Seeking an ultimate vacation? Forget planet Earth. The time is fast approaching when you can go into space to see a sunrise and sunset every 90 minutes. A team of international researchers has predicted that space tourism will rocket into reality in this century and the "final frontier' could begin showing up in a number of travel guides by the year 2010. Till now, only a few multi-millionaires have been able to afford the current $ 20 million price tag to go up in a Russian rocket for a two-week stay at the International Space Station. But, according to the researchers, shorter and more affordable "suborbital' space flights, costing $ 80,000 per trip, will drive space tourism in the near term. "During these flights, a spacecraft reaches space, but it does not enter Earth's orbit. Suborbital trips are likely to become available to tourists by 2010-2015, while tourism in space hotels is on a longer trajectory, predicted to become a reality in 2025. "Passengers will enter a world that only astronauts and cosmonauts have experienced