Spacetravel How fast...??
How fast can our most advanced space faring vehicles travel?
Maximum speed for rockets is roughly whatever the exhaust
velocity is - since everything we have put into space so far
depends on chemical reactions for propulsion, that limits
things to not much more than escape velocity from the solar
system - somewhere around 25,000 miles per hour. There are lots
of proposals for getting space vehicles to go much faster
than that, but so far nobody's actually put one together yet.
Many of these proposals rely on nuclear energy, which people are
still very afraid to actually use. Other techniques include using
light (from a very strong laser) to propel a sail-like spaceship.
To some extent, they all require either a very large initial cost
or some kind of technology beyond what we currently have available.
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Update: June 2012