Surviving the death of Earth

kw: book reviews, science fiction, far future fiction

Terraforming Earth, by Jack Williamson: Why would there be a need to terraform Earth? As the second-ever Grandmaster of SciFi tells it, someday Earth will get clobbered by a big asteroid or comet. His someday just comes around sooner.

The comet in the 1998 movie Deep Impact is 11 km (7 mi) across, which is considered big enough to end civilization. The initial impactor of this book—there are more than one, with unknown amounts of time in between—is stated as ten miles across, or 16 km. The Cretaceous impact that made the dinosaurs, and 85% of all animal species, extinct was 10 km (6 mi), so the size is in the right range, except for one thing. The aftermath of the 16 km impact, with about four times the energy of the Cretaceous impact, is described as making Earth entirely lifeless. That's a bit implausible.

Life is tough. Metazoan (complex) life is not nearly as tough as bacterial life, but it is pretty durable. The biggest danger from an impact that doesn't melt the planet's crust is "impact winter" caused by the heavy dust cover that would block the sun for a year or two. Lots of unlikely critters survive the long winters of the polar latitudes.

Jack Williamson's post-impact Earth is running with lava. That would require multiple impacts with objects in the 200 km range. A renewed Hadean Era would last a few tens of millions of years. Those self-repairing robots had better be able to make repair parts from moon dust! With such quibbles aside, what's the story? Pretty cool, really.

A visionary scientist, who is fortunately a pretty good fund-raiser, establishes a colony on the Moon, designed to preserve a cross-section of Earthly life, cultural artifacts and learning. Overseen by advanced robots (I pick the 23^d Century for this to be possible), the colony is prepared to clone selected persons and train them to return to Earth and re-establish an ecosystem, and finally to re-populate the planet. All is designed for the very long term.

Everything goes awry when the comet comes too soon, and only a handful of people escape the Earth. Only a fraction of the tissue bank is in place in Tycho Station, and only a fraction of the storage spaces for artifacts and libraries is in use. Nonetheless, there is enough to make an attempt. Beginning some decades after the impact, the clones of five people are "born", raised, and trained for their mission.

The book, told from the point(s) of view of a succession of clones of the colony Historian, follows the staccato journey through time of these five and a few others who are added to them at various stages. In some intervals, thousands or millions of years pass before a new set of clones is deemed to be required by the overseeing computer system. Earth is actually terraformed several times, as successive impacts, unknown amounts of time between them, re-sterilize Earth, fortunately also removing an inimical race of aliens at one point.

Finally, Earth's population clears up the impact risk by developing to the point that their technology can remove all threatening comets and asteroids. At this point, living clones of the original Tycho colonists are redundant, and face an uncertain future.

A yarn like this one makes me wonder, how likely is it that any agency or organization will be able to set up a repopulation colony on Moon or Mars? So far, it takes great amounts of resources for a major nation like the US just to accumulate about a hundred man-hours of Lunar visits: It cost $2Billion in the 1969-73 time frame. That's about $10-20B today, but at a time when there's less interest in doing something like that among the nation's people. We are about to retire the Space Shuttles; in at most five years they will fly no more. No viable replacement has been identified, and it would take ten years to produce, anyway.

Someday I'll gather the data to write a riff on how space has proved to be too expensive for us.