Following a first day of delays due to weather, an errant boat, and stuck valves, NASA launched its first new spacecraft for carrying astronauts to and from space on Friday morning. This test flight of the Orion capsule — the first test flight of a crewed spaceship since 1981 — is intended to demonstrate technologies critical to astronaut safety. While Orion will eventually hold four crew members, the capsule was launched on Friday without anyone on board. Astronauts won't be sent into space aboard the Orion until other relevant vehicles are declared operational, which is expected to be sometime around 2021.
For Friday's test flight, the Orion capsule was carried to space on top of a Delta IV Heavy rocket. Over the course the four-and-a-half-hour mission the capsule will go into orbit, transition to a wider elliptical orbit, and reach a maximum altitude above the planet of 3,600 miles. For reference, the International Space Station orbits Earth at a distance of roughly 200 miles. The capsule is going into such a deep orbit in order to accurately simulate the conditions it is expected to endure in operational use.
When used for exploration missions, the Orion capsule will be sent into space on top of a different rocket, the massive Space Launch System (SLS). The SLS is currently under development and is expected to carry out a test flight no sooner than 2018, when it will be paired with another uncrewed Orion capsule to assess the entire launch and capsule system.
Ultimately, the Orion will be used as a workhorse in a number of different missions including, but not limited to, NASA's planned asteroid retrieval mission and eventual human missions to Mars. During a full-up exploration mission like that, the crew module (a.k.a. the multi-purpose crew vehicle, or MPCV) will be only one part of a larger system that will, at minimum, include a European-built service module that will provide power and other support to the Orion and the SLS.
The Orion capsule itself has a very specific role in these future missions — to carry astronauts through the risky launch and reentry mission phases. Considering that the two fatal Space Shuttle accidents — the destruction of the Challenger on liftoff in 1986 and the disintegration of the Columbia in 2003 — occurred during ascent and descent, it's unsurprising that NASA has paid extra attention to these two mission phases.
To enhance crew safety on ascent, the Orion will incorporate a new Launch Abort System (LAS) — the small, narrow, pointy tip on top of the rocket. The LAS is actually a small, high-thrust rocket attached to the top of the capsule. In the event of a problem on launch, the LAS will produce a very brief, very high burst of thrust that should — in theory — pull the capsule away from the rocket, getting it clear of danger. Once safely away from the rocket and impending calamity, the capsule would then stabilize and deploy its parachutes to return the crew safely.
But the main purpose of this flight is to test the thermal protection system that will keep the astronauts from burning up on re-entry. Because using rockets to slow down before re-entry involves the costly and difficult proposition of lifting into space even more fuel and more engines, spacecraft returning to Earth generally rely on passage through the atmosphere to slow the spacecraft down.
The faster a spacecraft is going when it is trying to slow down, the higher the re-entry temperatures it faces. In missions that involve returning from destinations beyond an orbit close to Earth, the spacecraft will be coming back at a very high speed indeed.
Making sure those systems work in those incredibly hostile conditions is the main focus of Friday's test flight. In this case, the Orion will be trying to slow down from 20,000 miles per hour to about 300 miles per hour in just under six minutes. This will expose the capsule to re-entry temperatures of 4,000°F — more than twice the temperature of lava. That's right. Compared to the re-entry environment, an Orion capsule plopped in molten lava would find the lava relatively cool and soothing.
In a future lunar mission, the capsule will experience re-entry temperatures that will be another 25 percent higher than the ones being tested this morning. A future Mars mission will involve an even faster return. But first things first: worry about 4,000°F — hot enough to melt the inside of a nuclear reactor — before tackling 5,000°F or higher.
Assuming everything is peachy and the spacecraft and hypothetical crew survives the experience of seeing the very air turn into an incandescent, glowing plasma around them, there's a couple of other things the capsule needs to do on its way home, like deploy parachutes to slow it down to a genteel 20 mph. It almost seems insignificant after plummeting through screaming napalm death at five and half miles per second, but without those parachutes for that last little bit of breaking, the sudden stop at the end would still turn the capsule and everything inside to shrapnel and tragedy.
Once slowed to a more stately speed, the Orion will then splash down in the ocean and float along merrily — at which point it's the Navy's job to recover the spacecraft and ensure that the astronauts aren't forced to turn to piracy as they spend the rest of their days sailing the seven seas in their capsule. Although the idea of astronaut pirates boarding unsuspecting ships from a floating space capsule is undeniably cool, both the Orion and the astronauts are intended to be reusable, and the US government will be keen to get both the crew and the spacecraft safely back to shore so that it has the option of shooting them up into space again.
Successful re-entry, splashdown, and recovery won't mean that NASA is quite ready to start flinging astronauts to the far corners of the cosmos; the service module and launch vehicle aren't yet ready for prime time. Even if it all goes as planned, getting all the other systems ready will take a few years. But a success on Friday will mean that NASA has developed effective technologies that are vital to getting the people with the Right Stuff through the toughest commute in (or off) the world.
Follow Ryan Faith on Twitter: @Operation_Ryan
Image via NASA