<p>While humans may be running out of unexplored regions on Earth, space remains a deep and intriguing frontier, especially for tourists. <a href="http://www.nasa.gov/">NASA</a>'s push to get private "space taxis" flying to the International Space Station in five years is fueling interest in retail space travel. And private companies are rushing to launch the non-astronauts among us into space, albeit for a high price.</p><p>One of the more immediately plausible new efforts is SpaceShipTwo, a jet-propelled spacecraft developed by London-based Virgin Group and an aeronautical design company called <a href="http://www.scaled.com/">Scaled Composites</a>. The companies are finishing orbital tests and aim to offer suborbital flights for several hours at around 60 miles (96 kilometers) above Earth's surface by the end of this year. The price? A hefty $200,000 per seat. Virgin Group's <a href="http://www.virgingalactic.com/">Virgin Galactic</a> is already <a href="http://www.virgingalactic.com/booking/">taking bookings</a>.</p>