Screwing the air valve to on in his helmet, he opened the door and stepped out on to the soft, grey surface. Here, he decided, was as good a spot as any to start.

The diamond-tipped drill began to descend from the side of the Vehicle. Its tip sparkled minutely as it began to spin on the flat floor of the arena, and there it stayed, spinning regularly, without making an impression on the surface.

Phillip banged the controls. He thought the mechanism must be jammed. He blamed the hydraulics. He accused the drill of bluntness. Angrily, he got back into the cab and backed his Vehicle over to some lunar soil to test it on something else. The mechanism wasn't jammed. It cut beautifully into a lump of meteorite.

Trying to surpress his emotions, he drove back to the flat area and tried the drill again. Same result as before. It made a tiny circle in the flat material and spun aimlessly. It would take hours, and several drills to get any further.

"Acid," thought Phillip, pressing some buttons. The onboard computer guided a small nozzle, equipped at the end with a number of small pads, down to the surface. One by one, the acids were released, and the gases drawn off were immediately analyzed. Methodically, the computer went through its program, and sent the results to the screen.

All acids checked in as nonfunctional against the material tested.

"Acid-resistant?" said Phillip to himself, then he checked himself. "Nonreactive? That can't be!"

He got down on his knees and peered closely at the place where the acids had been tipped. There was no sign of corrosion.

He began to shake slightly as the first of the three big machines lumbered into view. John called across with his radio.

"How'd the stuff check out?" he asked.

"Not too good," said Phillip, "We're in for a tough job I'd say."

"What do you mean?"

"Can't make much of an impression on it. Too hard. Similar to diamond in structure I think Acid can't get at it either."