viewpoint swivelled up and down, and some augmentation routine in the virtual generators was tickling her hind brain, making her feel as if she was riding right along with the robot over this choppy, rocky sea. With a sub-vocalized command, she told the software to cut it out; some special effects she could live without.
Xenia whispered to her audience of VIPs. ‘As we move we’re being extremely cautious. The surface gravity is even weaker than you might expect for a body this size. Remember this “dumbbell asteroid” is a contact binary, a compound body; imagine two pool balls snuggled up against each other, spinning around their point of contact. We’re a fly crawling over the far side of one of those pool balls. The dumbbell is spinning pretty rapidly, and here, at the pole, centrifugal force almost cancels out the gravity. But we modelled all these situations; Bruno knows what he’s doing. Just sit tight and enjoy the ride.’
And now something was looming beyond that close horizon. It was like the rise of a moon – but this moon was small and dark and battered, a twin of the world over which she crawled. It was the other lobe of the dumbbell.
Xenia said, ‘We’re studying the ground as we travel. As we don’t know what to look for, we’ve carried broad-spectrum surveying equipment. For instance, if the Gaijin came here to extract light metals such as aluminium, magnesium or titanium, they would most likely have used processes like magma electrolysis or pyrolysis. The same processes could be used for oxygen production. In the case of magma electrolysis the main slag component would be ferrosilicon. From a pyrolysis process we would expect to find traces of elemental iron and silicon, or perhaps slightly oxidized forms …’
We are crawling across a slag heap, Maura thought, trying to figure out what was made here. But are we being too anthropomorphic? Would a Neandertal conclude that we must be unintelligent because, searching our nuclear reactors, she could find no chippings from flint cores?
But what else can we do? How can we test for the unknowable?
The asteroid’s second lobe had all but ‘risen’ above the horizon now. It was a ball of rock, black and battered, that hung suspended over the land, as if in some Magritte painting. She could even see a broad band of crushed, flattened rock ahead, where one flying mountain rested against the other.
The second lobe was so close it seemed Maura could see every fold in its surface, every crater, even the grains of dust there. How remarkable, she thought.
The probe’s mode of travel had changed now, she noticed; the pitons were applying small sideways or braking tweaks to an accelerating motion towards the system’s centre of gravity, that contact zone. Gravity must be decreasing in strength the tug of the rock below her balanced by the equal mass of rock above, so that the net force was becoming more and more horizontal, and the probe was simply pulled across the surface.
Now the second lobe was so close, in this virtual diorama, it was over her head. Its crumpled inverted landscape formed a rocky roof. It was dark here, with the sun occluded, and the slices of starlight in the gap between the worlds were growing narrower.
Lamps lit up on the probe, and they played on the land beneath, the folded roof above. She longed to reach up and touch those inverted craters, as if a toy Moon had been hung over her head, a souvenir from some Aristotelian pocket universe.
‘… I think we have something,’ Xenia said quietly.
Maura looked down. Her field of view blurred as the interpolation routines struggled to keep up.
There was something on the ground before her. It looked like a blanket of foil, aluminium or silver, ragged-edged, laid over the dark regolith. Aside from a fringe a metre or two wide, it appeared to be buried in the loose dirt. Its crumpled edges glinted in the low sunlight.
It was obviously artificial.
Brind had next met Malenfant a few months later, at Kennedy Space Center.
Malenfant found KSC depressing; most of the launch gantries had been demolished or turned into rusting museum pieces. But the visitors’ centre was still open. The Shuttle exhibit – artefacts, photographs and virtuals – was contained within a small geodesic dome, yellowing with age.
And there, next to the dome, was Columbia, a genuine orbiter, the first to be flown in space. A handful of people were sheltering from the Florida sun in the shade of her wing; others were desultorily queuing on a ramp to get on board. Columbia’s main engines had been replaced by plastic mock-ups, and her landing gear was fixed in concrete. Columbia was forever trapped on Earth, he thought.
He found Brind standing before the astronaut memorial. This was a big slab of polished granite, with names of dead astronauts etched into it. It rotated to follow the sun, so that the names glowed bright against a backdrop of sky.
‘At least it’s sunny,’ he said. ‘Damn thing doesn’t work when it’s cloudy.’
‘No.’ The granite surface, towering over them, was mostly empty. The space program had shut down leaving plenty of room for more names.
Sally Brind was short, thin, intense, with spiky, prematurely grey hair; she was no older than forty. She affected small round black glasses, which looked like turn-of-the-century antiques. She seemed bright, alert, engaged. Interested, he thought, encouraged.
He smiled at her. ‘You got any answers for me?’
She handed him a folder; he leafed through it.
‘Actually it was a lot of fun, Malenfant.’
‘I’ll bet. Gave you something real to do.’
‘For the first time in too long. First we looked at a continuous nuclear fusion drive. Specific impulse in the millions of seconds. But we can’t sustain a fusion reaction for long enough. Not even the Japanese have managed that yet.’
‘All right. What else?’
‘Maybe photon propulsion. The speed of light – the ultimate exhaust velocity, right? But the power plant weight and energy you’d need to get a practical thrust are staggering. Next we thought about a Bussard ramjet. But it’s beyond us. You’re looking at an electromagnetic scoop that would have to be a hundred kilometres across –’
‘Cut to the chase, Sally,’ he said gently.
She paused for effect, like a kid doing a magic trick. Then she said: ‘Nuclear pulse propulsion. We think that’s the answer, Malenfant. A series of micro-explosions – fusion of deuterium and helium-3 probably – set off behind a pusher plate.’
He nodded. ‘I’ve heard of this. Project Orion, back in the 1960s. Like putting a firecracker under a tin can.’
She shaded her eyes from the sun’s glare. ‘Well, they proved the concept, back then. The Air Force actually ran a couple of test flights, in 1959 and 1960, with conventional explosives. And it’s got the great advantage that we could put it together quickly.’
‘Let’s do it.’
‘Of course we’d need access to helium-3.’
‘NASDA will supply that. I have some contacts … Maybe we should look at assembly in lunar orbit. How are you going to keep me alive?’
She smiled. ‘The ISS is still up there.
