What’s It Like to Spacewalk at 17,500 mph?

A former NASA astronaut describes looking down at earth from inside a spacesuit.

Throughout humanity’s history, nothing has fascinated us more than the heavens above. With

astronaut Scott Kelly returning to earth after

nearly a year in space, and SpaceX’s Falcon 9 rocket lifting off last month, we wondered: What is it like do a spacewalk? Dr. Garrett Reisman—a former NASA astronaut and currently the Director of Space Operations at SpaceX, who flew two Space Shuttle missions (STS-123 in 2008


STS-132 in 2010, totaling over three months in orbit)—tells the story. To read Dr. Reisman’s earlier piece on the experience of blast off, click here.

Space shuttle commanders often tell rookie spacewalkers: When you’re out there, take a moment. Do something for yourself to capture a memory. The pressure on you is incredible. You have a laundry list of jobs you’re out there to perform and everyone is counting on you. You may never get another chance. You’ve been training for this for over a year. It’s going to be strenuous physically and mentally, and the clock is ticking; you only have so much time. I imagine it’s like what pro athletes experience when they take the field for a Super Bowl or World Cup final. You know when you’re sitting in a rocking chair in a retirement home in the future, you’ll be reflecting back on this day with either a great sense of accomplishment or tremendous regret. So it’s easy to forget to take a moment for yourself. In my three spacewalks, I’ve had a few, but one in particular.

It was nighttime where we were in space, and I was standing on the top of the International Space Station. We were flying toward the earth’s horizon at roughly 17,500 mph. That’s fast enough to orbit the globe every 90 minutes, but because there is no air, there is no wind, and no sensation of speed whatsoever. Ahead, I could see the sun begin to rise over the earth’s horizon. I had a Leo DiCaprio moment from Titanic, standing on this space station so the station itself was behind me—nothing blocking my view of the sun rising over the earth.

That is beauty. That is what it truly feels like to be on top of the world.

Even at the time I first interviewed with NASA to become an astronaut, I knew I wanted to do a spacewalk. One of the things you do when you interview in Houston is spend time with a current astronaut to find out what you’re getting into. I remember talking to this one guy who was very tall. I said, “I’ve been doing some surfing, rock climbing, and scuba diving. I wonder if those skills will make me a good candidate for a spacewalk.” He literally laughed in my face. He said, “What are you, four foot what? You’re too small. You’ll never do a spacewalk. The suit is one-size-fits-all. You’ll get swallowed up in that thing.” I didn’t let it stop me. If something is really important to you, don’t listen to anyone who says it’s impossible. Just do it.

There’s this magical time when you first get assigned to a space mission. You get an email that has a table that lists what everybody’s going to do. On my first mission, I was assigned a spacewalk. I was ecstatic. And that’s when the heavy training began.

In space it doesn’t matter if your head is up or down. There is no up or down.

Much of the training occurs under water. In Houston NASA has this enormous pool: 40 feet deep by 100 feet wide by 200 feet long. That’s a big pool. Inside is a replica of the Space Station. For every one hour of work you are assigned to do, you train 10 hours in the pool. The suit is exactly like a space suit, only there’s an umbilical chord that connects you to an air pump. You jump into the pool and divers put weights in these pockets to make you neutrally buoyant underwater, so you don’t bob up or sink down. That’s pretty much what it feels like to be in space, with two major differences: In the pool, if you’re upside down, blood rushes to your head and that gets uncomfortable. In space it doesn’t matter if your head is up or down. There is no up or down. Also, in the water, things stay pretty still because of the friction of movement through water. In space it’s the opposite. If you move something, there is no friction to slow it down, so it will keep on moving. Or, if you let go of what you’re holding onto, you could float away.

You do everything in the pool that you’ll be doing in space. Connecting electrical cables, strapping things down, learning how to work the suit. You also spend a lot of time in the gym, especially on the muscles in your hands, like a rock climber does. By the time you blast off the planet, you‘re ready to go.

Once you’re in orbit, preparation for the spacewalk starts days before you step out into the void. You have to check every part of your suit, make sure it’s assembled properly, that the batteries are charged, that the canister that scrubs out the CO2 is fresh. You put your tools together, and make sure they’re tethered properly. It’s like preparing for a construction project on a desert island; once you’re out there, there’s no turning back.

NASA via Getty Images

Twenty-four hours before you go, you move into the airlock for a camp out with your partner (spacewalks involve two people). Inside the space shuttle and the space station, the air is pressurized as it is on earth at sea level: 14.7 psi, or one atmosphere. Inside the space suit, it’s 4.3 psi. If you go from 14.7 to 4.3 right away, nitrogen bubbles come out of your blood and get stuck. That’s what you call the bends. You have to do that process gradually. So you go into the airlock the night before your spacewalk with your partner, your sleeping bag, and your food. In the airlock the pressure is 10.2 psi. You do all your last minute cramming (remembering the torque settings, the order of operations, etc..) and you try to sleep (though sleep is hard because of the adrenalyne). Meanwhile your blood starts getting rid of some nitrogen. You also put on a mask and breath 100% oxygen, to further purge your blood of nitrogen. There’s only one problem here: There’s no bathroom in the airlock.

It was a wonderful moment. Then he shoved me into the airlock and closed the hatch.

In the morning, you open the door and your buddies help you get to the bathroom inside the space station. You’ve got this mask on with a big hose; it’s not easy, but this is your last chance for a long time, so you try to get the toilet ops done. After that, it’s time to put on the space suit. In microgravity, this is pretty strenuous. You get your helmet on; you do one last check of your tools. At this point, you’re just about ready to go, and you’re feeling the pressure of what’s about to happen.

On my last mission, I was in charge of the most challenging of my three spacewalks. My commander was an astute guy, and he could sense what I was feeling. He grabbed my shoulder and looked into my eyes. He got his mouth right up to my helmet and yelled so I could hear him: “Don’t! Fuck! Up!” I immediately burst out laughing and so did he. He was telling me that everything was going to be okay. It was a wonderful moment. Then he shoved me into the airlock and closed the hatch.

Just before you go, you enter an outer chamber of the airlock and a pump begins to empty this chamber of air. Air is a scarce commodity on the space station, and you don’t want to waste any. While the pump is working, you can still hear things. A wrench hits a wall, and you can hear it. But once the last bit of air is pumped out of the airlock, you can no longer hear anything because, without air, sound cannot carry. A wrench may bounce off a wall, and you hear nothing. At this point, you turn on your suit, open the hatch, and step outside.

The first time I came out of the airlock, it was at night. Your eyes are adjusted for the bright lights of the airlock, so when you go into space, you have this overwhelming sensation: You have never seen such darkness. Nothing in training can prepare you for this shock. Space appears viscous, like black ink. I remember sticking my hand out and moving it left to right slowly, expecting to feel a liquid. Of course I didn’t. This moment is incredible, but it passes quickly. You don’t have long, and you have to get to work.

Spacewalk is a misnomer. It’s more like a space crawl.

All three of my spacewalks were between 7 ½ and 8 hours, and there is a list of complicated tasks to complete. The folks in Houston have done a good job training you. Everything around you feels familiar. Things are where you’ve been told they would be, everything is the size you were told it would be, and the mechanisms work the way you were told they would. The big mistake you can make is fatiguing too quickly because you have so much adrenaline. I whispered this mantra to myself: slow and gentle. Don’t squeeze too tight. In the movies, they make it sound like you’re in complete silence, but actually it’s pretty noisy inside the suit. It has fans and pumps, and you’re talking over a headset, which delivers some static.

Spacewalk is a misnomer. It’s more like a space crawl. You use mostly your hands to get around, pulling yourself where you have to go, careful to keep ahold. You are tethered to the space station, but still, you do not want to let go and float away, because you never want to take the chance that the tether might break, or that it might not be hooked up properly. In my first spacewalk, the first thing I had to do was pull myself over the space station to where the space shuttle was docked. We had this new element we had brought up with us, the first piece of a Japanese laboratory that required some assembling. We also had to start assembling a Canadian robot that we had brought up in nine pieces. It was named Dextre. We had to connect the hands of the robot, these manipulators, to the arms.

Performing these intricate mechanical tasks while wearing the space suit is immensely difficult. It’s like trying to change the oil of your car while wearing a medieval suit of armor. The suit is puffed up like a balloon, and it wants to hold its shape. Even closing your hand around a wrench takes effort. The gloves are rigid and thick. Lifting your arms up to your shoulders requires muscle. Now is when you thank yourself for all those hours in the gym.

Every now and then, you stop and catch a glimpse of the earth moving by underneath you as you fly around it. You look down and you’ve got a face full of Seattle. Minutes later, you’re looking at New York. The entire U.S. has flown by in 10 minutes. You have this giant fishbowl of a helmet, but after a while you forget it’s there. You feel like you’ve become pure energy rather than a corporal being, like you are part of the ether.

On my first spacewalk, despite my efforts to conserve energy, I found myself incredibly fatigued by the end. I’d been working hard for nearly eight hours, with no food or rest, and I got scared because I knew I had to get the hatch open and there were things I had to do to get inside. You only have so much oxygen, so you need time to do these things. Yet you’re racing to get everything done that you can. I felt my arms and fingers getting more and more tired and I was getting nervous. At one point, I was holding onto this thin nylon webbing, and I could feel my grip slipping. It was a really bad feeling. All kinds of things can go wrong if you lose your grip and have to rely on the tether to pull you back in. You could damage your suit, damage the space station—or worse. But the adrenaline gave me strength, and I was able to complete the job.

When you get back into the airlock and close the hatch, you still can’t hear things like a wrench hitting a wall. Air flows back into the airlock through a valve, and you know air is present when you tap on the wall and you can hear the sound. In all three of my spacewalks, I accomplished all our objectives and some additional things too. So in each case, I was overwhelmed with this wonderful feeling of elation. You’re hungry, so you chow down. And you’re exhausted, so you just want to lie down. I remember after my first spacewalk, I was so happy I did not screw things up that I had this wonderful dream, involving Scarlett Johansson. (The truth is, I refused her, because I couldn’t be unfaithful to my wife, even in my dreams. Yeah, my wife is that awesome.)

To come back to the metaphor of athletes taking the field for a championship—that’s what it felt like, I imagine. Like I had taken the field, and I had won.

Follow Dr. Garrett Reisman @astro_g_dogg on Twitter.