"Make your reservations now. The space tourism industry is officially open for business, and tickets are going for a mere $20 million for a one-week stay in space. " Space tourism is already happening, but for unrealistic prices. It is only for people who can pay a great sum of money.

"Space tourism is space travel for recreational, leisure or business purposes. A number of startup companies have sprung up in recent years, such as Virgin Galactic, hoping to create a space tourism industry." Space tourism, in the future, would be the equivalent of taking a trip to the beach. It would be easy to simply vacation on the Moon.

"It is a real possibility -- a "space elevator" -- that researchers are considering today as a far-out space transportation system for the next century." Spacec travel is becoming a more realistic idea. This form of transportation may become widespread in the near future.

"In a nuclear thermal rocket a working fluid, usually liquid hydrogen, is heated to a high temperature in a nuclear reactor, and then expands through a rocket nozzle to create thrust." A nuclear rocket would have nuclear reactors in it to power it. This would replace the chemical energy of rockets now.

"A space elevator is a proposed type of space transportation system.[1] Its main component is a ribbon-like cable (also called a tether) anchored to the surface and extending into space." The space elevator is a not yet actual idea of travelling into space without the large space shuttles.

"The terraforming of Mars is the hypothetical process by which Martian climate, surface, and known properties would be deliberately changed with the goal of making large areas of the environment more hospitable to human habitation, thus making human colonization much safer and more sustainable." Terraforming Mars is the idea of making Mars suitable for humans to live there. It hasn't become an actual thing yet.

"The Laser Interferometer Space Antenna (LISA) is a proposed space mission concept designed to detect and accurately measure gravitational waves" LISA is also called a Big Bang Observer. Those who believe in the Big Bang are hoping that LISA will be able to prove their theory.

"Kepler is a space observatory launched by NASA to discover Earth-like planets orbiting other stars." Kepler was launched in 2009 and still orbits.

"The Terrestrial Planet Finder (TPF) was a proposed project by NASA to construct a system of telescopes for detecting extrasolar terrestrial planets." The TPF is the most likely option we have to further the goals of Kepler.

"An exoplanet, or extrasolar planet, is a planet outside the Solar System" More than a thousand extrasolar planets have been discovered. There are more than 100 billion planets in the Milky Way.