Google co-founder Sergey Brin has put down $5 million toward a flight to the international space station with the company that has sent millionaires and even a billionaire into orbit. ...

The 34-year-old Brin, who founded Google along with Larry Page, was the moving force behind his company's sponsorship of the $30 million Google Lunar X Prize. That competition would reward the first teams to put a privately funded probe on the moon.

If he goes through with the flight, Brin could become the richest human to go into space. He ranks as the fifth-richest American on Forbes magazine's 2007 list, with an estimated net worth of $18.5 billion. -- (MSNBC)