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Strapping On A Centrifuge: Suborbital Scientist Training

Keith Cowing
Wednesday, May 18, 2011

image Last week I had a rather remarkable experience: I flew into space in Pennsylvania. Well, almost.

I attended a three day Suborbital Scientist Training Program conducted by The NASTAR Center. The program includes altitude chamber exposure to hypoxia, training and multiple rides in a centrifuge including full-acceleration simulations of a ride aboard Virgin Galactic's SpaceShip Two, and classes on physiology, physics, and operations. This was not my first exposure to this class having covered the first one back in January 2010 (see "NASTAR's Inaugural Suborbital Scientist-Astronaut Training Course")

Excitement Junkie

Image: Getting ready for my first day of training

I have somewhat of a fondness for extreme and remote science and operations - and reporting such experiences - preferably live. Weightless parabolas in 2006 and 2007, three stints on Devon Island in 2002, 2003, and 2007 (total of 50 days), a month living at 17,500 feet at Everest Base Camp in 2009, and several forays to NASA Desert RATS in 2009 and 2010. Add in a number of 800-1,000 foot rock climbs, and some SCUBA and with some impending skydiving this summer, I thought I would have had the range of crazy things lightly covered - at least once. Then I rode in the NASTAR Centrifuge.

I have flown in a simulated shuttle mission (and crash landed one I was "piloting" killing some virtual alligators at Kennedy Space Center) in the Motion-based Shuttle Simulator at Johnson Space Center wherein the noise, shaking, orientation and overall simulation is great. But while that was certainly realistic from a look and feel point of view, I never fully got the impression that I as "going" somewhere. I later flew the VMS (Vertical Motion Simulator) at NASA Ames Research Center which is lower on the visual fidelity aspect but higher in the movement category (up, down, left, right). But aside from making two perfect landings, this time, it also left me lacking that "kick in the pants" experience that goes with rocketship rides.

Image: weightless with Matt Reyes on G-Force One

Flying two "weightless" parabolic flights certainly gave me small, tantalizing taste of "Zero G". But most of the time I had people's arms and butts slamming me in the face, thus detracting from any attempt to fully experience the weightless environment without interference. Then again, spacecraft are usually crowded. A funny coincidence - my "commander" on the motion-based simulator "mission" at JSC was astronaut Chris Ferguson. Several years later I was weightless on a ZeroG jet at the precise moment he was being launched into space aboard STS-115.

Analogs to Reality

To be certain, however realistic a centrifuge ride may be, it is not the real thing. You only get to do the real thing by actually doing it (rocketship riding) for real. And there are some aspects of riding a centrifuge that are rather different than the accelerations one gets when riding a rocket (but I'll get to that). Centrifuges are analogs - they replicate many (but not all) aspects of an extreme environment. They do not attempt to do everything - since they can't. But what they do replicate they replicate in a most convincing fashion. Add in good training and it is exceptional.

Image: Standing on the rim of Astronaut Canyon on Devon Island

NEEMO (NASA Extreme Environment Mission Operations) replicates many operational aspects of working in space - but you are underwater. Devon Island is a lot like Mars and is exceptionally remote - but you are still on Earth. Yet, if you focus on the similarities between an unusual environment off-Earth and a terrestrial analog (in this case the increased forces acting on your body during powered flight) you can gain useful knowledge from these analogs for extreme environments than can be applied to learning to actually function when you go see the real thing (space). So long as you pay attention to the similarities and the differences - and not be fooled by the wrong things - you can derive value and training from these analogs.

By the time I took my last two centrifuge rides at full acceleration at NASTAR, the experience was utterly convincing. I simply could not dissuade myself from the perception - conscious and subconscious - that I was sitting inside a rocketship shooting straight up into space on a fiery pillar of energy.

But before you ride in one of these things so as to gain the full benefit of the experience, you need some training. The NASTAR folks go through a lot of classroom material so that everyone has the same basic understanding of the forces that will be acting upon their bodies and how to endure or negate some of the less desirable effects. They then introduce you to the hardware in away that enhances familiarity and adaptation.


The "gravity" you feel in a centrifuge is not gravity at all but rather the tendency for things being spun (you) trying to travel in a straight line (due to inertia) while being moved and simultaneously constrained by something (the centrifuge gondola). This forces things (you) to take a circular (angular) path. You are pressed harder (and the centrifuge is pressed harder on you) the faster you are spun - and you feel yourself under greater physical stress. In many ways this mimics increased accelerations one experience on a large planet or in an accelerating spaceship. But only partially.

Image: The centrifuge gondola

When you are being spun inside a centrifuge you are exposed to a mix of accelerations that do not happen (to a great extent) in daily life. As such, you tend to avoid them when they do. Much of this would not really happen in rocket flights unless something goes wrong. However, when it comes to fighter jet training, these devices become much more useful in their ability to really spin you around in odd, unnatural ways.

Coriolis forces cause things that are being spun (inside a centrifuge for example) to move in a curving direction opposite to that with which they are being spun. If you move your head around the wrong way so as to place your vestibular system in a provocative orientation, you are eventually going to get sick because of the way that fluids and structures inside your vestibular system react. Your vestibular system simply is not designed to function normally in such conditions. As such, care is taken to minimize either though design or behavior one's exposure inside a centrifuge to the things that would make you sick. You are trained not to cross-couple these various forces and expose oneself to excessive Coriolis forces.

This centrifuge is rather large (by design) thus decreasing the perceived gravity gradient you feel across your body. The large design also allows it to move more slowly to achieve specified G loads, thus lessening the Coriolis forces you experience - to some extent. That said, the best thing you can do to minimize dizziness and motion sickness is not move your head while you are moving and let your eyes serve as your main inertial reference system. Like looking at the horizon on a boat when you start to feel queasy. The seat inside the gondola is also adjusted such that the forces are targeted at your vestibular system in a way that minimizes these troublesome forces. Go here for more detail on "artificial" gravity.

These caveats aside, if everything is adjusted right, and you get a certain level of training, you can negate the deleterious artifacts of being spun such that you can experience a rather amazingly realistic simulation of what it would be like to be traveling inside a rocketship accelerating in a more or less linear fashion.

Spinning Things

My interest in centrifuges and gravitational effects is long-standing - and dates back to the first time I saw "2001: A Space Odyssey" in 1968. (video of exercise in a large centrifuge) In grad school my research utilized a device called a "clinostat" to slowly rotate chicken eggs and thus create an ambiguous gravity vector (i.e. everywhere and no where is "up" or "down") and examine its effects on bone development in chicken embryos. I was writing a letter to a student with a chicken egg experiment aboard Space Shuttle Challenger when the accident happened. By some coincidence I now find myself on the Challenger Center board of directors.

When I worked for NASA I wrote papers about the use of centrifuges on the moon and in space, organized a workshop on the effects of gravity at the cellular level, and ran peer review panels for NASA's gravitational and space biology programs. Later, when I worked on the space station program, I ended up as the Payload Accommodations Manager for the 2.5 meter Centrifuge Facility (later cancelled). And ... the only part of the otherwise awful movie "Mission to Mars" that is accurate (in my opinion) is when the crew plays Van Halen's "Dance The Night Away" very loud while exercising in a centrifuge. I'd do that. Yea. (Here's the scene)

So I have been thinking about these spinning devices for a very long time.

The Rest of the Training

Image: The altitude chamber at NASTAR

In addition to the centrifuge training, we also received hours of familiarization on hardware, the associated physics and physiology of centrifugation and altered atmospheres, and the overall operations of vehicles that fly people at high speeds to far away places. We also had a session on how to work on experiments in a short 5 minute window of weightlessness. As a result, I am not certain that tourists and scientists will easily mix on these suborbital flights.

We also did an altitude chamber run. The intent of this exercise was to expose us to the symptoms of hypoxia so that we'd be able to recognize them and respond if they occurred during flight. We were all placed into the chamber, pre-breathed Oxygen to purge Nitrogen from our blood, and were then taken up to an altitude of 24,000 feet. While a few of the class were giggling, most everyone handled it well until it was time to put our masks back on and come back to sea level.

Image: Reaching Everest Base Camp again in an altitude chamber

I have to say that I did notice something familiar: the cold, thin, dry air inside the chamber reminded me of living for a month at Everest Base Camp. Looking at my climbing watch's altimeter tick past 5,360 meters was fun in a deja vu sort of way. To be honest, I only had a mild cognitive side effects. The test I was asked to take turned out fine with the exception of the circular maze I was supposed to run with a pencil. Somehow I cheated and found myself heading back to the beginning. But I did remember (and wrote down) my social security number - and I was able to Twitter.

This video shows SwRI scientist Con Tsang's 100% acceleration ride on a SpaceShip Two profile on 11 May 2011 as part of the NASTAR Center's suborbital scientist astronaut training program.

Strapping On The Centrifuge

The simulated cockpit inside the centrifuges' gondola is designed for one person. Based on Virgin Galactic's SpaceShip Two, it is equipped with an adjustable seat and sturdy foot rests, a five-point restraint harness, and a hemispherical curved screen that covers 180 degrees of view - very immersive. There is a deployable set of stairs you walk up to get into the gondola which is then retracted and closed to form the back end of the container within which you sit. I had been in this gondola for a few minutes the last time I visited NASTAR - but it was not closed - and I was not about to ride in it.

Once I was in my seat, strapped in, and comm checks were complete NASTAR's Tech wished me luck and closed the stairway, thus sealing me in. I have zero claustrophobia issues. But when that hatch slammed shut it became very clear that this was something I was going to experience all by myself and that I only had my own resources to draw upon in order to make it work. My anxiety level was rather low by now. Indeed, like the rest of my class, I was actually eager with anticipation. One's mindset is very important when doing stuff like this. If you are anxious then the stresses can interfere with your ability to make your body do what it needs to do. If you are looking forward to the ride, then you are extra keen to do the right things at the right time with the expectation that the end result will be gratifying - or at least that it won't suck too much.

Image: The cockpit

When I was asked if I was ready to go my response (without thought or hesitation) was always "Good to go". At first I did not stop to think why I said this - everyone said something different. Then it struck me. The process of getting into the cockpit, being strapped in and then closed off was eerily familiar. I now knew why: I was thinking of that scene in the film "Contact" when Jodie Foster is escorted into the alien device for her "ride", strapped in, and then sealed in - resulting with her being all alone inside a device that was going to shortly apply a lot of energy to the exact position she was sitting in. When asked if she was ready she proclaimed "OK to go." So I guess I was channeling Jodie Foster. ("OK to go"/wormhole segment)

This video is from a 11 May 2011 centrifuge run at the NASTAR center with SwRI scientist Cathy Olkin in the cockpit. The view simulates what one would see on a suborbital flight profile aboard Virgin Galactic's SpaceShip Two.

On 11 May 2011 I took three simulated Virgin Galactic SpaceShip Two rides in the NASTAR Center centrifuge. This video contains the first two rides. The first ride is at 50% acceleration, the second is at full, 100% acceleration. The portions of the video while I was under acceleration contain audio only since the helmet camera he was using to record these rides was stowed inside my flight suit. During the Zero G portion of the simulated ride I took the camera out to provide a view inside the cockpit.

Getting Used To Spinning

The centrifuge regimen starts with acclimatization rides that focus on different aspects of the final experience. Later, everything is integrated together. My first flight was at +2.0 Gz i.e. with the prime forces acting from my head down to my feet - thus creating a tendency for blood to drain from my head. You are taught to tense leg muscles and push or grunt and resist the flow of blood to your feet so as to counter most if not all of that tendency. The second run was at +3.5 Gz. This is where I first experienced the beginnings of loss of peripheral vision. I did what I was trained to do which halted, and then reversed, these symptoms quickly.

The next flight exposed me to +3.0 Gx i.e. forces going straight through my chest toward my back. Since your body is much thinner in this profile than it is from head to foot, the gradient across your body is smaller and you can take much more of a G load without fluids and things not being where they needed to be. Here, however, the issue is the mechanics of breathing. Curiously, when I first started to do the breathing exercises to counteract the compression I'd experience, I was reminded of my trek to Everest Base Camp and how I had to purse my lips as I exhaled so as to increase the pressure in my lungs and force more Oxygen into my lungs. This became increasingly important on the next run which was +6.0 Gz. This is where the proverbial "elephant standing on one's chest" experience kicks in. But if you get the breathing right it is possible to endure quite a lot of Gs pushing down on your chest. Indeed, if you are positioned just right you almost start to feel at one with the centrifuge - or your rocketship - take your pick.

Integrating Everything

The next day was the real thing, so to speak. Our first flight was a 50% acceleration exposure to a trajectory taken directly from data derived from an actual SpaceShip One flight. It requires some effort, but you reach "space" none the worse for wear. When you do you see the cockpit in full animation for the first time, it is very cool - thus adding to the creative and mechanical illusion used to simulate suborbital spaceflight. The hemispherical screen in the cockpit now showed a forward looking view with the Earth moving into view. Given the intense physical stress it took to get to see this view, my brain was primed for the suggestion that this was for real. Add in the fact that the sudden lack of extreme G loading made me feel weightless and, well, the illusion was rather realistic.

Everything is computer generated and suffers a little bit from not being utterly photorealistic. But, having seen "2001" at such a young age, this experience was, as I said to my classmates in the observation lounge, "like actually being in the film 2001". But for me, a 55 year old Apollo baby, this left me with an interesting impression. All I would have needed was to hear the "Blue Danube" and the experience would have been complete (video of 2001's Earth orbit docking ballet)

Once I was in simulated space, the media/reporter in me came through and I pulled out a portable "helmet cam" and started to give my live viewers a tour of my simulated spacecraft. Of course, I was channeling Jodie Foster from "Contact" again - minus the headset. I was also building up on the trail blazed by my friend Dan Durda who hammed it up (video) during the first NASTAR class in January 2010.

The ride home was more forceful, but not that hard to take. Some additional loading happens when you reach lower altitudes and slow down, but it is rather pedestrian. But the real trip had yet to begin.

Full Throttle

Then came the full monty, a 100% acceleration profile. When you see the centrifuge start up for these runs from the observation lounge, it is startling to see how fast the gondola goes from slow movement in the 11:00 position to full speed at the 6:00 position - it is almost instantaneous - all while the gondola pivots. You then start to imagine what it is like to be inside of such a spinning device.

Image: Taking the full G load (larger view)

The flight profile at 100% acceleration is as follows: you start by pulling +3.5 Gz, then slack off a bit and then get hit with +3.5 Gx which abruptly stops when the engine stops firing. You then spin slowly (to simulate the coast phase to your high point in "space" and then re-enter. Re-entry is just over +6 Gx which drops off fast to be followed by a short jolt of around +2 Gx and then you are home.

Your state of mind is important - probably the most important thing. Our class synched instantly and we all had fun and encouraged one another and provided hints as we each took our turn. This resulted in a fast melting away of anxiety such that when the time came we all met the course requirements. Due to our smaller class size we were able to take two 100% full profile rides. Only one person declined.

When you first ride a SpaceShip Two profile you feel the jolt as the White Knight carrier aircraft drops you. You pitch forward a bit and then the rocket lights. Bang, you are accelerating and you fell like you are turning to your right. The force continues to build. By now you quickly integrate the Gz and Gx countermeasures and learn how to keep blood from draining out of your head and breath properly.

I first noticed a slight loss of peripheral vision after a few seconds. By pushing my feet and legs down hard and squeezing hard I halted that process and reversed it. Once I got into the groove the forces were smoothly flowing through me. There was absolutely no doubt in my mind that I was on a rocketship punching a flaming hole straight up through the sky.

Image: Gazing at the simulated Earth below

Then it stopped. The sudden loss of acceleration was much more pronounced this time and you really do feel lighter. Not weightless, but close enough to not let the simulation stall. My response was slightly awed: "so this is what it is like" I said. I pulled out my small webcam again and started to record my environs while being chatty to my live audience. I felt as if I had worked hard to get here and that this was a special moment to savor - even though I was in a spinning metal machine in Pennsylvania.

All too soon it was time to re-enter. Now the Gx loads kick in - up to 6Gs. By now I really started to integrate these various tricks and it was much easier to take.

As I mentioned before, my class had some extra time so we all had a shot at a second flight at 100%. I couldn't wait to try it again. This time I felt totally at ease, knew when to push my legs so as to preemptively thwart any hint of peripheral vision loss, and breathed very smooth. I could talk easily while under full G loads. After this one last visit it was time to come home. Of course, I had to Twitter one last time. On my way down, under 6Gs, I managed to sign "WOW" in American Sign Language before my arms were pulled back to the arm rests as if they suddenly had magnets in them.

And then I was back on Earth - in Pennsylvania.

This archived webcast is from a Suborbital Scientist Astronaut Training Class on 11 May 2011 at the NASTAR Center. My three centrifuge runs flying a Virgin Galactic SpaceShip Two flight profile (one at 50% acceleration and two at 100% acceleration) starts at 51:50.

Walking Away

When you exit the centrifuge you suddenly encounter a radically different regime i.e. the world you live in. When I exited after my +Gz runs, I tended to walk in a curved path to one side (my left). When I exited after my +Gx runs, I felt like someone was pushing down on me. After the full acceleration runs with both +Gx and +Gz forces, I felt like I was a pogo stick with each step - but I walked straight. I guess what I was feeling was some sort of resultant after effect of both +Gx and +Gz exposures combined. I learned later that not everyone had the same experiences inside the centrifuge and outside. Some people felt loads in their neck. Others (me) felt them in my sternum. Some walked one way, others walked another way. Some were a little dizzy, others were not.

Later, on the drive home from Pennsylvania to Virginia, I have to admit that I had a lot of fun passing people on the freeway. The sudden accelerative kick, albeit far more gentle, was a very pleasant reminder of my experiences barely 2 hours before. Friends of mine who have flown jets and spacecraft for real soon started teasing me about the "need for speed". Busted.

Image: Prebreathing Oxygen

At some point prior to our arrival someone in our class (Con Tsang from SwRI) started making "Top Gun" jokes. Well, that caught on and we were soon spouting lines from the movie. And course I played the theme from "Top Gun" ("Danger Zone" by Kenny Loggins) on my iPod as I drove home. By a strange coincidence, someone in the Twitterverse had previously decided that Friday of that week, 13 May, was TopGunQuote day. The next day a local TV station showing the movie back to back. I smelled synchronicity.

Everything I derive from these wild experiences seems to have inherent ironies and resonances - and synchroncities - for me. I guess I am always seeking them out. When the movie "Top Gun" first came out I was in grad school and had to make regular runs to a hatchery to get chicken eggs for my research. One day, as I drove back from the hatchery down a winding New England road, "Danger Zone" came on the radio. Well, I felt "the need for speed" and sped up only to quickly slow because of the dozens of eggs I had in my car - eggs I did not want to jostle any more than I had to.

Back then I was focused on spinning eggs. Thirty years later I was the one being spun - all while in the Danger Zone.

Ok, well I thought it was ironic.

About This Course

This NASTAR Suborbital Scientist Training Program class I attended was the fourth such class held by NASTAR since the program debuted in January 2010. To date, 42 researchers from 18 different universities and organizations have completed the training. And demand is growing even though flights have not even begun. NASTAR is fully booked for an upcoming class on 11-13 July and a custom version of the class has been booked for a university on 18-20 July. To meet growing demand additional courses are being offered later in 2001 on 12-14 September and 14-16 November. Check here for more information.

Related links

Video: Dan Durda Takes A Simulated Ride on SpaceShipTwo in NASTAR's Centrifuge

Video: Internal camera: Dan Durda Takes A Simulated Ride on SpaceShipTwo in NASTAR's Centrifuge

Video: Alan Stern Takes Two Simulated Rides on SpaceShipTwo in NASTAR's Centrifuge - Flight 1

Video: Alan Stern Takes Two Simulated Rides on SpaceShipTwo in NASTAR's Centrifuge - Flight 2

Commercial Space Transportation Safety Approval Performance Criteria: NASTAR

NASTAR's Inaugural Suborbital Scientist-Astronaut Training Course

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