MongGrel
Lifer
- Dec 3, 2013
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There has been for a long time now.
I won't even bother commenting on the rest of your post.
There has been for a long time now.
I won't even bother commenting on the rest of your post.
norseamd
Lifer
- Dec 13, 2013
- 13,990
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Nope. It might have been some projections from earlier SDLV after Ares was cancelled, but it was not Ares. Given what has just been posted, I think it is the SLS, either current planned blocks, or past conceptual blocks.
Paratus
Lifer
- Jun 4, 2004
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While nuclear thermal is better than straight chemical it still fairly fuel inefficient when compared to electric designs, (ion, Hall effect, VASIMR).
- NERVA - 850 Isp
- ION - 1700-4100 Isp Average
- Hall Effect - 1500-3000 Isp Average
- VASIMR - 3000-30000 Isp (tuneable in real-time)
So while all of the above require a large amount of power the electric ion/plasma propulsion gets much better specific impulse (mileage). With ISS assembly techniques and a heavy launch vehicle like SLS or Dragon Heavy we can build a vehicle of whatever arbitrary size you (and your budget) want without a nuclear thermal booster. For interplanetary flight nuclear electric works better because it requires less propellant for a given delta V than even nuclear thermal.
It also means you don't have the nasty nuclear byproducts in the reactor until it's already safely on orbit because the reactor isn't required until it's on orbit.
EM drive is interesting. There's an OT thread I just updated a few days ago about the paper in peer review. I actually have a friend who was part of the group investigating it for a while. They hypothetically think it's pushing off quantum vacuum virtual particles that pop in and out of existence, (see Casmir force).
It's still not clear the small amount of anomalous thrust isn't caused by experimental error. The exciting thing is as they reduce experimental error the thrust remains. By analysis an EM drive would have an equivalent specific impulse of over 10,000,000. It would be a huge breakthrough if it actually does check out.
They are also puting the EM drive in the path of a laser interferometer to see if it works by warping space.
Blue_Max
Diamond Member
- Jul 7, 2011
- 4,223
- 153
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MongGrel
Lifer
- Dec 3, 2013
- 38,466
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Apparently he looks like he needs one, when he's being a dick.
Enough of that, the thread deserves better.
Blue_Max
Diamond Member
- Jul 7, 2011
- 4,223
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Yes it does, so why did you start it, then claim the moral high ground afterwards?
Care to talk about the details of space elevators rather than insinuate stupidity?
Care to mention why you don't think practice domes are a good prerequisite before attempting to colonize Mars?
Disagree that traffic fatalities are embarrassingly high so the average person probably shouldn't be attempting to travel with a Z coordinate added?
What did I have to say that was SO unintelligent that you had to scoff at the lot of it? As it is, the only argument you've made is that you disagree with my political stance of free speech vs. your preferred PC-only speech, therefore you also can't agree with anything I have to say on any other subject. Not exactly as open-minded as the progressives claim to be...
MongGrel
Lifer
- Dec 3, 2013
- 38,466
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Paratus
Lifer
- Jun 4, 2004
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That's not entirely accurate.
Deep Space 1 Ion drive launched in 1998:
Dawn Ion engine launched in 2007:
VASIMR Variable Specific Impulse Magento Plasma Rocket lab test article VX200 (2015)
The moon is a pile of dust and rocks with almost no gravity and no atmosphere. Nothing to stop all the asteroids from making pock marks all over the moon and it will not even block out radiation. Might make a nice jump-off point for future deep space missions, but that is about it.
NASA just launced a satellite into space and it ended up in 3 or 4 pieces. There goes 273 Million $$ down the drain.
https://science.slashdot.org/story/...-satellite-has-broken-up-into-multiple-pieces
https://science.slashdot.org/story/...-satellite-has-broken-up-into-multiple-pieces
Paratus
Lifer
- Jun 4, 2004
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By NASA you mean JAXA. Right?
Space flight is hard. The only way to not risk a loss is to stay home.
Kind of timid if you ask me.
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While nuclear thermal is better than straight chemical it still fairly fuel inefficient when compared to electric designs, (ion, Hall effect, VASIMR).
- NERVA - 850 Isp
- ION - 1700-4100 Isp Average
- Hall Effect - 1500-3000 Isp Average
- VASIMR - 3000-30000 Isp (tuneable in real-time)
So while all of the above require a large amount of power the electric ion/plasma propulsion gets much better specific impulse (mileage). With ISS assembly techniques and a heavy launch vehicle like SLS or Dragon Heavy we can build a vehicle of whatever arbitrary size you (and your budget) want without a nuclear thermal booster. For interplanetary flight nuclear electric works better because it requires less propellant for a given delta V than even nuclear thermal.
It also means you don't have the nasty nuclear byproducts in the reactor until it's already safely on orbit because the reactor isn't required until it's on orbit.
EM drive is interesting. There's an OT thread I just updated a few days ago about the paper in peer review. I actually have a friend who was part of the group investigating it for a while. They hypothetically think it's pushing off quantum vacuum virtual particles that pop in and out of existence, (see Casmir force).
It's still not clear the small amount of anomalous thrust isn't caused by experimental error. The exciting thing is as they reduce experimental error the thrust remains. By analysis an EM drive would have an equivalent specific impulse of over 10,000,000. It would be a huge breakthrough if it actually does check out.
They are also puting the EM drive in the path of a laser interferometer to see if it works by warping space.
Holy crap, I had no idea that the EM drive could potentially have that high of a specific impulse. That is insane.
But I was under the impression that electric drives were more suited to long term probes and stuff that didn't need to get there that quickly (for relatively short journeys) as they have a very slow rate of acceleration? I know that they can reach huge speeds because they can continue to accelerate for a very long time versus getting all of your speed in a few minutes of burn with chemical propulsion but for manned missions you have to spend half the time slowing back down.
I kind of assumed that was the reason I haven't heard NASA studying any of those drives for manned missions but admittedly I know just enough about all of this to get myself in trouble. Anymore input would be greatly appreciated.
As far as the EM drive, can it be scaled up and if so is there a reason they haven't tried yet? Everything I have heard is it produces very very little, but constant, thrust. With a probe that is great but with people we want to minimize the time they are in space to limit the danger of basically everything trying to kill them. With normal chemical rockets the trip to mars is roughly 8 months, with nuclear thermal I've read it can be shortened to 3 months. What would the trip take with electric propulsion?
Paratus
Lifer
- Jun 4, 2004
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Electric propulsion does produce low levels of thrust. To make them useful for manned missions you need a lot of electrical power. Generally in the multi MW range. For comparison the ISS with nearly and acre of solar arrays has an instant ours maximum power of less than 250KW, (actual usable is around 100KW, less as the arrays age). So we are talking nukes for power.
Let me clear somethings up about the EM drive. It's either:
- Groundbreaking Nobel Prize winning new physics OR
- Subtle experimental error
(Here's the OT thread BTW Link)
It's effectively a microwave resonance chamber where microwaves at a certain frequency bounce around inside an enclosed tapered cavity. While the measured thrust is very small, (10-100s of millinewtons) it's orders of magnitude higher than a radiation pressure drive. (Anything that radiates photons asymmetrically actually produces tiny amounts of thrust. A flash light for example)
The amazing thing is the drive requires NO propellant. While other plasma and ion drives produce similar low levels of thrust they all require a propellant to accelerate per Newtons laws of motion, (every action has an equal and opposite reaction - conservation of momentum).
If it actually works it's basically Star Trek impulse power. The controversy comes from the fact it has no verified theory for operation and it appears to be violating conservation of momentum. These two facts means we should be skeptical about it actually functioning or not.
If it was only the two independent inventors who were promoting this it could likely be ignored as a hoax. However three independent teams have tested these devices and recorded anomalous thrust.
- A Chinese university research team
- Eagleworks - a small advanced propulsion research group at NASA Johnsons Space Center
- A research team at the University of Dresden
The NASA folks have tested it in and out of vacuum, reversed direction of the thruster and it has produced a measurable thrust. When they tried an RF sources without the tapered cavity as a control they did not see thrust. Currently they are upgrading their test rig to reduce experimental error from magnetic fields and thermal interactions while increasing input power to get a larger thrust signal. These were things recommended to them by a panel of physicists after their first round of tests. If they can reach a bit higher thrust levels other NASA centers will try and replicate their results.
What was recently reported is they now have a paper undergoing peer review. This should hopefully shed some light on what's actually going on.
The benefit of an EM drive to space exploration is enormous. As long as your vehicle has electrical power it can thrust. Most vehicles must have propellant as a major portion of the vehicles mass. Not with EM drive. Eagleworks did a rough estimate of what some crewed missions would look like at various thruster efficiencies. Mars in 28 days could be feasible:
Hell probes to Alpha Centauri would be possible in a human lifetime.
At any rate it's exciting technology but one we should approach with skepticism. Because of that skepticism NASA is not betting the farm on it. They have however put a nickel in the slot machine. With that low level of funding it will still take awhile to chase down every possible source of experimental error to definitively show it works or it doesn't.
Stay tuned.
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The real problem is nobody knows how to do math
LMAO :thumbsup:
justoh
Diamond Member
- Jun 11, 2013
- 3,686
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Makes you wonder how or why it was a such a huge event.......and why we spent BILLIONS of dollars to do so.
Think of it as a way for politics to wave their dicks to communist and say "we are better than you".
When in reality, communist/Russia had most of the records and won most of the races and had better results........with 1/100th of the budget or resources.
Now you are starting to realize that America is great at selling it's people ideas to suck their tax money out of them......
And they have done a better job with Iraq......just think of the money spent vs actual results.
America - world leader of BS
Im only going to comment on the bolded portion and ignore eveything else. What he said is true. Russia has probably the most efficient space program and we need them to get us into orbit. The Soyuz launcher and capsule is the worlds safest and cost effictive manned launcher. Has flown almost 2000 times since I last checked, far more than any other launcher. And far safer than resulting in less fatalities as well than other launchers. A very old, basic design that has beeen honed and refined since the 50s when it began life as the R-7 ICBM. It just works and the Chinese have copied it as the basis for the Shenzhou space capsule.
Paratus
Lifer
- Jun 4, 2004
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Well they've learned some lessons the hard way.
They killed 126 ground personnel during a failed rocket launch in 1960
http://m.phys.org/news/2010-10-russia-years-space-disaster.html
They lost 3 cosmonauts on re-entry when a valve failed and they suffocated.
All 4 of their N1 moon shot test flights ended up exploding including one in the running for largest non-nuclear explosion.
Then there was the time in the 90's they almost lost MIR when a remote piloted Progress crashed into one of the modules.
Now I'm not saying the Russians are bad at space flight. I happen to agree that the Soyuz is a very robust design. I'm just pointing out they've had similar issues and problems during space flight just as NASA has.
Compare the space shuttle to soyuz fatalities and you'll see what I mean.
Your link details the "Nedelin catastrophe" as known in Russia and was actually an explosion while military were readying the R-16 ICBM for a test launch and arguably does not have any significance to manned spaceflight.
Of course, there have been space fatalities but my post was to highlight that the Russians are doing something correct. Soyuz has an unparalled length of operational history with only 2 missions where crew have died: Soyuz 1 in 1967 where parachutes failed to open resulting in cosmonauts dying when they struck the ground after re-entry. And Soyuz 11 in 1971 where the pressure valve you referenced was stuck open during preparation for reentry leading to cabin depressurization and death: the only humans to have ever died in space. The last death from Soyuz was 45 years ago. The shuttle flew for 30 years and killed many more astronauts.
Paratus
Lifer
- Jun 4, 2004
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As someone who has supported Shuttle, Progress, Soyuz, and ATV dockings with the ISS and various failures with each of them, I am exquistely aware of the strengths and weakness of the various vehicles.
I'm not denying that the Russians do things right. What I'm saying is their methods are different than ours and come with their own unique strengths and weaknesses. I'm saying their methods are no better than NASAs. Just different.
Shuttle was a much more capable vehicle than Soyuz. It supported more crew, had more cross range capability, and due to the cargo bay and robotic arm US ISS modules have more volume for equipment than their Russian counterparts. Those were the benefits.
The shuttles biggest weakness was its positioning on the stack, in the way of debris with no chance for a realistic abort scenario until SRB sep. It had two fatal events.
The Soyuz strength is its an older simpler design that takes three people to LEO, hangs around dormant for upto 180 days and the returns to Earth. It does its job well.
It doesn't have a real weakness because it doesn't push the envelope in any meaningful way.
That's the real difference. The Russians have been launching basically the same capsule to basically the same Salyut/Mir/ISS type modules for 30+ years. There's much less risk but there's nothing new either.
MongGrel
Lifer
- Dec 3, 2013
- 38,466
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Why are you trying to make an argument about it to begin with ?
Russia covered up many failures in the past, yes they still have a working launch system in operation.
In cooperation with the NASA on the ISS it works well, still.
Brovane
Diamond Member
- Dec 18, 2001
- 6,390
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That jump off point is going to be very important if you want to drive down costs. The Moon has vast amount of resources, especially water which can be used to make propellant.
ULA's vision of Cislunar 1000 is very interesting. https://www.youtube.com/watch?v=uxftPmpt7aA
norseamd
Lifer
- Dec 13, 2013
- 13,990
- 180
- 106
Might the cancellation of the J2X be why the rated lift numbers of SLS could have dropped?
https://en.wikipedia.org/wiki/J-2X
https://en.wikipedia.org/wiki/J-2X
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