What a week it has been! Today is the last of my six full days here at Pavilion Lake, and it feels like we’ve done a month’s worth of work. Days begin with breakfast at 7 am and a team meeting at 7:30, and conclude with science debriefs that often end at 10 or 11 pm. The pace is not quite as fast and relentless as a Shuttle flight…but it’s close. It’s one more way in which Pavilion Lake is a good analog for an actual space flight. (Differences include the excellent food and, on the rare occasions when time permits, being able to go fo a long jog with fresh air and lovely mountain scenery!)
With two more “flights” in the Deepworker submarine under my belt since last I wrote, I’ve gotten a lot more familiar with the machine. Although the miniature submarine looks nothing like a space suit, there are a lot of similarities. And someday, when humans visit near-Earth asteroids or other objects with very low surface gravity, I expect they’ll do their spacewalks in something that looks a lot more like a Deepworker than a traditional person-shaped space suit. Here’s why. A small asteroid has such weak gravity that even the slightest nudge with a hand or foot would send a spacewalking astronaut soaring high above the surface, and it might take hours to come back down. A stronger shove might send an astronaut away at a speed higher than the escape velocity, in which case gravity would not bring them back ever! Not so good. On the International Space Station, which of course has no noticeable gravity of its own, astronauts keep from floating away by holding on to special handrails. Asteroid do not come equipped with handrails. They do have rough surfaces which might provide hand- and foot-holds, but unfortunately most asteroids are not solid blocks of material. Instead they are “rubble piles,” flying clumps of sand, gravel, and boulders held together not by material strength, but by their own weak self-gravity. So if you were moving hand-over-hand across the surface of the asteroid and accidentally pushed yourself off on a suborbital trajectory, you could grab onto a rock to keep yourself down–and the rock would simply come away with you! The practical result is that hands and feet are probably not the best way to move around an asteroid. Better might be a suit with tiny thrusters that you could use to maneuver yourself around the landscape. But if you’re not using your hands and feet to move around like a person climbing a tree, there’s no need to enclose them in a flexible suit. Instead, you could keep them inside a hard pressure shell where they could be used to control thrusters, manipulators, and onboard systems. Such an arrangement might look a lot like a Deepworker. As a side benefit, the operator might be a bit more comfortable than in a traditional space suit.
Our underwater work here at Pavilion Lake ends this afternoon. I’ll be the pilot for one of the last two “flights.” The flight planner, Dr. “Mars” Marinova (who was just recently awarded her Ph.D. from the Geological and Planetary Sciences division at Caltech, where I worked as a postdoc more years ago than I care to admit), set up an especially interesting flight plan for me. I’ll visit one of the “deep mounds,” outcroppings of microbialites growing on isolated boulders on the otherwise rather flat and monotonous central floor of the lake. Then I’ll head off to do some vertical transects along the western shore. These transects begin in deep water, then move upslope through the depth zone where the microbialite population is richest. As I fly the transects I’ll record video of what I see from the submarine, and keep a running monologue (also recorded on board) of my observations. It should be a lot of fun…and I’m sure I’ll miss piloting the submarines when the field season ends.
This wraps up Dr. Love’s Underwater Blog. If I’m fortunate enough to be able to participate here next field season and spend more quality time underwater, I’ll be sure to reactivate the blog.