NASA's O'Flyin'

The Orion is so important because it's the first craft in a long, long time built to explore beyond LEO. This is what will take us back to the moon and to Mars.

Here's the rundown, stolen shamelessly from Gizmodo.

Officially dubbed the Orion MPCV (Multi-Purpose Crew Vehicle), this craft is specifically built to travel far, far beyond Low Earth Orbit—like the Moon, Mars, or even deep space—then return safely home. NASA plans to use a fleet of these spacecraft for just about everything, from routine supply runs to the ISS to dropping a crew on a passing asteroid.

Launch Abort System

NASA is dead serious about preventing another Challenger disaster. As such, the uppermost section of the Orion is dedicated to the launch abort system (LAS). This tower is designed to instantly detach and rocket the crew capsule to safety if something goes awry during liftoff. It also helps shield the crew from heat and pressure changes during the rise to orbit before popping off and falling back to Earth once the MPCV reaches altitude.

Crew Module

The crew module sits between the LAS and the Service Module (aka the engine and life-support). Constructed of an aluminum-lithium alloy, it can hold up to six crew members along with all their equipment.

It offers a range of improvements over previous capsules including a better-designed cockpit, more-powerful computers, indoor plumbing, and an emergency auto-docking feature. It takes over the repetitive monitoring tasks that Apollo crews used to have to continually check themselves. Once in orbit, the on-board computers will autonomously rendezvous with other spacecraft rather than rely on humans to do it. However, the most exciting new feature—for the astronauts at least—is the inclusion of a "relief tube" in the capsule. Rather than crap in a plastic bag, as the Apollo guys did, the Orion will use a more discreet and sanitary system originally developed aboard Skylab.

Opposed to the Space Shuttles, with were each used over and over, the Orion crew module is only slightly reusable. Each one is expected to withstand ten flights before being retired. And, interestingly, the crew module has no landing gear—it is a water landing or nothing for the Orion.

Service Module

The service module is where the magic happens. Magic, meaning, the technologies that keep astronauts from freezing/exploding in the dark void. The service module is built of the same aluminum-lithium alloy as the Crew Module. It controls in-flight propulsion—generated by a "7500-pound thrust, pressure-fed, regeneratively cooled, storable bi-propellant, rocket engine made by Aerojet" according to NASA—and provides water and breathable air for the crew as well as prevents the control systems from freezing. It even has unpressurized cargo space for equipment and unlucky stowaways. And, while the LAS pops off just after liftoff, the Service Module remains connected to the Crew Module until the orbiter is ready to begin reentry.

In another American first, the Service Module will incorporate deployable solar panels to capture solar energy while in flight, much like the Mars Landers' UltraFlex wings. This integration eliminates the need to carry heavy, unreliable fuel cells and all the necessary bits and pieces to use the fuel, which makes the Orion lighter and more agile.