Space is the second area, the importance of which seems to have faded into the background in recent years. The Bush Administration is well aware of space's importance in military terms and has recently issued new rules governing what it will not permit likely enemies to do there. But I am thinking more in the long term, particularly in regard to large-scale space travel, colonization and commerce. If the human race survives, I have no doubt that it will eventually colonize space. But will working actively and purposefully for such enterprises actually help us to survive? I believe so.
Gloomy Greens argue that unrestrained human activities can, by changing the climate, doom humanity to extinction. But they've yet to prove their case, and it looks increasingly improbable that they ever will. However, large-scale natural disasters--though rare and well spaced out in time--undoubtedly have that power. Such an incident took place about 65 million years ago, when an object about 6 miles across hurtled through Earth's atmosphere and landed in the sea off the coast of Mexico, releasing energy equivalent to billions of A-bombs and a fireball hotter than the sun. After 150 million years of triumphant existence the hardy dinosaurs, unable to withstand the resultant climatic changes, became extinct. The human race would have suffered the same fate had it then existed.
Bill McGuire, professor of geophysical hazards at University College London, has written a book entitled Global Catastrophes: A Very Short Introduction in which he calculates the size of objects big enough, if they struck Earth, to end life as we know it. This book is a good read (though I disagree with the professor about man-made threats). Depending on whether an object hitting us were a fast-moving comet or a slower asteroid, it would need to be about 2.5 miles across to set in motion the process of reducing light and destroying photosynthesis, without both of which Homo sapiens and the other forms of life on our planet could not survive.
In addition to developing the ability to detect and deflect large asteroids and comments, we need to get ready to take the ultimate step:
As well as being able to detect and deflect objects, we need to have a workable planetwide evacuation plan. We must stop thinking of space travel as a childish fantasy or a movie or television plot and recognize it as a serious project that may at some point become an absolute necessity. Practical space travel is one answer to all calamitous danger--man-made or natural--and I would like to see Mr. Bush give it serious consideration during the last phase of his presidency. It is the next great adventure for man, as well as his survival ticket.