d ask specific questions like that, and it would turn out they didn’t have any such criteria. Mr. Covert and Mr. Walker were the same way. Everybody was asking good questions, but I was fogged out most of the time, feeling a little bit behind.
Then this business of Thiokol changing its position came up. Mr. Rogers and Dr. Ride were asking two Thiokol managers, Mr. Mason and Mr. Lund, how many people were against the launch, even at the last moment.
“We didn’t poll everyone,” says Mr. Mason.
“Was there a substantial number against the launch, or just one or two?”
“There were, I would say, probably five or six in engineering who at that point would have said it is not as conservative to go with that temperature, and we don’t know. The issue was we didn’t know for sure that it would work.”
“So it was evenly divided?”
“That’s a very estimated number.”
It struck me that the Thiokol managers were waffling. But I only knew how to ask simpleminded questions. So I said, “Could you tell me, sirs, the names of your four best seals experts, in order of ability?”
“Roger Boisjoly and Arnie Thompson are one and two. Then there’s Jack Kapp and, uh… Jerry Burns.”
I turned to Mr. Boisjoly, who was right there, at the meeting. “Mr. Boisjoly, were you in agreement that it was okay to fly?”
He says, “No, I was not.”
I ask Mr. Thompson, who was also there.
“No, I was not.”
I say, “Mr. Kapp?”
Mr. Lund says, “He is not here. I talked to him after the meeting, and he said, ‘I would have made that decision, given the information we had.’ “
“And the fourth man?”
“Jerry Burns. I don’t know what his position was.”
“So,” I said, “of the four, we have one ‘don’t know,’ one ‘very likely yes,’ and the two who were mentioned right away as being the best seal experts, both said no.” So this “evenly split” stuff was a lot of crap. The guys who knew the most about the seals—what were they saying?
Late in the afternoon, we were shown around the Kennedy Space Center. It was interesting; it wasn’t as bad as I had predicted. The other commissioners asked a lot of important questions. We didn’t have time to see the booster-rocket assembly, but near the end we were going to see the wreckage that had been recovered so far. I was pretty tired of this group stuff, so I excused myself from the rest of the tour.
I ran down to Charlie Stevenson’s place to see more pictures of the launch. I also found out more about the unusually low temperature readings. The guys were very cooperative, and wanted me to work with them. I had been waiting for ten days to run around in one of these places, and here I was, at last!
At dinner that night, I said to Mr. Rogers, “I was thinking of staying here over the weekend.”
“Well, Dr. Feynman,” he said, “I’d prefer you come back to Washington with us tonight. But of course, you’re free to do whatever you want.”
“Well, then,” I said, “I’ll stay.”
On Saturday I talked to the guy who had actually taken the temperature readings the morning of the launch—a nice fella named B. K. Davis. Next to each temperature he had written the exact time he had measured it, and then took a picture of it. You could see large gaps between the times as he climbed up and down the big launch tower. He measured the temperature of the air, the rocket, the ground, the ice, and even a puddle of slush with antifreeze in it. He did a very complete job.
NASA had a theoretical calculation of how the temperatures should vary around the launch pad: they s
hould have been more uniform, and higher. Somebody thought that heat radiating to the clear sky had something to do with it. But then someone else noticed that BK’s reading for the slush was much lower than the photograph indicated: at 8 degrees, the slush—even with antifreeze in it—should have been frozen solid.
Then we looked at the device the ice crew used for measuring the temperatures. I got the instruction manual out, and found that you’re supposed to put the instrument out in the environment for at least 20 minutes before using it. Mr. Davis said he had taken it out of the box—at 70 degrees—and began making measurements right away. Therefore we had to find out whether the errors were reproducible. In other words, could the circumstances be duplicated?
On Monday I called up the company that made the device, and talked to one of their technical guys: “Hi, my name is Dick Feynman,” I said. “I’m on the commission investigating the Challenger accident, and I have some questions about your infrared scanning gun…”
“May I call you right back?” he says.
“Sure.”
After a little while he calls me back: “I’m sorry, but it’s proprietary information. I can’t discuss it with you.”
By this time I realized what the real difficulty was: the company was scared green that we were going to blame the accident on their instrument. I said, “Sir, your scanning gun has nothing to do with the accident. It was used by the people here in a way that’s contrary to the procedures in your instruction manual, and I’m trying to figure out if we can reproduce the errors and determine what the temperatures really were that morning. To do this, I need to know more about your instrument.”
The guy finally came around, and became quite cooperative. With his help, I advised the ice-crew guys on an experiment. They cooled a room down to about 40 degrees, and put a big block of ice in it—with ice, you can be sure the surface temperature is 32 degrees. Then they brought in the scanning gun from a room which was 70 degrees inside, and made measurements of the ice block every 30 seconds. They were able to measure how far off the instrument was as a function of time.
Mr. Davis had written his measurements so carefully that it was very easy to fix all the numbers. And then, remarkably, the recalculated temperatures were close to what was expected according to the theoretical model. It looked very sensible.
The next time I talked to a reporter, I straightened everything out about the temperatures, and informed him that the earlier theory expounded by the Nobel Prize winner was wrong.
I wrote a report for the other commissioners on the temperature problem, and sent it to Dr. Keel.
Then I investigated something we were looking into as a possible contributing cause of the accident: when the booster rockets hit the ocean, they became out of round a little bit from the impact. At Kennedy they’re taken apart, and the sections—four for each rocket—are sent by rail to Thiokol in Utah, where they are packed with new propellant. Then they’re put back on a train to Florida. During transport, the sections (which are hauled on their side) get squashed a little bit—the softish propellant is very heavy. The total amount of squashing is only a fraction of an inch, but when you put the rocket sections back together, a small gap is enough to let hot gases through: the O-rings are only a quarter of an inch thick, and compressed only two-hundredths of an inch!
I thought I’d do some calculations. NASA gave me all the numbers on how far out of round the sections can get, so I tried to figure out how much the resulting squeeze was, and where it was located—maybe the minimum squeeze was where the leak occurred. The numbers were measurements taken along three diameters, every 60 degrees. But three matching diameters won’t guarantee that things will fit; six diameters, or any other number of diameters, won’t do, either.
For example, you can make a figure something like a triangle with rounded corners, in which three diameters, 60 degrees apart, have the same length.
I remembered seeing such a trick at a museum when I was a kid. There was a gear rack that moved back and forth perfectly smoothly, while underneath it were some noncircular, funny-looking, crazy-shaped gears turning on shafts that wobbled. It looked impossible, but the reason it worked was that the gears were shapes whose diameters were always the same.
So the numbers NASA gave me were useless.
During that weekend, just as I had predicted in my letter home, I kept getting notes from the commission headquarters in Washington: “Check the temperature readings, check the pictures, check this, check that…”—there was quite a list. But as the instructions came in, I had done most of them already.
One note had to do with a mysterious piece of paper. Someone at Kennedy had reportedly written “Let’s go for it” while assembling one of the solid booster rockets. Such language appeared to show a certain recklessness. My mission: find that piece of paper.
FIGURE 17. This figure has all its diameters the same length—yet it is obviously not round!
Well, by this time I understood how much paper there was in NASA. I was sure it was a trick to make me get lost, so I did nothing about it.
Instead, I pursued something surreptitiously.
It was rumored that the reason NASA tried to make the shuttle fly on January 28th, in spite of the cold, was that the president was going to give his State of the Union address that night. According to the theory, the White House had it all cooked up so that during the State of the Union address, the teacher, Mrs. McAuliffe, would talk to the president and Congress from space. It was gonna be great: the president would say, “Hello! How are you doing?” And she would say, “Fine”—something very dramatic.
Since it sounded logical, I began by supposing it was very likely possible. But was there any evidence? This kind of thing I didn’t know how to investigate. I could only think of this: it’s very hard to get through to the president; I also can’t just call up an astronaut and talk to her—if she’s in space. Therefore, switching the signals down from the shuttle over to the president while he’s talking to Congress must be a complicated business.
To find out whether anybody had set up to do that, I went down to the lowest levels and asked guys at the bottom some technical questions.
They showed me the antennas, they told me about the frequencies, they showed me the big radio system and the computer system; they showed me all the ways they did things.
I said, “If you had to send a transmission somewhere else—to Marshall, say—how would you do it?”
They said, “Oh, we’re just a relay station. Everything is automatically sent over to Houston, and they switch everything out from there. We don’t do any switching here.”
So I didn’t find any evidence—at least at Kennedy. But the guys there were so nice to me, and everything was so pleasant, that I feel bad. I don’t like to cheat people. It was a little sneaky, what I was doing. Nevertheless, I thought I’d better do the same thing when I got to Houston.
On Monday, Mr. Hotz came down to Florida to work with me. (He told me later that he had been sent down with specific instructions to see what I was doing, and to keep me from “going wild.”) Mr. Hotz brought a list of things to look into: “There are a lot of things on this list,” he said, “so I’d be happy to split the work with you.” Some things he said he could do more easily, and the rest of the things I had already done—except for that piece of paper which said “Let’s go for it.” Mr. Hotz hinted around that it might have come from the diary of someone in the booster-rocket assembly. That wasn’t enough of a clue for me; I just wasn’t gonna do it. Instead, I went to see a Mr. Lamberth, who had said he wanted to talk to me.
Mr. Lamberth was way up in the works, a big cheese in charge of assembling the solid-rocket boosters. He wanted to tell me about some problems he had. “The workers used to have much better discipline,” he explained, “but nowadays they’re not like they used to be.” He gave me a couple of examples.
The first incident had to do with taking the booster rockets apart after they had been recovered from the
sea. The rocket sections are held together by 180 pins—each about an inch and a half in diameter and two inches long—all the way around.
There was some kind of procedure for taking sections apart, in which the workers were supposed to pull the rocket up a certain distance. They had gotten to paying attention only to the amount of force they were applying—about 11,000 pounds. That was a better method, from a physical standpoint, because the idea is to take the load off the pins.
One time the force gauge wasn’t working right. The workers kept putting more force on, wondering why they weren’t reaching 11,000 pounds, when all of a sudden one of the pins broke.
Mr. Lamberth reprimanded the workers for not following procedures. It reminded me of when I tried to make things work better at my aunt’s hotel: your method is better than the regular way, but then you have a little accident…*
The second story Mr. Lamberth told me had to do with putting the rocket sections together. The regular procedure was to stack one section on top of the other and match the upper section to the lower one.
If a section needed to be reshaped a little bit, the procedure was to first pick up the section with a crane and let it hang sideways a few days. It’s rather simpleminded.
If they couldn’t make a section round enough by the hanging method, there was another procedure: use the “rounding machine”—a rod with a hydraulic press on one end and a nut on the other—and increase the pressure.
Mr. Lamberth told me the pressure shouldn’t exceed 1200 pounds per square inch (psi). One time, a section wasn’t round enough at 1200 psi, so the workers took a wrench and began turning the nut on the other end. When they finally got the section round enough, the pressure was up to 1350. “This is another example of the lack of discipline among the workers,” Mr. Lamberth said.
'What Do You Care What Other People Think?' Page 13
