Rocket Scientist to Pay Way into Space     What would it be worth to be the first tourist in space? For Dennis Tito, it's reportedly a mere $20 million to a lifelong dream. For that price, Mr. Tito is headed to MIR, the Russian space station that has been orbiting the Earth for the past 14 years, 250 miles out in space. Tito, a former rocket scientist, has already made his mark here on Earth. He's the founder of L.A.-based Wilshire Associates and its Wilshire 5000 index of stocks, known as the broadest measure of the markets. But soon, Tito will be known for something, well, out of this world.