spacecraft in collisions with natural objects

Other than energy concerns, probably the most serious obstacle to interstellar travel, or even interplanetary travel, is the danger of collision with objects. The "Space Junk" problem with man-made rubbish in earth orbit is small in comparison with the dangers that high-speed travel brings about. For, the faster we travel, the less time we have to detect objects in a collision course and the less time we have to react to the threat.

The problem can, in part, be addressed by the same precise and accurate survey that is required by the other parts of interstellar travel and "starsystem engineering (which includes terraformation). Yet any evasion of a collision will be costly, in terms of energy.

The assumption that that an encounter with such objects is to be avoided may be overcautious. There are methods of spacecraft design which make some encounters not only less dangerous, but beneficial. Proper design can make encounters with objects too small to be detected at a distance, actually beneficial to in the propulsion of the spacecraft.

To back up a bit, it makes sense that the gravitational replacement be that provided by rotational inertia. This has been a well accepted concept, even in the 1969 movie '2001', and ever since it has been a prefered method of providing artificial gravity. This means that the internal 'core' of the spacecraft is not to be inhabited because it has zero gravity. Why not do away with the 'core' entirely? This would results in a conical spacecraft with a hollow interior. Yet this interior might not be useless: a replusion system could narrowly direct either around or through the spacecraft. When lightweight matter is funneled in such a way, it can perhaps be used as reaction mass. Simply speaking, the 'junk' funneling through the center of the spacecraft can be used to 'push against' an accelerated the craft, thus improving its efficiency.

In conclusion, it is a combination of early detection of large hazards, and design to death with, even take opportunity of, smaller bodies that will protect an inter (or even intra) stellar mission. Of course, super-velocity bodies will still be beyond our ability to deal with. Which is why, there maybe an advantage to a star system which has 'sweeper' high gravity bodies, such as Jupiter and Saturn provide in the solar system, to 'clean' of minor bodies (i.e. junk).

As I write this, I am watching the movie 'Contact' for the first time, on TV. I have been hesitant to watch if for so many years because I had this idea that it would be a reproduction of "E.T.". Thankfully, it was an adult movie and had much more to offer than the typical Spielburg juvenelia. Yet I still feel that any aliens will not come to us, but we will go to them. Perhaps more alarmingly, that their systems of intelligence and communication will be so different than ours, along with their biology and time scale, that we will not identify them until we are in the midst of them, and too late for either species to communicate with the other as to non-interference, never mind mutual benefit. But I believe this deserves a totally different subject heading, and I am not sure is even appropriate for this blog.

"Are we alone?" - I feel this when posting here. Who reads my posts? I can only hope that either Google or some other force can archive this for the ages, and that future generations mine my exposions for ideas and guidance.

That means that some appreciation would be most welcome. Even if you disagree with me, please let me know that my posts are being read.