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Methane Rocket Engine Successfully Tested

Earlier this year, researchers successfully conducted a rocket engine test that was powered by methane.  The engine, constructed and tested byNASA contractor Alliant Techsystems/XCOR Aerospace, is far from space-ready.  

The test appears to have been the first attempt for rockets powered by methane specifically for spaceflight.

NASA traditionally uses rockets that powered by hydrogen and liquid oxygen or solid fuel.  The space shuttle's rocket boosters offers around 3,300,000 pounds of thrust, while the test rocket from XCOR Aerospace pushes just 7,500 pounds of thrust.

However, methane has a number of advantages compared to NASA's Hydrogen and LOX engines.  Methane is much easier and cheaper to collect than liquid oxygen or hydrogen.  Future space probes may collect methane from other planets and moons, allowing for shuttles to possibly refuel during missions.

Terri Tramel, project manager at the NASA Marshall Space Flight Center, wondered why it has taken scientists so long to look into methane as a viable alternative.  

The next step for researchers is to work on the engine so that it is able to operate for longer durations with a lower chance of overheating. 

Methane's large drawback right now is that gases mixed with methane are fairly difficult to ignite.  One of the qualities that makes methane safe is its high autoignition temperature, just shy of 580 degrees. Autoignition occurs at much lower temperatures in hydrogen-oxygen mixtures.

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Specific Impulse comes to mind
By ralith on 5/9/2007 8:30:59 AM , Rating: 5
quote:
Terri Tramel, project manager at the NASA Marshall Space Flight Center, wondered why it has taken scientists so long to look into methane as a viable alternative.

Well low specific impulse comes to mind, but I guess it could be worth it if you could easily get refueled while on other planets/moons.




RE: Specific Impulse comes to mind
By masher2 (blog) on 5/9/2007 9:41:11 AM , Rating: 2
> "Well low specific impulse comes to mind..."

Exactly. Honestly, NASA should be testing nuclear rockets these days, not wasting time on methane. Its Isp is about 20% lower than hydrogen and I don't see us building a methane purification and cryogenic liquefaction plant on Titan anytime soon.

Nuclear propulsion would make space travel safe, cheap, and easy. Safe, because the vastly higher Isp means you don't need tremendous acceleration to leave the earth's surface...you can boost at a far more moderate rate, which puts much less strain on both the ship and occupants. You also have enough energy to allow you to brake directly on reentry, so you don't need aerobraking manuevers, nor the heatshields, high temperatures, and risks that come along with them.

Cheap, because payload as a percentage of fuel is dramatically higher, and the spacecraft themselves endure less stress, meaning operating times are higher.

Easy, because nuclear propulsion would enable you to travel the entire solar system and back in a reasonable timeframe. Unlike a chemical rocket, which has only enough fuel for a few minutes of full burn, a nuclear craft carries fuel to last years. A lengthy voyage would require picking up some additional reaction mass...but this need only be water...and it wouldn't need the extensive refining and purification process that fuel would require.


RE: Specific Impulse comes to mind
By mamisano on 5/9/2007 10:54:35 AM , Rating: 3
Perhaps use current technology to launch from Earth, then use nuclear propulsion once out of Earth's orbit. That would add a bit of safety in the event of a catastrophic failure on launch.


RE: Specific Impulse comes to mind
By masher2 (blog) on 5/9/07, Rating: 0
RE: Specific Impulse comes to mind
By joust on 5/9/2007 11:56:54 AM , Rating: 2
That may be true, but how big of a reactor would you need? I can imagine encasing something the size of a breadbox or refrigerator is one thing, but what if the reactor was the size of a small room? Making sure that is structurally sound would require a massively larger (and heavier) structure. Also, you need to be quite concerned about nuclear shielding and other factors.


By masher2 (blog) on 5/9/2007 12:16:11 PM , Rating: 1
The NRX reactor NASA built was about 40 meters long...but only about a quarter of that was the reactor core. And it wasn't miniaturized; it was a development prototype.

In any case, you don't need to shield the entire reactor. You just need to encapsulate the fuel rods to the point where they won't break up in the event of a catastrophic failure...they'll simply sink into the ocean.


RE: Specific Impulse comes to mind
By Egglick on 5/9/2007 11:21:53 AM , Rating: 3
Those sound like some pretty strong points in favor of going with nuclear, but keep in mind that with the current Space Shuttle design, the solid rocket boosters detach and jettison into the ocean shortly after takeoff. This was also the case with the launch rockets of the Mercury, Gemini, and Apollo missions.

Detachment and jettisoning into the ocean likely isn't an option with nuclear, due to the risk of environmental contamination should one of the rockets become damaged. That means using nuclear would probably require the rockets/boosters to remain attached to the craft at all times.

Obviously this would add a significant amount of weight to the craft, as well as pose all sorts of new problems during re-entry. That is, unless they could manage to do the job using a much smaller rocket (and also much longer ascent).


RE: Specific Impulse comes to mind
By joust on 5/9/2007 11:51:36 AM , Rating: 3
The rockets that detach are Solid Rocket Boosters (SRBs). They are needed because the lift from the main shuttle engine simply doesn't provide enough lift to get out to orbit. You can think of them as a hack/kludge to allow the shuttle to get off the earth.

The whole point of going nuclear is to avoid having to use SRBs on liftoff. Imagine a space shuttle that:
(1) requires no extra massive tank which drops foam and ice which threaten the fuselage.
(2) requires no SRBs which are expensive to set up, refuel, and repackage.
(3) is MUCH less reliant upon heat tiles because it can very slowly reenter the atmosphere.
Suddenly you are looking at a MUCH safer vehicle, both in terms of liftoff AND reentry.

In exchange for a much higher cost of catastrophic failure, you have a much reduced chance of failure. You are eliminating the the largest stresses: extreme takeoff Gs (which threaten the whole structural integrity), fuel explosions, reentry heat, reentry stresses, etc.

The problem here is that a nuclear reactor, in the event of catastrophic failure on a slow reentry (improbable due to slow speed) will most likely leave a radioactive debris field. Doh. Imagine the Columbia disaster, but only you would need a nuclear contamination cleanup -- that's pretty ugly. I think for this reason NASA and others will avoid nuclear powered propulsion near the Earth.

There may be ways to mitigate the effects of a disaster, such as reentering over ocean slowly, then flying over to the LZ at a low altitude. That way if there is a crack up it's either over the ocean (which can absorb the radioactive material well, as 1000's of nuclear tests have been performed underwater, as well as there have been leaky dead nuclear subs there), and if the crack up occurs at low altitude, at least the debris field will be small. It's not pretty to potentially drop nuclear debris in the ocean, but it's better than on land.

So, if you reduced accidents by a factor of 1 in a 1000, but multiplied the cleanup cost by 1000, would it be worth it? Probably, because you will probably reduce the marginal cost of a flight.

Of course, the accident rate and cleanup costs were figures I pulled out of my ass. If the accident reduction rate is relatively less than the cleanup cost, then we probably shouldn't use nuclear propulsion on Earth.


RE: Specific Impulse comes to mind
By General Disturbance on 5/9/07, Rating: 0
RE: Specific Impulse comes to mind
By stromgald on 5/9/2007 11:50:12 AM , Rating: 4
Think and maybe do some research before you post. What masher's referring to are probably nuclear-thermal rockets.

http://en.wikipedia.org/wiki/Nuclear_thermal_rocke...
http://en.wikipedia.org/wiki/Project_Timberwind

Wikipedia doesn't have much on the Timberwind project, but I think there's probably some more details about it online and what testing they've done. I have a book on it at home.


RE: Specific Impulse comes to mind
By General Disturbance on 5/9/2007 12:07:48 PM , Rating: 2
Hmm cool articles.
Now, why don't you "think" and learn some tact. And same goes for me. hehe
Still, development stopped on these thing 50 years ago or so. I doubt we're going to see them within our lifetimes. But simultaneously being able to produce thrust AND electricity from the same source would be a boon.


By saratoga on 5/9/2007 12:20:02 PM , Rating: 5
quote:
till, development stopped on these thing 50 years ago or so.


The 1970s weren't 50 years ago.

quote:
I doubt we're going to see them within our lifetimes.


Depends if your life time included the 1970s.

quote:
Now, why don't you "think" and learn some tact. And same goes for me. hehe


How about in the future when you have no god damn idea what you're talking about, you just don't post. I'd rather have less clueless people then more worthless but tactful people.


By masher2 (blog) on 5/9/2007 12:00:16 PM , Rating: 1
> "only thing that comes close to nuclear propulsion technology is ion-drive prop systems, and those are the lowest impulse engines around..."

Sorry, this is incorrect on several points. First, ion-drives are the highest impulse engines around...but the lowest thrust, which makes them infeasible for a launch vehicle.

Second of all, nuclear propulsion has been investigated since the 1950s...NASA built several test prototypes, and very nearly based the Apollo program on pulsed-fission propulsion....but the signing of the Nuclear Test Ban Treaty barred the way.

The political climate would never allow a pulsed-fission spacecraft today. However, LANL (Project Rover) also tested solid-core thermal nuclear propulsion (which releases no radiation during operation) in the 1950s and 1960s as well. NASA got involved as well, under the NERVA program, and actually built a test-fired a nuclear engine many times.

There were unsolved programs, primarily with material strength...but I stress this was 1960s-era technology, and once the political climate changed, development dollars basically dried up to nothingness. A concerted effort today could yield a working nuclear spacecraft in ten years or less.


RE: Specific Impulse comes to mind
By mac2j on 5/9/2007 3:34:32 PM , Rating: 2
I agree we should be focussing on nuclear rockets.

The Russians actually had pretty good success with them during the late 70s and early 80s and I know we acquired some of that technology.

By far, nuclear rockets would provide the best chance for getting a manned craft to Mars in a reasonable amount of time.


RE: Specific Impulse comes to mind
By goz314 on 5/9/2007 3:54:41 PM , Rating: 3
quote:
Exactly. Honestly, NASA should be testing nuclear rockets these days, not wasting time on methane. Its Isp is about 20% lower than hydrogen and I don't see us building a methane purification and cryogenic liquefaction plant on Titan anytime soon.


I don't disagree with you. NTRs are the way to go for manned interplanetary missions. One of the reasons NASA is funding research into methane/LOX based rockets right now, however, is for potential future use on Mars missions where ISRU (In-Situ Resource Utilization) can yield significant quantities of methane by using C02 from the air and a relatively small feedstock of H2. The idea follows that a landing/return craft destined for the martian surface need only carry a fraction of the propellant (i.e. mass) needed for a subsequent return to orbit and, depending on the mission type, TEI burn back home to earth. Also, the planned Mars sample return robotic mission is supposedly going to use this approach for its Earth return vehichle.


RE: Specific Impulse comes to mind
By ralith on 5/10/2007 8:43:06 AM , Rating: 2
I agree that we need to find a different way to power space craft, but for some reason I still cringe a bit when people talk about nuclear rockets. Anyway, while refreshing my memory on specific impulse yesterday I ran across the most interesting space propulsion system I've read about in a long time called VASIMR. Its one of the coolest concepts I've ran across in a very long time. Probably old news to masher, but I figured there might be some out there that might find it as fasinating as I did. http://en.wikipedia.org/wiki/Variable_specific_imp...


RE: Specific Impulse comes to mind
By iollmann on 5/11/2007 11:58:56 PM , Rating: 2
quote:
Well low specific impulse comes to mind, but I guess it could be worth it if you could easily get refueled while on other planets/moons.


Methane is only half the equation. You still need an oxidant, which is by far most of the weight in a H2/O2 system.

In principle, refueling means you have less of the reduced part to carry around. However, methane is 8x heaver than H2 per mole, and twice as heavy per chemical bond, so you're going to have to refuel early and often, I'd say, to make it pay off.


Anyone else?
By aebiv on 5/9/2007 7:04:35 AM , Rating: 2
Does anyone else find that rocket fire incredibly beautiful to look at?




RE: Anyone else?
By FITCamaro on 5/9/2007 7:20:54 AM , Rating: 1
Watching the shuttle take off is far more impressive. Especially when you've been closer than 99.9% of people. :)

But yes. Barbeque anyone?


RE: Anyone else?
By bupkus on 5/9/2007 7:39:16 AM , Rating: 5
The look of bright pulses in the photo looks better than anything to be found in any of the UT3 pics.


RE: Anyone else?
By Seemonkeyscanfly on 5/9/2007 9:36:57 AM , Rating: 1
Cool video. I would add, that's what happens when I light my farts....


RE: Anyone else?
By Seemonkeyscanfly on 5/9/2007 9:39:04 AM , Rating: 2
sorry, I must be tired...it was suppose to be under...
quote:
I heartily agree, but I think that seeing it in video is even better:


RE: Anyone else?
By Souka on 5/9/2007 11:27:02 AM , Rating: 2
Kids have been lighting their own methane rockets for years.... guess NASA finally got around to it also... heh..


RE: Anyone else?
By stromgald on 5/9/2007 11:42:55 AM , Rating: 2
NASA avoided methane rockets because of their poor performance relative to everything else that NASA is using now.


RE: Anyone else?
By LatinMessiah on 5/9/2007 1:18:54 PM , Rating: 1
...and because they couldn't stand the smell.


RE: Anyone else?
By stromgald on 5/9/2007 11:45:50 AM , Rating: 4
The bright "pulses" are shock diamonds or Mach disks. You can see them when they test fire other rockets or afterburning jet engines. However, they usually don't show that many disks because rocket engines are usually tested in a more closed environment.


RE: Anyone else?
By Exirtis on 5/9/2007 8:11:43 AM , Rating: 4
I heartily agree, but I think that seeing it in video is even better:

http://www.space.com/php/video/player.php?video_id...

The only problem, of course, is that it leaves me wanting more... so sad. ;-)


RE: Anyone else?
By Schadenfroh on 5/9/2007 9:27:18 AM , Rating: 2
My uncle is an engineer at one of NASA's main engine testing facilities (Stennis Space Center). Hopefully he will get to play around with one of these puppies and let me come to a test to see it in action. (some of the tests there are open to the public)


RE: Anyone else?
By gaetanomarano on 5/9/2007 11:10:34 AM , Rating: 3
.

a methane engine is an interesting device for Mars missions but NOT so good for Moon missions since there is NO methane on the Moon

now that doesn't matter, but, in future, it would be BETTER to have ALL moon vehicles refueld with LOX/LH2 made with ISRU plants from lunar poles' water

http://www.gaetanomarano.it
http://www.ghostNASA.com

.


starcraft
By goku on 5/9/2007 5:25:04 AM , Rating: 1
Vespene gas anyone? Man, a real life starcraft.. LOL that'd be awesome




RE: starcraft
By Gnoad on 5/9/2007 5:39:18 AM , Rating: 3
Soon we will also construct all buildings from minerals found on other planets, and we will need many SCV's and supply depots for them.


RE: starcraft
By bubbacub616 on 5/9/2007 5:45:24 AM , Rating: 3
the question is - will we all develop southern accents while we are torn to pieces by giant insects/aliens


RE: starcraft
By rdeegvainl on 5/9/2007 12:15:24 PM , Rating: 2
Don't worry, I'm sure Ender can take care of the buggers for us. if that fails we can always have Bean do it.


RE: starcraft
By jay401 on 5/9/2007 7:22:45 AM , Rating: 2
I believe you mean "kekeke that'd be awesome".


One Whiffy Rocket..
By Felofasofa on 5/9/2007 6:09:46 AM , Rating: 2
This would be a very smelly rocket, maybe they could use it to prove the existence of the Sulphur Methane Aliens?




RE: One Whiffy Rocket..
By mehran on 5/9/2007 8:06:46 AM , Rating: 5
Methane does not smell, they add the smell to natural gas(mostly methane)to make it safer. what come from your other end is smelly not because of the methane in it.


Whoa
By Egglick on 5/9/2007 5:14:43 AM , Rating: 2
Wow......Starcraft was right on the money, almost a decade before the idea was proposed.




RE: Whoa
By Egglick on 5/9/2007 5:17:53 AM , Rating: 2
Er....wait, maybe it was vespene gas. It's been a while.


RE: Whoa
By goku on 5/9/2007 5:28:39 AM , Rating: 2
While it was vespene gas, if you watch how it's mined and see it is strikingly similar to methane, you'll see vespene gas is really just methane... So yes I'd say blizzard was right on the money by using that stuff as a resource to mine.


Cool...
By vortmax on 5/9/2007 11:23:35 AM , Rating: 2
The engine appears to be quite small. I wonder if that's why the thrust isn't so high (compared to the Shuttle's). Anyway, it'd be interesting to see what one of those puppies would do to my 1/4 mile time if I installed it in my wagon...hmmm.




RE: Cool...
By 91TTZ on 5/9/2007 12:24:48 PM , Rating: 2
Yeah, that's one of the reasons. But even if it was the same size, it still wouldn't be as powerful, since hydrogen contains more energy than methane.

I don't see this going anywhere, as they'd be building an expensive rocket and then filling it with fuel that contains 20% less energy than hydrogen.

When you're already paying millions of dollars to lift each pound into orbit, skimping on fuel and being able to lift 20% less payload doesn't sound like a very smart idea.


Cows have a NASA program?
By Mitch101 on 5/9/2007 9:17:27 AM , Rating: 2
Do Cows have a NASA program?

Its something like this that might bring back the writer for THE FAR SIDE comics.




The musical fruit......
By rumptis on 5/9/2007 11:20:41 AM , Rating: 2
Bean powered space travel anyone?




Apples to oranges??
By McTwist on 5/9/2007 12:30:06 PM , Rating: 2
quote:
The space shuttle's rocket boosters offers around 3,300,000 pounds of thrust, while the test rocket from XCOR Aerospace pushes just 7,500 pounds of thrust.


That's not really a fair comparison. The Space Shuttle's SRBs are a completely different animal built for a completely different purpose than these LOX/CH4 engines. I believe these engines are being designed as a possible lunar return engine for the Orion CEV.

If anybody is interested, here are more pictures from XCOR's website: http://www.xcor.com/gallery/main.php/v/engines/XR5...




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