‘The Lord Protected Grandpa’: 30 Years Since Mission 51B (Part 2)

During the majority of the seven-day mission, Challenger operated in a gravity gradient orientation, with her vertical stabilizer directed Earthward and her starboard wing pointing in the direction of travel. Image Credit: NASA, via Joachim Becker/SpaceFacts.de
During the majority of the seven-day mission, Challenger operated in a gravity gradient orientation, with her vertical stabilizer directed Earthward and her starboard wing pointing in the direction of travel. Image Credit: NASA, via Joachim Becker/SpaceFacts.de

Thirty years ago, this week, a seven-man crew with a combined age of 340 years rocketed into orbit aboard Shuttle Challenger on Mission 51B. For seven days, the astronauts—Commander Bob Overmyer, Pilot Fred Gregory, Mission Specialists Don Lind, Norm Thagard, and Bill Thornton, and Payload Specialists Lodewijk van den Berg and Taylor Wang—worked around the clock in two shifts to support 15 life and microgravity science experiments from U.S., European, and Indian researchers in the pressurized Spacelab-3 module. As described in yesterday’s AmericaSpace history article, they became the first U.S. crew to include as many as three over-50s, including the then-oldest man in space, but unbeknownst at the time they came within milliseconds of disaster, soon after liftoff.

For Gregory, his first launch proved exhilarating. “I was very excited,” he told the NASA Oral History Project. “I think I was probably anxious, but certainly not afraid. It was similar to the simulations, but they left out the 5 percent, and that was the ‘wow’! I remember the feeling inside when the main engines started; how it was almost a non-event. I could hear it and I was aware of it, but I looked out the window and saw the tower move back. At least that’s what I thought, but then I realized the orbiter was moving forward and then back, and when it came back to vertical, that’s when those solids ignited and there was no doubt about it: we were going to go someplace pretty fast! I just watched the tower kind of drop down below me and was probably laughing during this timeframe. Since we had trained constantly for failures, I anticipated failures and was somewhat disappointed that there were no failures. That was Challenger and she went uphill, just as sweet as advertised. The sensation of zero-G was like a moment on a roller coaster, when you go over the top and everything just floats. Once we got there, it was business as usual, just as we had practised and performed on the ground.”

For Overmyer, Gregory, and Thagard, the first order of business was pulsing their spacecraft’s twin Orbital Maneuvering System (OMS) engines to position themselves in a 225-mile (360-km) circular path. The orbit was inclined at 57 degrees to the equator to provide greater observation coverage for ATMOS. For Don Lind, the reality of actually traveling into space was surprisingly close to the training. “The simulations are spectacularly accurate,” he said later. “With the motion-based simulators, you even got some of the visceral sensations, because they can move the machine around and give you the sense of onset of zero-G. You can’t hold it indefinitely, but we had flown hundreds of parabolas in the KC-135 aircraft, so we were quite accustomed to those things.”

Challenger roars into orbit on 29 April 1985. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de
Challenger roars into orbit on 29 April 1985. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de

Gregory felt that he was well prepared, “but it took about half a day to adapt to microgravity. The body very quickly adapted to this new environment and it began to change. You could sense it when you were on orbit. You learned that your physical attitude in relation to things that looked familiar to you—like walls and floors—didn’t count anymore and you translated floors and ceilings and walls to your head is always ‘up’ and your feet are always ‘down’. That was a subconscious change in your response: it was an adjustment that occurred up there. You also learned that you didn’t go fast, that you could get from one place to the other quickly, but you didn’t have to do it in a speedy way. The only referencing system that you have are your eyes, so you can look at something and establish it as a reference that you use.”

Following launch, the seven astronauts split into their respective 12-hour teams. Very soon, one of the two squirrel monkeys exhibited the same symptoms—lethargy and loss of appetite, but no vomiting—as humans for the first half of the mission, being hand-fed by Thagard and Thornton at one stage, before recovering completely for the final three days. The second monkey displayed no ill effects. The primates proved to be much less active in space than on Earth, although both they and the rodents grew and behaved normally, were free of chronic stress, and differed from their “controls” on Earth only by way of gravity-dependent variables. The monkeys, in particular, were spoiled, too.

“I think the environment they had come from was a place where they received a lot of attention,” said Gregory. “Norm and I would look into the Spacelab and see Bill Thornton attempting to get these monkeys to do things, like touch the little trigger that would release the food pellets. I could tell they expected Bill to do that for them, even though he was outside, looking in. We looked back one time and could see that the roles were kind of reversed and Bill was doing antics on the outside of the cage and the monkeys were watching!” Thornton and Thagard could view the primates through a window in each of their cages, while a perforated opening gave them limited access to the interior.

The Spacelab-3 research module, pictured aboard Challenger's payload bay during Mission 51B. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de
The Spacelab-3 research module, pictured aboard Challenger’s payload bay during Mission 51B. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de

The rodents’ enclosures were similar to those of the squirrel monkeys, with the exception that they housed two occupants per cage, separated by a partition. Half of the 24 rats were rapidly-growing, eight-week-old juveniles and the remainder were mature 12-week-old adults. Although the animals were maintained in healthy conditions throughout their seven days in orbit, the rats proved not quite as “savvy” as the monkeys in terms of their adaptation to microgravity. Nonetheless, all of the animals were recovered in good physical condition, healthy and free of microbiological contaminants. However, the astronauts returned to Earth with a number of concerns because the animal enclosures leaked food crumbs, monkey and rodent feces, and unpleasant odors. “The later analysis was that primarily it was food,” said Gregory, “though there may have been some contaminants in it. Other than interest in watching it being ejected from the holding facility, I think it was just interest. It was a passing issue; not something that would have caused any disruption in the current activities.”

On the ground, however, it became a big news story. “One anecdote involved this bit of animal dung that escaped from a cage and made its way from the Spacelab module to the flight deck,” Thagard told this author in a March 2006 email correspondence, referring to an object that floated past the commander’s nose. “Bob Overmyer made a comment about it that prompted an editorial page cartoon that appeared in some newspapers. The cartoon depicts a shuttle astronaut saying to a crewmate words to the effect of: I’m not upset, I’m just glad we didn’t have elephants on board!”

Aside from the RAHF tests, the main “operational” focus of Spacelab-3 was fluid physics and crystal growth. Taylor Wang operated his own drop dynamics experiment whilst Lodewijk van den Berg focused on the crystal growth. Eighteen hours into the mission, Overmyer and Gregory maneuvered the shuttle into her gravity-gradient attitude to support six days of fluid physics and crystal growth research.

Taylor Wang's legs emerge from the Drop Dynamics Module (DDM) as Bill Thornton assists him with his experiment. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de
Taylor Wang’s legs emerge from the Drop Dynamics Module (DDM) as Bill Thornton assists him with his experiment. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de

Unfortunately, Wang’s DDM experiment shorted out and failed, early in the mission. “Not only that, but I was the first person of Chinese descent to fly on the shuttle,” he wrote later, “and the Chinese community had taken a great deal of interest. You don’t just represent yourself—you represent your family—and the first thing you learn as a kid is to bring no shame to the family. When I realized my experiment had failed, I could imagine my father telling me, ‘What’s the matter with you? Can’t you even do an experiment right?’ I was really in a desperate situation.” On the ground, Lead Flight Director Gary Coen told the crew that it was doubtful that the mission could be extended beyond seven days, since Challenger did not have the additional cryogenic reactant tanks carried by her sister, Columbia. There would be no opportunity for time lost on the troublesome experiments.

In his memoir, Riding Rockets, Mike Mullane did not specifically name Wang, but certainly made reference to the incident. “Its failure severely depressed him and he surrendered to episodes of crying,” Mullane wrote, “but this was just the beginning of his torture. He turned out to be a cleanliness freak. Living aboard the shuttle doesn’t leave its occupants feeling springtime fresh!” In the midst of this discomfort and upset, Wang asked Mission Control for permission to try to repair the DDM and when given the go-ahead he quickly got to work, opening the Spacelab rack, isolating the fault, and completely rewiring part of it. Several dramatic photographs, taken by his crewmates, showed Wang’s legs sticking out into the module as the DDM rack appeared to completely swallow his upper body. He had already threatened not to return home if NASA refused to allow him to fix the DDM, so it proved fortuitous that his bluff was not called.

“I hadn’t really figured out how not to come back,” Wang told a Smithsonian interviewer years later. “The Asian tradition of honorable suicide—seppuku—would have failed, since everything on the shuttle is designed for safety. The knife on board can’t even cut the bread. You could put your head in the oven, but it’s really just a food warmer. If you tried to hang yourself with no gravity, you’d just dangle there like an idiot!”

The patch for Mission 51B, emblazoned with the surnames of the seven-man crew. Image Credit: NASA
The patch for Mission 51B, emblazoned with the surnames of the seven-man crew. Image Credit: NASA

With the facility successfully repaired, there was no time for suicide and Wang worked virtually non-stop to complete almost all of his experiments in the last three days of the flight, assisted by his crewmates. The results confirmed several age-old assumptions about the behavior of liquids in a microgravity environment and, in spite of its delayed start, the experiment proved highly successful. Nineteen months later, in the fall of 1986, Wang received NASA’s Exceptional Scientific Achievement Medal in recognition of his “contributions to microgravity science and materials processing in space and for his exceptional contributions as Payload Specialist on Spacelab-3.” Elsewhere, Lind and van den Berg oversaw a range of crystal growth and fluid physics investigations on their respective shifts. “He’d brief me and then he’d go to sleep and when he woke up, I’d brief him on what I’d done during the last shift,” Lind remembered, years later. “That was pretty well worked out ahead of time.”

“I don’t think there was competition,” said Fred Gregory of the relationship between the silver and gold teams, “because the two shifts did two different kinds of science. Each shift had its own area of interest and would pick up any unclosed item from the shift preceding them, but would very quickly transition to the activities on orbit. There were really about four hours a day when there was an interaction between the two. During that time, it would just be a kind of status brief on orbiter problems or issues, any review of notes that had come up from Mission Control or some deviation to the anticipated checklist that we had.”

For Lind, the first Mormon astronaut, the gravity-gradient attitude provided a unique perspective of his home planet. “For the first two days of the flight, I did not take one single minute away from the timeline to just be a tourist,” he recalled, “but, on the third day, I had about ten or 15 minutes with no immediate assignment. I floated down to the flight deck. We were flying in an orientation with the tail always pointed toward the Earth and one wing always pointed forward in the velocity vector. That oriented the windows on the flight deck from the zenith to the nadir and from horizon to horizon, so it was like a Cinerama presentation. Both my wife and I are amateur oil painters. The sensation in space is that you are always right side up, no matter how you’re positioned. ‘Up’ and ‘down’ are just meaningless in space! Intellectually, you know you’re moving very fast, so that orbital velocity will cancel gravity, but the sensation is that you are stationary and the world is rotating majestically below you.”

The crew of Mission 51B pose for the traditional in-flight portrait. From left to right are Fred Gregory, Bob Overmyer, Don Lind, Norm Thagard, Bill Thornton, Taylor Wang and Lodewijk van den Berg. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de
The crew of Mission 51B pose for the traditional in-flight portrait. From left to right are Fred Gregory, Bob Overmyer, Don Lind, Norm Thagard, Bill Thornton, Taylor Wang and Lodewijk van den Berg. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de

Gregory found the heavens and Earth fascinating. “You immediately realize you are either a ‘dirt person’ or a ‘space person’,” he said. “I ended up being a space person. It was a high-inclination orbit, so we went very low in the southern hemisphere and I saw a lot of star formations that I had only heard about and never seen before. “I also saw the Aurora Australis, which is the Southern Lights. If you were a dirt person, you were amazed at how quickly you crossed the ground; how, with great regularity, every 45 minutes, you’d either have daylight or dark. The sensation that I got initially was that, from space, you can’t see discernible borders and you begin to question why people don’t like each other, because it looked like just one big neighborhood down there. The first couple of days, I was a citizen of Washington, D.C., but Overmyer was from Cleveland and Don Lind was from Salt Lake City and Norm was from Jacksonville and Lodewijk was the Netherlands and Taylor was Shanghai, so each had their own little location for the first couple of days. After two days, I was from America, and after five days the whole world was our home. You could see this sense of ownership and awareness. We had noticed with interest the fires in Brazil and South Africa and the pollution that came from eastern Europe, but it was only with interest. Then, after five or six days, it was of concern, because you could see how the particulates from the smoke stacks in eastern Europe circled the Earth and how this localized activity had a great effect. When you looked down at South Africa and South America, you became very sensitized to deforestation and how it affected the ecology.”

It has often been remarked on dual-shift Spacelab flights that the only times the entire crew really got together were shortly after launch and just prior to re-entry. “I think on that particular mission, it may have been anticipated that we would prepare a meal and everyone would eat at the same time,” said Gregory. “In reality, that’s not what actually happened. I called it ‘almost grazing’. You would go down and perhaps get a package of beefsteak and heat it and cut it open and eat it. You may stay on the middeck or you may go back up to the flight deck or you would go back into the laboratory and eat as you were doing your other routine duties.”

Their descent into Edwards Air Force Base, Calif., on 6 May 1985, proved to be among the most dramatic memories of the mission for Gregory. “Though it takes 8.5 minutes to get up to orbit,” he said, “it takes more than an hour to re-enter and it feels very similar to an airplane ride. You get an excellent view of the Earth. You’re going pretty fast, but you are not aware of it, because you’re so high. It’s an amazing vehicle, because you always know where you are in altitude and distance from your runway. You know you have a certain amount of energy and so you also know what velocity you’re supposed to land, and you watch this amazing vehicle calculate and then compensate and adjust as necessary to put you in a good position to land. We normally allow the automatic system to execute all the maneuvers for ascent and for re-entry, but as we slow down for landing, it is customary for the Commander to actually fly it in, using the typical airplane controls.”

Challenger touches down at Edwards Air Force Base, Calif., on 6 May 1985. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de
Challenger touches down at Edwards Air Force Base, Calif., on 6 May 1985. Photo Credit: NASA, via Joachim Becker/SpaceFacts.de

The de-orbit burn, lasting closely to 4.5 minutes, began at 8:04:48 a.m. PDT (11:04:48 a.m. EDT) and slowed Challenger sufficiently to drop her out of orbit and set her on course for a touchdown on the west coast of the United States. “Absolutely nominal,” was Overmyer’s description of re-entry at the post-flight press conference. “I sat there with my hand on top of my helmet, with essentially nothing better to do than watch, at least down to Mach 0.9.”

Quipped Norm Thagard in response: “Yeah, but the rest of us didn’t know you were doin’ that, or we’d have been more worried!”

After performing a graceful, 193-degree heading alignment circle turn, Overmyer guided the orbiter to a precision landing on Runway 17 at 9:11 a.m. PDT (12:11 p.m. EDT). Post-mission inspections of the shuttle revealed only superficial damage to her thermal protection tiles. However, following the loss of Challenger in January 1986, the Rogers Investigation would uncover worrisome signs that Mission 51B itself came close to disaster.

Post-flight examination of the twin Solid Rocket Boosters (SRBs) indicated erosion of the secondary O-ring seal and highlighted the failure of its primary seal. So serious was the incident—the seals were meant to prevent hot gas leakage from the structure of the boosters—that launch constraints were placed on several missions, later in 1985, but routinely waived.

“The first seal on our flight had been totally destroyed,” recalled Lind in his NASA Oral History, “and the [other] seal had 24 percent of its diameter burned away. All of that destruction happened in 600 milliseconds and what was left of that last O-ring, if it had not sealed the crack and stopped that outflow of gases—if it had not done that in the next 200 to 300 milliseconds—it would have gone. You’d never have stopped it and we’d have exploded. That was thought provoking! We thought that was significant in our family. I painted a picture of our liftoff, then two great celestial hands supporting the shuttle and the title of that picture is Three-Tenths of a Second. Each of [my] children have a copy of that painting, because we wanted the grandchildren to know that we think the Lord really protected Grandpa.”



This is part of a series of history articles, which will appear each weekend, barring any major news stories. Next week’s article will focus on STS-49, the maiden voyage of Shuttle Endeavour in May 1992, which featured the world’s first three-person EVA.



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  1. Spacelab, and the international cooperation that it epitomizes (wow, finally got to work epitomizes into a conversation!!!) is the true result of the Shuttle program. For years we had a booming international community that allowed European, Japanese, U.S. and even Russians to work together in a research program. Europe and Japan had Spacelab missions, international crew members were integral parts of the team. We did assembly in space of huge systems like the ISS and Mir.

    The ISS is a result as well but the seamless merging of the crews and ground support people is far different. For one thing the capability of the Shuttle to do assembly, EVA, etc etc etc is gone and along with it many of the people that made that happen.

    We let the Shuttle and all of its capability slip away and will not see a similar community probably ever again. Now the center of gravity for people who want to fly into space is Star City in Russia – a place that is subject to the whims of mercurial people like Vladimir Putin.

    • I wouldn’t despair too much about losing the Shuttle if you think that means another Mir/ISS scale station will never be built. For starters, Mir was not built using the Shuttle. Launching station modules and crews to do the EVAs separately turned out to work just fine. Similarly, the launch and assembly of the Russian segment of ISS did not involve the Shuttle.

      Although personally, I’d hope the next LEO station (aside from the Tiangong series, of course) will be built around Bigelow modules. The two successful Genesis stations have already shown it’s viable, now it’s up to the BEAM testing to prove to NASA that its own technology worked. After all, Bigelow’s modules are evolved from one of many NASA efforts (TransHab) that were a casualty of politics before having the opportunity to prove themselves. Combine just two BA-330’s, and you’ve got 72% of the interior volume of ISS. We don’t need to spend hundreds of billions of dollars building stations anymore, and we certainly don’t need the Shuttle to do it.

  2. Another great article by Ben Evans! Thank you Ben.
    I would like to collaborate with you on a book. I have been trying to get someone to write a book with me for a couple years but this is of course common for all wannabe authors- we just don’t have what it takes. We are actually trying to get people to write a book for us but won’t admit even to ourselves we don’t have the money to pay anyone. So we want to “collaborate.” Kind of reminds of all the space clown wannabe’s who put in their hours for SpaceX on these websites thinking it is somehow going to help pay for that space station vacation with Elon. They have about as much chance of being astronauts as I do of getting a Pulitzer.

    Concerning the Shuttle I have often commented that loaded with extra life support pallets and a solar panel array the orbiter could have stayed in orbit for six months at a time- the same length as an ISS tour. Not much doubt about it being the ultimate spyplane for the military. So why didn’t this happen? My guess is that with no cargo version the shuttle was doomed to be a failed pickup truck for satellites. For want of funding for a cargo version the shuttle might have flown several hundred more missions than it did and possibly still be in service: Soyuz is. A cargo version and long duration military missions would have removed the fatal pressure to launch. The loss of Challenger put an end to military use and the loss of Columbia ultimately resulted in the abomination called NewSpace.

    With long duration missions no space station would have ever been built. With a cargo version the system would have answered all of America’s space launch needs and more. A cargo version would have had a 70 ton lift and been able to place Earth Departure Stages into LEO and enabled Beyond Earth Orbit missions. The opportunity to build a cargo version was always there and it makes one wonder why this was overlooked for over 30 years. Even at the end Sidemount was proposed by John Shannon and if adopted would be launching crews to the Moon right about now. It makes me sad and depressed to think about it to this day.

    • X-37b deploys solar panels and can remain in orbit literally for years. There’s no reason this tech could not have been developed for STS.

      • Yes Mark, my point being that Skylab was solar powered so it was not like we did not know how to do it. The interesting problem with a six month shuttle mission would be landing it; an auto-land system would have had to be relied upon (it actually did have this capability with a few added pieces of equipment) and if a healthy pilot was insisted upon it would have meant a rendezvous with a freshly launched shuttle to transfer an un-debilitated pilot for the landing.

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