beneath the tripod. Rachel had seen it earlier and assumed it was simply some sort of visual indicator-a pointer demarking the spot where the object was buried.
"That's a gallium arsenide semiconductor laser," Norah said.
Rachel looked more closely at the beam of light and now saw that it had actually melted a tiny hole in the ice and shone down into the depths.
"Very hot beam," Norah said. "We're heating the meteorite as we lift."
When Rachel grasped the simple brilliance of the woman's plan, she was impressed. Norah had simply aimed the laser beam downward, melting through the ice until the beam hit the meteorite. The stone, being too dense to be melted by a laser, began absorbing the laser's heat, eventually getting warm enough to melt the ice around it. As the NASA men hoisted the hot meteorite, the heated rock, combined with the upward pressure, melted the surrounding ice, clearing a pathway to raise it to the surface. The melt water accumulating over the meteorite simply seeped back down around the edges of the stone to refill the shaft.
Like a hot knife through a frozen stick of butter.
Norah motioned to the NASA men on the winches. "The generators can't handle this kind of strain, so I'm using manpower to lift."
"That's crap!" one of the workers interjected. "She's using manpower because she likes to see us sweat!"
"Relax," Norah fired back. "You girls have been bitching for two days that you're cold. I cured that. Now keep pulling."
The workers laughed.
"What are the pylons for?" Rachel asked, pointing to several orange highway cones positioned around the tower at what appeared to be random locations. Rachel had seen similar cones dispersed around the dome.
"Critical glaciology tool," Norah said. "We call them SHABAs. That's short for 'step here and break ankle.'" She picked up one of the pylons to reveal a circular bore hole that plunged like a bottomless well into the depths of the glacier. "Bad place to step." She replaced the pylon. "We drilled holes all over the glacier for a structural continuity check. As in normal archeology, the number of years an object has been buried is indicated by how deep beneath the surface it's found. The farther down one finds it, the longer it's been there. So when an object is discovered under the ice, we can date that object's arrival by how much ice has accumulated on top of it. To make sure our core dating measurements are accurate, we check multiple areas of the ice sheet to confirm that the area is one solid slab and hasn't been disrupted by earthquake, fissuring, avalanche, what have you."
"So how does this glacier look?"
"Flawless," Norah said. "A perfect, solid slab. No fault lines or glacial turnover. This meteorite is what we call a 'static fall.' It's been in the ice untouched and unaffected since it landed in 1716."
Rachel did a double take. "You know the exact year it fell?"
Norah looked surprised by the question. "Hell, yes. That's why they called me in. I read ice." She motioned to a nearby pile of cylindrical tubes of ice. Each looked like a translucent telephone pole and was marked with a bright orange tag. "Those ice cores are a frozen geologic record." She led Rachel over to the tubes. "If you look closely you can see individual layers in the ice."
Rachel crouched down and could indeed see that the tube was made up of what appeared to be strata of ice with subtle differences in luminosity and clarity. The layers varied between paper thin to about a quarter of an inch thick.
"Each winter brings a heavy snowfall to the ice shelf," Norah said, "and each spring brings a partial thaw. So we see a new compression layer every season. We simply start at the top-the most recent winter-and count backward."
"Like counting rings on a tree."
"It's not quite that simple, Ms. Sexton. Remember, we're measuring hundreds of feet of layerings. We need to read climatological markers to benchmark our work-precipitation records, airborne pollutants, that sort of thing."
Tolland and the others joined them now. Tolland smiled at Rachel. "She knows a lot about ice, doesn't she?"
Rachel felt oddly happy to see him. "Yeah, she's amazing."
"And for the record," Tolland nodded, "Dr. Mangor's 1716 date is right on. NASA came up with the exact same year of impact well before we even got here. Dr. Mangor drilled her own cores, ran her own tests, and confirmed NASA's work."
Rachel was impressed.
"And coincidentally," Norah said, "1716 is the exact year