A few years ago, back when the Constellation Program was still alive, NASA engineers discovered that the Ares I rocket had a crucial flaw, one that could have jeopardised the entire project. They panicked. They plotted. They steeled themselves for the hundreds of millions of dollars it was going to take to make things right.
And then they found out how to fix it for the cost of a happy meal.
The problem facing Ares 1 wasn’t a booster malfunction or a computer glitch — it was simple cause-and-effect physics. During the final stages of a launch, as the solid booster rocket burns down it makes the entire vehicle oscillate rapidly. Add that oscillation to the resonant frequency of the large tube that separates the booster and the crew cabin, and you get a crew capsule that vibrates like crazy. When humans are vibrating to that extent, it’s impossible for them to read a digital display. If the astronauts can’t read, they can’t do their jobs. If they can’t do their jobs, no more mission.
To evaluate the extent of the problem, NASA called in its Human Factors Division. They’re the ones who study human perception and performance, from very basic research to very applied research. In fact, they were the ones who had done the most recent round of vibration tests: 50 years ago, for the Gemini project, back when displays were analogue, steam-actuated dials instead of the computer screens of today. Cockpits, like everything else, have changed a lot since those days. It was time for some new tests.
Step one was to set up a chair so it would vibrate purely in an up-down motion (or in-out, if you’re lying on your back like an astronaut would be), which is how the launch vehicle was predicted to shake. The vibrational frequency of the rocket would be 12Hz (on average, but it would fluctuate between 10Hz and 13Hz) so they needed something that could hit that range exactly. Luckily, that technology already existed; the same mechanism that causes your chair to shake in simulation rides at amusement park made for a perfect prototype.
The engineers also knew that as Ares I gained speed the shake would increase. They calculated that toward the final stage, when astronauts would be already subjected to 4 G’s of acceleration, they would be getting an additional 0.7 G’s of vibration. As NASA slowly ramped up testing in the chair, they discovered that at 0.7 G’s even the largest numbers on the digitized display were almost entirely illegible.
Houston, we have a major effing problem.
Plans were drawn up to reduce the vibrations. Spring and counter-firing motors. Hundreds of millions of dollars to implement. Added years of development and implementation. A nearly insurmountable setback.
And then the people in the Vibration Lab had a really, really good idea: By simply strobing the display in time with the vibration, they could kill this problem altogether. They bought a handful of circuits that only cost a few bucks, hooked them up to the screen, and set it to strobe at 12Hz. And it worked!
Well, almost.
The readability was vastly improved, but it wasn’t perfect. The chair was vibrating at 12Hz and the screen was strobing at 12Hz, but they weren’t perfectly in sync. The text was more visible, sure, but it looked like it was swimming around. NASA could do better. So they grabbed a few accelerometers and attached them to the chair. With the vibration and the strobing now perfectly in sync, the display became crystal clear. Victory.
If it sounds too simple to actually work, believe me, I felt the same way until I saw it with my own eyes during a recent visit to NASA Ames. My guides were only willing to take me up to 0.5 G’s, but even at that rate the smallest column of numbers was completely illegible. As soon as they flipped on strobing? I could see it perfectly. The effect was stunning. We did our best to show the before/after by putting our camera on the sled, but the image-stabilization was just too damn good (well played, Sony. Well played). You’ll have to take my word for it.
Because it was also important to know if the system worked while vibrating and feeling the real, face-melting G-forces that astronauts experience, NASA’s big brains have incorporated a similar strobing rig into the iconic G-force simulation centrifuge. They wouldn’t let me anywhere near that thing without all kinds of medical evaluations. Begging, bribery and tearful theatrics proved ineffective. Maybe someday.
NASA has a patent pending on the technology, although the problems it solves are decidedly not NASA-specific; helicopters, planes and fast-moving boats have similar vibrational issues, so it’s very possible we’ll see this implemented elsewhere. I just want to sync my TV up to a shiatsu massage chair. Nobody blurs my Beyonce.
So while the the Ares I rocket has been grounded, there’s no question this research will live on and be implemented in NASA’s next launch vehicle. It’s nice to know that the next generation of astronauts will be able to see what they’re doing, and that it didn’t cost the tax-payers hundreds of millions of dollars. Good deal.
Space Camp is all about the under-explored side of NASA. From robotics to medicine to deep-space telescopes to art. For these couple of weeks we’ll be coming at you direct from NASA JPL and NASA Ames, shedding a light on this amazing world. You can follow the whole series here.
Video shot by Bill Bowles, edited by Woody Jang.
Special thanks to Mark Rober, Jessica Culler, Dan Goods, Val Bunnell and everybody at NASA JPL and NASA Ames for making this happen. The list of thank yous would take up pages, but for giving us access, and for being so generous with their time, we are extremely grateful to everyone there.