Annie acknowledged him with a nod as he reached the foot of the platform, and then waved him over, continuing to inspect one of the shuttle fragments. A soldered clump of tubes and valves in a cracked, scorched housing, it was attached to a component that, though also burned and dented, nonetheless retained something of an identifiable bell shape. Nimec thought he could make an educated guess about what it was, but didn't, not aloud anyway, wanting to give them some more breathing room.

Finally Annie glanced up at him from her crouch.

"You're looking at what's left of a main engine," she said, confirming his hunch. "The shuttle has three of them below the vertical tail fin. It's no secret that the recorded dialogue between Orion's flight deck and ground control tells us a red warning light went on at T minus six seconds, and indicated Main Engine Number Three was overheating."

He nodded. "This it?"

She paused before answering, then said quietly, "SSME Three was essentially vaporized in the initial blast. SSME Two, which was situated right beside it at the aft end, is being partially reassembled from what little of it we've been able to recover. You're looking at SSME One. I'm not sure why, but it's been left relatively intact. The engines are in a triangular configuration, and this would have been at the apex, so maybe its position above the other two allowed it to escape the worst brunt of the explosions in some way. That'll be determined. What's important to me right now is that we have it to study."

"These mothers feed off a potent mixture of cryogenic liquid hydrogen and liquid oxygen," Jeremy said. He was bent over the opposite side of the engine bell. "Annie' ll correct me if I'm wrong, but I think the propellants in a shuttle engine generate 1.7 million newtons--that's equivalent to, what, about 375 thousand pounds of thrust at sea level. Makes it the most efficient dynamo of a power plant ever built. On the other hand, the ignition of hot hydrogen gas can be savage unless it's precisely regulated. Remember the Hindenberg."

"Which means exactly what regarding Orion?" Nimec asked.

"Getting back to the shuttle-to-ground communications record, it's apparent that a problem developed with the flow of liquid hydrogen fuel," Annie said, her face solemn. "Again, this is information that's been very widely circulated in the media, so I doubt I'm saying anything you don't already know. One of the last things Jim ... Colonel Rowland ... said to the controller was that LH2 pressure was dropping. Then he broke off for a second."

Nimec had listened attentively, but felt a little baffled. "If I'm following this at all, you're implying a reduction in liquid hydrogen pressure may have caused the increase in engine temperature that in turn sparked the fire. But I'd think it'd be the other way around--less fuel, less burn."