BOUNDARY(40)

It was later than he'd thought. There was hardly anyone left around, except Bernie Hsiung over at the Nike construction section, overseeing some of the remote construction work in orbit. NASA had been assembling the material for Nike slowly but surely over the past year, and the work would continue for some time. Like him, Bernie often spent much of his time just keeping an eye on otherwise automatic processes, but it was still necessary to have someone around who had the capability to respond in an emergency.



"Let's see what we got. Hmm . . . the internals are still weird, I'm going to have to let the experts argue over this stuff. Water emissions as plotted over time . . . heating patterns correlations . . . There's water in there, no doubt, and possibly quite a bit of it. That'll make it a lot more attractive as a base. Transporting water is such a pain. Emissions and internal mapping plus heat signatures . . . Ah-ha! Two possible emission sources. Ariel, my sprite, come to me! Time for you to earn your living."



As Ariel was already closer to Phobos, A.J. would use her as his "point man." Ariel would examine the surface up close near the areas where water vapor was apparently escaping. If he got lucky, there would be a crack or cave in the area.





After another hour and a half, with Ariel now conducting its survey of the Phobian surface, A.J. headed off for a bathroom break. He stopped off for a candy bar and soda and then headed back. By then, Ariel's transmitters were showing the gray, soft-edged surface covered with fluffy regolith—powdered stone the consistency of flour—up close as it drifted along with a carefully defined path of examination.



The first emission site was a bust. There were some cracks, which clearly were the source of some of the outgassing. But they wouldn't have admitted a mouse, let alone a sensor drone the size of a large breadbox. Ariel continued along her way, approaching the locale of the second outgassing.



As it cleared a small crater ridge, A.J. couldn't quite restrain a triumphal "Yes!"



Even to eyes still accustoming themselves to the sharp-edged perceptions needed in the airless setting, there was a clearly darker streak that couldn't be anything other than a crack in the surface of Phobos. It seemed to be a crack yawning wide about two meters above the surface in one of the many little cliff ridges that meandered across the moon's surface.



"That's why it's not buried in regolith," A.J. muttered to himself. "Horizontal entryway instead of vertical. Hope that doesn't mean it's to some shallow deposit in the cliff."



As Ariel approached the crack, the automated sensor platform slowed according to prior instructions and directed illuminators into the chasm. It was wider than Ariel by a good half meter in any dimension. Ariel hovered, waiting for instructions. It wasn't permitted to proceed into the interior unless A.J. directly ordered it to.



There was considerable risk here, of course. The width of the crack was sufficient, but there was no way of knowing how far that ran, and even so the margin of safety was very thin. Piloting would be purely in the hands of the automatics, as there was no way A.J. could react in time to change anything that happened. And an accident could easily destroy Ariel.



On the other hand, looking at Ariel's sensor data, there was clearly water outgassing from below. Ice had to be present, possibly in significant quantities. And all of his other Faeries were running perfectly. Speaking cold-bloodedly, he could afford to lose one of them.



The call was entirely A.J.'s to make, since this was his project and no one else could make the judgments necessary. That fact didn't make it all that much easier. In some ways it made it harder, because if something went wrong he could hardly shove the blame away to someone else. But the way A.J. looked at it, finding out as much as possible about Phobos was his mission. He didn't see any reasonable alternative.



He went through the back and forth of order and confirmation once more. This time, once the acknowledgement came through, he stayed glued to his screen. It was true that he couldn't really do anything for Ariel if something went wrong, or at least not immediately, but he still wanted to know right away if something damaged her.



Slowly, turning on both ion and low-powered chem thrusters, Ariel drifted into the darkness, illuminating it with LED strobes timed with her frame captures to minimize power drain. Tinkerbell positioned itself above the chasm as a telemetry relay, since the farther into rock the drone descended the less signal would penetrate.



Twenty-two meters in, the dark lateral chasm intersected with another going almost straight downward. A.J., enhancing the view ahead slightly, could see that the lateral one narrowed and eventually ended a few dozen meters farther in.