James Oberg has an interesting article on crazy ideas about space flight. Here's a few choice excerpts:
No-gravity myth #1: One terrifying but dying myth is that satellites with nuclear weapons or spy cameras can hover over particular ground targets such as Washington, DC. That's easy if there's no gravity in space, but it's impossible in the real world except at a precise distance over the equator (the so-called geostationary orbits).
No-gravity myth #2: For those fascinated by the possibilities of "war in space, Earthside analogies have been stretched beyond the breaking point. The oft-repeated idea of "shooting down a satellite" falls into that category because a satellite struck by a weapon would retain its speed and hence would stay in orbit, dead or alive, whole or in pieces.
No-gravity myth #3: If the notorious clouds of "space junk" stay up there because the fragments float around aimlessly, why can't we send up a shuttle or two and pick up all the trash as it goes by? But when you realize that each piece of junk flies through space at tremendous speeds in different locations and directions, the "obvious solution" evaporates.
No-gravity myth #4: Another tipoff that someone possesses an inadequate understanding of space physics is if they ever use the phrase "falling into the sun." For example, some people seem to believe that if nuclear waste can be thrown across the nonexistent "gravity boundary" between the earth and outer space, it will fall harmlessly into the sun. While disposing of dangerous wastes in space is not entirely a hare brained scheme, serious analysts realize that all probes launched away from Earth enter orbit around the sun with the earth's own forward speed, which is more than adequate to prevent them from falling into the sun. It's far easier to push the junk outward to interstellar space 3.7 billion miles away (if you're patient) than to push it into the sun 93 million miles away.
Read the entire article on Jim Oberg's website.