Squyres and his colleagues clearly favored the hovering SEV approach, when the submersible was also outfitted with a short stinger equipped with a portable foot restraint.  A shuttle legacy tool, the foot restraint gives spacewalkers both mobility and stability at scientifically significant sites. “That has turned out to be a very effective technique,” Squyres says.

Throughout much of the analog, the astronauts coped with a 50-sec. time delay in their communications with their Mission Control team, even in their off-duty chats with friends and families — long enough to simulate a mission to an asteroid more than 9 million mi. from Earth.

When properly equipped, the undersea astronauts found few obstacles exploring the ocean floor without a constant dialogue with Mission Control, Squyres says.