The rumours of the existence of a ship fast enough to reach Planet Nine in a mere few years – compared to the decades taken by the Conservers’ spindly sail ship – leaked out of Earth, were picked up by the Conservers’ own sparse information-gathering networks – and were passed on, ultimately, to Shadow, at its station orbiting Nine.
And that prompted Salma to take, belatedly, another look at her own craft, the craft that had brought her and her companions out here.
She had always taken it for granted, she supposed. She had been born aboard the Shadow; it was her home, all she had ever known. Somehow the prospect of new ships arriving, of probably quite different designs, and new people, made her want to understand her own ship better – and her own life, and how she had got here.
It had been a long journey for sure. Hild Kanigel, Salma knew, was the ship’s oldest crew member, as well as serving as captain since the launch of the Shadow. Thanks to an assiduous exercise regime Hild was compact, confident, her build stocky. Only her near-white hair gave away her age, around seventy standard years – even a Conserver living at the edge of the Solar System still counted her age by Earth years. But Hild had been a mere thirty-something years old when the Shadow had been launched, an event itself some thirty-five years ago.
The ship had been fabricated by the culture that had already been labelled ‘Conservers’ by the commentators on Earth, and even by the venture-capitalist miners of the Lunar Consortium. The Conservers – consciously seeking a way for humans to expand and live across the Solar System without depleting its resources in the process – were despised by both sides. They had accepted a label meant as contempt. Conservers. That would do.
And in that spirit they had constructed Shadow using mainly the discarded, mined-out remains of an asteroid, a near-Earth object from which all supposedly valuable materials had already been extracted. It wasn’t easy, but the Conservers were making tangible their basic policy: tap as many plentiful or renewing resources as possible, use the waste of others.
So Salma had learned as she grew up. All this was history, a culture war Salma had never thought she would see close up. She had been born on this ship, a Conserver vessel, and she had always believed, at the back of her mind, that she would die on the ship – if not on the mysterious Planet Nine. Now everything seemed likely to change, and she tried to find out more.
And, she learned, it had been necessary for this ship, this one austere Conserver initiative, at least, to dip deep into the inner Solar System, and ‘steal’ a little of the Sun’s energy, its radiation output, even its gravitational energy, to achieve its tremendous journey.
Salma had been born twenty years ago, in the mission’s fifteenth year.
And she had been born, or allowed to be born, because of the death of her mother.
It had been a form of bone cancer that, it seemed, was rare but not unknown in denizens of deep-space zero-gravity habitats, and not eradicated even after more than two centuries of human spaceflight. A deep weakness yet to be scrubbed from a genome of ever-improving resilience. So she had been earnestly told.
And so here was Salma, having once been a harvested and frozen embryo, created from the union of her mother and a man still alive in the outer Kuiper belt – a father she never expected to see. Here was Salma, allowed to live only because her mother had died, and had made room for her on this small ship – and the older she got the more complicated her feelings about that became.
She had only ever seen images of her mother, a few other records – and nothing at all of her father. All the images, save for excursions outside the ship, showed her mother wearing the onyx pendant that had been her only legacy for Salma – and her mother had given Meriel Breen, ship’s medic, an identical gift, as if to acknowledge Meriel’s necessary role as an honorary aunt to Salma in the future.
As Salma had grown, she was starting to look like her mother – so her crewmates said – with her dark hair, pale skin, rather empty blue eyes. The onyx pendant somehow reinforced that impression. For a time Salma had put aside her mother’s images – and, too, had become averse to looking at her own face in mirrors and monitors.
She never gave up her pendant, though. Nor Meriel hers.
And meanwhile she got on with living.
With their whole lives confined to a few habitat modules, and with, frankly, not much change to the view outside, most of the crew spent the journey time – thirty-five years of it now – in virtual environments. Most of these were essentially play, augmented with downloads from the inner System, and Salma had slowly learned to explore the suite with help from her crewmates.
That had been her childhood, pretty much.
In recent years she had, with subtle guidance, even been encouraged to find virtual worlds rich in romance and sexuality, for it had been made plain to her all her life that, on the ship, she would find no partners among a set of adults who regarded her as an honorary niece, if not a daughter. Even the second youngest of the crew, Zaimu, propulsion specialist, was sixteen years older. And Salma came to perceive a shifting network of romantic and sexual relationships among the rest of the crew – a network of which she had no part.
But as her own adolescent frenzy had faded a little she had been gradually drawn to other stuff, more sober material. Mostly on the culture that had produced this ship, the mission of the Shadow itself, and its target in Planet Nine.
So here was Salma the adult, at twenty years old, having been gently trained all her life to take her mother’s place in the crew. And here was Salma doing just that, learning to fulfil her mission at its climax.
The only difference being, she supposed, she hadn’t been given the privilege of being able to choose to take part in this mission. She liked to think she would have been swept up by the heroics, even if she had had the choice to opt out. Anyhow she would never know; she had never been given the opportunity to find out.
But now she had her reward.
Now she had been the first to see it. The real Planet Nine.
Planet Nine: an old label for a hypothetical planet-size mass beyond the eighth true planet, Neptune – an inadequate, parochial, probably incorrect label for a phenomenon discovered more than two centuries ago, in an antique time when astronomers were still mostly confined to Earth.
Salma learned the theory.
The Solar System in large was a thing of layers, like an onion, if a flattened onion. You had the Sun at the centre of it all, with the eight major planets in roughly the same orbital plane, some with moons the size of planets themselves. Between Mars and Jupiter were the main-belt asteroids, the debris of the System’s origin – including the largest and richest, Ceres, full of precious water, settled in its orbit.
Beyond Neptune, outermost major planet, lay the Kuiper belt, full of trans-Neptunian objects – TNOs – some resembling planets or moons, such as chill Pluto.
And beyond even that, stretching into interstellar space, was the Oort cloud, a realm still poorly mapped but inhabited by objects massive enough, if they chanced to wander into the inner System, to blossom into comets, bringing beauty and occasional doom.
And it was to the Oort cloud that the Shadow had come searching for the elusive Planet Nine. Supposedly seven hundred times as far from the Sun as Earth was, and at least the mass of Neptune.
The point was, from Earth you couldn’t see Planet Nine itself, for whatever reason – but you could see the marks of its passage among the wider cloud of Oort objects.
Salma had grown up trying to understand this mystery – how you could see the unseen. When she was still quite small one older man, a non-specialist engineer called Boyd – or ‘Uncle Boyd’, at that point – had tried to explain.
He dropped a cup of rice grains into a transparent flask of water. When he shook the flask, without gravity or acceleration the rice grains would not settle. But then Boyd opened the flask, popped in an ice cube, and pushed it with one finger so it sailed, gravity-free, through the water, perturbing the cloud of grains as it went. Can you see the ice in the water? Just barely? Imagine you can’t see it at all, so that it’s invisible …
He had had to explain that word, invisible, and she had to practise for two days before she could say it herself.
Even if you couldn’t see the ice, you could see where it has been and where it is going, from the way it stirs up the rice grains …
And that is how we know Planet Nine is out there, even though we can’t see it, yet. We think it is on a long, slow, looping orbit around the Sun – travelling all the way out into the far Oort cloud when it’s at its extreme. We can’t see it, for whatever reason, but we can see how it scatters the other TNOs – the trans-Neptunian objects, the comet cores and other stuff out there. And if we put all that in the computer it can work out where Planet Nine is – or where it must have been before, and where it is going now.
So we know that right now it is about seven hundred times as far out as Earth is from the Sun, although it probably loops around in a big ellipse: it comes further in, it goes further out, and it takes about twenty thousand years to complete one orbit around the Sun. And as it passes it tweaks and twangs the orbits of small objects that we can see.
And that’s also how we know how big it is, by the way – ten times the mass of Earth, we think. And when I say ‘big’ I just mean how massive, not how wide. If it’s a rocky planet like Earth, it will have about twice Earth’s diameter. If it’s not a rocky planet – and it may well not be, given we haven’t seen it after centuries of searching – well, all bets are off …
A lot of that made not much sense to Salma, as she grew up, never having seen Earth, or walked on it.
For another thing, for a long time she didn’t know what a ‘bet’ was.
But she got the essence. That this thing was big, and they were steadily sailing out to find it – or at least going to where they thought it must be, as most of the adults said to her more cautiously.
Although she was never sure why they had come so far to find Nine. When Salma asked Meriel about that, she suggested Salma read a book called Moby-Dick.
With time, and with the precisely scheduled mission unrolling through its slow stages – and as she grew herself – Salma’s attention started to veer away from the unfathomable mysteries of the universe beyond the curved walls of the enclosures that confined her, and away from the bunch of adults who all treated her with faultless kindness – and towards the mechanics of the craft in which she lived.
After all, Planet Nine was a dry abstraction; you could touch the stuff of the ship, and (under suitable supervision) you could even tinker with it. The others encouraged this. As Boyd said, ‘Somebody’s going to have to fix the plumbing when the rest of us are in our basket chairs.’
So she had started to learn about engineering, or at least about the engineering of the faithful Shadow.
And it soon struck her how apt that name was.
She saw images of the more brutal, heavy craft of Earth, and the Moon miners’ freighters. They were mostly huge, mostly ungainly collections of cylinders and spheres, mostly pushed here and there by the power of nuclear fission: ferocious energies released by the consumption of irreplaceable resources, on Earth and in space.
By contrast the Shadow complied with the Conservers’ basic philosophy that you should consume the absolute minimum possible of the resources of Earth, the wider Solar System – even the Sun – while achieving your goals. The ultimate dream was to use nothing that was useful for other purposes at all – to live off sunlight, and the slow rain of comets wandering into the Solar System from beyond even the Oort cloud, from deep interstellar space.
So, four decades after the fact, Salma had studied the unique commissioning, design, building and launch of a ship with a touch as light as a shadow’s.
Constructed mostly of that waste asteroid material, the ship’s main hull was a block with, Salma had been oddly pleased to learn, about the same mass as the old ISS – the International Space Station, the first purpose-built multinational station to orbit the Earth, although Shadow’s expansive, thin-walled, inflated modules offered a lot more leg room.
And, like the ISS, the Shadow gained much of its power from sunlight – and, in the case of the Shadow, its motive force too.
Even now, seven hundred times as far from the Sun as Earth, the collecting area required to supply sufficient solar energy for the ship’s systems was only a few kilometres in diameter. From the beginning that solar energy sustained the ship’s bubble of life – the raw, focused sunlight to grow onboard crops, a conversion through light-collecting panels to make electricity for heating, cooling, air cleansing, water purification.
And, more spectacularly, that solar capture area was embedded in a much wider sail, for it was solar propulsion too that had driven the whole craft out into deep space.
A relatively friendly Earth government had allowed the craft to complete its assembly in a high orbit of Earth, with the ‘loan’ of some resources purchased from the Moon: a few hundred tonnes of aluminium and other products from Moon rock and dust, even some of the Moon’s precious water, to assemble and provision it.
Relatively friendly: Salma learned that the Earth authorities had no great love for the Conservers, but the simple fact that they weren’t Moon miners made them worth cultivating. Hild would say that Earth’s support for the Shadow project was, in fact, a cynical ploy to manipulate possible long-term allies. But the Conservers took those gifts just as cynically, it seemed to Salma, looking back at those times. She wondered if she would have made the same choices, had she been around then.
The six crew members of the Shadow, carefully selected from a wider pool of volunteers, had been smart, educated, well informed and healthy – or they had been at launch. Later they liked to debate the ethical compromises made by Earth and Conservers that had led to the creation of their ship, and as she grew older they had used such debates as a learning exercise for Salma, their only child. In life, she was taught in those sessions, you for ever had to make compromises with your values to achieve greater goals.
Well, however it was funded and resourced, however morally compromised, the Shadow was built.
Then, in the year 2220, a punch from a small nuclear stage had knocked the completed Shadow out of Earth orbit and into the first leg of its long, complicated journey.
The nuke was quickly discarded (and retrieved for use elsewhere). From now on, renewables only. In particular, the ship would sail into deep space on the light from the Sun – but, at first, it would sail towards the Sun, and not away.
After the launch, Salma learned, at first the craft had spiralled inwards, reaching a minimum distance from the Sun of about a third Earth’s orbital radius after the first year’s travel, holding up its solar-energy capture sail like a shield. And then the great propulsive sail was opened – this one with a radius nearly six times that of the energy capture sail, some forty kilometres across. Light exerted a measurable force, even on the palm of a hand held up to Earth’s sunlight. Now this immense sail trapped enough light from the close-in Sun to push the ship at an acceleration of about three per cent of Earth’s gravity.
The final dive into the Sun’s gravity well was conducted as an ‘Oberth manoeuvre’, a tactic evidently used from the earliest days of spaceflight. At closest approach, the craft ‘stole’ some kinetic energy from the Sun in those brief moments when ship and star were coupled through the Sun’s gravity. And after a day of this the ship shot out of the Sun’s deep gravity well at a speed of more than a hundred kilometres per second – more than three times Earth’s own orbital velocity.
All of this was a classic Conserver tactic, Salma had learned. Thanks to Oberth, the Shadow had needed only a little sunlight, a little of the Sun’s enormous fund of radiative and orbital energy.
Salma was never sure she fully understood any of this. Anyhow it had evidently worked.
After that, as the ship sped away from the Sun and inner System with its new, enormous velocity, as Hild and her crew had grown steadily older – as Salma waited to be born – the milestones were reeled off: three months to pass Jupiter’s orbit around the Sun, Saturn’s in six months, Neptune’s in two years – three years to the outer edge of the Kuiper belt. And at last, after a full thirty-five years, to reach the computed position of Planet Nine.
On arrival they had managed to slow into orbit around Nine with an Oberth manoeuvre in reverse, effectively giving Nine a little of the ship’s kinetic energy. (To get away, Salma knew – if they chose to return to the inner Solar System at all – this crew of Conservers could cheat a little, sacrificing some of the mass of the sail to create a small fission rocket.)
And now here they were.
Salma knew that some of the adults were surprised that there had been no further effort from Earth (or Moon) to send a faster, if more wasteful craft to overtake the Shadow and claim the prize. She got the sense that in an inner System full of political turmoil and fast interplanetary industrialisation, such abstractions as distant Planet Nine were irrelevant. Which wasn’t to imply, cynical old Boyd would say, that if Nine turned out to be made of diamonds, or better yet helium-3, the inner civilisations would not come chasing out to seize it.
In the end, though, Salma had always been more interested in where this ship onto which she had been born was going, rather than how it had got there – or where it had come from. Earth’s federal government, the Lunar Consortium and the factional politics of mankind: these were all just words to Salma, without emotional content. Even the cautious creed of the Conservers themselves, into which she had been born, left her unmoved. She knew this was a kind of personal flaw; but at twenty years of age she was growing up to suspect that it was probably a necessary outcome of her peculiarly isolated upbringing.
For better or worse she was more interested in what was out there in the universe than in what was in people’s heads. Just because she didn’t know many people.
So she had deliberately studied what she could of Planet Nine long before the slow, final, agonising crawl to this position, a high orbit about the object.
Which was turning out not to be what they had expected.
‘What a mystery,’ Hild had said, going through the first observations. ‘We were right to come, though. As we said all those years ago, We’ve got to get a ship out there …’