The Astronaut Question
How long will humans remain better than robots at exploration?
- By James R. Chiles
- Air & Space magazine, September 2012
(Page 3 of 4)
In true Right Stuff fashion, the crew rose to the emergency. With mere seconds before the spin would have made them black out, the astronauts fired the retro-rockets to stop the spin. According to mission rules, once the reaction control system had been used, an abort was required, so the pair headed back to Earth.
Story Musgrave, veteran of six shuttle missions and the only person to have flown in all five orbiters, dismisses the idea that manned spaceflight should be an independent venture. “A manned spacecraft isn’t autonomous,” he says. “Astronauts receive their orders from mission control. Pilots are part of a system, and the system can save your ass.” That system is not just hardware; it’s also rules, tests, training, and simulator runs. When things go wrong, astronauts benefit from the bigger system on Earth to help with analyzing and fixing the problem. In a manner of speaking, engineers go into space too: shoulder to shoulder with the astronauts, embodied in the machine they built.
There is a fourth “A”: Awareness, as in “situational awareness.” It’s almost a sixth sense, the ability to detect that something is out of whack before the alarms go off. A trained, aware astronaut can pick up on problems never anticipated on the ground. Rising out of some ancient instinct for survival, it draws on our vision, smell, hearing, and touch, as well as on our training.
“Computers are really good at making a lot of decisions quickly and dealing with anticipated events and acting precisely with those events,” says Ken Bowersox, former shuttle astronaut and now head of SpaceX’s Astronaut Safety and Mission Assurance Department. “Humans act less precisely. The certainty of an absolutely correct outcome can be lower than with computers. But because humans care about the outcome, they tend to make decisions optimized for survival.”
Bowersox recalls a pertinent situation on shuttle mission STS-61, the first time astronauts serviced the Hubble Space Telescope. As the airlock was depressurizing in preparation for a spacewalk, the crew noticed that the Hubble’s solar panels were shaking. “The standard rule is that if something unexpected just happened after you took an action and you’re not sure why, you undo what you just did,” says Bowersox. “So we shut the [depressurization] valve and the panel quit moving. We hadn’t anticipated this: It was a no-momentum, no-thrust valve, but it was discharging under a blanket and acted like a gas jet on the solar array. A computer wouldn’t have known the array was moving at all.” These kind of glitches, not registered by the computer at the scene, have wrecked or stunted robotic missions. One such mission was Japan’s Hayabusa: The mothership released its asteroid-hopping mini-lander at the wrong moment, and it drifted off into space.
“Humans, even without complete programming, can deal with the unexpected,” Bowersox says. “Humans are cheap and fast to program, handling things that suddenly come up, where there’s no software.”
The human ability to be situation-aware can grow into something even more remarkable if there’s a machine alongside that is able to sift mountains of data, picking out trends and anomalies and highlighting things that need human attention. Erik Bailey, a technology development task manager at the Jet Propulsion Laboratory in Pasadena, California, sees a role for machine-advised lunar landings. The goal is an astronaut-friendly, reliable, fast-acting set of remote-sensing aids to make lunar and planetary touchdowns safer. NASA has developed such a system, called Autonomous Landing and Hazard Avoidance Technology. The difference between ALHAT and the Instrument Landing System for airplane pilots is that ILS guides a pilot to the threshold of a well-known strip of paved land, marked with beacons. Not so with ALHAT, which has mere moments to scan a looming terrain that lacks any beacons but could be fraught with hazards. Using laser ranging and imaging, ALHAT will circle patches of moonscape that are level and free of boulders and craters; astronauts can select from these or decide to proceed on their own judgment. Finally, using a Doppler laser, ALHAT will help the craft land right side up and vertically, regardless of dust clouds.
“The point is to see a 30-centimeter hazard from one kilometer away [a one-foot hazard from 3,280 feet away],” says Bailey. “The purpose is to give humans the information and confidence to land safely. But it doesn’t take humans out of the loop…. The idea of ALHAT is to identify safe landing circles. Then the astronauts can choose among those, based on priorities like fuel use.”
Though the six Apollo lunar modules all landed safely without an ALHAT on board, the information provided to the astronauts about the landing sites had gaps in it, and poor visibility from rocket-raised dust made it tough to see obstacles and to stop dangerous drift to the side or rear. After the Apollo 15 landing, astronauts emerged to find that their lander straddled a crater rim. This canted the lander off horizontal and damaged the exhaust engine bell. Serious damage or a major lean would have left the pair stranded on the moon, without any hope of rescue.