My Experience with Zero Gravity

Those of you out there who follow me on Facebook or Picasa – or who know me personally – have already seen the pictures from my zero-g (well, microgravity) experience. Here’s the illustrated saga, for your reading pleasure:

My research group at Cornell got an opportunity to fly an experiment on a microgravity flight sponsored by NASA. We’ve been doing research on how an effect called magnetic flux pinning, in which a magnet sticks to a superconductor without touching it, could be used to assemble, hold together, and reconfigure spacecraft. While I was interning at Johnson Space Center this summer, my team designed and built a shoebox-sized dewar for holding cryocooled YBCO superconductors and two mockup CubeSats – 10x10x10 cm spacecraft – containing magnets and electromagnets. We took them to Houston to try out flux pinning on the Zero-G Corporation’s aircraft – “G-Force One” – a modified Boeing 727 that is now of the sort of aircraft known affectionately as the “Vomit Comet.”

Before I was cleared to fly, I had to jump through some medical qualification hoops. I have type I diabetes, and have in the past been diagnosed with asthma. Several letters from my doctors and one pulmonary function test later, I had the okay for physiological training and then flight. “Physiological training” consists of classroom lectures about what happens to a human body during ascent to altitude, oxygen deprivation (hypoxia), and spatial disorientation, followed by a session in a pressure chamber designed to simulate a flight to 25,000 feet.

View of the Neutral Bouyancy Lab's 40-foot-deep tank and the altitude chamber below it

Physiological training was at the Sonny Carter Training Facility, home of the Neutral Bouyancy Lab (NBL) where astronauts train for spacewalks. That photo above shows off the 40-foot-deep pool, which looms over the altitude chamber – that chunky rectangular room directly below the “Welcome to the NBL” banner. In the chamber run, they bring in 16 participants and seat them in two rows of 8, facing each other, put them on 100% oxygen through a mask system (all wear fighter-pilot-style masks and snoopy communications caps), and then pump air out of the chamber until it gets to the same pressure as an altitude of 25,000 feet. Then, they have half of the participants take off their masks for five minutes to learn how they react to hypoxia (while under very strict supervision). You see, everyone’s hypoxia symptoms are different: loss of concentration, peripheral or color vision, shaking, euphoria, lethargy, blue lips and fingernails, or dizziness. The purpose of the altitude chamber run is for us to recognize what our hypoxia symptoms are, so that if we’re in an airplane that decompresses, we’ll recognize when we need to go get emergency supplemental oxygen equipment. (In other words, we were learning exactly why they tell you, “Put your own mask on first, then assist others.”)

When it came time for me to take part in the demonstration, I dropped my mask and stared ahead at Max, my Cornell teammate. He had dropped his mask for five minutes earlier, while I observed. They handed us a worksheet to fill out while we were off the masks, consisting of some simple brain exercises. At first, nothing seemed terribly different from breathing normally. I looked around the chamber, at the other participants, my teammate, the worksheet, and some color wheels placed around the interior of the chamber. I held my fingers up to either side of my head to check my peripheral vision, and glanced at my fingernails to see if they were turning blue, and started in on the brain teasers. Almost immediately, my hands started to shake visibly. I scrambled to answer the worksheet questions, nervous about what might happen while I was writing. My chief worry was that loss of concentration would be one of my hypoxia symptoms. I kept checking peripheral and color vision, and didn’t notice any change. After a few minutes, I felt like the muscles just under the skin in my torso and ankles started to shake along with my hands. But then, after about four minutes at 25,000 feet, I found out that I’m one of the lucky ones for whom euphoria is a hypoxia symptom – the shaking stopped, and I felt much better. That’s a false feeling, though – as I was actually becoming quite dizzy without my brain realizing it. Max can attest that after five minutes, as soon as I put the mask back on, I suddenly registered my dizziness – and I reeled for a moment before the 100% oxygen flow got back into my system. About fifteen minutes later, the chamber was back to 1 atm pressure and we were filing out.

Our flight week involved a lot of work in intense heat and humidity in a hangar at Ellington field, as well as late nights at my sublet while we finished up NASA documentation and got our equipment up to the loading standards for the Zero-G aircraft. A lot of pizza, hardware store runs, typing, metal-sawing, The Beastmaster, and one 4 AM run to Kinko’s later, and we were ready for our Test Readiness Review by NASA officials.

The team after a *very* successful TRR: Max (holding the superconductor dewar), Laura (with one of the CubeSat mockups), me (and a high-speed camera), and William (holding the other mockup CubeSat)

The team after a *very* successful TRR: Max (holding the superconductor dewar), Laura (with one of the CubeSat mockups), me (and a high-speed camera), and William (holding the other mockup CubeSat)

We passed with flying colors and got ready to load the plane! (One of the NASA reps told me afterwards that our TRR was one of the best of the day.) The 727 has a rear stairway under the tail engine, standard airliner seating in the rear of the cabin, and the middle and forward part of the cabin is just open, padded space. We carried in our mounting boxes, laid them out, and had them bolted to the airframe. Eight other experiments flew both days we were up, each with at least three flight crew, plus there were about five or six NASA crew each day, so it got kind of crowded. Then we left Ellington Field and went out for a steak dinner – since Max and I heard at physiological training that a high-protein diet helps stave off motion sickness.

The modified Boeing 727, ready for staging and loading of experiments

The modified Boeing 727, ready for staging and loading of experiments

Flight day 1 began with some frantic setup in the hangar as Max got the dewar filled with nitrogen to keep our superconductors cold. Laura, William, and I were the flight team for the day, so we headed off to get our preflight briefing and medical briefings. At the med briefing, they gave us all some scop-dex, a two-medication cocktail tailored to shut our inner ears down and help prevent motion sickness. The preflight brief let us all know about the flight plan for the day: since none of the experimenters specifically requested a break, we were going to go up over the Gulf of Mexico and knock out as many parabolic trajectories as possible before the plane would turn around and parabola its way back towards Ellington.

Laura, William, and I came back to the hangar to grab the dewar, which Max kept topped off and had ready to go just before flight. We boarded the plane through the rear stairway, secured the experiment in its case, and then came back to the seating in the rear of the cabin. We got a brief safety overview (cards in our seat-back pockets and everything). Takeoff and climbing to cruise altitude was more uneventful than on a standard airliner, given that there weren’t any windows to be seen from our seats. Then, we got a signal that we were free to move about the cabin. We unstrapped, climbed out into the aisle, and made our way forward into the padded central cabin where our experiment cases were bolted to the airframe.

Getting the laptop set up to control the experiment and getting situated with a legstrap.

Getting the laptop set up to control the experiment and getting situated with a legstrap.

We got our cases undogged, our feet under some legstraps, and got ready to pull out the CubeSat mockups. The aircrew waited until all nine teams of experimenters said they were ready to go, and then the plane unceremoniously went into a high-g climb. I saw the flight surgeon lie down behind me a moment before, so I emulated him and lay on my back next to the laptop. There’s a monitor at either end of the cabin that shows the current parabola number and the effective gee force, but lying down, I couldn’t see it. I could definitely feel it as the plane poured on the g’s up to about 1.8g. (I don’t understand fighter pilots who get up to 6g. Or 8g. Or 10g. 2g was uncomfortable enough for me.) The extra “gravity” pressed me tightly into the floor padding.

In two gravitites, getting my camera ready for zero-g.

In two gravitites, getting my camera ready for zero-g.

Then the plane nosed over. As it comes into the top of its parabolic trajectory, the downward acceleration of the plane exactly matches gravity and everything inside the cabin is in freefall for about 26 seconds. Almost immediately, I felt like I was falling and flailed my arms around a bit to grab onto something – which, of course, does nothing except for maybe letting me hit something. I had the legstrap over my lower right thigh, thinking that would hold me. It didn’t: the single point of contact acted as a pivot rather than securing me, so the first thing that happened to me was that I floated around and twisted involuntarily towards the side of the plane, shouting “Waaaauuugh!”

Coming up off the floor as we go into microgravity

Coming up off the floor as we go into microgravity

One of the first things that I learned about microgravity is how hard it is to control yourself in a short timescale. Unless you’re methodical in your movements from the start (I got used to counting from about three to five from when I first felt like I was in “zero gee” before I started actually moving around) you kind of bounce around. Again, to us physicists and engineers, this shouldn’t be a surprise, but it takes intuition a while to catch up!

Free-floating!

Free-floating!

Microgravity almost doesn’t feel exciting at all, once the falling sensation fades. I mean, it doesn’t feel like anything. I just hung there in space. My inner ears told me nothing (partially thanks to the scop-dex). My sense of touch didn’t tell me that I was touching anything, because if I did, the normal force would push me away pretty quickly. I wasn’t sitting or standing on anything. The best way I can describe it is to say, “you’re just there.”

As an example of what I mean, take this little maneuver:

That looks like tremendous fun, but I have to say, it was kinda boring. The only thing I had to go on to know that I was spinning at all was my eyes. Even my partially functional inner ears were silent – after all, once I lost contact with the floor, I was rotating at constant velocity! (Now, of course, being a physicsy guy, I know how to make that fun. Given a bit longer than 25 seconds, or maybe just some careful planning, I’d love to try out some other experiments with linear and angular momentum, or exploit the human body’s nonholonomic constraints. And, really, I’m not going to contend that I didn’t love every second of that.)

We worked diligently at our experiment for about 20 parabolae, after 3 just getting used to handlign ourselves and our equipment in zero g. William and Laura had the tasks of pulling our experimental dewar and CubeSat mockup out of a padded case at the beginning of each parabola, shepherding them together and watching the magnets and superconductors flux pin together, and then stuffing them back into the case when the NASA crew gave us the “feet down!” warning. My job was to set up and record high-speed video of each parabola, call out general directions to Laura and William for the best video, and control the CubeSat mockup via computer. Here’s a video I compiled of our research highlights:

For the last fifteen or so parabolae, our nitrogen had run out and the experiment no longer functioned. We tried a couple times to just pose the equipment to take some pretty pictures. After a bit of that, we just started to play around in zero gravity! At one point, to try and take photos from a different angle, I floated myself over to Laura and William’s side of our little experimental area, propelling myself along with a few pats of my hands against the floor and the cases bolted to the airframe. Now that is fun, just moving yourself along effortlessly! Look for a clip of that at the end of this next video.

All good things must come to an end, and after 20-25 seconds of microgravity, the NASA crew shouts for all the experimenters to get their feet under them once again and the effective gravity in the plane waxes up to 2 g’s in about a five-second transition period. I found that at 2 g’s, movement in general was difficult. I felt like I had to push my arms through soup. And, a couple times, I made the mistake of moving my head too quickly in 2 g. Then I can tell you my inner ears felt it. In fact, I will admit that of our flight crew, I was the sickest of the bunch – but only for the last two or three of 35 parabolae, and I did not vomit! By “sick,” I just mean that in the last 2 g parabola, I had to sit still with my head facing along the aircraft axis to line up with its motion. But I was fine. Here’s me towards the end of our run:

IMG_3319

And then we went back to our seats, the aircraft landed, we unbuckled, and high-fived as we disembarked!

High-fives all around as we walk back across the tarmac!

High-fives all around as we walk back across the tarmac!

The Day 1 flight team immediately postflight

The Day 1 flight team immediately postflight

That was the end of flight day 1, and my flight crew involvement. Max, the fourth member of our team, was on ground crew the first day and, since he’d done a lot of machining and gruntwork for us over the course of the summer (he wins my “destroying his body for the team” award for, erm, “machining” some steel) I volunteered that he could go up on day 2 instead of me. I just hung around on the ground and poured liquid nitrogen:

Dispensing LN2 from the big dewar, in protective gear in the 100+ F hangar.

Dispensing LN2 from the big dewar, in protective gear in the 100+ F hangar.

The great news is that our team was successful enough that we’re going to be working towards another microgravity demo in summer 2010! This will probably be the capstone of my research. It’s certainly a great life achievement!

Apparently, it has been only two years since the Reduced Gravity Office at JSC has allowed anyone with diabetes onto the plane at all. I got all the clearances I needed and have been thrilled to be a part of such an experience. This might be the closest thing I get to going into space – but given what I’ve taken part in this summer (and will again next summer, if all goes according to plan), I don’t think I’ll rule that out. In a way, things have come full circle: the space program of the ’60s gave us the high-tolerance manufacturing capability and jump-started the microprocessor industry in such a way as to make, decades down the line, insulin pumps. My Animas pump, in turn, has given me the control over my diabetes I needed to pass NASA physical evaluations and get a flight spot on the Zero-G aircraft.

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