This Thursday, the capsule that has the best chance of eventually taking humans to Mars will finally go into space.
It's been a long time coming for the Orion Multi-Purpose Crew Vehicle, which grew out of several earlier canceled projects that were started in the wake of the Columbia accident in 2004. But NASA says it's time to let Orion orbit the Earth, albeit without any humans on board (this time).
The "multi-purpose" bit of Orion is important—as far as NASA is concerned, this is the space capsule of both the near and relatively far future. Orion won't be going to the International Space Station—NASA has SpaceX and its Dragon capsule (and whatever Boeing eventually dreams up) for that. Instead, Orion will be used for NASA's controversial asteroid-lassoing mission, which is planned for the early 2020s and, eventually, for a manned mission to Mars.
So Thursday's test is pretty important. NASA has seemingly given up on low-Earth orbit and is focusing on further-flung adventures and exploration. That move has been somewhat controversial, considering that, for the time being, American astronauts have to rent out seats on Russian Soyuz ships to get to and from the ISS. Considering that Russia and the US don't have the greatest of relationships right now, Congress isn't happy about that.
Earlier this summer NASA administrator Charles Bolden told Congress that reworking Orion to go to the ISS would ruin the whole plan, which is to go to Mars and to an asteroid. He says that the asteroid mission, which would take place in cislunar space (the area around the moon) will allow NASA to learn what's necessary to make it to Mars, and, presumably, back.
"That's where you develop the technology," he said. "The asteroid redirect mission allows us to get to cislunar space and fulfill a number of requirements [for eventually getting to Mars], such as solar propulsion."
Even though it's an unmanned test, Thursday's flight represents NASA's first real step towards sending astronauts beyond the moon.
"It is designed to go farther than humans have ever traveled, well beyond the moon, pushing the boundaries of spaceflight to new heights," NASA wrote in a blog post. "The area around our moon, in particular, called cis-lunar space, is a rich environment for testing human exploration needs, like advanced spacewalking suits, navigating using gravity, and protecting astronauts from radiation and extreme temperatures."
Thursday's test won't get into any of that. Instead, Orion will orbit the Earth twice before returning. During this time, it will be subjected to temperatures of roughly 4,000 degrees Fahrenheit, a critical test for the spacecraft's heat shield. The capsule will eventually land 600 miles off the coast of San Diego, somewhere in the Pacific Ocean, where it will be recovered.
Also worth noting: On Thursday, Orion will be launched aboard a Delta IV rocket, which has been used for years. Eventually, when we go to Mars, Orion will be launched attached to the still-in-development Space Launch System, which is the biggest rocket NASA has ever built and is supposed to enter use sometime in 2017.
NASA says the weather looks decent this Thursday, saying there's roughly a 60 percent chance the Orion launch will be a "go."