Interstellar Travel - Possibilities and Human Physiology

This one interested me the most.First on the list are the life forms that we already take with us everywhere, our normal human flora (e.g. skin flora, gut flora). As for supplementary life forms, a minimum requirement would be seeds for high protein plants such as soy beans that can be planted once you reach the destination or grown hydroponically. For in flight, genetically engineered algae and yeast could serve as a nutrient rich food source. Unicellular life forms are the most effecient and the least picky. I see no reason why we would need large plants or animals in flight to supply food. One could certainly argue that there are psychological reasons that we need plants and animals with us.

There are small amounts of interstellar hydrogen, not to mention micrometeors in the Oort clouds and other small dust particles. This would produce drag, but I don't know if it would be significant at relativistic velocities.

In the absence of gravity, lots of exercise where force is applied to the person. Modern astronauts strap themselves down to treadmills and bicycles. The bones need to experience a force load in order to keep bone density.This can also be solved by accelerating at >0.5 g or having a cylindrical ship that spins to produce centrifugal force. I don't think there would be any problems pre-natal, but I have no idea on post-natal health. The only "artificial" gravity we can produce is centrifugal force. Just think about those carnival rides where the ring of cages spins around and pins you to the back of your little cage.

Depends on the shielding. You would need a thick physical barrier to shield you from micrometeors. You would also need shielding from radiation. As Ned points out, at relativistic speeds the amount of deadly radiation increases. I don't know if magnetic shield would suffice for all sources of radiation. You might need more cadmium control rods if a fission reactor is exposed to external neutron sources, but other than that I don't see why you couldn't use one.

It's actually simpler than that. In order for a planet to be habitable it must have oxygen. For a planet to have oxygen it must have life. Specifically, it must have photosynthesizers that are producing oxygen. Oxygen is a very reactive element and it disappears quickly if it is not constantly replaced. In fact, our planet has massive iron sediments which marked the emergence of oxygen producers on our planet. The sediments themselves illustrate that lifeless planets will probably have massive oxygen sinks that will have to be filled before oxygen levels can increase in the atmosphere. Short term terraforming will probably be very difficult and energy intensive.

Since we are the travellers of interest, I thought this was assumed.

The gravity assist is actually given by the planets orbital speed. If you are going with the movement of the planet then it's velocity can be added to yours. If you are going in the opposite direction then the planet's velocity will be subtracted. Wiki linkFor powered gravity assist with a static object the gravity assist is due to the loss of propellant. Think of sand bagging with bungee jumping. Jump off the bridge with sand bags and let go of the sand bags at the bottom of the fall. You will spring up with more velocity.

First off, acceleration at 1xg is pretty fast. If you are accelerating at 9.8 m/s^2 it would only take 3 months to get to 0.5 c. For a trip that will take years this isn't a problem.For constant g forces above 1xg we can take a cue from nature, specifically the womb. If you submerge the passengers in water they experience much lower g loads.

It's everything. History, environment, language, society, and oh yes, DNA.Perhaps a way to bridge the gap between the home planet and a freshly seeded population of humans would be anthropomorphic androids trained to raise a new human generation and a vast library containing art, history, primers on human society, etc.

It would work, but the savings would be pretty small assuming that you are slowing down from relativistic speeds. It works great for our satellites that are crawling through the solar system, but they aren't going that fast.

It would seem to me that robotics would work really well for this task. It might be slow at first, but it could really build momentum over time. We might even invent something like a von Neumann machine that can make more copies of itself. This could lead to a exponential increase in resources.Edited by Taq, : No reason given.

If your manufacturing robots double in number every year your resources will grow exponentially.