@rosborne979,
I have no idea how any contamination could be avoided with our present knowledge. Weve steam cleaned and 'claved many satellites and Ill bet they still went into space loaded with yeasts and other microbes that were picked up just sitting there in the humid Florida climate waiting to blast off.
Its better, should we really want to develop a "prime directive", that we learn how to conduct sterilization of the crafts environmental surfaces by some energy intensive means , and this be done en route. Wed have detailed procedures (just like how we managed to develop good lab practices to limit lab innduced errors in medicine and science. Stuff like "all mission duds" will be kept in hermetic storage unused until they land, and at some point, close to the mission terminus, wed go through a sterilization protocol (obviously wed need to move the crew into an area that would be a "safe room" ). I think all that is a difficult thing to accomplish but it will be doable and not a mission killer.
Im more concerned about wailing into some piece of space debris and ending the mission in a catastrophic collision with a small rock. That requires a whole new batch of technology that we dont have yet.(Gene Rodenberry thought of it first)
First things first. Do we have the capability to develop the requisite power source in a thousand years or so?
I think a whole new arena of science will open up to us when we are able to better understand and exploit fusion reactions and magnetic flux of bodies like jupiter and our sun. (Followed by Alpha and Proxima).
Whatever we do for deep space travel, we will require ships of extreme masses and these would obviously be planetessimal versions of the ISS with resources borrowed from the asteroids, moons and planets. Maybe itll be 10000 years but, really, We s need to think more geologically, not in terms of next quarter or what can we accomplish in one generation even.
Small steps, with time and pressure , and maybe another earth based catastrophe like a few supervolcanoes or a Vredefort bolide