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Moonshot, CEV Modifications
DarkNemesis618 writes "In the latest round of budget cuts, NASA introduced plans to modify the CEV for the planned Moon landing in 2018. The original plan called for an engine used on the space shuttle to be modified for the CEV. The new plan is to use an updated J-2 engine. The J-2 engine was first used on the Saturn V rocket which took the Apollo astronauts to the moon in the late 60's early 70's. It is not expected to save any money in the near-term, but in the far term, it should be a cost saver since the technology already exists and is proven. In the 10 Apollo launches aboard the Saturn V rocket, there were no problems with the launch vehicle."
What am I not getting here?
This space available.
Note that this isn't really a surprise to those who have been following the CEV development. The original plan called for a modification to the SSMEs for multiple restarts as the J-2 (the upper stage engine for the Saturn V) is no longer in production. However, there was a lot of discussion inside NASA that restarting production on the less powerful J-2 would be cheaper, faster, and easier than trying to modify the more powerful (but far more complex) SSME to do the job.
To give quick rundown on which engines are which:
SSME (Space Shuttle Main Engines) - LHOx Fuel - 1.8 MN
SRB (Solid Rocket Booster) - Solid Fuel - 14.7 MN
J-2 (2nd and 3rd stage Saturn V) - LHOx - 890 kN
F-1 (1st stage Saturn V) - Kerosine - 6.7 MN
The SSME and J-2 are directly comparable, and the SRB and F-1 are directly comparable.
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I'm a bit confused as to how it takes us longer to get to the moon now than it did in the 60s.
Project Apollo was announced July 28th, 1960. July 20th, 1969, we set foot on the moon. Just under 9 years. (My dates may be a bit off.)
Even if you say the new project starts now, that's still 12 years. How frustrating.
What you're not getting is the time, money and risk of debugging a new design.
The other point is that the SSME was never designed to be started at altitude.
I can see this one coming:
In the latest round of budget cuts, NASA introduced plans to modify the CEV for the planned Moon landing in 2038. The original plan called for an updated J-2 engine first used on the Saturn V rocket. The new plan is to have a guy sitting on the outside with a fire extinguisher. The fire extinguisher engine was first used in a high-school physics lab in the 1930s. It is not expected to save any money in the near-term, but in the far term, it should be a cost saver since the technology already exists and is proven.
- Jim
And yes, I AM a rocket scientist...
#include "humorous_pop_culture_reference.h"
As the mouths of politicians travel close to the speed of light, time slows down. Thought everyone knew that.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
In the 10 Apollo launches aboard the Saturn V rocket, there were no problems with the launch vehicle.
I seem to rember in Apollo 13 the center 2nd stage engine, a J-2, went out early. The flight computer burned the outter four a bit longer to compensate, but I'd still say that was a problem, if not with the engine itself, at least with the launch vehicle. Then theres the whole lightning strike thing on what was it, Apollo 12? SCE to Aux.
#include <signature.h>
Surely if the use is initial liftoff the important statistic is thrust to weight ratio. The question of efficiency -- which is what specific impulse measures -- seems rather secondary, unless I'm missing something. An ion engine, for example, would have a far greater specific impulse than either chemical engine, but since its thrust is so pathetic it couldn't get itself off the ground.
To put it in plebian terms, if you need to outrun the cops (i.e. achieve escape velocity), surely it's better to be driving this instead of this.
Apollo cost about $135 billion in 2005 dollars, and the CEV is expected to cost $15 billion.
http://www.space.com/adastra/adastra_tumlinson_060 130.html
At this point I would rather save money by ending NASA's manned space program instead of continuing to piss money down ratholes such as the Shuttle, ISS and now the Crude Exploration Vehicle all of which are just ways for NASA to hand money to large aerospace companies so that they can pad their bottom lines and continue to bribe congressmen.
cheap labor conservatives - they want to keep you hungry enough to be thankful for minimum wage.
The expendable portion of a lunar mission isn't necessarily waste. You took a bunch of survey equipment (including a golf cart) to the moon. Why would you expend structure and fuel to bring it back? Similarly, you need structure and tanks to contain the fuel you're using to get to the moon. When the tanks are empty, why would you haul that empty (and now useless) mass around? Nope, the most efficient method requires you to be an interstellar litterbug. As soon as a resource is depleted, you jettison as much as you can.
In space, mass is the one variable you can control. Escape velocity, orbital velocity, and a host of other parameters are dictated by the math - your orbital altitude is a function of your velocity, not your mass. So to obtain a particular orbit, you need to achieve velocity V. The energy required to do so is dictated by E = 1/2mv^2. There's a direct relationship between the mass of the vehicle and the energy required to achieve a particular delta-V.
If you look at the Rocket Equation, you'll see that the overall relationship between wet mass (fuel) and dry mass (structure + payload) is exponential in nature. At the bottom of the Wiki page (link above) there's an example comparing single- and two-stage-to-orbit vehicles. All things being equal, the two-stage vehicle can put more mass into LEO by shedding the first stage.
Besides, bringing back used equipment is usually pointless. All of the Apollo-era vehicles used ablative shielding techniques, and couldn't be re-used (by design.) The Shuttle is technically re-usable, but it's largely rebuilt in-between flights. It pays a huge penalty in payload mass in exchange for bringing the brick-lined wings on a round-trip journey.
The expendable portion of a lunar mission isn't necessarily waste. You took a bunch of survey equipment (including a golf cart) to the moon.
It wasn't really cargo, though, because we had to send up one with each mission. If the rovers were reusable, I would concede the point. Same with the lunar lander. (14 metric tonnes) The RTG generators used for lunar experiments have been in continual usage, however, and meet the critera of cargo.
Unfortunately, even if you didn't count all of this as direct waste, the Saturn V rocket itself easily eclipsed any amount of hardware that actually made it to the moon.
Besides, bringing back used equipment is usually pointless.
Not true. If you can reuse a rover, you can bring something else next time. If you can reuse a LEO to LMO shuttle, then you don't have to relaunch another craft. If you can reuse a pair of SRBs, you can save money by not manufacturing new ones. That is the infrastructure the CEV will put in place. The Saturn V program never had such an infrastructure, nor did it intend to. It was a simple, "Get up and get the hell back down" mission.
Javascript + Nintendo DSi = DSiCade
Now I remember!
The only thing that makes me leery of the manned configuration (J2 ontop of an SRB in a vertical stack): Have they solved the temperature related problems on the SRB yet? Or have they implemented a workaround of only launching in warm weather?
Of course, without an ET to catch fire and burn on the manned configuration, a Challenger type failure should be survivable due to an escape tower.
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
In fact, when the Apollo series is looked at critically - one becomes astonished by the number of near misses and diving catches. NASA was lucky, very lucky.
NASA needs to start thinking outside the 1930-1970 technology box they keep finding themselves trapped in. Both engines are hopelessly obsolete. The current shuttle main engines have a poor reliability track record and have materially increased the cost of the launches by constantly delaying launches or forcing costly orbiter engine replacements. The J2's have nothing like the POH's of the shuttle main engines, so God only knows what their long term reliability is.
For example, whilst NASA dozed off, the military has become very proficient in the applications of U-238.
U-238 would make an excellent replacement for the tissue delicate RCC blocks on the shuttle leading edges, and the CEV's high temperature re-entry components. But instead NASA's "Rocket Scientists" sit around publishing papers about how difficult it is to bond foam to a cryo fuel tank. Hey, if you can't make the foam stick on, why no fix the real issue: the damn RCC is too delicate. Replace the RCC and the shuttle can survive other things than pieces of foam striking it during lift off. We need a shuttle that works like a military duce and a half, not a pimp mobile that blows up on re-entry because a 5lb piece of foam hit it during take off.
NASA could also find lots of available talent for engineering U-238 into rocket nozzles to produce more reliable rockets for primary thrust and orbital adjustments. These engines could be tested on the shuttle fleet. NASA doesn't like to talk about it, but I don't think they have a single shuttle still running on original engines. So keep on swapping out engines.
Similarly aerogel's could be used to update insulation systems, acoustic heat pumps engineered in for cooling along with modern nano material heat radiation systems and newer higher capacity fuel cells could be employed. Perhaps even employ reformer technology so the fuel cells could be fueled by alchohol/gasoline rather than the much more difficult to handle (and far more dangerous) liquid hydrogen.
NASA is also way behind the times in space suit design. I read this puff piece NASA produced about a women sewing space suit gloves and how she helped sew a better glove for her astronaut Father. Why isn't she using 3D scanning and CAD with NC sewing? Where are the phase change materials? Where are the RTD heater/energy units or enhanced chemistry/nano material battery systems? Where are the MEMS cryocrackers to remove CO2 and crack it back to C and O2?
NASA spin off technology helped develop all kinds of consumer technology back in the 60's and 70's, but what have you done for us lately baby? NASA money into reformers and CO2 crackers would have a large impact on many consumer technologies, including Bush's new program to kick our dependence on oil.
Time to stop living on past achievements and create new ones.
You're kidding right? What a wonderful idea! Let's replace the RCC with depleted uranium (U-238)which is 70% denser than lead and as a bonus a pyrophoric on a vehicle that is traveling at Mach 25 when it re-enters the earth's atmosphere. Why don't we just go ahead and replace the RCC with C4? The result would be the same and we would save money. Ditto with manufacturing the main engines out of U-238.
... oh wait, that would be reinforced carbon carbon.
Apart from ICBMs, I don't know of any military vehicles that would survive the harsh re-entry conditions that the shuttle is asked to endure every mission. Hmm, maybe we should use the same materials that are used to help ICBMs survive
This isn't Star Trek, we don't have anti-gravity devices, nor magical force fields that would protect the vehicle. This really is rocket science and it is tough and risky.
OK, I admit it ... you snookered me. Congratulations, it doesn't happen all that often, but you got me real good :):):)
One of the original stated benefits of the program was that by tinkering a little with shuttle derived components, they could create new launch vehicles without much new work. If they aren't using shuttle parts, why the hell don't they just design a new vehicle from scratch?
No, it doesn't defeat it at all. They will still be tinkering with pre-existing, proven hardware. Designing a new engine from scratch and flying it dozens of times to obtain the same confidence in it's reliability that we have about the Saturn, Apollo and Shuttle hardware would be vastly more expensive.
Personally, I think that someone at NASA finally woke up. Using an SSME in an expendable sustaner configuration is like shooting a thoroughbred racehorce after one race. You might win the race, but you paid way too much for it.
People keep saying "well, we haven't made J-2's in 30 years". Well, nobody has made an airstart-capable SSME ever. Either way, changes will have to be made in production. Airstart isn't just a matter of throwing a switch and having the thing light up. Someone in a previous post mentioned the Atlas. One of the tenents of it's original design was a ground start for all engines, due to worries over staging failure. According to Encyclopedia Astronautica: "It was estimated by ATK Thiokol in 2005 that restarting the J-2S program, including engine fabrication, design and reliability verification, certification, and production, would require four years. Although no J-2S tooling was known to exist, modern soft tooling could be developed quickly and less expensively than the original hard tooling. There was an existing manufacturing and supplier network in place to support a J-2S restart." How long would it take to develop the airstart-capable SSME?
There was also some talk earlier about J-2 failures in Saturn V launches. When that did occur, the other engines were burned longer to "take up the slack" caused by the lost engine. What happens if the single modded-SSME fails in the sustainer stage? You start wondering where you'll land.
Then there's the KISS factor. Everyone has been talking about performance issues, but the J-2 wins by a landslide in KISS. The bonus is that given the advancements in technology since the original J-2 in 1960 should provide excellent advancement in performance over the original item. In fact, a modified J-2S was used as the basis for the X-33 linear aerospike engine. This is not some old POS that they're dusting off to keep someone happy. It was chosen because of the extensive design studies and testing done on this engine since it was first built.
The J-2 also adds to the nostalgia value and cool factor. It helped us to get to the moon before, it would be great if it helped us get back.
Thanks to Encyclopedia Astronautica and Mark Wade for references.
"Well Ranger Brad, I'm a scientist. I don't believe in anything." - Dr. Roger Fleming
In the 1960s it took America slightly more than 8 years to go from a dead start (John Kennedy's initial announcement of the moon program) to landing on the moon using a J-2 engine. Now, 40 years later, it's going to take 12 years to land on the moon again, using a J-2 engine. My country peaked a long time ago.
When this came out a month ago, it was clear that NASA had embarked on the path you already know. Time to start cutting back. Due to the lack of thrust from the J-2 engine, they had to reduce the size of the spaceship. Due to lack of money, they had to abandon the methane engine and abandon a docking system. Due to the lack of a methane engine, they had to abandon synthesizing fuel on other planets.
As said before, there is no moon program. If they ever get anything, it's going to be a low earth orbit capsule with moon landings bought from China. More likely, it's going to be low earth orbit bought from China.
If they can't build a single SSME system, there's no way they're going to build a 5 SSME system to launch a lunar lander.
Lose the game and buy the trophy seems to be the pledge of allegience in that country. They should stick to advertizing and keynote speeches and leave space travel to the pros.