by Terry Virts
This was by far the most stressful moment of my entire shuttle mission. Node 3 and Cupola were launched while firmly attached to the payload bay by two keel pins, or clamps, on the bottom of Node 3. In order to remove the modules from the shuttle, those clamps had to be released. However, a lot of tension had built up because of the stress of launch, so when they were released the entire 35,000-pound assembly lurched and floated toward the right side of the shuttle, coming to rest a few inches from the wall of the shuttle. My task was to manually lift these modules straight up and out into free space, like a crane lifting construction equipment. But after the module had moved so close to the payload bay, there was no room for error without bumping our precious and massive cargo into the shuttle’s thin walls, possibly damaging our ride home. At least all of my friends and family and colleagues and people all over the world would be watching the majestic moment when our massive cargo was gently floated into space and handed to the station’s waiting arm in a slow-motion orbital ballet. By me. All I had to do was thread the needle of this extremely narrow corridor with barely a few inches of tolerance from Endeavour’s starboard wall. What’s the worst that could happen?
Long story short—I was able to do it, with a lot of fellow astronauts back on Earth probably saying to themselves, “Man, I’m glad that’s not me.” What a huge sigh of relief I gave when the bottom of Node 3 had finally cleared that very fragile-looking shuttle wall and been successfully grappled by the station’s arm. For me and my fellow robotics operator Kay Hire, that wasn’t the end of our job—we still had to float over to the station and do several more robotic operations with the big ISS arm—but this was a significant task completed and a huge morale booster.
Best of all, I had avoided getting a new nickname from my fighter-pilot buddies. Some possibilities that were floating in my head: “Bump,” “Crash,” “Robo,” “Ding,” etc. Air Force fighter pilots are fond of giving call signs that emphasize a fault or defect, as opposed to gratuitous call signs that our Navy colleagues are fond of giving, like “Maverick,” “Iceman,” and “Cougar.”
Another important task that the shuttle arm fulfilled during the final twenty-two shuttle flights was performing an inspection of the orbiter’s heat shield on the bottom of the vehicle. This was a critical lesson learned after the Columbia accident on STS-107, when a fragile heat shield was damaged during launch and neither the crew nor ground had a good idea of the extent of the damage. NASA made the fateful decision to ignore that damage and not even try to take a photo of any potential damage, and the crew was killed as Columbia burned up during re-entry because of the hole in their heat protection. After that terrible tragedy, NASA developed the OBSS (NASA acronym for inspection boom). It was a 50-foot-long, massive extension of the shuttle’s arm that had several cameras and a laser sensor. On the second day in space, before docking with the ISS, we grabbed the OBSS with the arm, and with cameras running we slowly moved it along the leading edge of the orbiter’s wings and along much of the tile on the bottom of the vehicle to verify that no damage had occurred during launch. This whole procedure was repeated again on the day before landing to make sure that no meteorites or orbital debris had damaged the heat shield during our two weeks in orbit. The process was very tedious and time-consuming, because the sensors needed to move slowly so they could get very detailed images of the heat shield. Most importantly, we needed to be very careful not to bump into a fragile part of the orbiter, potentially damaging critical thermal protection.
Anybody who has used an Xbox or PlayStation controller could figure it out pretty quickly. Alas, most senior (i.e., old) astronauts are not familiar with such things.
During STS-130 I was tasked to do this inspection, together with my crewmate “Stevie-Ray” Robinson. It was scheduled to occur as we were flying over South America at dusk, and I still vividly remember those spectacular thunderstorms. It was dark enough that we could see the brightness and detail of lightning flashes, but there was still enough sunlight to see the fading colors of the Amazon, along with the white and gray shading of the clouds. It was a sight that I never saw again, not even during my 200-day-long mission, which taught me an important lesson—enjoy every amazing moment in life, because you don’t know if or when it will happen again. While I was gawking at our beautiful planet, poor Steve was having to fly the arm by himself. I still owe him for that.
The space shuttle’s arm was what is known as a “six-degree-of-freedom arm” (or 6 DOF). Much like a human arm, there was a shoulder joint that could yaw and pitch, an elbow that was pitch only, and a wrist that could yaw, pitch, and roll. Which basically meant it could move like your arm on your body. On the other hand, the station arm was much bigger and also had an extra degree of freedom—its shoulder joint was exactly like its wrist joint, so they could each roll, pitch, and yaw. This “7-DOF” configuration meant there were a lot of possibilities for arm motion, but it also meant that you could get really confused. So, we would usually lock one of the shoulder joints while the arm was moving to turn it into a 6-DOF arm like the one on the shuttle. The problem with letting all seven joints rotate while moving the arm was that it would swing unpredictably, especially the elbow area, and we really wanted to prevent unexpected arm motion so that it didn’t accidentally bump into structure.
The critical reason for giving the arm seven degrees of freedom was that it could inchworm across the station: The wrist would grab on to a grapple fixture and become the new shoulder, and the old shoulder would let go and move out into space, becoming the new wrist. We needed this capability because the station was so large; no single arm could have provided coverage to the whole exterior without being able to move itself around.
There is also a robotic arm on the Japanese module that is used to pull equipment from their airlock, which is located inside the station, and stow it on an external platform, exposed to the extreme environment of open space. This is a very useful capability that allows a lot of science to happen without the overhead and danger of astronaut spacewalks. The Russian segment also has a robotic arm that is manually controlled and especially useful during their spacewalks. Finally, there is Dextre, also known as SPDM, the Canadian acronym for “fine manipulator.” Although it is quite massive, it has several smaller arms and hands that can perform certain tasks that the big arms cannot, such as pulling small equipment out of the trunks of cargo ships, or manipulating bolts or small equipment.
There were two basic jobs for all of these arms. First, to move equipment from point A to point B. This was the main task during the years of station assembly; we were constantly moving massive modules around and assembling them. The second task was to reach out and grab approaching cargo ships—they would fly in formation, hovering about 30 feet below, while the crew would fly the arm down and grapple the vehicle and then attach it to a free docking port. Most arm motion today is controlled by the ground in order to free up precious crew time. But grabbing those free-floating vehicles is something that the crew still does because it is such a time-critical operation, and it is one of the most fun, dynamic tasks that ISS astronauts have, breaking up the monotony of repairing equipment and performing science experiments. Well, we also have launch, landing, rendezvous, and spacewalks, so I hear you, monotony for astronauts really isn’t that bad.
There are basically three techniques to fly a robotic arm in space: manual, automatic, or joint control. Manual was my favorite but was typically only used for grappling visiting vehicles. Anybody who has used an Xbox or PlayStation controller could figure it out pretty quickly. Alas, most senior (i.e., old) astronauts are not familiar with such things. In order to move the arm, you take the THC (controller in your left hand) and push forward, and the arm moves forward toward the target. You could move it left/right/up/down and get corresponding motion from the arm’s end effector—this motion is called translation. You also use the RHC (controller in your right hand) to pitch, roll, and yaw the arm to be aligned with the grapple fixture on the cargo shi
p—this motion is called rotation. Once the hand of the arm moves over the target’s grapple fixture, you squeeze the trigger, some steel cables inside the hand pull tight, and the arm attaches firmly to the target—the cargo ship floating below the station, hardware to be moved, or the new home for the arm, as its hand becomes its new shoulder and vice versa.
Much of our arm motion was done in automatic mode. In this mode, flight controllers would calculate a position and orientation for the arm to go to and come up with computer commands to move it there. Then either the crew or ground could command the arm to move to the desired position and attitude. It wasn’t very exciting, but you still needed to have good camera views to make sure that all parts of the arm (wrist, elbow, booms, shoulder, etc.) were clear of structure. The big concern in any arm motion was accidentally bumping into something, and this required constant vigilance by looking out the window in the Cupola, monitoring the many external video cameras available, and following the expected trajectory on a laptop.
The third method of moving the arm was by directly controlling each individual joint angle. Imagine moving your own arm by pitching your shoulder up 20 degrees, yawing it right 20 degrees, bending your elbow down 50 degrees, yawing your wrist 10 degrees, and rolling it 30 degrees, etc. You get the point. You can point the arm exactly how you want it by telling each joint what angle to go to. This is tedious and time-consuming, but precise. I always enjoyed challenging myself in the simulator to control the arm with joint angles only, trying to grapple a target or rescue a stranded spacewalking crewmember with the arm, trying to move him quickly to the airlock before his oxygen supply ran out. These far-fetched and difficult scenarios in the simulator were unlikely to ever happen in real life, but they were a critical part of my training because they forced my brain to fully understand how the arm worked and to visualize complex 3D problems. Those tough exercises made me a better arm operator than any other training I did.
Humans and robots are going to continue to work together more and more in the future, both here on Earth and in space. Flying these twentieth-century-vintage robotic arms was a blast. I hope that robots in the future help crews in space as well as us poor earthlings—and don’t fulfill the dystopian Hollywood visions of HAL or the Terminator.
Phones, Email, and Other Horrors
Communicating with Earth (Slower than Dial-Up)
How do astronauts keep in touch with friends and family back on Earth? The answer is both simple and complicated. There are lots of ways to connect with loved ones (and not-so-loved ones), which forced me to ask an introspective question. Did I really want to connect? In many ways I looked at that half year off the planet as a once-in-a-lifetime opportunity to disconnect. No internet. No texting. Limited phone and email. For me, it was the imperative to disconnect that was a blessing.
There were several ways to communicate with our fellow earthlings stuck on our planet. The most common method was by email. Good old Microsoft Outlook. For the first fifteen-plus years of the ISS, email was synchronized thrice daily. So you’d write an email, wait a few hours for it to be sent, then wait a few more hours until the next sync period happened, and hope there was a reply. Or not, depending on the subject of the email! If there were no reply, you’d have to wait hours for the next sync. This process went on for years, rendering email a not-very-efficient method of communication. Luckily, a few years ago the station program transitioned to a new system of continuous email syncing, where as long as the station is in satellite coverage, email accounts constantly synchronize. This allows emails to be used as a poor man’s text. You still have to float back to your crew quarters’ laptop to check email, and you have to have appropriate satellite coverage (roughly 90 percent of the time), and your buddy on Earth has to be checking his email religiously. But if all of those conditions are met, voilà—space iMessage!
There is also the possibility of logging on to the internet while on board the ISS. It is very slow, with speeds reminiscent of the good old dial-up days. It is only available when the appropriate comm satellites are in view of the ISS. And it requires a relatively painful log-in process. Despite all of these limitations, some astronauts love using the internet because it allows them to log on to their social media accounts so they can tweet directly, without having to email photos and quotes to a middleman on Earth who would post them to the appropriate social media account. It also allows you to surf the web, looking up such obscure questions as “How tall are the sand dunes in Namibia?” and “Where is the south magnetic pole located?”—two questions I asked the Google while in space. However, I quickly concluded that whatever strange facts I could learn through the internet weren’t nearly worth the pain required to log on and then wait forever for a Google query to get processed. I looked at my flight as a blessed opportunity to mostly go without the internet for 200 days, and only rarely logged on when absolutely necessary. It was exactly the detox that most of us could use.
There were several other methods of communicating besides email. The most common was a telephone system that used voice over IP technology, appropriately called IP Phone. Today, there are many apps that do this exact thing on your smartphone—WhatsApp, Viber, FaceTime, Signal, Vonage, and the list goes on. But back in the 2000s, when we first got this system, we thought it was hot stuff. Once again, it depends on those comm satellites, which warrants a brief description. The ISS doesn’t normally communicate by sending radio signals directly to ground stations on Earth; it sends them to TDRSS (pronounced tea druss) satellites operating in geosynchronous orbit, which means they are usually 30,000 miles or more away from the ISS. There are two radio frequencies that we use with TDRSS: S-band and Ku-band. S-band is for voice communication and very low rate data. Ku is a much higher data rate, and we use it for things like payload data, video, and the IP Phone system. Our phone software was on our laptops and unfortunately didn’t have an address book system, so I had to memorize everyone’s phone number, just like back in the twentieth century.
I like to joke that this is the most perfect phone in the world—you can call anywhere for free, and nobody can call you. Another advantage is that it suddenly and unexpectedly hangs up. As the ISS flies along at 17,500 mph, it jumps from one TDRSS satellite coverage zone to the next, and when it flies out of view of the satellite it is using, there is Ku-dropout and the phone suddenly hangs up. No long, drawn-out goodbyes, just “click” and the call is over. Plus, the maximum length for which you might have any one particular TDRSS satellite in view is about forty minutes, so every phone call is naturally limited. Like I said, it’s the best phone in the world.
Another method of communicating is via video teleconferencing, similar to Skype or FaceTime, using the same laptops and Ku-band system. NASA scheduled a twenty-minute call every weekend with our families, which required special equipment in my house to tie into the NASA system, so it wasn’t quite as easy as FaceTime. But it was still nice to be able to see faces. Those weekend sessions were normally extended to an hour or so if desired. There was also a perk to being an astronaut: NASA set up two special video sessions with anyone we wanted—a celebrity or politician or musician, anyone at all. The NASA family support team would cold-call that person and say that an astronaut in space wanted to talk. They almost always said yes! My awesome family support helper, Beth Turner, set up some amazing talks for me, which were huge morale boosts in the middle of a very long cruise. We keep those events private for many reasons, but I can say for sure that you’ve heard of some of the folks I talked with. Those calls were a blast for all involved!
I often thought of the tribulations my grandparents went through in World War II—they left home and then had no contact for years, other than letters that were censored by their commanding officer. And now there I was, in outer space, not even on Earth, emailing every day. Making phone calls every day. Video conferencing weekly. There are many hardships that go along with spaceflight, but staying connected is generally not one of them. Today’s astronauts are
very lucky to be able to maintain contact with Earth, or cursed, depending on how you look at it.
Hearing Voices
How Psychologists Prepare You for What Spaceflight Does to Your Head
It is a fairly easy thing to hire astronauts who are technically capable. There are a lot of people out there who can repair broken equipment, perform spacewalks, fly complicated vehicles, or do science experiments. Those things are all important and require a wide range of technical skills, but at the end of the day there are a lot of technically skilled folks in the world. From my perspective, the much more difficult skill for an astronaut candidate was being psychologically adept for space travel. When I was reviewing astronaut applications, I would always look for clues to their suitability from a personality and psychological viewpoint, more than their technical ability.
Everyone who makes it through the first few gates of NASA’s astronaut application process has serious technical qualifications. They will be a fighter pilot/test pilot, a medical doctor, or an accomplished scientist or engineer, along with having a broad range of experience in flying, climbing mountains, working on race cars, etc. We received more than 18,000 applicants for the last astronaut class, so it wasn’t hard to find candidates with strong backgrounds. But the hard part was determining who would be psychologically suitable. Who would be able to handle the stress of constantly putting their life on the line, knowing that if the rocket malfunctions there is probably nothing they can do about it and they would likely die, or if a meteor comes flying through the station or their spacesuit at the wrong time, again they would probably die? Who could handle being stuck with a handful of other astronauts and cosmonauts for months at a time in a very confined space? For me, the soft skills were much more important than the technical skills when selecting new astronauts.