The fastest speed so far recorded by a spacecraft was by Galileo at a speed of nearly 100,000 miles per hour ( 0.00014 c). To travel to Lalande 21185 at 8.1 light years would take 56,000 years. To get to one of the other stars at 35 light years would take 240,000 years. So far, our best technology can only guarantee that our spacecraft will work for 10 years. Also, although there are many THEORIES of how to design spacecraft that could travel closer to the speed of light, not a single design has ever been built and actually tested to see if it works. So, I doubt that in your lifetime, or that of my two daughters, we will ever see a probe launched to these stars.
Instead, a far more efficient way is to build interferometer-type devices in Earth-orbit that can image these planets and study them spectroscopically. In principle, we can detect Earth-sized planets out to 50 light years, and determine whether their atmospheres have free oxygen ( indicating life as we know it) or not. NASA's Terrestrial Planet Finder hopes to do this in the next 20 years. The Terrestrial Planet Finder (TPF) Mission will be an infrared interferometer operating in an orbit designed to detect planets and planetary atmosphere constituents that fall into the category of "earth-like." It will search out planetary systems around the brightest 1000 stars within 13 parsecs of our solar system and will characterize spectra of the brightest 50-100 of the detected planetary systems. TPF will be capable of synthetic imaging as well as spectroscopic analysis. This is an EXCITING prospect that will help us discover life-sustaining worlds within your lifetime!
For a comprehensive essay on interstellar travel have a look at Hugh Ha and also read my essays on Hyperspace and Space Travel in science fiction. New Scientist also has a great page about the physics of Star Trek and warp drive.
Copyright 1997 Dr. Sten Odenwald
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