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J-2X engine  (Source: cache.boston.com)
NASA plans to test the J-2X engine throughout the rest of this year

NASA announced that its next-generation J-2X engine will begin its second round of tests starting today.

The J-2X engine is a redesign of the J-2 engine that carried astronauts to the moon during the 1960s and 1970s. It was developed by Pratt and Whitney Rocketdyne, which were awarded a $1.2 billion NASA contract.

The J-2X is the first new liquid oxygen and liquid hydrogen rocket engine made in 40 years that will be able to send humans into space again. In fact, the J-2X engine is designed to power deep space missions and will be used for NASA's Space Launch System (SLS), which is a heavy-lift rocket intended for deep space missions.

Last year, NASA conducted the first round of testing on the J-2X engine, which resulted in successful test firings. In that particular round of sea-level tests, the J-2X engine was fired 10 times total for 1,040 seconds, reaching 100 percent power in just four tests. It also met a full flight-duration firing of 500 seconds in the eighth test, which proved to be quicker than any other U.S. engine.

Now, the J-2X is on to its second round of testing starting today. NASA will now simulate high-altitude conditions where there is lower atmospheric pressure. According to Tom Byrd, J-2X engine lead from NASA's Marshall Space Flight Center in Huntsville, Alabama, J-2X engines will be tested in the SLS' second stage of flight where nozzle data and overall performance will be monitored.

"We're making steady and tangible progress on our new heavy-lift rocket that will launch astronauts on journeys to destinations farther in our solar system," said Charles Bolden, NASA administrator. "As we continue test firings of the J-2X engine and a myriad of other work to open the next great chapter of exploration, we're demonstrating our commitment right now to America's continued leadership in space."

The United States' role in space has been a hot topic since NASA retired its space shuttle fleet last year. Since that retirement, American astronauts have been forced to depend on Russian Soyuz rockets to make their way to the International Space Station (ISS), where the cost of one seat on the Russian spacecraft is expected to increase to $63 million by 2015. The U.S. knew it had to find another way to the ISS without depending on Russia, so it jumped on the private space travel industry to fill in the gap.

SpaceX, which is expected to be the first private company to send a spacecraft to the ISS on May 7, stepped up with its Dragon cargo capsule in an attempt to fill the void of the space shuttle fleet.

With the U.S. back in the space race, NASA plans to test the J-2X engine throughout the rest of this year. The engine is currently on the A-2 Test Stand at NASA's Stennis Space Center in Mississippi.

Source: NASA



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not a bad start
By chromal on 4/25/2012 8:05:24 PM , Rating: 5
Now they just need to refresh the Rocketdyne F-1 to a new F-1X, and we can build the Saturn V mkII and pick up where we left off in the early 1970s when we allowed the space shuttle to distract us from deep space progress.




RE: not a bad start
By delphinus100 on 4/25/2012 8:14:19 PM , Rating: 2
The only reason we carried out Lunar missions on single-launch, heavy-lift rockets, was because it was the fastest way to get one done (always being mindful that we were under the explicit time constraint of; 'before the decade is out,' and the implicit constraint of also doing so before the Soviets), not the most sustainable or cost-effective. (IOW, Lunar Orbit Rendezvous was estimated to take less time to develop than Direct Ascent or Earth Orbit Rendezvous)

The Cold War is over, as is Apollo. It's not the way we need to go back.


RE: not a bad start
By gamerk2 on 4/26/2012 1:27:34 PM , Rating: 2
LOR was also far cheaper. Direct Ascent was the favored mode, but the engine kept getting bigger and bigger and bigger...[nevermind no one ever figured out how to actually sight the thing down...]. EOR requires several smaller launches, but if any one fails...

Remember, once in space, your requirements for an engine drop rapidly. Most of the power used on an Apollo flight was exiting the atmosphere. Hence why a single use booster to get to orbit made the most sense, both from an economy and speed standpoint.

Compared to the cost of the CSM, the Saturn V's were cheap.


RE: not a bad start
By sparkuss on 4/25/2012 9:55:19 PM , Rating: 3
As much as I know, I understand the need for a heavy lift vehicle to get major systems into space.

But with commercial ability to get as far as they can already with non-rocket (Spaceship One), is it just cost prohibitive to get to a flight based vehicle just for crew flight up to orbit?


RE: not a bad start
By sportswear13 on 4/26/12, Rating: -1
RE: not a bad start
By Gondor on 4/26/2012 5:28:00 AM , Rating: 2
What ???


RE: not a bad start
By mellomonk on 4/26/2012 8:56:06 AM , Rating: 3
The notion of landing wheels down on a runway is romantic, but it is tough to beat the safety and simplicity of a ballistic re-entry and parachute landing. The new generation of 'capsules' will be reusable, unlike Apollo-era tech. As great as the shuttle was it's ground handling and refurbishment was a manpower and cost nightmare. Human flight will be far safer and ironically cheaper in the new generation of rockets and capsules.

I think that wings could return with some sort of partial air breathing, scramjet powered orbital craft, ala the X-30 NASP. Or even a fully reusable shuttle design similar to the original NASA concepts that where canned in 72'in lieu of the Rockwell Shuttle due to costs. Hopefully with forty plus years of experience and tech we could overcome the development and safety issues to build a new winged spacecraft.

But then there is the funding issue......


RE: not a bad start
By Solandri on 4/26/2012 3:49:31 PM , Rating: 3
quote:
The notion of landing wheels down on a runway is romantic, but it is tough to beat the safety and simplicity of a ballistic re-entry and parachute landing. The new generation of 'capsules' will be reusable, unlike Apollo-era tech. As great as the shuttle was it's ground handling and refurbishment was a manpower and cost nightmare.

Correct. The rationale for the Shuttle was the huge amount of equipment being thrown away with each Apollo and Gemini launch. The financial calculations were done and it was decided that re-using significant parts of the spacecraft would be more cost-effective.

Unfortunately, those calculations were done assuming 50-60 launches a year (yes we were supposed to be launching one shuttle every week - having two in orbit at a time was supposed to be common). With the 6-12 launches a year we were getting, the overhead of maintaining the refit and refurbishing facilities and staff far outweighed the cost savings of reusing the spacecraft.

Long-term I think we're going to see rockets and space planes used only to ferry delicate payloads like people. The more robust payloads like fuel, water, food, and most spacecraft equipment will be shot up into space via gas guns or rail guns. Those will have accelerations of 100g or more, making it unsurvivable for people. But they avoid the need to burn fuel to lift fuel, and so should afford considerable cost savings. Once all the pieces are in orbit, you can assemble them to build your space station / spacecraft, and off you go.


RE: not a bad start
By gamerk2 on 4/26/2012 1:31:06 PM , Rating: 2
The issue is escape velocity. Getting into Low Earth Orbit is easy enough, getting out of orbit requires more power. So there are two ways to get out of orbit:

1: Use a large rocket to get into orbit, and have the spaceship fitted with a smaller engine.

2: Have a engine capable of escape velocity built into the spaceship.

Option 2 greatly increases the spaceships mass, requiring an ever larger engine. Hence why Direct Ascent never would have worked in the long run. Disposable rockets to get into orbit greatly reduces the aircraft size, allowing a smaller engine that is capable of JUST getting out of orbit.


RE: not a bad start
By Jaybus on 4/26/2012 4:25:11 PM , Rating: 2
There is also still the multi-ship approach. The deep space ship consists of a reusable crew module, one or more disposable cargo modules, and one or more disposable booster modules. Those modules are launched separately with a heavy lift booster into LEO and assembled at the ISS. All of the heavy lift launches are automated and without crew. Crew are brought back and forth from the ISS by Space-X.


RE: not a bad start
By Hammer1024 on 4/27/2012 10:21:19 AM , Rating: 3
Kerosene.
By drycrust3 on 4/26/2012 3:53:02 AM , Rating: 2
quote:
The J-2X engine is a redesign of the J-2 engine that carried astronauts to the moon during the 1960s and 1970s. ... The J-2X is the first new liquid oxygen and liquid hydrogen rocket engine made in 40 years ...

According to Wikipedia, the fuel used in the first stage of the Saturn 5 rocket was RP1 and Liquid Oxygen. RP1 is a refined form of Kerosene. Apparently RP1 is superior to Liquid Hydrogen as a fuel.




RE: Kerosene.
By mellomonk on 4/26/2012 8:28:33 AM , Rating: 1
No RP1 is not superior to liquid H2. But it is much easier to work with and non-cryogenic. The Russians have done great work with Kerosene. It has it's place, like first stages of Saturn Vs, but when performance per pound is needed, H2 is the way to go.


RE: Kerosene.
By erple2 on 4/26/2012 11:30:32 AM , Rating: 2
True, but the volume of H2 can be a factor. While it has a drastically higher specific impulse (a measure of its efficiency per weight) that just about every other fuel, it isn't very dense (as far as liquid propellants go). So if you can't afford the volume constraint, you might have to go with other alternatives.

As you mentioned, anything that requires cryogenics is a PITA to handle (from cost to safety).


RE: Kerosene.
By Bubbacub on 4/26/2012 4:21:53 PM , Rating: 2
cryogenic H2 tanks and plumbing weigh a hell of a lot more than non-cryogenic tanks and plumbing.

the extra weight penalty does take much of the specific impulse advantage of h2/lox engines.

personally i think we should concentrate on making cheap, reliable large slightly lower performance engines.

rp1/h2o2 engines seem IMO to have a lot of advantages, non cryogenic, hypergolic, non-toxic, reasonable specific impulse, cheap fuels and very reliable technology. The UK is the only country with much experience in orbital launchers using these engines - they didnt have a single failure of a h2o2/rp1 engine throughout the british space program (till it was killed in 1970).


RE: Kerosene.
By m51 on 4/26/2012 9:39:04 PM , Rating: 3
rp1/h202 is not hypergolic.

With the current state of technology RP1/Lox is the fuel of choice for a LEO booster stage. RP1/Lox engines can achieve very high thrust, high thrust to weight ratios, and the high fuel density reduces over all size and tank weights. Although Lox is cryogenic, it's a mild cryogenic and tanks and insulation are particularly difficult to fabricate nor particularly heavy, especially for a booster stage that can take advantage of ground support equipment. High ISP is not nearly so important for a booster stage as it is for an upper stage or orbital departure stage.

For upper stages LH2/LOX is the fuel of choice because of it's high ISP. Although LH2 requires very large tanks and very aggressive tank insulation because of it's low density and boiling point only 20 degrees above absolute zero, the high ISP more than makes up for these drawbacks where weight and ISP are critical.

The appeal of H2O2 (hydrogen peroxide) was for ballistic missile systems where the missile needed to constantly sit on standby. This pushed the design tradeoffs to sacrifice performance for propellants store-able at room temperature for long periods. Thus the RP1/H2O2 engines in the UK, and the Hydrazine/Nitrogen Tetroxide engines developed in the US and USSR. Even further performance comprises were made for the submarine based missiles and the MX missile that used Solid fuel rockets, but required more stages.

The J2-X project came out of the now cancelled Constellation program. The original plan to use Space Shuttle Main Engines (SSME) as the upper stage engines for the Ares 1 and Ares V turned out not to be feasible because the SSME could not be modified to be air startable (or more accurately Re-startable) an essential requirement. A program was then started to design the J2-X, a modernized and higher thrust version of the venerable J2 engine that was used on the upper stage of the Saturn 5. However it was not possible to achieve the very high performance of the SSME. This forced the redesign of the booster stages which grew larger and larger, and in the case of the ARES I solid rocket motor which could not be made large enough to achieve the original performance forced the cannibalization and weight reduction of the Orion crew capsule. A whole cascade of design changes resulted that pushed the ARES V size and weight up to the point where the Crawler and crawler way could not support the enormous weight and were in danger of needing to be entirely replaced. Program cost kept climbing and even though the shuttle was cancelled and the ISS was planned to be splashed into the ocean in 2015 to redirect those funds to feed the monster there would still have been something like a $70 Billion shortfall in the program. Obama inherited this mess and made the only rational decision possible cancelling it after the Augustine commission report came out.

At any rate the J2-X engine project lives on.


RE: Kerosene.
By Bubbacub on 4/29/2012 8:44:47 AM , Rating: 2
hot decomposing h2o2 combusts with rp1.

though i agree that the two fuels when put into contact at room temperature and pressure minus a catalyst will not combust.

in a rocket engine with the appropriate catalyst the two fuels are effectively hypergolic.

the engines are very very simple and are hence very reliable and also very cheap.

the isp achievable in the sixties out of shed in coventry was ~270. i'm sure with modern manufacturing techniques this could go up a bit.

historically decision making about which fuels to use has always been about performance.

in the days of saturn v - money was no object - everything was orientated around maximum performance in the shortest time.

there is a lot of inertia in the aerospace industry. pressure to keep jobs and factories running at costs has instilled a degree of dogma into rocket design. hell congress have decided that they know more than rocket scientists and have dictated which booster technology is going to be used in SLS.

i would argure that our needs now are different.

we need acceptable performance, reliably and cheaply.

we need a rocket engine design that can be stamped out of an automated production line in a few days rather than have 50 engineers slaving away for weeks on CNC machines.

i think rp1/h2o2 has some advantages in this way.


Aerospike, anyone?
By mitchebk on 4/26/2012 1:27:06 PM , Rating: 2
When is the aerospike engine going to make it into space. this eingine is pretty cool and provides a more optimal thrust profile. The Vernturestar/X-33 was supposed to use this engine. From my memory I thought all the test went very well.

It's time for something newer than the old bell nozzle design (even though it was first built in the 60s).




RE: Aerospike, anyone?
By Bubbacub on 4/26/2012 1:43:51 PM , Rating: 2
no point in an aerospike in a staged rocket.

if you have a single stage design (SSTO) then you get a performance advantage by having an altitude compensating nozzle.

at best an aerospike works at 90% of the efficiency of an appropriately designed bell nozzle operating at its designed atmospheric pressure. obviously once high up in the troposphere a nozzle designed for sea level pressure won't work well.

if you have 3 stages then you are better off with a range of bell shaped nozzles perfectly designed for the narrow range of atmospheric pressures that each engine will be firing in.

there is a reason why the saturn V was built the way it was!


RE: Aerospike, anyone?
By Bubbacub on 4/26/2012 1:44:08 PM , Rating: 2
no point in an aerospike in a staged rocket.

if you have a single stage design (SSTO) then you get a performance advantage by having an altitude compensating nozzle.

at best an aerospike works at 90% of the efficiency of an appropriately designed bell nozzle operating at its designed atmospheric pressure. obviously once high up in the troposphere a nozzle designed for sea level pressure won't work well.

if you have 3 stages then you are better off with a range of bell shaped nozzles perfectly designed for the narrow range of atmospheric pressures that each engine will be firing in.

there is a reason why the saturn V was built the way it was!


Yay! More expensive! Inferior to the original!
By voronwe on 4/28/2012 11:53:34 AM , Rating: 2
As Tiffany failed to point out, the J-2X is a completely new design, not an update of the J-2. It's double the weight of the original J-2, and brings the thrust-to-weight ratio down from 73:1 to 55:1. It pulls a lot from the RS-68, and I wouldn't be surprised if it costs more in inflation-adjusted dollars than the original J-2. See astronautix.com - the Wikipedia entry isn't much good.

Very frustrating. The J-2X concept was originally chosen because it would supposedly cost less than updating the SSME to be restartable. In the end it's the other way around. The SSME started out as a really poor design, but over the years P&W engineers mostly fixed the original Rocketdyne mistakes and turned it into an excellent engine. I can't find any logic behind what's taken place with the J-2X, except for politics and a need to funnel pork to Huntsville.

Coincidentally, politics is why Rocketdyne was originally chosen to build the SSME, despite the fact that P&W had been working the problem for ten years, had spent a bundle of their own money developing it, and had reliable, reusable (designed for 1000's of flights) engines. But aside from illustrating the politics, that's off-topic.




By Bubbacub on 4/29/2012 6:47:47 PM , Rating: 2
"I can't find any logic behind what's taken place with the J-2X, except for politics and a need to funnel pork to Huntsville."

good post

even better userid!


waste
By Bubbacub on 4/26/2012 9:41:15 AM , Rating: 2
i can't really see the point in the development of these engines.

they have taken really complicated technology required for the development of high performance re-usable space shuttle engines (i.e. the inside of the combustion chamber is copper and is very cleverly connected to an outer layer of steel with channels CNC'ed for liquid H2 cooling) and applied this to an expendable engine.

this massively increases the cost of each rocket for not much gain.

if we were going re-use these j2-x engines then spending a bit more to get a bit more specific impulse and thrust would be fine.

we all know that we have the technology to get 100 tonnes into LEO.

what we need is a cheap and reliable way of getting that much payload to LEO.

a really complicated expensive expendable rocket is not the way to achieve this.

i shouldnt get annoyed - after all the only aim behind this pork barrel project is to carry on employing as many people as possible regardless of the utility to the nation.




Yawn...
By Rob94hawk on 4/25/12, Rating: -1
RE: Yawn...
By ClownPuncher on 4/25/2012 7:23:31 PM , Rating: 2
What good would a few hundred pounds of "thrust" do for clearing the atmosphere?


RE: Yawn...
By Rob94hawk on 4/25/2012 7:31:45 PM , Rating: 2
It's better than 236 milliNewtons:

[quote]Although NSTAR and NEXT both use xenon gas as a propellant, NEXT accelerates the xenon ions more efficiently, providing up to 236 milliNewtons of thrust compared to NSTAR's maximum of 92 mN.[/quote]

http://www.newscientist.com/article/dn12709-nextge...


RE: Yawn...
By Odysseus145 on 4/25/2012 7:36:59 PM , Rating: 2
...which is fantastic for an ion engine. Still it's less than one ounce of actual thrust.


RE: Yawn...
By rs2 on 4/25/2012 9:23:19 PM , Rating: 2
You mean the gravity well. Atmosphere has fairly little to do with the amount of thrust required to attain orbital velocity (beyond creating friction). Even if the Earth were in a vacuum, an ion drive would not produce enough thrust to reach orbit.


RE: Yawn...
By delphinus100 on 4/25/2012 8:08:07 PM , Rating: 2
Ion engines are alive and well, but they'll never get you into orbit. They're of greatest value when you're already in space.


RE: Yawn...
By geddarkstorm on 4/25/2012 8:32:07 PM , Rating: 3
Short of putting a fully functional nuclear reactor on board, there's no way to even remotely power an ion engine at the levels needed to give thrust comparable to a chemical rocket.

The laws of physics (action creates opposite equal reaction) are just too stubborn to be bent quite yet.

In short, sorry, for leaving a gravity well starting at sea level, there's nothing, not even theoretically on the drawing board, that can accomplish that except a chemical rocket.


RE: Yawn...
By Fritzr on 4/25/2012 10:30:06 PM , Rating: 2
A space elevator (aka Beanstalk) would get the ion engine out of the gravity well.

Designs exist, but construction schedule is still in the "we're thinking about doing it someday" stage.

Laser boost is in the X-craft phase and may one day be capable of getting an ion engine out of the gravity well.

Chem engines will never be obsolete though. They will be required for entering and leaving gravity wells which do not have a launch infrastructure in place.

Atomic rockets likely could be used to enter/exit a gravity well, but safety concerns will prevent that usage.


RE: Yawn...
By geddarkstorm on 4/26/2012 12:38:12 AM , Rating: 2
No way a laser can give the thrust capacity of a chemical rocket. The amount of energy needed would destroy whatever you're lasering at. Laser ideas are for small course adjustments for craft already in space.

A space elevator is a fun idea but... one has to consider the stress from the planet's rotation (things in orbit are moving VERY FAST compared to things on the ground, how do you account for that while elevating up? You'd have to accelerate sideways as you elevate or you'd slow down the space based tether and drop it into the atmosphere, not to mention the sheer stress is enormous; it'd use more fuel than just rocketing up conventionally), weather patterns (what happens if a hurricane or tornado hits it, or an earthquake at the earth side tether point?), electrical effects (so much ionization in the upper atmosphere, and now you've given it a convenient path to get to the ground), temperature differentials (if it's 80F on the ground and -150F in the mesosphere, and 2,700F (though not practically, just theoretically) in the thermosphere where the ISS is, what is that going to do to your materials since heat can now flow through it and conduct? Expansion, contraction? Effects on material defects and microfractures? Light versus Night?), space/atmosphere debris (animals) and meteors (the elevator is an immobile target; vanishingly small, as space scales go, but still a sitting duck that can't maneuver much out of the way of danger), and of course gravity itself (how heavy would something dense enough to support the elevating weight you're moving into space have to be, and how would that ever have the strength to survive the material stress of gravity?).

How would you move over a ton of cargo weight as rockets can lift with these issues? It isn't ever going to happen with our current physical law constraints (maybe we'll find a new law and be able to circumvent it).


RE: Yawn...
By futrtrubl on 4/26/2012 5:08:10 AM , Rating: 2
Are you thinking of laser propulsions systems that reflect the laser to impart momentum? If so then sure they'll never get there for your reasons. But there are other methods for using lasers for propulsion. There's the use of microwave lasers to create plasma that can be electrodynamically accelerated to give thrust. Hell you could shoot a powerful laser at an ablative target within a nozzle to give thrust BY the destruction you mentioned.

Yes as a mass travels up a tether the counter weight mass would become retarded, however if the counterbalance is oversized correctly this would cause the net force on the mass to no longer be vertical and would tend to right the system (potentially with oscillation which is a problem) little fuel needed. If there is cargo transfer earthbound (there's little point in industry in space if goods don't come back to a human market) they can be scheduled to effectively negate each other.

Hurricanes and tornadoes can cause issues but the thickness of a tether at the Earth's surface is not that great.

Regarding earthquakes, sure they can strike randomly and do significant damage but you can mitigate that danger by selecting low risk sites and at worst if the cable detaches at the Earth's surface it drifts up, how much depends on the counterbalancing, and then it's a matter of repositioning it to reattach it, something that would have had to have been solved to install the tether in the first place.

Debris strikes can my mitigated by redundancy and ability to repair sections. Animal strikes.... I doubt a bird strike will do much to a cable capable of of suspending multi-tonne loads. The counterbalance itself is not much of a sitting target itself, it can raise and lower its orbit, retard and advance it. Considering the mass required it would be a captured comet or asteroid itself and most of that would be shielding for an structures so only large debris would be an issue which are easier to track and avoid.

It's not how dense the cable needs to be it's how strong/density the cable material needs to be and it's already been calculated how strong it needs to be. For a non-tapered cable (a worst case cable profile) carbon nanotube and graphene cables are both theoretically strong enough, it's just scaling it up is the issue. So no laws of physics need to be rewritten.


RE: Yawn...
By Gondor on 4/26/2012 5:33:51 AM , Rating: 3
RE: Yawn...
By JediJeb on 4/26/2012 9:13:18 PM , Rating: 2
quote:
No way a laser can give the thrust capacity of a chemical rocket.


Where the space elevator is concerned the laser is used to beam power to the climbing elevator carriage. You shine the laser up to a photocell which allows you a way to get electricity to the carriage without the weight of batteries, generator or power cable adding weight to the assembly.

You can find quite a bit of information on where the technology is currently at this site:

http://www.spaceelevatorblog.com/

They are even running an XPrize type contest looking for different components.


RE: Yawn...
By voronwe on 4/28/2012 12:03:26 PM , Rating: 2
All of these potential problems were sorted out decades ago. There are several good books on the topic, and lots of websites.

The only real remaining obstacle has been the power beam engineering and the wait for roll-to-roll graphene to go into mass production, or roll-to-roll carbon nanotubes. Graphene is already roll-to-roll; you can now go out and buy a single molecule of infinite length if you have the money. Nanotubes are proving very difficult to produce in the lengths required, but considering the value of the material (much more conductive than copper, much stronger than steel) it will probably happen some day soon.

Then it's strictly an engineering and funding problem. And it's not that expensive.


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