Rockets are what have gotten all those satellites, spaceships, and people to Earth's orbit and outer space in the past, so building a better rocket is the most pressing ­concern, Chang Diaz believes. Harnessing plasma energy, he says, is one way "to give the United­ States a capability no one else has, and that will get us ahead of the game."

VASIMR (Variable Specific Impulse Magnetoplasma Rocket) was researched at MIT, found a home at NASA's Advanced Propulsion Lab, and is now in the creative custody of Chang Diaz's company, Ad Astra (Latin for "to the stars"). Both NASA and Ad Astra will share intellectual property rights in what Chang Diaz considers an all-win situation for government, the private sector, and his company. Ad Astra is hoping their prototype business arrangement with NASA will fuel not only future rockets but faster implementation.

"I think we are witnessing the birth of commercial space transportation," says Chang Diaz. "Something similar happened in the '30s and '40s with the explosion of air travel."

SAILING AWAY

Hundreds of years ago, sails caught the earth's winds to propel a major era of exploration. Today, a growing group of people envision sails propelling voyagers in a new age of discovery throughout the universe.

There is no air in the void of space, but light particles called photons can push against a very thin, reflective material. Unlike a traditional rocket's short bursts of thrust via heavy toxic fuels, sunlight applies a continuous thrust. Changing the angles of sails can adjust attitude and direction. Proponents say initial speeds would be very slow, but a space sail craft could reach speeds of 36,000 mph in a year, and 100,000 mph (2.4 million miles in a day) in three years.