An astronomical unit: the average separation between the Earth and the sun. As a measure of length, the AU was destined for the obscurity of furlongs and cubits. The realization saddened Dana.
“Not habitable, then, without extensive terraforming,” she said.
“Quite right,” Marvin said. “Bringing us to the second planet, its orbit shown in blue, at about ninety-one percent of an AU. It has water oceans and an atmosphere with oxygen. This is the world we came for.”
Blake had shipboard diagnostics running on his console. He looked up from the scrolling text. “Earth-like, then?”
“So it seems,” Antonio said. “But water…oceans, Marvin? You’re sure? That far from the star, it seems like the water would be…frozen.”
“I am certain,” Marvin said. “Water vapor would not be this prevalent in the atmosphere without significant liquid water on the surface.”
“Can we have a look?” Blake asked.
A tiny disk appeared alongside the blue loop. The only features Dana could make out were white specks at opposite ends. Polar icecaps, she presumed.
“I cannot yet provide much detail,” Marvin said. It managed to sound apologetic. “When we get closer, we will see better.”
“It’s dim,” Antonio said. “Apart from the icecaps.”
Blake nodded. “I suspect that’s a good thing. That means it’s soaking up sunlight.”
Where was Rikki with some damn food? “Big picture, here,” Dana said. “Is this world habitable, or not?”
“Habitable, yes,” Marvin said. “It may not be hospitable.”
“What does that mean?” Rikki called.
She stood in the hatchway bearing a tray piled high with snacks. With a grin, Blake got up and began handing around plates and drink bulbs.
Marvin said, “It will be colder on average than on Earth. The air will be dryer than on Earth and thinner than at Earth’s sea level. Still, parts of this world will be friendlier to life than, say, Earth’s deserts and high plateaus.”
The Earth of some dusty database. Earth now was a charnel house gripped in an ice age.
Dana turned her attention to coffee. Habitable: that was damned good news.
“What else do we know about this world?” Rikki asked.
There was that circumlocution again.
Their new home needed a name, no matter how uninspired Dana found some of the suggestions. In hindsight, though, setting everyone to talking—arguing—about names hadn’t been her smartest decision.
She set down the coffee bulb. “Blake can catch you up later. Marvin, go on with the grand tour.”
“The next world, at a bit over two AU is…”
Green, yellow, orange, and red: all the outermost worlds were gas giants, the one nearest to the star Saturn-sized and the rest much smaller. Green and yellow showed prominent ring structures; orange and red offered hints of rings. Green and red, at least, had substantial moons. The outer planets ranged from about two AU to about thirteen AU from the star.
Her headache easing, Dana tried her sandwich. She chewed, oblivious to whatever was between the bread slices, reviewing. An almost sun-like star. Six worlds, one habitable.
She should be ecstatic. And yet—
“The separation between blue and green worlds looks wrong to me,” she said. “Too big a gap. Could there be a planet you haven’t spotted?”
“Possibly,” Marvin said. “Based on the other interplanetary gaps, theory suggests there should be a planet orbiting at about 1.3 AU. But if there were one, I should have spotted it.”
“An asteroid belt?” Rikki guessed. “Maybe that big gas giant prevented a planet from forming, just as Jupiter seems to have done back home.”
Marvin said, “If there are asteroids, I could not spot them from this distance.”
“Not just asteroids. 1.3 AU will be right by…the ice line. There might be very short-period…comets, too.”
Blake squinted at the graphic. “Comets or asteroids, they would be too damned close. Lots of rock and ice will orbit nearer to our new home than Earth does to Mars. I have to wonder, how often does our future home get slammed?”
“Is there a significant bombardment risk?” Dana asked Marvin.
“Insufficient information, Captain. Sorry.”
Rikki said, “Maybe the planet looks dark because of a recent impact. An asteroid strike would put dust and smoke in the atmosphere.”
“Same answer,” Marvin said. “I cannot know more until we get closer.”
Her head once more throbbing, Dana wondered if the human race had a cosmic bull’s-eye on its metaphorical back.
Not that they had a viable alternative to continuing on their course.
Dana said, “Let’s get closer and find out.”
20
Antonio took refuge on the bridge, relinquishing the copilot’s seat only for food, the toilet, and twice to splash water on his face. He needed order and routine, and as the ship swooped toward the new planetary system, the scurrying of his shipmates denied him both.
For once, he was not the only one obsessing. Everyone labored till they dropped. Not that there was a reason to rush about, or any suspected harm that might come of a few days’ delay before a closer look—
There was only the longing to declare their odyssey at an end.
Most intercom mikes were active across the ship, the better to coordinate, and some half-heard thud brought Antonio shuddering awake. He had no memory of having closed his eyes. Trying to orient himself, he heard grunts and terse directions as Blake and Rikki continued rearranging crates, still digging for a full set of parts for at least one short-range shuttle. He heard tuneless humming and staccato bursts of keystrokes as Carlos reconfigured some of their synth vats. He heard the squeaks and squeals of hinges unused for decades, the captain inspecting her ship. From the central corridor, not via the intercom, he heard a rustle of clothing: by process of elimination, Li. She moved about the ship more than anyone, ostensibly to lend a hand wherever she could be most useful, in practice lobbying for her scheme of planet names.
He was too clumsy to handle irreplaceable cargo, too impractical to touch the synthesis equipment or to program nanites.
That left studying the worlds toward which they hurtled. He had terabytes of data, and
