Authors: David Hitt,Heather R. Smith
After clearing the launchpad, the shuttle begins to roll so that the orbiter is below the external tank, to better allow its engines to offset the tank’s weight. Around one minute into flight, the shuttle encounters “Max Q,” the period in which the increasing velocity of the vehicle produces the maximum amount of pressure on the shuttle before the decreasing resistance of the atmosphere reduces that pressure. To reduce the strains of the pressure of Max Q, the vehicle throttles down its engines and then, seconds later, past the point of maximum pressure, throttles back up.
Just over two minutes into the launch, the solid rocket boosters separate from the vehicle, and the orbiter and external tank continue toward orbit. The solids deploy parachutes and land in the ocean, where recovery ships locate them and bring them back for refurbishment and reuse.
“At the solid rocket motor separation . . . there was this brilliant orange flash, orangeish-yellow flash across the windscreen, and then the solid rocket motors are gone,” Ross recalled. “As the solid rocket motors tailed off, like at a minute forty-five or so, it almost felt like you had stopped accelerating, almost like you’d stopped going up. At that point we were already Mach 3-plus and well above most of the sensible atmosphere at that point, some twenty miles high or so. And at solid rocket motor jettison, then you’re at four times the speed of sound and twenty, twenty-five miles high.”
Hart also recalled the separation of the solid rockets as a memorable experience. For the first two minutes of ascent, the g-forces that the crew experiences have been building up, and then, at
separation, they drop off dramatically.
Very quickly, then, the solid rockets taper off and separate, and that was the first surprise I had. . . . The sensation that you have at that point I wasn’t quite prepared for, because you go from two and a half gs back to about one and a half. Well, when you get used to two and a half, and it feels pretty good. You’re going somewhere, you know. When you go back to one and a half, [it] feels like about a half. So you don’t think like you’re accelerating as much as you should be to get going. And, of course, I had worked the main engine program anyway, so I was very familiar with what the engines could do or not do. And I think in the next minute, every five seconds I checked the main engines to make sure they were running, because I swear we only had two working, because it just didn’t feel like we had enough thrust to make it to orbit. But then gradually the external tank gets lighter, and as it does, of course, then, with the same thrust on engines, you begin to accelerate faster and faster. So after a couple of minutes I felt like, yes, I guess they’re all working.
Ross also had the experience of worrying that all main engines were not working when they actually were.
I literally had to look to see that the three main engines were still working, because it became so smooth, and it almost felt like you weren’t going anywhere;
you weren’t accelerating at all. . . . At one point I can remember looking back behind me out the overhead windows again. In artists’ renditions of the flames coming out of the three main engines, it’s a nice, uniform cone of fire back there and stuff. Not true. The fire was all over the place. It was not static. It was dancing. It was not uniform. And again you go, “Is this thing working okay?” You don’t know what to expect.
As the shuttle nears the end of its powered ascent, with the bulk of the atmospheric drag behind it, it begins to accelerate dramatically. “As we got up to about the seven-and-a-half-minute point, then, is when you get to the three gs of acceleration, and that’s a significant acceleration,” Ross said.
It feels like there’s somebody heavy sitting on your chest, and it makes it pretty hard to breathe. I mean, you kind of have to grunt to talk, and you’re just waiting for this three gs to go away. . . . You’re accelerating at 100 feet per second, which is basically like going from 0 to 70 miles per hour every second. So it’s pretty good. And then at the time that the computers sense the proper conditions, the main engines . . . shut off and you’re in zero g. And for me, the first flight, sitting in the back seat, I had the sensation of tumbling head over heels, a weird sensation. And it was the three
g transition, from three gs to zero gs. . . . But as soon as I got out of the seat, then I was okay.
The main engine cutoff, or
, comes around eight and a half minutes into the launch, and shortly thereafter the external tank separates from the orbiter and reenters Earth’s atmosphere. As the only major component of the shuttle stack that isn’t reusable, the external tank burns up on reentry.
Gregory explained how he felt in that moment, when the main engines cut off and he was floating in the microgravity of space: “The first indication that this was not a simulation was when the main engines cut off and we went to zero g, and though [Steven] Hawley, I think, had been attributed with this comment, it was a common comment: ‘Is this space? Is this it? Is this real?’ And it was an amazing feeling. I’d never sensed anything like this before. So this sensation of zero g was like a moment on a roller coaster, when you go over the top and everything just floats.”
Hart described being surprised once in orbit, but unlike Ross and Gregory, not by the experience of zero g.
The zero g I was pretty well prepared for. As a fighter pilot and the experience at
in the zero-g trainer, you’re pretty familiar with what it feels like to be weightless. But what I wasn’t prepared for was the first look out the window. You don’t know what black is until you see space. I mean, I was startled with just how black it was. You don’t see stars. You could barely see the moon; it’s because there’s so much light coming off the Earth and off the tiles of the shuttle, that there’s a tremendous ambient light from all those sources, so your eyes are constricted greatly. And then because of that constriction, when you look into space you can’t see the stars or anything. I mean, it’s like really black. It’s palpable. You think you can almost reach out and touch it. I don’t know quite how to describe it. It’s sort of like black velvet, but it’s just totally palpable. . . . I guess I knew that I wouldn’t be able to see the stars when we were on the day side of the Earth. But still, when you look out there and see the blackness, it really was striking to me.
While most astronauts report experiencing an overwhelming excitement or elation upon their first arrival in orbit, Fred Gregory jokingly recalled an odd bit of disappointment stemming from his first ascent. “Since we had trained constantly for failures, I anticipated failures and was somewhat disappointed that there were no failures, because I knew that any failure that occurred, I could handle. It was where I slipped back into an ego thing. I anticipated failures that I would correct and then the newspaper would say, ‘Gregory Saves Shuttle,’ but heck, none of that happened. It just went uphill, just as sweet as advertised.”
As pilot, Gregory said his main job once the vehicle was on orbit was to make sure it was working properly. Since there were no major issues, he found that he had frequent opportunities for looking out the window. Said Gregory,
You immediately realize that you are either a dirt person or a space person. I ended up being a space person, looking out in space. 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 before and never seen before. I also saw aurora australis, which is the southern lights. I was absolutely fascinated by that. But if you were an Earth person, or dirt person, you were amazed at how quickly you crossed the ground; how, with great regularity, every forty-five min
utes you’d either have daylight or dark; how quickly that occurred, about seven miles per second; how quickly you crossed the Atlantic Ocean.
Although he was a self-described “space person,” Gregory still enjoyed occasionally gazing down on Earth below him and found it a fascinating experience.
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 longer I was there, the greater my “a citizen of” changed. The first couple of days
was where I concentrated all my views, and I was a citizen of Washington
. I was confused because I thought everybody loved
, but [Bob] Overmyer was from Cleveland [Ohio], and Don Lind was Salt Lake [City, Utah], and Norm [Thagard] was Jacksonville, Florida, and Lodewijk [van den Berg] was the Netherlands, and Taylor Wang was Shanghai [China], so each had their own little location for the first couple of days. After two days, I was from America, looked at America as our home. Taylor, China. Europe for Lodewijk. And after five or six days, the whole world became our home.
During his flight, Gregory developed a sense not only of Earth as a whole being his home but of just how interconnected the global community truly is, and the extent to which all people are sharing one planet.
You could see this kind of 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. After five or six days, then it was of concern, because you could see how the particulates from the smokestacks in Eastern Europe, how that 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 what the results of it was with the runoff, how it affected the ecology. Then you’d have to back up and say, well, this is not an intentional thing to destroy; this is something that they use coke as part of their process, and in order to get coke, you’ve got to burn. So you began to look at things from different points of view, and it was a fascinating experience. So that was the science that I was engaged in, but never anticipated it. And it was a discovery for me, so as each of these other great scientists who were with us discovered something that they had never anticipated, I also did, and I think the whole crew had.
In order to live and work in space during their missions, astronauts must learn to adapt to the microgravity environment, and that adaptation varies from individual to individual. Part of the adaptation is simply learning to get around; moving through the vehicle without gravity is an entirely different process than walking through it on the ground. For many other astronauts, adaptation involves a physical unease as the vestibular system adjusts to the lack of the orienting influence of gravity.
While it may take different amounts of time for astronauts to be back to 100 percent, most are at least functioning fairly quickly, Gregory said.
Whatever the adaptation was, within a day, everybody had adapted to it and so it was just a matter of working on all the programs and projects of the projects that you had. 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 and things like that, didn’t count anymore, and you translated [from thinking about] floors and ceilings and walls to [thinking] 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. You always knew that when you started, you had to have a destination, and you had to have something that you could grab onto when you got there. But, again, this was a transition that occurred, perhaps subtly, but over a very short period of time. I can remember we all kind of joked up there that we had become space things, and we were no longer Earth things anymore. The first couple of days, a lot of bloated faces, because there was no gravity settling of the liquids. But after a couple of days, you lost that liquid in your body, and you looked quite normal. So it was a fascinating experience. I think it was surprising to us how quickly we adapted to this microgravity environment.
With launch complete and their bodies adapting to space, the astronauts would go about their mission, spending days on any variety of different tasks carried out by shuttle crews during the early years of the program. Finally, though, the time would come to return to Earth. The orbiter would turn backward relative to its velocity and fire its engines to slow itself down, before rotating back to begin its descent.
-8, Commander Richard “Dick” Truly and Mission Specialist Guion Bluford sleep on
’s mid-deck. Courtesy
The experiences of launch and landing are very different, Gregory said. Ascent is relatively quick and marked by rapid changes in the g-forces experienced by the crew. Landing, on the other hand, is far more gradual.