Authors: David Hitt,Heather R. Smith
On reentry, it is entirely different. Though it takes eight and a half minutes to get up to orbit, it takes more than an hour to reenter, and it feels very similar to an airplane ride that most people have been on. You get an excellent view of the Earth. If it’s night when you reenter the atmosphere, then you see a kind of a rolling plasma over the windows. . . . But other than the onset of g that occurs at less than 400,000 feet above the Earth, it is like flying in an airplane. The sensations that you have are very similar to a normal domestic airplane flight. 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 velocity, and so you also know what velocity you’re supposed to land, and you can watch this amazing electric 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 reentry, but as we proceed through Mach 1, slowing down for landing, it is customary for the pilot, the commander, to take command of the orbiter and actually fly it in, using the typical airplane controls. But, you know, as I look at it, the ascent is very dramatic. It’s very fast, a lot of movement, but quick. The entry is more civilized but exposes the orbiter to actually a greater danger than the ascent, as far as the influence of the atmosphere on the orbiter. The temperatures on the outside of the orbiter really get hot on reentry, and that’s not the case on ascent.
Astronaut Charlie Bolden flew on the Space Shuttle four times, two of those as commander, and became
administrator in 2009. A former naval aviator, Bolden described landing the Space Shuttle as a unique experience. “The entry and landing is unlike almost anything you ever experience in any other kind of aerospace machine because it’s relatively gentle,” Bolden said.
In terms of g-forces and stuff like that, it’s very docile. Unless you do something wrong, you don’t even get up to two gs during the reentry, the entire time of the reentry. When you bank to land, you come overhead the landing site, and then you bank the vehicle and you just come down like a corkscrew. . . . It feels like
you’ve got gorillas sitting on your shoulder because you’ve been weightless for
number of days. And so it’s just a really different feeling. You have to hold your head up because you’ve got this big old heavy helmet on and it probably weighs [a few] pounds, but it feels like it weighs a hundred. It takes a little bit of energy to get your hands up off the console, because once you start feeling gravity again, your hands just kind of go down and they want to stay there; everything does. So the two pilots on board are doing a lot of isometric exercises all the way down.
Even when an astronaut lands the shuttle for the first time after a mission, Bolden said, it already feels very familiar because of all the training in preparation for the missions. “It’s like you’ve done it all your life, because you have,” Bolden said.
You’ve done it thousands of time by now in the shuttle training aircraft for real, and you’ve done it probably tens of thousands of times in the simulator. So it doesn’t look abnormal at all; it’s just something that you’re accustomed to. When you touch down, if you do it right, again, you hardly know you touched down. As big as the orbiter is, the way that we land it is we just get it into an extremely shallow approach to the landing, and so it just kind of rolls out on the runway, and if you do it right, you all of a sudden notice that things are starting to slow down real quick and you’re hearing this rumble because the vehicle’s rolling down the runway on this grooved runway. So you know you’re down, put the nose down and step on the brakes and stop. That’s it. And then you go, “Holy G. I wish it hadn’t been over so quick.” I don’t think it makes a difference how long or how short you’ve been there, it’s over too quick. You’re ready to come home, but once you get back, you say, “Boy, I wish I had had a few more days,” or something like that. And for me, my last two, being the commander and actually being the guy that had the opportunity to fly it to touchdown, was thrilling.
Once the landing is completed and the orbiter is safely back on Earth, the crew begins the process of reacclimating to the planet’s strong gravity after days of feeling weightless. Charlie Walker, the first commercial payload specialist, who flew on the shuttle three times, recalled waiting in the orbiter at the end of the mission.
The guys on the flight deck were going through the closeout procedures. Ground crews were closing in. We sat unstrapped, but we would sit in our seats for another ten, fifteen minutes as the ramp was brought up, the sniffers checked for am
monia leaks and/or hypergolic propellant leaks, found none, and put the stairway [up to the hatch], and opened the hatch. All that time, all of us are beginning to get our land legs back, unbuckle, start to try to stand up. “Ah, this doesn’t feel good yet. Wait a little bit longer.” So you kind of move around, move your arms first, your feet first, your legs first, then stand up, make sure you’ve got your balance back. The balance is the one thing that you just don’t have. Again, the brain hasn’t been utilizing the inner ear or senses of where the pressure is on the bottom of feet, for instance, to use as cues to balance itself against gravity. It hasn’t done that for a week. So you’ve got to carefully start through all that and consciously think about balance and consciously think about standing up, and we very consciously do that, because the last thing you want to do, in front of hundreds of millions of people watching on television, is to fall down the ramp leaving the orbiter.
Normally, on Earth, the body works hard to make sure the brain is adequately provided with blood. From a circulatory perspective, the brain, the part of the body that most needs blood, is located inconveniently at the top of the body, so the heart has to pump blood against gravity to get it there. In orbit, on the other hand, blood flows much more easily to the head, but it doesn’t fill the legs the same way without gravity pulling blood into them. Astronauts develop bloated heads and “chicken legs” due to the body’s confusion over how to distribute blood without gravity. The body takes the increased fluid flow to the head as a sign that it is overly hydrated and begins to shed what it sees as excess fluid. After the return to Earth, fluid redistributes again, which can cause problems.
“The body adapts by, among other things, letting go of a lot of fluid, about a liter of liquid, which makes you clinically dehydrated while you’re in space, except the whole condition of the body is different up there, so you’re really not dehydrated in that environment,” Walker said.
But if you come back without replacing that liter of fluid, then you are dehydrated. You try to stand up with not so much fluid to go to the head, and so you literally could pass out. Nobody did that, but I know I had sensations of lightheadedness for the first few minutes until I just literally worked at getting my balance back and focusing attention, and the body was adapting all that time, too. But leaving the spacecraft, I was holding onto the handrail as I went down the stairway. Got to the bottom of the stairs, and I was walking like a duck, because I was trying to keep my balance.
Once they’ve adjusted enough to walk, crew members board the Astrovan, which takes them to the medical quarters for postflight medical exams and a shower. Walker said it felt good to take a shower after days without one.
Every sensation for the next many hours, normal sensations of water running over you in a shower, [felt] strange. Because again, here this water’s hitting you, and it’s running down. And hours later, I found that I still could at any moment just think about the sensations in my body, and it was odd to feel this pull down toward the surface of the Earth, to be stuck to the surface of the Earth. [When I flew], it was still fairly new to hear comics or some wag note that this or that “sucks.” [Coming back] the astronauts were saying, “Well, the Earth really does suck.” So it keeps me drawn right down to the surface. Gravity is really real, and it stands out in your mind to, again, the freedom of weightlessness when you’ve had that opportunity. And that was just very much on my mind. I remember even a day, two days later, probably like a day later at a meal, I was sitting down, and I could not easily figure out whether I should sit back against the back of the seat or lean forward, because my head was telling me I was leaning forward at an angle, and, in fact, I was sitting almost straight up and down. So the inner ear is still adapting to its own senses and the body’s cues to orient itself and still doesn’t have itself figured out completely yet.
Even if an astronaut spends only a few days in orbit after a lifetime of living in the gravity of Earth, habits developed during those few days of weightlessness can persist for a little while after the mission. “I also remember waking up the next morning back here in Houston, waking up and going into the bathroom and wanting to brush my teeth, and I did that, and I remember letting go of the toothbrush, and it fell to the sink top, and I probably laughed,” Walker noted.
Then I pick up the cup of water to rinse my mouth out, and then proceed to let that cup go again. It’s like, again, you’re still thinking weightlessness, and you’re really used to that. Finding the situation where gravity is ever-present is just such an interesting experience, because now, again, you’ve had that contrast of a different place where that wasn’t part of the environment and you note when you get back how remarkable and how constraining gravity is. . . . We’ve all grown up for some decades, before we go fly in space, in gravity, and it’s just natural. Except it is programmed in, and that programming is submerged with new
habits that you gained to work in weightlessness, and you have to pull that programming back, or the brain does, and it does so at different rates, I think. So within tens of minutes, you can walk comfortably. You may look a little odd, because you’re not walking as expertly as you had done for twenty, thirty, forty years before. It takes a few more hours, maybe a couple hours to do that. But you can walk, so balance comes back pretty darn quickly. But it’s probably the nonautomatic stuff, like I’ve remarked about just automatically leaving a glass hanging in the air, thinking it’s going to stay there. You just get into habits there that are semiconscious, and it takes a little while for the body and the brain to let go of that and to relearn that, no, I’m stuck here again to the surface of the Earth. I’ve got to put the glass right up here on the table directly.
In the Beginning
Arguably, it could only have happened when it did.
Astronaut John Young, who would go on to become the commander of the first Space Shuttle flight, was standing on the surface of the moon during the
mission in April 1972 when he heard the news that Congress had approved vital funding for the development of the shuttle in its budget for fiscal year 1973. He reportedly jumped three feet into the air on the lunar surface upon hearing the news.
The Space Shuttle would be the most complex piece of machinery built by humankind. It was an incredible challenge and a daunting undertaking. At another point in history, a decade earlier or even a decade later, it might have seemed too challenging, too ambitious. But the project was born when men were walking on the moon. From that perspective, anything was possible.
It would be, far and away, the most versatile spacecraft ever built. But to many of the early astronauts who were involved in its creation, it was something even more fascinating—an aircraft like no other. Talk to the astronauts brought in as pilots during the 1960s, and there’s a fair chance they’ll refer to the orbiter as “the airplane.” Many of them will talk about its development not in terms of rocket engines and life-support systems but in terms of avionics and flight control systems. They had been pilots, many of them test pilots, and they had come to
to help the agency fly capsules through space. But now—now they were aircraft test pilots again, helping to design an aircraft that flew far higher and far faster than any aircraft before.
Since the selection of the first astronauts, members of the corps had been involved in the development of new spacecraft and equipment, providing an operator’s perspective. These were the people who would have to use the things that the engineers were designing, so it was their job to give the engineers feedback on whether the things they were designing were actually usable. For much of the time the Space Shuttle was being developed, most
of the astronaut corps was grounded, with only a dozen flying between the last moon landing in 1972 and the first shuttle flight in 1981. As a result, there was plenty of opportunity for astronauts to be involved in the development of the shuttle, and they participated more in the development of this vehicle than any before.
Even so, there were some at
with the idea that the moon would be just the first step into the solar system, who were concerned about what the shuttle wouldn’t be able to do—go beyond Earth’s veritable backyard.
In January 1973 astronaut T. K. Mattingly was assigned to be head of Astronaut Office support to the shuttle program. This was around the same time that the contracts were being awarded to the companies that would be responsible for making the shuttle’s various components. Mattingly, who had orbited the moon on
while Young was walking on it, recalls talking to Deke Slayton, the head of flight crew operations at
’s Johnson Space Center (
) in Houston, Texas, about the assignment. “When I got back from
, Deke asked me, he said, ‘You know, there’s only one more flight, so if you really want to fly again anytime near-term, you might want to take the backup assignment on [
,’ he said. ‘Chances aren’t very good, but we do know that we replace people occasionally. So if you would like to have that chance, you can do it, or you could work on the shuttle program.’ Really, I hadn’t paid much attention to it,” Mattingly said of the shuttle program at that point.