Built by Lockheed, the Aurora looked like a flattened American football. It was 110 feet long, sixty feet wide, smoothly contoured with a crystalline patina of thermal tiles much like the space shuttle. The speed was primarily the result of an exotic new propulsion system known as a Pulse Detonation Wave Engine, which burned a clean, misted, liquid hydrogen and left a telltale pulse contrail in the sky. For this reason, it only flew at night.
Tonight, with the luxury of enormous speed, the Delta Force was taking the long way home, out across the open ocean. Even so, they were overtaking their quarry. At this rate, the Delta Force would be arriving on the eastern seaboard in under an hour, a good two hours before its prey. There had been discussion of tracking and shooting down the plane in question, but the controller rightly feared a radar capture of the incident or the burned wreckage might bring on a massive investigation. It was best to let the plane land as scheduled, the controller had decided. Once it became clear where their quarry intended to land, the Delta Force would move in.
Now, as Aurora streaked over the desolate Labrador Sea, Delta-One's CrypTalk indicated an incoming call. He answered.
"The situation has changed," the electronic voice informed them. "You have another mark before Rachel Sexton and the scientists land."
Another mark. Delta-One could feel it. Things were unraveling. The controller's ship had sprung another leak, and the controller needed them to patch it as fast as possible. The ship would not be leaking, Delta-One reminded himself, if we had hit our marks successfully on the Milne Ice Shelf. Delta-One knew damn well he was cleaning up his own mess.
"A fourth party has become involved," the controller said.
The controller paused a moment-and then gave them a name.
The three men exchanged startled looks. It was a name they knew well.
No wonder the controller sounded reluctant! Delta-One thought. For an operation conceived as a "zero-casualty" venture, the body count and target profile was climbing fast. He felt his sinews tighten as the controller prepared to inform them exactly how and where they would eliminate this new individual.
"The stakes have increased considerably," the controller said. "Listen closely. I will give you these instructions only once."
High above northern Maine, a G4 jet continued speeding toward Washington. Onboard, Michael Tolland and Corky Marlinson looked on as Rachel Sexton began to explain her theory for why there might be increased hydrogen ions in the fusion crust of the meteorite.
"NASA has a private test facility called Plum Brook Station," Rachel explained, hardly able to believe she was going to talk about this. Sharing classified information out of protocol was not something she had ever done, but considering the circumstances, Tolland and Corky had a right to know this. "Plum Brook is essentially a test chamber for NASA's most radical new engine systems. Two years ago I wrote a gist about a new design NASA was testing there-something called an expander cycle engine."
Corky eyed her suspiciously. "Expander cycle engines are still in the theoretical stage. On paper. Nobody's actually testing. That's decades away."
Rachel shook her head. "Sorry, Corky. NASA has prototypes. They're testing."
"What?" Corky looked skeptical. "ECE's run on liquid oxygen-hydrogen, which freezes in space, making the engine worthless to NASA. They said they were not even going to try to build an ECE until they overcame the freezing fuel problem."
"They overcame it. They got rid of the oxygen and turned the fuel into a 'slush-hydrogen' mixture, which is some kind of cryogenic fuel consisting of pure hydrogen in a semifrozen state. It's very powerful and very clean burning. It's also a contender for the propulsion system if NASA runs missions to Mars."
Corky looked amazed. "This can't be true."
"It better be true," Rachel said. "I wrote a brief about it for the President. My boss was up in arms because NASA wanted to publicly announce slush-hydrogen as a big success, and Pickering wanted the White House to force NASA to keep slush-hydrogen classified."
"Not important," Rachel said, having no intention of sharing more secrets than she had to. The truth was that Pickering's desire to classify slush-hydrogen's success was to fight a growing national security concern few knew existed-the alarming expansion of China's space technology. The Chinese were currently developing a deadly "for-hire" launch platform, which they intended to rent out to high bidders, most of whom would be U.S. enemies. The implications for U.S. security were devastating. Fortunately, the NRO knew China was pursuing a doomed propulsion-fuel model for their launch platform, and Pickering saw no reason to tip them off about NASA's more promising slush-hydrogen propellant.
"So," Tolland said, looking uneasy, "you're saying NASA has a clean-burning propulsion system that runs on pure hydrogen?"
Rachel nodded. "I don't have figures, but the exhaust temperatures of these engines are apparently several times hotter than anything ever before developed. They're requiring NASA to develop all kinds of new nozzle materials." She paused. "A large rock, placed behind one of these slush-hydrogen engines, would be scalded by a hydrogen-rich blast of exhaust fire coming out at an unprecedented temperature. You'd get quite a fusion crust."
"Come on now!" Corky said. "Are we back to the fake meteorite scenario?"
Tolland seemed suddenly intrigued. "Actually, that's quite an idea. The setup would be more or less like leaving a boulder on the launchpad under the space shuttle during liftoff."
"God save me," Corky muttered. "I'm airborne with idiots."
"Corky," Tolland said. "Hypothetically speaking, a rock placed in an exhaust field would exhibit similar burn features to one that fell through the atmosphere, wouldn't it? You'd have the same directional striations and backflow of the melting material."
Corky grunted. "I suppose."
"And Rachel's clean-burning hydrogen fuel would leave no chemical residue. Only hydrogen. Increased levels of hydrogen ions in the fusion pocking."
Corky rolled his eyes. "Look, if one of these ECE engines actually exists, and runs on slush-hydrogen, I suppose what you're talking about is possible. But it's extremely far-fetched."
"Why?" Tolland asked. "The process seems fairly simple."
Rachel nodded. "All you need is a 190-million-year-old fossilized rock. Blast it in a slush-hydrogen-engine exhaust fire, and bury it in the ice. Instant meteorite."
"To a tourist, maybe," Corky said, "but not to a NASA scientist! You still haven't explained the chondrules!"
Rachel tried to recall Corky's explanation of how chondrules formed. "You said chondrules are caused by rapid heating and cooling events in space, right?"
Corky sighed. "Chondrules form when a rock, chilled in space, suddenly becomes superheated to a partial-melt stage-somewhere near 1550 Celsius. Then the rock must cool again, extremely rapidly, hardening the liquid pockets into chondrules."
Tolland studied his friend. "And this process can't happen on earth?"
"Impossible," Corky said. "This planet does not have the temperature variance to cause that kind of rapid shift. You're talking here about nuclear heat and the absolute zero of space. Those extremes simply don't exist on earth."
Rachel considered it. "At least not naturally."