NASA successfully tests Orion main engine

[Borgholio]

http://www.space.com/30251-nasa-sls-roc ... -fire.html

NASA put the engine at the heart of its huge next-generation rocket to the test again today (Aug. 13).

The agency performed a nearly 9-minute-long "hot fire" test of an RS-25 engine at Stennis Space Center in Mississippi. Four RS-25s will power the core stage of the Space Launch System (SLS) megarocket, which NASA is developing to get astronauts to asteroids, Mars and other deep-space destinations. You can see a video of the rocket engine test here.

The RS-25 blazed on the test stand for 535 seconds — the same amount of time the core engines will fire during an actual SLS launch. [See images of NASA's SLS megarocket]

"There are probably some people in the control center high-fiving, because that was a very successful test," Gary Benton, RS-25 test project manager at Stennis, said on NASA TV just after the test concluded.

Today's test was the sixth of seven planned hot-fire trials for the RS-25, which also served as the main engine for NASA's now-retired space shuttle fleet.

The seven-test series is "designed to put the upgraded former space shuttle main engines through the rigorous temperature and pressure conditions they will experience during a launch," NASA officials said in a statement.

"The tests also support the development of a new controller, or 'brain,' for the engine, which monitors engine status and communicates between the vehicle and the engine, relaying commands to the engine and transmitting data back to the vehicle," the officials added. "The controller also provides closed-loop management of the engine by regulating the thrust and fuel-mixture ratio while monitoring the engine's health and status."

The initial version of SLS will stand 321 feet (98 meters) tall and be capable of lofting 77 tons (70,000 kilograms) to low Earth orbit. But NASA also plans to develop an "evolved" 384-foot-tall (117 m) SLS variant that can loft 143 tons (130,000 kg) and generate about 20 percent more thrust than the agency's famed Saturn V rocket, which sent the Apollo missions on their way to the moon.

On crewed flights, SLS will be topped by NASA's Orion capsule, which is also in development.

SLS and Orion are scheduled to blast off together for the first time in late 2018, on a flight known as Exploration Mission 1 (EM-1). The seven-day EM-1 will send an uncrewed Orion on a journey around the moon, to test out many of the capsule's key systems.

A number of tiny cubesats will launch as secondary payloads on EM-1; some of these bantam craft will hunt for water ice on the moon, measure how deep-space radiation affects DNA and perform an up-close investigation of a near-Earth asteroid.

[Jaepheth]

Took me a minute to remember there's an Orion engine whose testing wouldn't break international treaties.

#NotMyOrion

[Eternal_Freedom]

Indeed, that was my first thought. Followed by "no way are they testing that I'd have seen it on the news" followed by "I'd probably have felt the blasts first."

[Sea Skimmer]

This is physically an engine taken off a space shuttle, that flew into space multiple times before. It damn well better work. They've made a few changes to increase thrust, but not much, and considering the engine will now be one use in flight this is not so demanding anyway. The original engine was designed on the basis of flying every 2 weeks and never even remotely faced that kind of duty cycle. The entire SLS effort remains functionally crippled and pointless by a lack of real payloads. They've come up with some small, light randomness to put on the two funded test flights but funding for actual relevant missions remains as remote as ever. We have dozens of proposals on paper of course, but not even detailed paper in most cases.

[Borgholio]

They've made a few changes to increase thrust, but not much,

I read that their eventual goal was to have a max thrust on the heavy-lift vehicle that was 10-20% greater than the Saturn V.

[Simon_Jester]

Thaaat's not happening with only four engines. An SSME in its original design has a thrust of, what, two million newtons? Less? The F-1 was a lot more powerful than that, and the Saturn V first stage had five F-1s.

[orbitingpluto]

Thaaat's not happening with only four engines. An SSME in its original design has a thrust of, what, two million newtons? Less? The F-1 was a lot more powerful than that, and the Saturn V first stage had five F-1s.

A SSME, per wikipedia, produces 1.8 million newtons at sea-level compared to the F-1's 6 million, so you're right about that that. What's missing is the boosters the Shuttle relied on, and the SLS will rely on too. A single Shuttle-era SRB produces 12 million newtons at sea level, and the Shuttle derived SLS solids are said to have 16 million newtons- two of those solids, plus the contribution from the liquid engines on the core, and the SLS should out thrust the Saturn V.

Anyway, since we're talking about launch vehicles that out thrust a Saturn V, the Energia deserves to be mentioned. The Energia already beat the Saturn V back for sea level thrust in the 1980s, and that effort, while it died due to being expensive and without compelling missions, at least resulted in new engines and processes that did feed back into Russian rocketry. SLS should have more sea level thrust than even Energia, but SLS draws more from existing equipment and processes than Energia did, and while that means SLS could be cheap to develop and build compared to Energia, it doesn't add new things to American rocketry.

[Simon_Jester]

Thaaat's not happening with only four engines. An SSME in its original design has a thrust of, what, two million newtons? Less? The F-1 was a lot more powerful than that, and the Saturn V first stage had five F-1s.

A SSME, per wikipedia, produces 1.8 million newtons at sea-level compared to the F-1's 6 million, so you're right about that that. What's missing is the boosters the Shuttle relied on, and the SLS will rely on too. A single Shuttle-era SRB produces 12 million newtons at sea level, and the Shuttle derived SLS solids are said to have 16 million newtons- two of those solids, plus the contribution from the liquid engines on the core, and the SLS should out thrust the Saturn V.

Ah. Now that's a horse of a different color.

Of course, solid rocket boosters have some issues of their own, among them the way they interfere with the "oh shit" options available to abort if a launch goes wrong. But they certainly work.

Honestly, the US space program is floundering to such an extent that I'm just happy if we even end up having the relevant capabilities in any form. I doubt there will be any significant innovation until the Chinese manage to humiliate us by sending astronauts to take selfies of themselves standing in front of our flags on the moon making goofy faces or something.

[Guardsman Bass]

It'll be the mid-2020s before they realistically do anything with SLS other than test flights, around the time when the ISS is due to end its mission. There may be some funding available for missions at that point, although those missions then won't be done until the early 2030s unless NASA starts funding them some time in the next five years. I don't take that "asteroid around the moon" mission seriously, because the crewed component has shrunk and shrunk - it's at the point where you might as well ask why they don't just pull it into Earth orbit if they're going down the robotic tug route.

I think NASA's pretty comfortable with the hardware and missions they've got right now. They've got a space station with international support, a good robotic program, and ten years from now they'll hopefully have a good lifter for when they actually need to try and figure out a post-ISS mission. Trying to do anything else faster without additional funding would be risky, and would require them to give up something (namely, they'd have to end the ISS sooner).