"Correct," Tolland said. "This species would have collapsed under its own weight if it walked around on earth."

Corky's brow furrowed with annoyance. "Well, Mike, unless some caveman was running an antigravity louse farm, I don't see how you could possibly conclude a two-foot-long bug is earthly in origin."

Tolland smiled inwardly to think Corky was missing such a simple point. "Actually, there is another possibility." He focused closely on his friend. "Corky, you're used to looking up. Look down. There's an abundant antigravity environment right here on earth. And it's been here since prehistoric times."

Corky stared. "What the hell are you talking about?"

Rachel also looked surprised.

Tolland pointed out the window at the moonlit sea glistening beneath the plane. "The ocean."

Rachel let out a low whistle. "Of course."

"Water is a low-gravity environment," Tolland explained. "Everything weighs less underwater. The ocean supports enormous fragile structures that could never exist on land-jellyfish, giant squid, ribbon eels."

Corky acquiesced, but only slightly. "Fine, but the prehistoric ocean never had giant bugs."

"Sure, it did. And it still does, in fact. People eat them everyday. They're a delicacy in most countries."

"Mike, who the hell eats giant sea bugs!"

"Anyone who eats lobsters, crabs, and shrimp."

Corky stared.

"Crustaceans are essentially giant sea bugs," Tolland explained. "They're a suborder of the phylum Arthropoda-lice, crabs, spiders, insects, grasshoppers, scorpions, lobsters-they're all related. They're all species with jointed appendages and external skeletons."

Corky suddenly looked ill.

"From a classification standpoint, they look a lot like bugs," Tolland explained. "Horseshoe crabs resemble giant trilobites. And the claws of a lobster resemble those of a large scorpion."

Corky turned green. "Okay, I've eaten my last lobster roll."

Rachel looked fascinated. "So arthropods on land stay small because the gravity selects naturally for smallness. But in the water, their bodies are buoyed up, so they can grow very large."

"Exactly," Tolland said. "An Alaskan king crab could be wrongly classified as a giant spider if we had limited fossil evidence."

Rachel's excitement seemed to fade now to concern. "Mike, again barring the issue of the meteorite's apparent authenticity, tell me this: Do you think the fossils we saw at Milne could possibly have come from the ocean? Earth's ocean?"

Tolland felt the directness of her gaze and sensed the true weight of her question. "Hypothetically, I would have to say yes. The ocean floor has sections that are 190 million years old. The same age as the fossils. And theoretically the oceans could have sustained life-forms that looked like this."

"Oh please!" Corky scoffed. "I can't believe what I'm hearing here. Barring the issue of the meteorite's authenticity? The meteorite is irrefutable. Even if earth has ocean floor the same age as that meteorite, we sure as hell don't have ocean floor that has fusion crust, anomalous nickel content, and chondrules. You're grasping at straws."

Tolland knew Corky was right, and yet imagining the fossils as sea creatures had robbed Tolland of some of his awe over them. They seemed somehow more familiar now.

"Mike," Rachel said, "why didn't any of the NASA scientists consider that these fossils might be ocean creatures? Even from an ocean on another planet?"

"Two reasons, really. Pelagic fossil samples-those from the ocean floor-tend to exhibit a plethora of intermingled species. Anything living in the millions of cubic feet of life above the ocean floor will eventually die and sink to the bottom. This means the ocean floor becomes a graveyard for species from every depth, pressure, and temperature environment. But the sample at Milne was clean-a single species. It looked more like something we might find in the desert. A brood of similar animals getting buried in a sandstorm, for example."

Rachel nodded. "And the second reason you guessed land rather than sea?"

Tolland shrugged. "Gut instinct. Scientists have always believed space, if it were populated, would be populated by insects. And from what we've observed of space, there's a lot more dirt and rock out there than water."

Rachel fell silent.

"Although...," Tolland added. Rachel had him thinking now. "I'll admit there are very deep parts of the ocean floor that oceanographers call dead zones. We don't really understand them, but they are areas in which the currents and food sources are such that almost nothing lives there. Just a few species of bottom-dwelling scavengers. So from that standpoint, I suppose a single-species fossil is not entirely out of the question."

"Hello?" Corky grumbled. "Remember the fusion crust? The mid-level nickel content? The chondrules? Why are we even talking about this?"

Tolland did not reply.

"This issue of the nickel content," Rachel said to Corky. "Explain this to me again. The nickel content in earth rocks is either very high or very low, but in meteorites the nickel content is within a specific midrange window?"

Corky bobbed his head. "Precisely."

"And so the nickel content in this sample falls precisely within the expected range of values."

"Very close, yes."

Rachel looked surprised. "Hold on. Close? What's that supposed to mean?"

Corky looked exasperated. "As I explained earlier, all meteorite mineralogies are different. As scientists find new meteorites, we constantly need to update our calculations as to what we consider an acceptable nickel content for meteorites."

Rachel looked stunned as she held up the sample. "So, this meteorite forced you to reevaluate what you consider acceptable nickel content in a meteorite? It fell outside the established midrange nickel window?"

"Only slightly," Corky fired back.

"Why didn't anyone mention this?"

"It's a nonissue. Astrophysics is a dynamic science which is constantly being updated."

"During an incredibly important analysis?"

"Look," Corky said with a huff, "I can assure you the nickel content in that sample is a helluva lot closer to other meteorites than it is to any earth rock."

Rachel turned to Tolland. "Did you know about this?"

Tolland gave a reluctant nod. It hadn't seemed a major issue at the time. "I was told this meteorite exhibited slightly higher nickel content than seen in other meteorites, but the NASA specialists seemed unconcerned."

"For good reason!" Corky interjected. "The mineralogical proof here is not that the nickel content is conclusively meteoritelike, but rather that it is conclusively non-earth-like."

Rachel shook her head. "Sorry, but in my business that's the kind of faulty logic that gets people killed. Saying a rock is non-earth-like doesn't prove it's a meteorite. It simply proves that it's not like anything we've ever seen on earth."

"What the hell's the difference!"

"Nothing," Rachel said. "If you've seen every rock on earth."

Corky fell silent a moment. "Okay," he finally said, "ignore the nickel content if it makes you nervous. We still have a flawless fusion crust and chondrules."

"Sure," Rachel said, sounding unimpressed. "Two out of three ain't bad."

83

The structure housing the NASA central headquarters was a mammoth glass rectangle located at 300 E Street in Washington, D.C. The building was spidered with over two hundred miles of data cabling and thousands of tons of computer processors. It was home to 1,134 civil servants who oversee NASA's $15 billion annual budget and the daily operations of the twelve NASA bases nationwide.