2061 Odyssey Three

chapter 6 The Greening of Ganymede
Rolf van der Berg was the right man, in the right place, at the right time; no other combination would have worked. Which, of course, is how much of history is made.

He was the right man because he was a second-generation Afrikaner refugee, and a trained geologist; both factors were equally important. He was in the right place, because that had to be the largest of the Jovian moons - third outwards in the sequence Io, Europa, Ganymede, Callisto.

The time was not so critical, for the information had been ticking away like a delayed-action bomb in the data banks for at least a decade. Van der Berg did not encounter it until '57; even then it took him another year to convince himself that he was not crazy - and it was '59 before he had quietly sequestered the original records so that no-one could duplicate his discovery. Only then could he safely give his full attention to the main problem: what to do next.

It had all begun, as is so often the case, with an apparently trivial observation in a field which did not even concern van der Berg directly. His job, as a member of the Planetary Engineering Task Force, was to survey and catalogue the natural resources of Ganymede; he had little business fooling around with the forbidden satellite next door.

But Europa was an enigma which no-one - least of all its immediate neighbours - could ignore for long. Every seven days it passed between Ganymede and the brilliant minisun that had once been Jupiter, producing eclipses which could last as long as twelve minutes. At its closest, it appeared slightly smaller than the Moon as seen from Earth, but it dwindled to a mere quarter of that size when it was on the other side of its orbit.

The eclipses were often spectacular. Just before it slid between Ganymede and Lucifer, Europa would become an ominous black disc, outlined with a ring of crimson fire, as the light of the new sun was refracted through the atmosphere it had helped to create.

In less than half a human lifetime, Europa had been transformed. The crust of ice on the hemisphere always facing Lucifer had melted, to form the Solar System's second ocean. For a decade it had foamed and bubbled into the vacuum above it, until equilibrium had been reached. Now Europa possessed a thin but serviceable - though not to human beings - atmosphere of water vapour, hydrogen sulphide, carbon and sulphur dioxides, nitrogen, and miscellaneous rare gases. Though the somewhat misnamed 'nightside' of the satellite was still permanently frozen, an area as large as Africa now had a temperate climate, liquid water, and a few scattered islands.

All this, and not much more, had been observed through telescopes in Earth orbit. By the time that the first full-scale expedition had been launched to the Galilean moons, in 2028, Europa had already become veiled by a permanent mantle of clouds. Cautious radar probing revealed little but smooth ocean on one face, and almost equally smooth ice on the other; Europa still maintained its reputation as the flattest piece of real estate in the Solar System. Ten years later, that was no longer true: something drastic had happened to Europa. It now possessed a solitary mountain, almost as high as Everest, jutting up through the ice of the twilight zone. Presumably some volcanic activity - like that occurring ceaselessly on neighbouring Io - had thrust this mass of material skywards. The vastly increased heat-flow from Lucifer could have triggered such an event.

But there were problems with this obvious explanation. Mount Zeus was an irregular pyramid, not the usual volcanic cone, and radar scans showed none of the characteristic lava flows. Some poor-quality photographs obtained through telescopes on Ganymede, during a momentary break in the clouds, suggested that it was made of ice, like the frozen landscape around it. Whatever the answer, the creation of Mount Zeus had been a traumatic experience for the world it dominated, for the entire crazy-paving pattern of fractured ice floes over the nightside had changed completely.

One maverick scientist had put forward the theory that Mount Zeus was a 'cosmic iceberg' - a cometary fragment that had dropped upon Europa from space; battered Callisto gave ample proof that such bombardments had occurred in the remote past. The theory was very unpopular on Ganymede, whose would-be colonists already had sufficient problems.

They had been much relieved when van der Berg had refuted the theory convincingly; any mass of ice this size would have shattered on impact - and even if it hadn't, Europa's gravity, modest though it was, would have quickly brought about its collapse. Radar measurements showed that though Mount Zeus was indeed steadily sinking, its overall shape remained completely unaltered. Ice was not the answer.

The problem could, of course, have been settled by sending a single probe through the clouds of Europa. Unfortunately, whatever was beneath that almost permanent overcast did not encourage curiosity.

ALL THESE WORLDS ARE YOURS - EXCEPT EUROPA.

ATTEMPT NO LANDINGS THERE.

That last message relayed from the spaceship Discovery just before its destruction had not been forgotten, but there had been endless arguments about its interpretation. Did 'landings' refer to robot probes, or only to manned vehicles? And what about close flybys - manned or unmanned? Or balloons floating in the upper atmosphere?

The scientists were anxious to find out, but the general public was distinctly nervous. Any power that could detonate the mightiest planet in the Solar System was not to be trifled with. And it would take centuries to explore and exploit Io, Ganymede, Callisto and the dozens of minor satellites; Europa could wait.

More than once, therefore, van der Berg had been told not to waste his valuable time on research of no practical importance, when there was so much to be done on Ganymede. ('Where can we find carbon - phosphorus - nitrates for the hydroponic farms? How stable is the Barnard Escarpment? Is there any danger of more mudslides in Phrygia?' And so on and so forth...) But he had inherited his Boer ancestors' well-deserved reputation for stubbornness: even when he was working on his numerous other projects, he kept looking over his shoulder at Europa.

And one day, just a few hours, a gale from the nightside cleared the skies about Mount Zeus.