NASA Test-Fires Key Engine for New Launch System

by Nancy Atkinson on November 9, 2011

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NASA successfully test-fired the J2-X rocket engine on Wednesday, a key component of the Space Launch System, NASA’s giant new rocket that is slated to take cargo and crew beyond low Earth orbit. A deafening 500-second firing test at the Stennis Space Center showed the engine is ready for the next steps in building the SLS rocket.

“What you heard to today is the sound of the front end of the critical path to the future,” said Stennis Director Patrick Scheuermann, speaking at a press conference immediately after the test fire, which began at 4:04 p.m. EST (2104 GMT).

The J-2X will power the upper stage of the SLS, the $10 billion next generation heavy-lift rocket. The first flight of the new rocket won’t be until 2021, however.

“The J-2X engine is critical to the development of the Space Launch System,” Dan Dumbacher, NASA’s deputy associate administrator for exploration systems development, said after the test in Mississippi. “Today’s test means NASA is moving closer to developing the rocket it needs if humans are to explore beyond low-Earth orbit.”

Data from the test will be analyzed as operators prepare for additional engine firings. The J-2X and the RS-25D/E engines for the SLS core stage will be tested for flight certification at Stennis. Both engines use liquid hydrogen and liquid oxygen propellants. The core stage engines were developed originally for the space shuttle.

“We have 500 seconds of good data, and the first look is that everything went great. The J-2X engine team and the SLS program as a whole are extremely happy that we accomplished a good, safe and successful test today,” said Mike Kynard, Space Launch System Engines Element Manager at NASA’s Marshall Space Flight Center in Huntsville, Ala. “This engine test firing gives us critical data to move forward in the engine’s development.”

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Nancy Atkinson is Universe Today's Senior Editor. She also works with Astronomy Cast, and is a NASA/JPL Solar System Ambassador.

Nathan November 9, 2011 at 11:16 PM

I don’t know why but I need one of those.

John Gorkos November 10, 2011 at 3:40 AM

Hooray for the Hawaiian shirts worn by the entire test crew in the control bunker. Serious rocket science should always be counterbalanced with levity in apparel.

Anonymous November 10, 2011 at 4:29 AM

I think I understand the reasons why the J-2X is a good engine for the SLS.

Can anyone please explain why NASA has been pursuing hydrogen/oxygen engines for the booster stage? My understanding is that it may have higher specific impulse than RP-1/LOX, but the huge tank size for (lower-density) hydrogen is a minus. Impulse means higher exhaust velocity, but the booster is really just getting the rest of the rocket out of the lower atmosphere.

The SSME went all the way from sea level to space, so that’s understandable. I don’t see why it’s a good fit here, especially since it’s a very complicated engine, and we only have a small number left.

Torbjörn Larsson November 10, 2011 at 2:59 PM

I think NASA would concede to your analysis, seeing that any liquid boosters would be RP-based. That link (and an earlier UT article) mentions the 14-15 salvaged RS-25 engines that makes one reason for “saving time and initial cost”.* Another is reusing external tank design.

The unmentioned reason would be that reuse also maintains the pork industry around NASA. SLS seems to be twice as large as the economical rocket of today. (I.e. you could launch two Falcon Heavy substitutes for less than the SLS cost.)

——————
* The problem is, IIRC, there are no such RP engines. At least in US, because Energia and its RP booster engines is the SLS forerunner. And, I would say, the 2nd most beautiful orbital launcher behind Saturn V.

The fully evolved Vulcan launcher would have been awesome, raising some ~ 175 ton to LEO. But as always, NASA suffers from pork or possibly “not invented here” syndrome.

Same as for the Buran tiles that kicked the Shuttle tiles ass in temperature hardiness and hull fixation robustness. You would think that anyone would by into the better product. But nooo …

Anonymous November 10, 2011 at 3:57 PM

It’s more due to pork then anything. Nasa is beholden to congressional decrees about what suppliers they must use for things, which really holds them back. If the engineers chose the designs instead of congress, we’d be on Mars by now.

Lucas Mearian November 10, 2011 at 9:57 PM

Could you have possibly provided less information about the J2-X engine? What the heck makes this engine NASA’s next-gen SLS rocket?

Torbjörn Larsson November 11, 2011 at 11:53 AM

Good questions.

That engine is the one that makes sense I think, and something similar would have to be provided anyway. It is a Saturn V development 2nd stage legacy, one of the first engines that could do a restart to break out of a parking orbit. (In Saturn V’s case to a translunar orbit.)

Of course it is a Constellation/pork legacy as well. You could question the LH use, but since it is on top a LH/LOX stage anyway, and it has a slightly better vacuum Isp, it makes sense in the context.

SpaceX makes do with a restartable RP/LOX engine on their RP/LOX stack. Such a Merlin has “dual redundant pyrophoric igniters (TEA-TEB)” for restart, which presumably means it can do at least and possibly max one restart. (In which case I would guess the same goes for a J2-X stage.)

Torbjörn Larsson November 11, 2011 at 11:53 AM

Good questions.

That engine is the one that makes sense I think, and something similar would have to be provided anyway. It is a Saturn V development 2nd stage legacy, one of the first engines that could do a restart to break out of a parking orbit. (In Saturn V’s case to a translunar orbit.)

Of course it is a Constellation/pork legacy as well. You could question the LH use, but since it is on top a LH/LOX stage anyway, and it has a slightly better vacuum Isp, it makes sense in the context.

SpaceX makes do with a restartable RP/LOX engine on their RP/LOX stack. Such a Merlin has “dual redundant pyrophoric igniters (TEA-TEB)” for restart, which presumably means it can do at least and possibly max one restart. (In which case I would guess the same goes for a J2-X stage.)

Robert Gishubl November 11, 2011 at 6:18 AM

It is nice to have an engine test but the whole SLS program is an inefficient waste of money. As the justification is based on false information.
The cost per unit carried for larger systems is lower providing you have comparable per unit development costs. But for the SLS development cost low low estimate of $15 billion and a high launch rate of 3 per year for 5 years that requires a $1 billion amortisation of development costs per flight before operating costs. Compare this with SpaceX Falcon heavy which is in build for flight in 2012/2013 and the core has already flown as Falcon 9 it has a payload of 53 tons and has no government development cost and all up flight cost of $125 million. So you could launch 6360 tons to LEO orbit for just the low low estimate of the development of SLS let alone flight costs. Or another way SLS costs a minimum of $14,285 per kg in development costs alone not including launch costs vs $2,358 per kg all up for Falcon Heavy. The Falcon Heavy will fly sooner and has much lower technical risk than SLS as the core stage has already flown.
Another issue is that the 70 tons or even possible future 130 tons is not enough for a single launch Mars direct spacecraft so it will need multiple launches to build a sufficiently large spacecraft for a Mars return mission. So there is no reason why a modular craft built of 70 ton modules could not be built of 50 ton modules.
If SLS could be developed for minimal government funding I would be all for it but it will cost many billions that could be spent on other systems that would make a real difference.

Torbjörn Larsson November 11, 2011 at 12:15 PM

Yes, over the years a lot of “must have’s” have been raised that blocks manned trips to specifically Mars. First it was the need for a space station,* then a lunar test facility/way station**, then “a big dumb booster”. I have fallen for all three, but as history made my choices irrelevant I have been forced to abandon them.

Now I am stuck with travel time vs potentially insufficiently closed biohabitats and too much radiation in addition to how to land large masses. But those may well turn out to be chimeras as well.

Musk is correct here, if you want to do something, go for the core issues first. In his case building a sufficient and affordable (multiple uses) infrastructure. NASA’s core issues is funding and public oversight, so pork and safety*** is their drivers.

———————-
* Speaking of multiple uses, a LEO space station has that in spades. Mars exploration isn’t just one of them, unless we consider some tests here instead of on the lunar surface and possibly assembly of large modular crafts in orbit.

It doesn’t seem to be affordable, however, despite all the science and development we get out of it. Next one needs to be more like the russian heritage – a Bigelow type, perhaps.

** To be fair, the lunar facilities started out as a goal all by themselves.

*** Safety often compromised by the political pork trade, as here: why use a new, extremely powerful, launcher for capsules too?

Torbjörn Larsson November 11, 2011 at 12:15 PM

Yes, over the years a lot of “must have’s” have been raised that blocks manned trips to specifically Mars. First it was the need for a space station,* then a lunar test facility/way station**, then “a big dumb booster”. I have fallen for all three, but as history made my choices irrelevant I have been forced to abandon them.

Now I am stuck with travel time vs potentially insufficiently closed biohabitats and too much radiation in addition to how to land large masses. But those may well turn out to be chimeras as well.

Musk is correct here, if you want to do something, go for the core issues first. In his case building a sufficient and affordable (multiple uses) infrastructure. NASA’s core issues is funding and public oversight, so pork and safety*** is their drivers.

———————-
* Speaking of multiple uses, a LEO space station has that in spades. Mars exploration isn’t just one of them, unless we consider some tests here instead of on the lunar surface and possibly assembly of large modular crafts in orbit.

It doesn’t seem to be affordable, however, despite all the science and development we get out of it. Next one needs to be more like the russian heritage – a Bigelow type, perhaps.

** To be fair, the lunar facilities started out as a goal all by themselves.

*** Safety often compromised by the political pork trade, as here: why use a new, extremely powerful, launcher for capsules too?

Robert Gishubl November 11, 2011 at 6:18 AM

It is nice to have an engine test but the whole SLS program is an inefficient waste of money. As the justification is based on false information.
The cost per unit carried for larger systems is lower providing you have comparable per unit development costs. But for the SLS development cost low low estimate of $15 billion and a high launch rate of 3 per year for 5 years that requires a $1 billion amortisation of development costs per flight before operating costs. Compare this with SpaceX Falcon heavy which is in build for flight in 2012/2013 and the core has already flown as Falcon 9 it has a payload of 53 tons and has no government development cost and all up flight cost of $125 million. So you could launch 6360 tons to LEO orbit for just the low low estimate of the development of SLS let alone flight costs. Or another way SLS costs a minimum of $14,285 per kg in development costs alone not including launch costs vs $2,358 per kg all up for Falcon Heavy. The Falcon Heavy will fly sooner and has much lower technical risk than SLS as the core stage has already flown.
Another issue is that the 70 tons or even possible future 130 tons is not enough for a single launch Mars direct spacecraft so it will need multiple launches to build a sufficiently large spacecraft for a Mars return mission. So there is no reason why a modular craft built of 70 ton modules could not be built of 50 ton modules.
If SLS could be developed for minimal government funding I would be all for it but it will cost many billions that could be spent on other systems that would make a real difference.

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