Resurgence

Nothing in the universe was so cold, nothing in the universe could be so cold. Radiation falling onto a planet’s surface must warm it, raising it at the very least to the 2.7 kelvins of the cosmic microwave background.

“So it doesn’t exist,” Rebka said. “But there it is.”

“Will we be going down?” Ben Blesh was crowding Darya, pushing her aside in his eagerness to see everything.

“Eventually.” Rebka was in the command pilot’s seat. “Before that happens I’d like to learn as much as we can from orbit. It may take a day or two, but I want to fly over every square kilometer and tickle the ground with something a bit more active.”

The Savior was moving along a spiraling orbit that would in time cover Iceworld’s whole surface like wool being wound evenly onto a great ball. The ship was less than two hundred kilometers above the surface. Such a close orbit would normally decay rapidly because of air drag, but Iceworld lacked the faintest trace of an atmosphere. The planet also seemed perfectly spherical. The gravity field supported the idea of an equally symmetrical interior, and nothing perturbed the Savior’s flight. Only Rebka’s natural caution prevented them from flying lower yet, fifty kilometers or five kilometers up.

“What do you mean, tickle?” Darya asked. “Don’t damage anything down there, Hans. I want to see the place in its unspoiled condition.”

“It’s a big planet, Darya. Twenty times the surface area of Miranda. And we’ll only be using the laser in a pulse mode, one burst every five seconds. Don’t worry. We’ll get enough burn to give us an emission spectrum for the points of impact, but we’ll be touching less than a billionth of the total area.”

“We’ve never experienced anything so cold before. Can you be sure you won’t ruin anything?”

“Not completely sure. But if it’s a choice of risking a little local damage down there, versus risking our skins when we descend, which do you prefer? Hmm.” Rebka was peering at a screen that displayed a graph composed of sharp peaks and valleys. “Darya, this is the return spectrum—it looks the same for every laser pulse. But it seems your name for the planet wasn’t the greatest choice.”

“Iceworld?”

“Right. This is a spectrum of the raw return signal, and over there we have the results after the spectrum analyzer has done its work. It’s reporting not a trace of ice—any kind of ice. No water, no carbon dioxide, no methane, no oxygen, no nitrogen, no chlorine, no fluorine.”

“No condensed gases of any kind?”

“Worse than that. The spectrum doesn’t match any material in our spectral signature library, solid, liquid, or gas. You were right, Darya, this place wasn’t formed naturally. It’s not made of any known material.”

“Are you sure that our laser isn’t disturbing things below the surface?” Lara Quistner was watching another display, this one showing a larger area than the immediate vicinity of the illuminated spot.

“As I said, not so we should notice.” Hans Rebka checked a dial. “We’re at low power and long wavelength. The top tenth of a millimeter of the ground should account for all the return.”

“Maybe it does—or maybe low power means something different down there. Do you want to see what I think I’m seeing? Zoom in on a line that trails behind the laser beam, and wait.”

It took a while, because as long as the moving light of the laser was in the field of view it dominated what the eye could detect. Even when the image moved far enough to put the pulse out of sight, Darya was at first convinced that Lara was imagining things. At last she saw it, so faint that it was at the very limit of visibility. A blue glimmer like a dust devil spurted up at the place where the laser beam had hit. It seemed to boil out of the surface for a moment, then was gone.

Lara whispered, “They come about twenty seconds after the laser has moved on. What are they?”

“No idea.” Rebka was changing control settings. “Let’s try some signal enhancement, see if we can get a spectrum we recognize.”

Before he could finish, a flash of orange startled their eyes. It was bright enough to obliterate all signs of the blue dust devils, then at once it too had vanished. Darya was left with a zigzag afterimage like a bolt of lightning. She blinked, waiting for her retinas to adjust after the overload.

Rebka said suddenly, “Hey. We got one.”

“One what?”

“A spectrum from that flash, one that the analyzer can recognize. We’ll finally understand what part of the surface is made of. Uh-oh. Take that back. We won’t understand.”

Ben Blesh protested, “But you just said—”

“I know what I said.” Rebka leaned back in his chair. “I can’t imagine how you knew, Darya, but you were right. What’s down there isn’t just something made by a random alien technology of the Sag Arm. It’s an artifact—made by the Builders.”

“How can you be so sure, from only one reading?”