If we seek to survive then, when it comes to planets, it would be unwise to put all of our eggs in one basket.  Steven Hawking apparently agrees with me on this, as can be seen here and here. In his words,

It will be difficult enough to avoid disaster on planet Earth in the next hundred years, let alone the next thousand, or million. The human race shouldn’t have all its eggs in one basket, or on one planet. Let’s hope we can avoid dropping the basket until we have spread the load.

Not unexpectedly in this hypermoralistic age, morality is being dragged into the debate.  The usual “ethics experts” are ringing their hands about how and under what circumstances we have a “right” to colonize space, and what we must do to avoid being “immoral” in the process.  Related discussions can be found here and here.  Apparently it never occurs to people who raise such issues that human beings make moral judgments and are able to conceive of such things as “rights” only because of the existence of emotional wiring in our brains that evolved because it promoted our survival and that of our prehuman ancestors.  Since it evolved at times and under circumstances that were apparently uninfluenced by what was happening on other planets, morality and “rights” are relevant to the issue only to the extent that they muddy the waters.

Assuming that others agree with me and Dr. Hawking that survival is a desirable goal, then ultimately we must seek to move beyond our own solar system.  Unfortunately there are severe constraints on our ability to send human beings on such long voyages owing to the vast amounts of energy that would be necessary to make interstellar journey’s within human lifetimes.  For the time being, at least, we must rely on very small vessels that may take a very long time to reach their goals.  Nanotechnology is certainly part of the answer.  Tiny probes might survey the earth-like planets we discover to determine their capacity to support life.  Those found suitable should be seeded with life as soon as possible.  Again, because of energy constraints, it may only be possible to send one-celled or very simple life forms at first.  They can survive indefinitely long voyages in space, and would be the logical choice to begin seeding other planets.  Self-replicating nano-robots might then be sent capable of building a suitable environment for more complex life forms, including incubators and surrogate parents.  At that point, it would become possible to send more complex life forms, including human beings, in the form of frozen fertilized eggs.  These are some of the things we might consider doing if we consider our survival important.

Of course, any number of the pathologically pious among us might find what I’ve written above grossly immoral.  The fact remains that there is no legitimate basis for such a judgment.  Morality exists because it promoted our survival.  There can be nothing more immoral than failing to survive.

The Daedalus Starship

Every other challenge we face and all the great political, religious, and ideological issues that have captured our imaginations and whipped us into self-destructive frenzies since the dawn of human existence pale in significance compared to the ultimate challenge of carrying life into interstellar space.  Unless we meet the challenge, all our pompous babbling about morality and ethics will be as meaningless as the life of a soap bubble.  There can be nothing more immoral than failing to survive.

Sail technology is not necessarily limited to the vicinity of the sun. The photons required for propulsion might also be supplied by ground based lasers or masers to enable sail-based interstellar travel. (Related links are here, here and here.)  Unfortunately, human travel using such systems is out of the question for the time being because of the inordinate amount of energy that would be needed to drive a manned spacecraft to the speeds required to cross interstellar distances within a human lifetime. However, it may be feasible to accelerate very small payloads of a few tens of grams to the speeds necessary to cross interstellar distances in times on the order of decades and decelerate them at their targets. Given continued advances in nanotechnology, useful scientific instruments of sufficiently small size might be developed to fit in such tiny craft.   More importantly, life in the form of spores or bacteria might be sent to seed promising planets. Given the very real possiblity that we will exterminate ourselves here on earth, and that survival trumps any other purpose or goal that we might reasonably set for ourselves, it seems to me that this should be one of our highest priorities.  We are related to every other life form on the planet, but are the only species capable of preserving that life indefinitely.  We should do so. 

Given the energy limitations noted above, it will probably be impractical to send spacecraft large enough to support a human crew over interstellar distances any time in the foreseeable future, barring some unforeseen advance in an enabling technology.  However, All the information necessary to assemble a human being is contained in the nucleus of every cell in our bodies.  It may prove more practical to send self-replicating nano-robots, programmed to eventually build the larger machines necessary to create dwellings, begin agriculture, etc., and finally build artificial wombs and ”nannies” of human size.  At that point, eggs and sperm, which it would be much more practical to send over interstellar distances in a reasonable time, could be combined to form a human population.  Fanciful?  Certainly, but it sounds better, to me at least, than waiting around for our extinction, which is inveitable and will probably occur sooner rather than later if we are foolhardy enough to remain on one planet.