Virgin Galactic's aerial launcher, WhiteKnightTwo, with a passenger rocket launching from its the midsection. Scroll down for a video of the flight simulation.
Credit: Virgin Galactic
“Be careful what you wish for!” says Wilson da Silva, the Editor-in-Chief of Cosmos, Australia’s biggest-selling science magazine.
In October 2008, he joined other would-be astronauts as they were put through their paces in a massive centrifuge outside Philadelphia, formerly used by NASA's Apollo and Mercury mission astronauts.
His sub-orbital spaceflight is being funded by Dr Alan Finkel, chancellor of Monash University and the scientist and entrepreneur who co-founded Cosmos. As a kid, da Silva dreamed of going into space: then in 2004, Finkel bought a ticket for himself and decided it would be fun to take da Silva along for the ride.
Both ticket-holders for the world’s first sub-orbital tourist flights are getting ready for blast off by testing their grit in one of the world’s most advanced centrifuges, to see if they can withstand the high G forces they’ll experience.
The centrifuge, called the Space Training System 400 (STS-400), is part of the high-tech aviation and space training equipment at the National Aerospace Training and Research (NASTAR) Centre.
NASTAR has been training military pilots for 30 years, and now tourists too, as space travel companies, led by Virgin Galactic, have emerged over the past few years. The STS-400 is one of the few centrifuges in the world that can dynamically position its cabin at almost any angles as it spins up, so that passengers inside experience G forces (or gravitational forces) in multiple directions.
Feeling the big Gs
“It’s like being shot straight out of a cannon and then ricocheting upwards at massive speeds,” da Silva says. “The display inside the cabin looks real, your senses tell you it’s real, and there’s no way to really restrain your composure.
“While I knew I was inside a centrifuge, my brain and body were screaming – ‘You’re blasting off! You’re in space! You’re re-entering! Aaargh’,” he says of the two days of simulated space launches and re-entries he experienced. “It’s amazing how realistic it all felt.”
Sometime in 2009, da Silva, Finkel and their fellow passengers will be strapped into a rocket riding in the underbelly of Virgin Galactic’s SpaceShipTwo and be taken 17 km above the Earth's surface.
There, the rocket will be dropped, the motor will ignite and they’ll fly at three times the speed of sound straight up into the darkening black of space. They'll experience the same physiological impact as a professional astronaut.
Blast off is the most harrowing, and re-entry the most uncomfortable, da Silva says. Upon launch, passengers experience an immediate 3.5 Gs, while the re-entry packs a whopping 6 Gs - the equivalent of 3.5 and 6 times the individual’s body weight, respectively.
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What a ride! A four-minute clip of da Silva's flight simulation inside the spinning centrifuge (Courtesy of the NASTAR Centre).
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Both the flight and the centrifuge simulation create G forces in two directions: against the chest (Gx) and from the top of the head downwards (Gz). These significant pressures can make a passenger feel like they have up to six people piled on top of them – for an 80 kg person, that’s the equivalent of an orchestral grand piano.
Some fairground rides allow you to experience 3Gs for fraction of a second; a launch on Virgin Galactic’s spaceliner service requires you to grit your teeth for 15 long seconds and not pass out, vomit or do any of the other things known to afflict first-timers. Screaming, however, is often unplanned but sometimes mandatory.
Even with previous training to prepare you, the sensation can be shocking. Da Silva says he previously did a test flight in 2007 during a visit to SpaceShipTwo’s manufacturer, Scaled Composites in California's Mojave Desert, where an ex-fighter pilot took him up in regular plane and, from a high altitude, corkscrewed straight down at high speeds to simulate 3 Gs.
But, even the G forces from this wild ride were no match for the Gs in the STS-400, as you can see for yourself in a video of da Silva inside the centrifuge (above), undergoing a complete spaceflight simulation routine: blast-off, coast and re-entry.
Countering the force
Considering the other anxieties one might feel blasting off into space in a small carbon-composite rocket, the NASTAR training aims to introduce passengers to high G-force, teach them how to counteract its physiological effects, and increase their tolerance. This helps them prepare for possibly the strongest forces they’ll feel in their lives.
Da Silva trained under NASTAR’s Space Flight Training Program, specifically designed to simulate the flight pattern of Virgin Galactic’s SpaceShipTwo.
Space flight trainees spend the first part of the two-day course in academic instruction, where they are lectured on G forces and how they affect body, and shown techniques to counteract the forces and minimise their physiological effects.
The forces in the Gx and Gz directions affect the body differently. In the x direction, a large amount of pressure is put directly on the chest, which can make it difficult to breathe. The natural instinct here is to breathe fast to get more air into the lungs.
But, perhaps counter-intuitively, the best way to keep positive pressure in the lungs is to actually compress the lips - like a trumpeter - and breathe slowly through the mouth, a technique taught in NASTAR’s course.
Doing the “funky chicken”
While having trouble breathing may seem a little dicey, the Gz force is actually the more dangerous of the two: high forces pressing down from the top of the head can cause complications with the hydrostatic column, which sends oxygenated blood from the heart to the brain. In other words, the brain could be deprived of oxygen, which it can’t survive without for longer than five seconds.
NASTAR’s technique for countering this problem is to direct blood away from the arms and legs and towards the heart, to give it a better chance of reaching the brain. Passengers brace their arms and legs against hand and foot rails in the STS-400 cockpit, a technique called the Anti-G Straining Manoeuvre (AGSM), which helps prevent blood from travelling to these appendages and forces it up to the brain.
If the technique fails, the brain is starved for oxygen, which could result in G-induced loss of consciousness (GLOC), causing a dangerous black out for several seconds. During GLOC, the body goes completely limp, risking head or neck injuries because the passenger is unable to control their motions.
During GLOC recovery, the body flails in a chaotic fit that insiders call the ‘funky chicken’, as the neurons in the brain – replenished with extra oxygenated blood pumped harder from the heart – begin firing once again. This causes arms and legs to thrash uncontrollably. Victims of GLOC also typically experience severe disorientation and discomfort. Not a fun thing to happen when you’re on a trip to space.
Taking a spin
Next comes the fun part: six rides in the centrifuge. The first four flight simulations break the G forces up into their components, so that passengers can identify the physical sensation of the force in both the x and z directions. These first rides give the passengers 50 per cent and then 100 per cent of the Gx and Gz forces felt on a real flight.
During these flights, passengers are able to test out the techniques for counteracting Gx and Gz forces separately.
In the final two spins, the forces are combined just like in the real flight for a full simulation, and trainees try out combining the techniques from the program. The only difference between these simulations and the actual SpaceShipTwo flight is the weightlessness felt during the 15-minute sub-orbital stop above the Earth during the real flight, which is shortened to a mere few seconds at 0.4G in the centrifuge.
Lucky for da Silva, he passed the STS-400 training with flying colours, as well as his mandatory physical and heart stress tests, and is now officially approved to fly on SpaceShipTwo, which may happen as early as next year.
When he does, he and Finkel will likely be the first Australian tourists in space. And da Silva hopes to be the first science journalist, and the first magazine editor. And taking up a copy of Cosmos with him, will make it the first science magazine in space.
Will he be writing about it? “You’d better believe it,” he grins.
Brooke Borel is former Cosmos intern and now regular correspondent based in New York City, USA.
