Space

Day 1,464 of the Mars rovers' 90-day mission to Mars (for those of you keeping track), and Steve Squires, the head of science operations for the Spirit and Opportunity rovers is getting us up to date on their latest findings. Most important: serendipity in action. The Spirit rover's right front wheel has broken, so engineers turn the rover around, drive it in reverse, and drag the wheel behind the rover. As it slogs across the planet, it carves a trench. And my, what a trench it carves.

It started out as a 10-ton satellite packed with hazardous materials plummeting towards Earth. Then it dropped down to 4 tons, and the materials turned out not to be hazardous. Details are still sketchy, but it now seems clear that the NROL-21 USA-193 satellite that failed just hours after its December 2006 launch is now on its way back down to Earth. Should we be worried?

Scenario 1: Sport

Sixty miles up, you sit in a chair on the open deck of a small rocket, admiring the stars above, the Earth far, far below. The vacuum beyond your visor is cold, but it would boil your blood if your pressure suit failed. You give your parachute straps a reassuring pat. It's utterly silent. Just you and your fragile body, hovering alone above the Earth. "Space Diver One, you are go," crackles a voice in your ear, and you undo your harness and stand up. There's nothing for it now: You paid a lot of money for this.

NASA hopes to someday use a robot like Bill Stone's DepthX to explore Europa, a frozen moon of Jupiter and one of the most probably places in our solar system to support life.

For a look at a prototypical Space Marine mission, launch the photo gallery.

For a gallery of Hubble's most incredible images, click "View Photos" at left The terrific thing about NASA chief Michael Griffin's decision to launch a Hubble servicing missionthe telescope's fifth since 1990isn't simply that the spacecraft will be able to limp along for another four years. After astronauts visit Hubble on this latest mission (set to launch no earlier than May 2008), the telescope will be more powerful than it has ever been, thanks to some incredible new instruments being tested now.

The Wirefly X Prize Cup kicked off Thursday with the exclusive X Prize Executive Summit, a high-powered brainstorming and networking event that brought together a distinguished group of the world's most influential entrepreneurs, astronauts, heads of NASA and the FAA, tech-industry experts and visionaries to talk about the future of the emerging personal-spaceflight industry.

Click 'View Photos' to look inside the cabin of SpaceShipTwo. And for an eye-popping video ride, scroll to the bottom of the page Virgin Galactic today unveiled a mock-up of the slick, Philippe Starckâ€designed interior of its SpaceShipTwo suborbital tourist vehicle.

Can't decide where to spend your fortune on a trip out of Earth's atmosphere? Check out our Tourist's Guide to Space.

Before NASA sends astronauts to live on the moon in 2020, per presidential mandate, the agency must first figure out what resources the lunar neighborhood has to offer. Are there stores of ice that could be melted and processed to provide oxygen to breathe and hydrogen for rocket fuel? Or is the potential fuel locked up inside rocks?

In July, the space shuttle Discovery is slated to deliver two tons of hardware and supplies to the partially built International Space Station. This mission is paid for. As for the 16 more needed to finish assembly, as mandated by President George W. Bush two years ago in his Vision for Space Exploration policy, NASA is short by as much as $5 billion.

NASA's Ion Engine

1. Charge the Fuel

Xenon is an inert gas, seemingly useless for rocketry. Before it´s used as fuel, the engine must convert it into an electrically charged gas, also called a plasma. An electron emitter fires electrons at the xenon gas. When an electron hits a xenon atom, it strips off an additional electron from the atom´s shell to create a positively charged xenon ion.

"We believe we have the Holy Grail," says Don Brownlee, the lead scientist for NASA's Stardust mission, in which a robotic spacecraft traveled nearly three billion miles to capture interstellar dust and comet particles and then flew back to Earth in a seven-year round-trip voyage. The touch-down this January in the Utah desert marked the first successful return of extraterrestrial material since 1976, when an unmanned Soviet probe last brought home moon rocks.

The X Prize Cup, an annual rocket race and showcase set to touch down every October in Las Cruces, New Mexico, held its inaugural gathering on October 9. Founder Peter Diamandis, whose X Prize Foundation last year awarded $10 million for the first private manned spaceship, plans for the XP Cup to be a chance for space fans to meet the engineers and pilots of a new generation of commercial spaceships and to watch them compete in rocket races both in and out of the Earth's atmosphere.