in the shaft." He looked at Norah. "You said the plankton species you saw in the extraction shaft was called-"
"G. polyhedra, Norah declared. "And now you're wondering if G. polyhedra is capable of hibernating inside the ice? You'll be pleased to know the answer is yes. Absolutely. G. polyhedra is found in droves around ice shelves, it bioluminesces, and it can hibernate inside the ice. Any other questions?"
Everyone exchanged looks. From Norah's tone, there was obviously some sort of "but"-and yet it seemed she had just confirmed Rachel's theory.
"So," Tolland ventured, "you're saying it's possible, right? This theory makes sense?"
"Sure," Norah said, "if you're totally retarded."
Rachel glared. "I beg your pardon?"
Norah Mangor locked stares with Rachel. "I imagine in your business, a little bit of knowledge is a dangerous thing? Well, trust me when I tell you that the same holds true for glaciology." Norah's eyes shifted now, looking at each of the four people around her. "Let me clarify this for everyone once and for all. The frozen brine pockets that Ms. Sexton has proposed do occur. They are what glaciologists call interstices. Interstices, however, form not as pockets of saltwater but rather as highly branched networks of brine ice whose tendrils are as wide as a human hair. That meteorite would have had to pass through one hell of a dense series of interstices to release enough saltwater to create a three percent mixture in a pool that deep."
Ekstrom scowled. "So is it possible or not?"
"Not on your life," Norah said flatly. "Totally impossible. I would have hit pockets of brine ice in my core samples."
"Core samples are drilled essentially in random spots, right?" Rachel asked. "Is there any chance the cores' placements, simply by bad luck, could have missed a pocket of sea ice?"
"I drilled directly down over the meteorite. Then I drilled multiple cores only a few yards on either side. You can't get any closer."
"Just asking."
"The point is moot," Norah said. "Brine interstices occur only in seasonal ice-ice that forms and melts every season. The Milne Ice Shelf is fast ice-ice that forms in the mountains and holds fast until it migrates to the calving zone and falls into the sea. As convenient as frozen plankton would be for explaining this mysterious little phenomenon, I can guarantee there are no hidden networks of frozen plankton in this glacier."
The group fell silent again.
Despite the stark rebuttal of the frozen plankton theory, Rachel's systematic analysis of the data refused to accept the rejection. Instinctively, Rachel knew that the presence of frozen plankton in the glacier beneath them was the simplest solution to the riddle. The Law of Parsimony, she thought. Her NRO instructors had driven it into her subconscious. When multiple explanations exist, the simplest is usually correct.
Norah Mangor obviously had a lot to lose if her ice-core data was wrong, and Rachel wondered if maybe Norah had seen the plankton, realized she'd made a mistake in claiming the glacier was solid, and was now simply trying to cover her tracks.
"All I know," Rachel said, "is that I just briefed the entire White House staff and told them this meteorite was discovered in a pristine matrix of ice and had been sealed there, untouched by outside influence since 1716, when it broke off of a famous meteorite called the Jungersol. This fact now appears to be in some question."
The NASA administrator was silent, his expression grave.
Tolland cleared his throat. "I have to agree with Rachel. There was saltwater and plankton in the pool. No matter what the explanation is, that shaft is obviously not a closed environment. We can't say it is."
Corky was looking uncomfortable. "Um, folks, not to sound like the astrophysicist here, but in my field when we make mistakes, we're usually off by billions of years. Is this little plankton/saltwater mix-up really all that important? I mean, the perfection of the ice surrounding the meteorite in no way affects the meteorite itself, right? We still have the fossils. Nobody is questioning their authenticity. If it turns out we've made a mistake with the ice-core data, nobody will really care. All they'll care about is that we found proof of life on another planet."
"I'm sorry, Dr. Marlinson," Rachel said, "as someone who analyzes data for a living, I have to disagree. Any tiny flaw in the data NASA presents tonight has the potential to cast doubt over the credibility of the entire discovery. Including the authenticity of the fossils."
Corky's jaw fell open. "What are you