Gregory Hammond Olsen is an American entrepreneur, engineer and scientist who, in October 2005, became the third private citizen to make a self-funded trip to the International Space Station with the company Space Adventures.

Space tourism is human space travel for recreational purposes. There are several different types of space tourism, including orbital, suborbital and lunar space tourism. Tourists are motivated by the possibility of viewing Earth from space, feeling weightlessness, experiencing extremely high speed and something unusual, and contributing to science.