Monthly Archives: May 2012

We expect the best, but prepare for the worse

Practice rescue in NBL

Fellow ESA astronaut Alexander Gerst bringing “unconscious” crewmate Reid Wiseman back to the airlock during a practice rescue scenario in the NBL (Photo courtesy Alexander Gerst)

Most astronauts dream of having the opportunity to perform a spacewalk at least once in their career and I am no exception to that rule. There’s something appealing about the idea of leaving behind the relative safety of the Space Station wearing your own little spaceship, about the thought of driving bolts while oceans and continents majestically pass by, about the challenge presented by the most physically and mentally demanding activity ISS crewmembers are confronted with.

There are also specific risks inherent to a spacewalk and one of the most dreaded scenarios involves a spacewalker going unconscious due to a medical issue or a malfunction of the pressurized suit. Over 150 spacewalks have been performed to assemble the Space Station and such a dramatic scenario has never occurred. However, you will not be surprised to hear that it does materialize quite often during training in the Neutral Buoyancy Laboratory (NBL).

During the EVA training flow future crewmembers are required to demonstrate the ability to rescue an unconscious fellow spacewalker by bringing him or her safely back into the airlock within 30 minutes. I had a chance to try the rescue for the first time last Thursday during a six-hour run in the NBL with veteran spacewalker Steven Swanson (Swanny).

Ready for NBL training run

Ready to be lowered into the water for an NBL training run. Notice lying on the floor the reel of an 85-foot safety tether. The big hook attached in front is connected to structure after airlock egress, while the reel follows along.

This being my first attempt at the rescue, the scenario was extremely simple. I knew in advance that Swanny was going to simulate unconsciousness and I was right next to him on the truss. Also, neither of us was carrying anything at that point, and we were both attached to structure only with our respective safety tethers and one extra tether. We call this latter the local tether, since we attach it locally at a worksit to be able to work with both hands.

Safety tethers, on the other hand, are thin steel cables that are coiled in a reel. We attach one end to structure as soon as we exit the airlock, and since we carry the reel with us, the cable uncoils as we move away and recoils when we come back. If we need to go far out on the truss, we might even have to carry a second safety tether to attach when the first one runs out, and having to make the swap on the way back with an unconscious crewmate would require extra precious time.

But it was not the case for me on my first try. I merely had to detach Swanny’s local tether and use it secure him to myself, and then stow his safety tether, since we would be both secured by mine. Sounds quick and easy, right? Well, I guess it could have been. In reality, when I was ready to move, I realized that I had created a tether tangle and I would have to take the time to fix it if I was going to go anywhere. Good lesson learned!

Christer Fuglesang stands on end of Canadarm2 (Credit: NASA)

ESA astronaut colleague Christer Fuglesang stands on a platform at the end of the Station's robotic arm, Canadarm2, during operations to relocate a CETA cart on the ISS (Credit: NASA)

Nothing in the suit is easy, but the rescue seems to be in a category of its own. It’s quite a challenge to manage the bulky suit of the unconscious crewmate by pushing or pulling it on a tether, while at the same time making sure that it doesn’t bump into structure, especially not with the relatively fragile visor. And it’s quite a challenge to manoeuvre him or her into the airlock in an expedient manner, and to enter as second without the colleague helping, or at least getting out of the way. I was sure thankful to Swanny for showing me some veteran’s tricks to do that!

For a scheduling coincidence, I had my first rescue scenario as a robotic operator the very next day. When EVA crewmembers are attached to the Space Station Robotic Manipulator System, or Canadarm 2, they must count on the robotic operator to bring them quickly and safely back to structure in case of an emergency. One more skill I’ll be trying to acquire in the next few weeks, but the details are for another day...

Outdoor staircases and brain gymnastics

Love the outdoor staircases in Montreal!

Love the outdoor staircases in Montreal!

I’ve been in Montreal for a week now, staying in the charming neighborhood of Plateau Mount Royal and spending full days of robotics training at the Canadian Space Agency.

I haven’t ventured far beyond the commute route so far, except for the brief stroll to nearby cafés for breakfast, a little daily ritual that has progressively shifted later in the mornings as I have slowly digested the six-hour time shift from Europe. I have taken great pleasure in exploring the little quaint streets flanked by trees and row houses, each with a unique façade and with an outdoor staircase leading to an independent entrance on the second floor. Straight or curved, simple or elaborate, rigorously in metal with open steps, these external staircases conjure up a dynamism that matches the colorful livelihood of the neighborhood.

With Canadian colleague David Saint-Jacques and a real-size Canadarm2 mockup. Every boom is 7 meters long, but it's an amazingly light piece of hardware

With Canadian colleague David Saint-Jacques and a real-size Canadarm2 mockup. Every boom is 7 meters long, but it's an amazingly light piece of hardware (Credit: CSA)

It’s a delightful way to start the day before making my way to the facilities of the Canadian Space Agency for training on the Space Station Robotic Manipulator System. Short: the SSRMS. For friends: the Canadarm2. In case you ever wondered how a 400-ton structure was put together on orbit, the short answer is: piece by piece, with the help of the SSRMS.

You can imagine the Canadarm2 as a robotic replica of your own arm in a bigger size. It has a shoulder, an elbow and a wrist. Like your arm, it has two straight booms between the joints. And like your arm it can bend the elbow and it can rotate shoulder and wrist in pretty much any orientation. In engineering terms it means that it has seven degrees of freedom, although we can lock one of degree of freedom to force the arm to move in a more controlled way. Station is precious; bumping into it is not an option.

Working at the Robotic Work Station. The two monitors relate to the simulator and are not present on orbit. Instructos using to run the simulation (Credit: CSA)

Working at the Robotic Work Station. The two monitors relate to the simulator and are not present on orbit. Instructos using to run the simulation (Credit: CSA)

To train future ISS crewmembers in SSRMS operations the Canadian Space Agency has Robotic Work Stations that are identical to the ones on orbit. There are hand controllers for translation and rotation, a computer and a control panel to configure the system and to input commands, and three monitors for camera images. There is no real arm, of course, but simulation software runs in the background and the camera views will show you exactly what you would see if you were flying the arm on orbit.

A typical simulator session might well start with what might look like playing with a toy. On a small-scale model of the robotic arm we reproduce the initial configuration based on the given deflections of each joint. I like to see it as a warm-up exercise for the brain.

Placing the Canadarm2 on the ISS model in proper position and configuration. The prop David is holding is useful to visualize coordinate frames (Credit: CSA)

Placing the Canadarm2 on the ISS model in proper position and configuration. The prop David is holding is useful to visualize coordinate frames (Credit: CSA)

If you’re a model-builder you’ll love what comes next: to be able to visualize the arm movement with respect to the Space Station, we have a tremendously detailed rapid-prototyping model of the ISS right next to the simulator workstation. I find it an object of intrinsic beauty, I’ll confess. But it’s of course intended as a tool of visualization and as an aid in the extensive brain gymnastics to come: mentally flipping camera images, predicting how the arm movement will look from different points of views, identifying the best camera combination to monitor clearances from structure, determining hand controller inputs in different coordinate frames, visualizing joint movements – these are some of the tasks that are sure to keep your brain on its toes as you fly the arm.

David and I trying to understand how one of the HTV coordinate frames is oriented (Credit: CSA)

David and I trying to understand how one of the HTV coordinate frames is oriented (Credit: CSA)

After one week of training I am starting to be familiar with nominal basic SSRMS operations. I’m now looking forward to learning next week about off-nominal situations like singularities and self-collisions, as well as practicing free-flyer captures, which consist in maneuvering the arm to grapple a vehicle that is not attached to the Space Station.

You can expect free-flyer captures to become more and more frequent on ISS in the coming years. Not only astronauts will continue to capture and berth the Japanese resupply ship HTV, but they will soon start doing the same for the new US commercial resupply vehicles Dragon and Cygnus. First Dragon capture is coming up soon, and I think it will be a historic moment. Make sure to watch!