Should we send an interstellar (unmanned) probe to Alpha Centauri? Would it be much more expensive than a manned mission to Mars? According to Wikipedia, velocities as high as 0.10c are possible with hydrogen bombs. That means that ~40 years flight time to the nearest star would be possible with today's technology! There could be a Earth-like planet in the Alpha Centauri system so maybe the probe should try to go into the orbit of the planet and even land there. How much would all this cost? What problems there are? I try to list here everything I know of: 1. Using hydrogen bombs in space violates the Partial Test Ban Treaty. 2. No one will use hydrogen bombs because...hey! we have these wonderful chemical rockets and flight times of hundres of thousands of years! 3. Micrometeoroids with speeds of 10% of the speed of light. 4. Very much fuel (hydrogen bombs) if the probe is to go into the orbit of the star(s)/planet. 5. No one knows the orbit of the (hypothetical) planet. 6. The probe and all its instruments should last at least 50 years without a human help. 7. Radiation. 8. Maybe the probe should have a very advanced Artificial Intelligence. See also: Project Daedalus Project Longshot (NASA's pdf file) Project Orion PS. A wise man once said: "Space, the final frontier. These are the voyages ... to explore strange new worlds. To seek out new life and new civilizations. To boldly go where no one has gone before." I do not recall who he was but I know he has done a good job in space exploration.