They were so close now Emma could see the texture of the surface: shaped by bombardment, crater upon crater, plains cracked open and reassembled, all of it coated with glistening black dust like a burned-out bombing range. And now when the attitude thrusters pulsed they raised up dust that drifted off into space or fell back in silent, slow fans.

We are already touching Cruithne, she thought. Disturbing it.

She had no sense of coming in for a landing. The gravitational pull of the asteroid was much too weak for that. The asteroid wasn’t down but straight ahead of her, a curving wall, pockmarked, wrinkled. It was more like a docking, as if she were riding a small boat toward some immense, dusty, oceangoing liner.

Michael was staring at the asteroid, eyes wide, mouth hanging open. On impulse Emma took his hand and held it to her breast.

Cornelius said, “There go the penetrators.”

Emma saw the penetrators snake out from O’NeiWs hull. They were miniature spacecraft shaped like golf tees, three or four feet long, trailing steel hawsers. Each had an armored exterior and a body packed solid with sensors — computers, heating devices, thermometers, seismometers, comms equipment to transmit data along the hawsers to the O ‘Neill. She could see the pulse of the tiny rockets in the penetrators’ tails, a spray of exhaust crystals that receded from the asteroid in perfectly straight lines, shining in the sun.

The penetrators hit the asteroid surface at six hundred miles an hour, as hard as an antitank round, and disappeared in puffs of black regolith. Soon there were smoke rings, neatly circular, rising from the crater floor, with slack hawsers trailing back to the spacecraft. The penetrators, after suffering a deceleration of maybe ten thousand G, had come to rest six feet under Cruithne’s surface.

Designing a probe that could return precise science data and yet survive being driven at speed into a rock wall was quite a feat, a project on which Bootstrap had spent a lot of money. But right now science lay in the future. The penetrators’ main purpose was fixing the O’Neill to Cruithne’s surface, mooring the ship like a smack to a pier.

Now Emma heard a whirr of winches. Languid vibrations snaked along the cables, and she could see the surface inch closer. One penetrator came loose in a puff of dust; its cable went slack and coiled away, out of sight.

There was the softest of shudders, a brief blur of dust.

Then there was only silence and stillness — and a piece of Cruithne framed in the window.

Malenfant came clambering up the fireman’s pole, his face split by a grin. “The O ‘Neill has landed.” He hugged her; she could see Michael was grinning, responding to Malenfant’s vigor and happiness.

“Now,” Malenfant said. “Now we go to work.”

The chains of fireflies, as they hauled giant loads of regolith like so many metallic dung beetles, were comical and inspiring.

Emma was amazed how quickly the fireflies were able to work in the peculiar environment of Cruithne. Autonomously controlled, with surprising grace and skill, they levered their way across the surface with their tethers and pitons and claws. And the low gravity allowed them to shift large masses with ease.

It was just hours before Emma was able to crawl through a tight fabric tunnel from the O ‘Neill and into the new dome.

She stood up and looked around. She was standing on plastic sheeting that merged seamlessly with the walls. The whole thing was just a fabric bubble thirty feet wide at the base, like an all-in-one plastic tent. The roof above her, ten feet up at its tallest, was a pale translucent yellow, supported by air pressure. The fireflies had thrown a cable net over the roof and then shoveled regolith over that, to a depth of three feet, for radiation shielding. Equipment, transferred from O ‘Neill, was piled up in the center of the dome.

The lighting, from yellow tritium bulbs, was utilitarian and harsh. There was a smell of burning, like autumn ash: that was asteroid dust, she knew, leaked into their hab environment despite all their precautions, thin fine stuff that was slowly oxidizing, burning in the air.

She knelt down. Regolith was visible through the floor, blurred lumps of coal-black rock. The crater floor had been scraped smooth by the fireflies before the dome was erected; she could see grooves and ridges where ancient ground had been raked like a flower bed in a suburban garden. She pushed a finger into the sheeting. It was very tough stuff, tougher than it looked; she was only able to make a dent of an inch or so. And as she pushed she felt herself lifting off the floor in reaction; Cruithne’s feeble gravity stuck her only gently to the ground.

Michael had crawled after her. He seemed relieved to be out of the ship. He started running around the perimeter of the dome — or rather he tried to run; with every step he went sailing into the air, bounced off the curving roof, and came floating back down again for another pace. After a few paces he started getting the hang of it, and he picked up speed, pacing and pushing against the ceiling confidently.

The shelter was crude. But Emma felt her spirits lift. After ninety days it was a profound relief not to be confined to the cramped metal cans of the O ‘Neill, for a while at least.

It also didn’t smell as bad as the O ‘Neill had become.

That night they had a party in the hab dome, raiding their precious store of candy bars and washing them down with Cruithne water.

The next day the four of them prepared to explore Cruithne.

Huddled together, they stripped naked — after ninety days, all shyness was gone, though Emma did feel unaccountably cold — and, clumsy in the low gravity, they began to help each other don their skinsuits.

Malenfant kept up a running stream of instructions. “Make sure you get it smoothed out. If the pressure isn’t distributed right you’ll have blood pooling.”

Emma’s skinsuit was just a light spandex coverall, like a cyclist’s gear. The material was surprisingly open mesh; if she held up her hand and stretched out her fingers she actually could see her flesh through fine holes in the weave. The spandex, a pale orange that turned blue around any rips, was used to avoid the outgassing and brittleness suffered by rubber in a vacuum. The suit had a hood and gloves and booties, and the pieces fit together with plastic zippers at her neck, wrists, and up her belly to her neck. The only thing she wore inside the suit was a catheter that would lead to a urine collection bag.

The light, comfortable skinsuits had replaced the old pressure garments — giant, stiff, body-shaped inflatable balloons — worn by earlier generations of space travelers. But it was important to have the skinsuit fit properly; the pressurization had to be equal all over her skin.

But this was actually old technology. Burn victims had long needed elasticated dressings that would apply a steady pressure over an extended area of the skin so that scarring occurred in a way beneficent to the patient. It didn’t surprise her to learn that an offshoot of Bootstrap had bought up a medical supply company from Toledo that had specialized in such stuff for decades and was now making a profit by selling better burn dressings back to the hospitals.

Over the top of the skinsuit came more layers, loose fitting and light. First there was a thermal-protection garment, a lacing of water-bearing tubes running over her flesh to keep her temperature even, and then a loose outer coverall, a micrometeorite protection garment. This actually had her name stitched on the breast, NASA-style: STONEY. She put on her bubble helmet with its gold sun visor, and her backpack, a neat little battery-powered rucksack with pumps and fans that could cycle the air and water around her suit for as long as twelve hours.