caffiend666 writes "According to an AP news article, NASA engineers are concerned about the design for the new rocket meant to replace the shuttle. Work on the project has revealed that the first few minutes of flight could see 'violent shaking', a serious flaw that might destroy the craft soon after launch. 'NASA officials hope to have a plan for fixing the design as early as March, and they do not expect it to delay the goal of returning astronauts to the moon by 2020. The shaking problem, which is common to solid rocket boosters, involves pulses of added acceleration caused by gas vortices in the rocket similar to the wake that develops behind a fast-moving boat.'
I see two things that make this a story. First, the design process for the Ares 1 would be of interest to slashdot readers. Second, this is pretty far along to be dealing with an obvious flaw of the rocket's design qnd strikes me as another example of the rushed nature of this particular platform. Before this, they had to strip the Crew Exploration Vehicle (CEV) down to basics to figure out how to pare it down to the point where the Ares 1 could carry the CEV. That particular effort was because the Ares 1 i
I disagree. This problem would have been obvious from the start. I simply don't understand how they got so far without addressing it. Sure, they wouldn't have known the full dynamical details of the SRB vibration, but they would know the crude resonance modes of the rocket and that the SRB kicked out vibration in these frequencies. Hence, they would have known at the very start that this was a problem. So why wait at least two years (until right after the Ares 1 supposedly passed [nasa.gov] its "system requirements review") before you start thinking about this problem? My take is that they put off discussion of it as long as they could. As I see it, the next year is critical not just to Ares 1 development, but to the entire VSE plan. If they haven't resolved the basic design problems with both the Ares 1 and the CEV (and yes, I think there are serious issues to be resolved here), then we might not see any of this survive the next administration.
so they found a problem with a preliminary design. big deal. that's why they call it research and development.
how long did it take to design the saturn Ib/saturn V and make sure that they'd mate well with the apollo capsule? how long did it take to come up with skylab, an orbiting lab that could be mounted on a saturn V?
i expect it'll take about five to six years to bring the orion program to a complete first generation system.
Indeed. In fact, the Saturn V itself had problems with pogo oscillation [wikipedia.org], a condition that affects liquid fueled rockets and caused the center engine shutdown during the first stage of Apollo 13.
April 1957 to July 1969 = 12 years from STARTING the Saturn project to landing on the moon. My biggest problem here is that they should already be flying X-vehicles. Wasn't that how progress was made? One to crash, One to fly, and One to hang up in the Smithsonian?
Since Ares keeps getting reduced in capabilities, I'm not confident that in 2015 ( when it's scheduled to start running ) we'll actually have anything delivered, and it's going to be another Turkey.
Mercury started launched amazingly shortly after Sputnik, in 1957 or so. Gemini launched in 1963, Saturn launched in 1967. That gives less than 10 years to build 3 generations of spacecraft and launch the third generation, successfully.
NASA has known that the Space Shuttle flies like a duck-taped cow since well before its first launch in 1981, since it was designed by committees lobbying wildly to have different components manufactured in different states to get Congressional approval and for many other political, rather than engineering, reasons. Development of replacement spacecraft has been hindered by funding, similar lobbying stupidity, and the unwillingness to admit that rockets have to be built and tested rather than modeled to death for decades before actually trying anything.
Private industry has already shown a far more capable design, when the Ariadne won the X-Prize. But NASA is blocking its development for numerous political reasons, not engineering reasons. You cannot expect NASA to do anything in real development and admit that complex craft are going to crash in the design and testing phase, and treats it as an acceptable risk rather than a political nightmare. And their current leadership is too politically hidebound to do anything profoundly innovative: it would interfere with the "5 year plans" of their contracts with Boeing and other manufacturers.
According to the articles I've read, NASA massively interfered with getting FAA approval to even test-fly it, repeatedly interfered with any tentative review by the FAA for approval of flight plans involving air craft, and insisted through such back-channel regulation with the FAA that the support structures be massively over-built. The result is that as wonderful as Ariadne was, they were never permitted to seriously consider using NASA's pre-built and under-used launching facilities, even on a rental basi
YOU, unfortunately, shot your mouth off without understanding what I was saying. I wasn't referring to the little guys.
If you'd followed this very much, you might realize a few things. Over the past few decades, the big boys have made noises about building their own stuff: there's a market in space launch and they'd like to profit from it (much like the Russians are now.) However, all those corporations are heavily dependent upon Federal contracts, and every time they talk about building a commercial lau
Well, the problem as I see it is that the prototype design has diverged so far from the original concept. The idea was that by using Shuttle components that are (a) in production and (b) have proven safe in their current designs, then (c) by configuring them in a way that avoids known problems, you end up with a safe and economical vehicle much faster.
The problem is that it might not be so simple. The first concept was a Shuttle solid rocket booster for the first stage, an second stage powered by a Shuttle
If anyone else has read Diane Vaughan's Challenger Launch Decision [amazon.com], he or she will know that launch schedule pressure from upper management was a leading cause of the rationalization of risk that NASA undertook to justify flying with known Shuttle desgign flaws. Hopefully, in this case, the NASA senior managers are not applying the same mindless schedule pressures that leads to quick fixes and mindless workarounds at the expense of long term safety.
How is it that astronauts managed to land on the moon in 1969 but the next mission to get people to the moon will take until 2020? With today's engineering tech - CFD software, advanced materials science, VR simulation, rapid prototyping technology - and lots of commercial sattelites shot into space every year, it should be much easier to get people to the moon and back safely than it must have been in the 60s. Unless of course that landing was faked as some people allege.
How is it that astronauts managed to land on the moon in 1969 but the next mission to get people to the moon will take until 2020? With today's engineering tech...
Basically they spent more in the 60's relative to today's budget to speed up the process. We're taking a slower, cheaper route this time.
Brilliant! I mean we have more computers nowadays! Computers everywhere means easier everything! That's some solid logic! Never mind the political atmosphere, what with its shoe string budgets and extreme shifts in public opinion. Never mind that there is no immediate, short term goal to be accomplished by expanding space travel. The fact that people haven't been truly interested in the long term benefits or concerned at all, really, with space exploration is completely irrelevant when compared to the amoun
With today's engineering tech - CFD software, advanced materials science,...
Well, if you exercise, has all that technology made you able to lift heavier weights than you might have in 1960? Generally not. Indeed, we are going back to the sort of design used in 1969 instead of the more sophisticated shuttle design. They had great technology for this particular problem back then. But they also had William Proxmire, architect of what is arguably the most stupid decision in the history of mankind: the turn bac
It's a harmonic vibration issue apparently, and these are generally solved quite easily. Adding or removing stiffness, a spiral wrap of an energy dissipating elastomer, isolation mounts, ading or removing mass (or simply moving mass around)... doesn't look like it's a severe issue at this early of the design stage. Someone's just being alarmist.
Actually the way I read it is the problem is in the gas inside the solid booster having turbulence that leads to vibrations. Thus it isn't dependent on the structure of the booster, but on the way the fuel inside it is shaped, at ignition and during the burn.
Yes, it's the gas that causes it, which would ordinarily just be a rumble. However, the frequency of the rumble apparently matches one of the harmonics of the rocket casing or motor, which causes a nasty bit of positive feedback.
Much like bouncing in the middle of a board. Changing the frequency of the input force means you won't go as high, changing the mass (lighter or heavier person) means the resonant frequency changes, making the board out of something stiffer or less stiff changes the optimum rate of bouncing...etc.
So long as they don't do what they have already done with the shuttle: 1) Build a flawed machine, with safety standards specified 2) Gradually remove the safeguards, kill some people in the process. 3) Wind up delaying with repeated patch jobs to the flawed design (instead of doing a proper redesign). Re-instate or intensify safeguards that aren't going to fix the issue. 4) Continue to launch despite seeing ongoing problems.
They need to either get this right and kill no one in the first few HUNDRED launches of
They need to either get this right and kill no one in the first few HUNDRED launches of the vehicle (if it's not superseded by then) or convince people that if we do incur a few deaths they are the price that has to be paid.
They've succeeded completely in the second count there -- in 120 launches, 14 human lives have been lost in two accidents (one on launch, one during reentry). Hundreds of humans have taken over a hundred trips into space on the shuttle, and the vehicle has killed only a handful of them
In other words, these are solved by *adding mass*. In a rocket optimized for low mass and a fixed size payload (like the Ares 1 is), removing mass just isn't an option. As I understand it, the resonance mode is due to the payload, the SRB on the bottom, and the coupling between the two masses. If you cut down either one, the coupling would be able to dampen vibration more (there's less energy that needs to be dissipated). I don't know if the SRB has a sharp peak at this frequency. If the vibrations induced
Solid Rocket Boosters are sort of like strapping yourself to a firecracker. We can't have liquid ones?
You could have liquid ones, but they take an awful lot of development to get right. NASA, and US institutions in general, typically don't like them because of the danger involved (the Soviets have had some major disasters with liquid fuels). The only people who really did get liquid fuels to be fairly safe and reliable were the British and their Blue Streak (HTP was used after the failure of LOX - impractical in an ICBM), Black Arrow and Black Knight projects:
These rockets were a departure from everything else around, and used Hydrogen Peroxide as an oxidiser - cheap, readily available and works well at normal temperatures and pressure. Most considered the fuel to be too hazardous, and a Hydrogen Peroxide fuelled torpedo allegedly sank the Kursk (probably not sensible on a submarine), but the British developed ways to handle it safely and efficiently. To this day, no one else has tried this method and its pretty advanced rocketry even forty years on. It certainly gets rid of the dangerous handling of liquid oxygen, which has to be kept ultra cool and under controlled cryogenic conditions.
After a textbook final launch, the project was cancelled. Given the need for commercial satellite launches over the past few decades, the mind boggles as to how cheap and useful this could have been if developed further. The British, as per usual, decided that simply reusing the Scout solid fuelled rocket would be cheaper. Go figure.
LOX is routinely handled by thousands of industrial facilities in the US alone. Its properties are well known and it has been used safely for over a century.
Liquid boosters have been used safely on dozens of rocket types. They have been used safely to launch crewed capsules. Liquid rocket engines are commercially available. (In fact, every single crewed American vehicle has had liquid fuels as their main source of energy. The SRB's on the Shuttle are booster assist and the only Gemini to fly on a solid was an unmanned test capsule).
What we are seeing here is a departure from decades of development. Solids have been considered unsafe for manned flight for decades as they are not able to be throttled in flight. Once lit, they burn to exhaustion. They have uneven burn characteristics due to uneven mixing of the propellants. No solid casing has ever been put in a load of this magnitude. (The SRB's on the Shuttle never carried the full weight of the shuttle and they were axially loaded as opposed to have the load directly along the case). There is no engine shutdown in an SRB.
Arguing that liquids would take a lot of development to get right is a bit misleading as it is just as much a statement to be made for SRB's.
The whole Shuttle-derived stuff is crap. These are essentially new engines along with a new booster design and they should have had a design competition and weigh the relative merits of various design proposals. This was a fiat decision made by Griffin when he came into office. There was no technical justification. No weighing of options. Even the sizing of the Orion is extremely questionable.
Liquid hydrogen and hypergolics (chemicals that spontaneously burn when mixed) tend to be rather dangerous for different reasons. Hydrogen leaks and can cause explosive conditions under the right concentrations. Hypoergolics often are corrosive or environmentally dangerous. For example, a popular mix is fuming nitric acid and hydrazine (which is highly toxic and can decompose releasing a lot of energy).
To this day, no one else has tried this method and its pretty advanced rocketry even forty years on. It
ALL of our early missiles from the 50's were liquid based. All of our space program has been liquid based. Mercury was based on Atlas. Gemini was based on Titans. Apollo used the Mighty Saturn V. ALL of these engines were liquid based. Some are kerosine/LOX, and others are Hydrogen/LOX. The main boost of the Shuttle is based on the SSME. The main boost of the Ares V will be liquid. Likewise, even spacex's engines are liquid based. The brits abanded their missles and their launch systems BECAUSE they had so
IANARS, but these do not blow up. Heck even the challenger did not blow up. A seal popped open that allowed the exhaust to hit the fuel tank. The simple fact is that these are VERY safe. It has only several issues; The mix is hard to get right. Considering that it is the same mix that has gone into all 120+ x 2 shuttles, I am not too worried. The second is that once lit, there is no stopping it, and there is no throttling it (other than building it into the mix). This is not like strapping yourself to a fir
The first Saturn V rockets for the Apollo program had a similar problem with pogo oscillations. http://www.time.com/time/magazine/article/0,9171,902216,00.html [time.com] . Engineers were able to solve the problem back then, I'm sure they can come up with solutions again.
Interesting article. It was written just after the Apollo 6 [wikipedia.org] unmanned test of the Saturn V in 1968.
The mission went quite poorly. 2 engines failed on the second stage, and the third stage engine failed to restart in orbit. Parts fell off the shroud, too.
Still, NASA went ahead and launched the next Saturn V with a crew to the moon (Apollo 8). Another unmanned test was not performed to "save about $280 million and avoid further delays in its program to place U.S. astronauts on the moon in 1969". This has of
Saturn V multi-engine pogo effects were solved by buffering the fuel supply with super-critical helium cells and adjusting the guidance system for smoother steering impulses.
A single solid propellant pogo on the other hand, is more complicated due to fact that you have variances in the solid, no matter how precise the mix is. The Japanese have been tangling with this for some time with success and failures, more failures are recorded though. Go with a clustered booster kit, then would be able to counter most of the pogo with each booster's own vibration frequency.
A Delta-Style cluster kit would resolve this problem and give a higher delta-v impulse to the stack as a whole. The ticklish part would be man-rating the stack with the added solids. One solution would be to stagger the cluster's firing as to maximize the dampening effects. This would add a safety factor in case there's a failure in the cluster at any stage, the opposing elements would be jettisoned along with the failed unit. Then the second stage would simply burn longer to make the orbit, or a contingency plan would kick in, with maximum of life safety.
This might be part of why other organizations are looking more at combination liquid/solid engines, in addition to the greater control provided. For many decades now, organizations - NASA included - have worked on replacing the first stage rocket completely with a turbine-assisted ramjet. TAR engines are much more efficient than rockets, the main difficulties are in building one large enough, building large enough bypasses for the engine to work efficiently at high speeds, and at the same time building a turbine large enough for the engine to work well stationary.
When stationary, the air must have a net velocity in excess of 400 mph for the engine to retain efficiency - which a turbine can easily do if there are no other complications. Eventually, the turbine gets in the way, hence the need for a really good bypass system. White Knight avoided the need for TAR by having the first stage as an actual aircraft, but a conventional aircraft isn't going to be capable of carrying the weight needed for true orbital flight, let alone interplanetary flight. Affordable space flight is probably going to require TAR engines.
(Other alternative launch-assist methods include using linear accelerators - basically strap the rocket onto something akin to a bullet train and then get the train up to the critical speed, or using a very powerful gas cannon to fire the rocket into the air at the critical speed. The first would likely end up more expensive to operate than a TAR, the latter would require a very sophisticated multi-charge arrangement if it is to avoid killing everyone onboard, but might end up being another viable method.)
One thing I think can be said for certain - by 2020, no sane engineer will be designing launch vehicles for space that use a rocket first stage. I'll give it a 40/60 chance that by 2020 commercial space flight will have surpassed NASA in terms of cost-per-unit-mass-launched, and 20/80 that hobbyist space flight will have done likewise. If NASA persists in long-outmoded next-gen launch vehicles, then somewhere in the 2030-2050 timeline, NASA will be redundant. Government-run organizations make sense for bleeding-edge work because that is generally too expensive for everyone else. However, once everyone passes said Government agency's technology, it has no value or merit. To have value for money, NASA should be working on systems that will become bleeding-edge in 2020, not what were bleeding-edge in 1920. R&D is the expensive work, everything else is meccano tech.
For many decades now, organizations - NASA included - have worked on replacing the first stage rocket completely with a turbine-assisted ramjet.
No, NASA gave it up years ago - as it simply doesn't work. The turbines are too heavy, useful for too small a portion of the flight profile, etc... etc...
Other alternative launch-assist methods include using linear accelerators - basically strap the rocket onto something akin to a bullet train and then get the train up to the critical speed, or using a very powerful gas cannon to fire the rocket into the air at the critical speed.
Two more ideas that don't work, despite years of fanboy cheerleading for them. Among other large drawbacks - you still need to get a substantial portion (99%+) of the required velocity from rockets, but the weight of the structure needed to withstand these methods of 'assisting' means a rocket launched this way is actually larger and heavier than one that launched in a conventional fashion.
Seriously, this was known about forty years ago and are called pogo oscillations. They are generally disastrous, and they were the cause of Apollo 13's fifth engine shut down after liftoff.
In general, I'm pretty non-plussed by NASA's moon landing attempts. Their design is basically Apollo rehashed plus forty years (fifty years if it actually launches - pretty depressing), the vast majority of it isn't reusable (I haven't got a clue how they can call it a shuttle replacement) and it really doesn't get us any further forwards in terms of making getting into space easier, safer and something that can be done on a regular basis.
Nope, Pogo oscillation was caused by compression waves that affected pump volume in liquid fueled rockets. This was solved in the SSME for the Shuttle by adding a chamber along the fuel feed that acted like a capacitor. Transient pressure waves would back fill the chamber, then the other side of the wave would suck it out. Constant flow, no pogo.
Seriously, this was known about forty years ago and are called pogo oscillations. They are generally disastrous, and they were the cause of Apollo 13's fifth engine shut down after liftoff.
They're "generally disastrous" only in the sense that they'll destroy the craft if they aren't addressed. Apollo solved the problem by essentially adding a big bellows to the fuel supply feed, allowing the pressure pulses to be damped instead of allowing the fuel flow to resonate. The Space Shuttle main engines have similar dampers in place, and their design was based on data acquired during Apollo.
In general, I'm pretty non-plussed by NASA's moon landing attempts. Their design is basically Apollo rehashed plus forty years (fifty years if it actually launches - pretty depressing), the vast majority of it isn't reusable (I haven't got a clue how they can call it a shuttle replacement) and it really doesn't get us any further forwards in terms of making getting into space easier, safer and something that can be done on a regular basis.
Your observation shows a shocking lack of perspective. Just because the design has a capsule on top doe
""I hope no one was so ill-informed as to believe that we would be able to develop a system to replace the shuttle without facing any challenges in doing so," NASA administrator Michael Griffin said in a statement to The Associated Press."
Well, duh, the whole point of the 'shuttle-derived' Stick design was that it was supposed to be safe to fly and fast and cheap to develop because the shuttle technology would avoid these kind of 'challenges'.
But instead of building a capsule that could fly on the shuttle-derived launcher they've expanded it into an orbital RV which requires major changes to the launcher design to have any chance of reaching orbit.
>they do not expect it to delay the goal of returning astronauts to the moon by 2020.
of course not, what's going to delay going to the moon again by 2020 is the fact that congress has no intention whatsoever of paying for that, and no one, not even Bush takes the program seriously.
Why are they wasting money on programs that are going to be thrown right out the window, never to be heard of again, as soon as the next president takes office?
I wish NASA would put more effort into developing gaseous core nuclear rocket engines. There was a nuclear engine project in the late 60s using a solid core reactor, but gaseous core reactors have not been thoroughly explored. Whereas solid reactors melt above about 3500C, a "light bulb" type of reactor consisting of a hollow quartz bulb with a cloud of gaseous nuclear fuel confined in the center could operate at 25000 C, radiating in the ultraviolet range instead of heat per se. In an engine based on this type of reactor, hydrogen flowing past the outside of the bulb would be superheated and expelled as rocket exhaust. No chemical combustion, no radioactive emissions, just heat transfer.
Check out this interesting article [nuclearspace.com], part 10 of a series, about a hypothetical design for a non-polluting, 100% reusable nuclear rocket based on the Saturn V form factor. Using existing engineering apart from the gaseous core reactor, it could lift 1000 tons of payload into orbit (6 times the capacity of the proposed single-use Ares 5 cargo rocket, and 30 times that of the shuttle), and then return 1000 tons of cargo to a powered vertical landing. No expendable fuel tanks, no solid booster recovery, just a big old Flash Gordon style rocketship. This is heavy lifting power that could take up a space hotel or moon base in one shot. It could power enormous ships to Mars in 3 months, not merely to explore but to colonize, carrying hundreds of people at a time, hundreds of tons of equipment and supplies, and highly effective radiation shielding.
I know it's the "N" word, but this rocket wouldn't be a nuclear disaster waiting to happen. If such a ship crashed or exploded and released its entire nuclear fuel load into the atmosphere, the nuclides released would be 1% of what came out of a single 1950s bomb test (and there were many of those).
I support the idea of nuclear rocketry, in theory.
Let's however get back from engineering dreamland and take a cold hard look at political reality. Anything with the word "nuclear" in it scares the shit out of the vast majority of people. Most people seem to be convinced that every nuclear device is a potential nuclear weapon waiting to go off, and that any nuclear accident will inevitably result in thousands of deaths and an area the size of Texas rendered uninhabitable.
What exactly is the issue? The problem is that any structure has a resonant frequency at which it naturally vibrates. If you excite the structure at that frequency, you can develop a positive-feedback system that will literally shake it apart (the Tacoma Narrows Bridge is the classic example).
Solid rocket motors don't run particularly smoothly (compared to well-designed or even poorly designed liquids) and large solid motors provide a very rough ride. Everyone who has ever ridden the Shuttle to orbit has commented on how much smoother the ride gets after staging the SRBs.
Now, one way to mitigate this is to damp it out with a large mass. The Shuttle does this by its nature, because even though it has two of the things, they are not directly attached to the orbiter--they are attached to a large external tank with one and a half million pounds of liquid propellants in it, and it can absorb a lot of the vibration. Moreover, the large mass has a frequency that doesn't resonate with the vibration.
As I understand it (and I could be wrong, and I'm not working Ares, but this is based on discussions, many off the record and all on background with insiders on the program), there is a very real concern that the upper stage on top of the SRB in "the Stick" will be excited at a resonant frequency, but that even if not, the stage will be too small to damp the vibrations of the huge SRB below.
If this is the case, there is no simple solution. You can't arbitrarily change the mass of the upper stage--that is determined by the mission requirement. Any solution is going to involve damping systems independent of the basic structure that are sure to add weight to a launch vehicle that is already, according to most reports, underperforming. Or it will involve beefing up the structure of the upper stage and the Orion itself so that they can sustain the acoustic vibration loads. In the case of the latter, it is already overweight, with low margins.
So this constitutes a major program risk, that could result in either cancellation, or a complete redesign (that no longer represents the original concept, because the problem is fundamentally intrinsic to it).
Now, let's take apart the response a little:
Thrust oscillation is...a risk. It is being reviewed, and a mitigation plan is being developed. NASA is committed to resolve this issue prior to the Ares I Project's preliminary design review, currently scheduled for late 2008.
The problem is that NASA can "commit" to resolve it until the cows come home, but if it's not resolvable, it's not resolvable. They can't rescind the laws of physics, and we're approaching a couple of anniversaries of times when they attempted to do that, with tragic results.
Now this next part is (to put it mildly) annoying:
NASA has given careful consideration to many different launch concepts (shuttle-derived, evolved expendable launch vehicle, etc.) over several years. This activity culminated with release of the Exploration Systems Architecture Study in 2005. Since then, the baseline architecture has been improved to decrease life cycle costs significantly.
NASA's analysis backs up the fact that the Ares family enables the safest, least expensive launch architecture to meet requirements for missions to the International Space Station, the moon and Mars. NASA is not contemplating alternatives to the current approach.
The problem is that NASA didn't give "careful consideration" to the previous analyses after Mike Griffin came in. As far as can be determined, all of the analysis performed under Admiral Steidle's multiple CE&R contracts, performe
Certainly better than financials... I think they do awesome work. I have been proud of the rover project, and I think the knowledge gains from NASA missions have long tails.
Actually, NASA's ROI is pretty good at about $7 returned for every $1 spent. They also develop a lot of technology that doesn't have a financial ROI, but rather a simple non-tangible benefit to society as a whole. For example, they developed the CCD imager for use in the Hubble Telescope. That technology is now widely used in inexpensive digital cameras but is more importantly also used in medical imagers for detecting breast cancer. It has eliminated something like a half a million unneeded biopsies which not only save that cost, but also the pain from the procedure itself.
I see the problem here being one of opportunity cost.
This of course assumes the technology would never have been discovered if we didn't spend the initial investment; but by beating the would-be discoverer to the punch, we get the return sooner
But what technologies are discovered later because we are inefficiently allocating resources via NASA? You can say that solar cells, fuel cells, and velcro came sooner because NASA helped invent them. But NASA has been wasting money for decades. You don't see what's missing.
This was brought up last NASA story.
Somebody pointed out that just ONE of the technologies produced for the Hubble telescope lead to more money saved on machines scanning for breast cancer than it cost for the Hubble in its entirety, and that's just the price tag, not the lives that have been saved because of that alone.
Better to find it now rather than later... (Score:5, Insightful)
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Re:Better to find it now rather than later... (Score:4, Insightful)
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so what? (Score:5, Insightful)
how long did it take to design the saturn Ib/saturn V and make sure that they'd mate well with the apollo capsule? how long did it take to come up with skylab, an orbiting lab that could be mounted on a saturn V?
i expect it'll take about five to six years to bring the orion program to a complete first generation system.
Re:so what? (Score:5, Insightful)
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Re:so what? (Score:5, Insightful)
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Only took 'em 12 years to get to THE MOON... (Score:2)
My biggest problem here is that they should already be flying X-vehicles. Wasn't that how progress was made? One to crash, One to fly, and One to hang up in the Smithsonian?
Since Ares keeps getting reduced in capabilities, I'm not confident that in 2015 ( when it's scheduled to start running ) we'll actually have anything delivered, and it's going to be another Turkey.
Step 1: Get NASA out of Manned Spaceflight.
Step
Re:so what? (Score:5, Insightful)
NASA has known that the Space Shuttle flies like a duck-taped cow since well before its first launch in 1981, since it was designed by committees lobbying wildly to have different components manufactured in different states to get Congressional approval and for many other political, rather than engineering, reasons. Development of replacement spacecraft has been hindered by funding, similar lobbying stupidity, and the unwillingness to admit that rockets have to be built and tested rather than modeled to death for decades before actually trying anything.
Private industry has already shown a far more capable design, when the Ariadne won the X-Prize. But NASA is blocking its development for numerous political reasons, not engineering reasons. You cannot expect NASA to do anything in real development and admit that complex craft are going to crash in the design and testing phase, and treats it as an acceptable risk rather than a political nightmare. And their current leadership is too politically hidebound to do anything profoundly innovative: it would interfere with the "5 year plans" of their contracts with Boeing and other manufacturers.
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Re: (Score:3, Interesting)
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If you'd followed this very much, you might realize a few things. Over the past few decades, the big boys have made noises about building their own stuff: there's a market in space launch and they'd like to profit from it (much like the Russians are now.) However, all those corporations are heavily dependent upon Federal contracts, and every time they talk about building a commercial lau
Holy cow! (Score:5, Insightful)
Re:Holy cow! (Score:5, Funny)
Yeah, how pathetic to run into problems already. It's not rocket science, guys.
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Re: (Score:3, Interesting)
The idea was that by using Shuttle components that are (a) in production and (b) have proven safe in their current designs, then (c) by configuring them in a way that avoids known problems, you end up with a safe and economical vehicle much faster.
The problem is that it might not be so simple. The first concept was a Shuttle solid rocket booster for the first stage, an second stage powered by a Shuttle
Nasa: Delay if Necessary (Score:5, Insightful)
If anyone else has read Diane Vaughan's Challenger Launch Decision [amazon.com], he or she will know that launch schedule pressure from upper management was a leading cause of the rationalization of risk that NASA undertook to justify flying with known Shuttle desgign flaws. Hopefully, in this case, the NASA senior managers are not applying the same mindless schedule pressures that leads to quick fixes and mindless workarounds at the expense of long term safety.
Moon landing 1969 (Score:3, Funny)
How is it that astronauts managed to land on the moon in 1969 but the next mission to get people to the moon will take until 2020? With today's engineering tech - CFD software, advanced materials science, VR simulation, rapid prototyping technology - and lots of commercial sattelites shot into space every year, it should be much easier to get people to the moon and back safely than it must have been in the 60s. Unless of course that landing was faked as some people allege.
Re:Moon landing 1969 (Score:5, Interesting)
Basically they spent more in the 60's relative to today's budget to speed up the process. We're taking a slower, cheaper route this time.
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Well, if you exercise, has all that technology made you able to lift heavier weights than you might have in 1960? Generally not. Indeed, we are going back to the sort of design used in 1969 instead of the more sophisticated shuttle design. They had great technology for this particular problem back then. But they also had William Proxmire, architect of what is arguably the most stupid decision in the history of mankind: the turn bac
It's simple to solve this problem (Score:5, Informative)
Re:It's simple to solve this problem (Score:4, Informative)
But, I am not a rocket scientist.
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Re:It's simple to solve this problem (Score:5, Informative)
Much like bouncing in the middle of a board. Changing the frequency of the input force means you won't go as high, changing the mass (lighter or heavier person) means the resonant frequency changes, making the board out of something stiffer or less stiff changes the optimum rate of bouncing...etc.
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Re: (Score:2)
1) Build a flawed machine, with safety standards specified
2) Gradually remove the safeguards, kill some people in the process.
3) Wind up delaying with repeated patch jobs to the flawed design (instead of doing a proper redesign). Re-instate or intensify safeguards that aren't going to fix the issue.
4) Continue to launch despite seeing ongoing problems.
They need to either get this right and kill no one in the first few HUNDRED launches of
Re: (Score:3, Insightful)
They've succeeded completely in the second count there -- in 120 launches, 14 human lives have been lost in two accidents (one on launch, one during reentry). Hundreds of humans have taken over a hundred trips into space on the shuttle, and the vehicle has killed only a handful of them
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In other words, these are solved by *adding mass*. In a rocket optimized for low mass and a fixed size payload (like the Ares 1 is), removing mass just isn't an option. As I understand it, the resonance mode is due to the payload, the SRB on the bottom, and the coupling between the two masses. If you cut down either one, the coupling would be able to dampen vibration more (there's less energy that needs to be dissipated). I don't know if the SRB has a sharp peak at this frequency. If the vibrations induced
Solid Rocket Boosters (Score:3, Insightful)
Re:Solid Rocket Boosters (Score:5, Insightful)
http://en.wikipedia.org/wiki/Blue_streak [wikipedia.org]
http://en.wikipedia.org/wiki/Black_Arrow [wikipedia.org]
These rockets were a departure from everything else around, and used Hydrogen Peroxide as an oxidiser - cheap, readily available and works well at normal temperatures and pressure. Most considered the fuel to be too hazardous, and a Hydrogen Peroxide fuelled torpedo allegedly sank the Kursk (probably not sensible on a submarine), but the British developed ways to handle it safely and efficiently. To this day, no one else has tried this method and its pretty advanced rocketry even forty years on. It certainly gets rid of the dangerous handling of liquid oxygen, which has to be kept ultra cool and under controlled cryogenic conditions.
After a textbook final launch, the project was cancelled. Given the need for commercial satellite launches over the past few decades, the mind boggles as to how cheap and useful this could have been if developed further. The British, as per usual, decided that simply reusing the Scout solid fuelled rocket would be cheaper. Go figure.
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Re:Solid Rocket Boosters (Score:4, Insightful)
Liquid boosters have been used safely on dozens of rocket types. They have been used safely to launch crewed capsules. Liquid rocket engines are commercially available. (In fact, every single crewed American vehicle has had liquid fuels as their main source of energy. The SRB's on the Shuttle are booster assist and the only Gemini to fly on a solid was an unmanned test capsule).
What we are seeing here is a departure from decades of development. Solids have been considered unsafe for manned flight for decades as they are not able to be throttled in flight. Once lit, they burn to exhaustion. They have uneven burn characteristics due to uneven mixing of the propellants. No solid casing has ever been put in a load of this magnitude. (The SRB's on the Shuttle never carried the full weight of the shuttle and they were axially loaded as opposed to have the load directly along the case). There is no engine shutdown in an SRB.
Arguing that liquids would take a lot of development to get right is a bit misleading as it is just as much a statement to be made for SRB's.
The whole Shuttle-derived stuff is crap. These are essentially new engines along with a new booster design and they should have had a design competition and weigh the relative merits of various design proposals. This was a fiat decision made by Griffin when he came into office. There was no technical justification. No weighing of options. Even the sizing of the Orion is extremely questionable.
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Re: (Score:3, Insightful)
Liquid hydrogen and hypergolics (chemicals that spontaneously burn when mixed) tend to be rather dangerous for different reasons. Hydrogen leaks and can cause explosive conditions under the right concentrations. Hypoergolics often are corrosive or environmentally dangerous. For example, a popular mix is fuming nitric acid and hydrazine (which is highly toxic and can decompose releasing a lot of energy).
To this day, no one else has tried this method and its pretty advanced rocketry even forty years on. It
How you got modded up is beyond me (Score:3, Insightful)
Not really (Score:3, Informative)
Everything old is new again (Score:2, Informative)
Re: (Score:3, Interesting)
The mission went quite poorly. 2 engines failed on the second stage, and the third stage engine failed to restart in orbit. Parts fell off the shroud, too.
Still, NASA went ahead and launched the next Saturn V with a crew to the moon (Apollo 8). Another unmanned test was not performed to "save about $280 million and avoid further delays in its program to place U.S. astronauts on the moon in 1969". This has of
Re:Everything old is new again (Score:5, Interesting)
A single solid propellant pogo on the other hand, is more complicated due to fact that you have variances in the solid, no matter how precise the mix is. The Japanese have been tangling with this for some time with success and failures, more failures are recorded though. Go with a clustered booster kit, then would be able to counter most of the pogo with each booster's own vibration frequency.
A Delta-Style cluster kit would resolve this problem and give a higher delta-v impulse to the stack as a whole. The ticklish part would be man-rating the stack with the added solids. One solution would be to stagger the cluster's firing as to maximize the dampening effects. This would add a safety factor in case there's a failure in the cluster at any stage, the opposing elements would be jettisoned along with the failed unit. Then the second stage would simply burn longer to make the orbit, or a contingency plan would kick in, with maximum of life safety.
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Yeah, well... (Score:4, Interesting)
When stationary, the air must have a net velocity in excess of 400 mph for the engine to retain efficiency - which a turbine can easily do if there are no other complications. Eventually, the turbine gets in the way, hence the need for a really good bypass system. White Knight avoided the need for TAR by having the first stage as an actual aircraft, but a conventional aircraft isn't going to be capable of carrying the weight needed for true orbital flight, let alone interplanetary flight. Affordable space flight is probably going to require TAR engines.
(Other alternative launch-assist methods include using linear accelerators - basically strap the rocket onto something akin to a bullet train and then get the train up to the critical speed, or using a very powerful gas cannon to fire the rocket into the air at the critical speed. The first would likely end up more expensive to operate than a TAR, the latter would require a very sophisticated multi-charge arrangement if it is to avoid killing everyone onboard, but might end up being another viable method.)
One thing I think can be said for certain - by 2020, no sane engineer will be designing launch vehicles for space that use a rocket first stage. I'll give it a 40/60 chance that by 2020 commercial space flight will have surpassed NASA in terms of cost-per-unit-mass-launched, and 20/80 that hobbyist space flight will have done likewise. If NASA persists in long-outmoded next-gen launch vehicles, then somewhere in the 2030-2050 timeline, NASA will be redundant. Government-run organizations make sense for bleeding-edge work because that is generally too expensive for everyone else. However, once everyone passes said Government agency's technology, it has no value or merit. To have value for money, NASA should be working on systems that will become bleeding-edge in 2020, not what were bleeding-edge in 1920. R&D is the expensive work, everything else is meccano tech.
Re:Yeah, well... (Score:5, Interesting)
No, NASA gave it up years ago - as it simply doesn't work. The turbines are too heavy, useful for too small a portion of the flight profile, etc... etc...
Two more ideas that don't work, despite years of fanboy cheerleading for them. Among other large drawbacks - you still need to get a substantial portion (99%+) of the required velocity from rockets, but the weight of the structure needed to withstand these methods of 'assisting' means a rocket launched this way is actually larger and heavier than one that launched in a conventional fashion.
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Apollo Called: It Wants its Saturn V Back (Score:4, Informative)
In general, I'm pretty non-plussed by NASA's moon landing attempts. Their design is basically Apollo rehashed plus forty years (fifty years if it actually launches - pretty depressing), the vast majority of it isn't reusable (I haven't got a clue how they can call it a shuttle replacement) and it really doesn't get us any further forwards in terms of making getting into space easier, safer and something that can be done on a regular basis.
Re: (Score:3, Informative)
This is a solid rocket, it's a different problem.
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Seriously, this was known about forty years ago and are called pogo oscillations. They are generally disastrous, and they were the cause of Apollo 13's fifth engine shut down after liftoff.
They're "generally disastrous" only in the sense that they'll destroy the craft if they aren't addressed. Apollo solved the problem by essentially adding a big bellows to the fuel supply feed, allowing the pressure pulses to be damped instead of allowing the fuel flow to resonate. The Space Shuttle main engines have similar dampers in place, and their design was based on data acquired during Apollo.
In general, I'm pretty non-plussed by NASA's moon landing attempts. Their design is basically Apollo rehashed plus forty years (fifty years if it actually launches - pretty depressing), the vast majority of it isn't reusable (I haven't got a clue how they can call it a shuttle replacement) and it really doesn't get us any further forwards in terms of making getting into space easier, safer and something that can be done on a regular basis.
Your observation shows a shocking lack of perspective. Just because the design has a capsule on top doe
Same old Griffin (Score:3, Interesting)
Well, duh, the whole point of the 'shuttle-derived' Stick design was that it was supposed to be safe to fly and fast and cheap to develop because the shuttle technology would avoid these kind of 'challenges'.
But instead of building a capsule that could fly on the shuttle-derived launcher they've expanded it into an orbital RV which requires major changes to the launcher design to have any chance of reaching orbit.
of course not (Score:4, Interesting)
of course not, what's going to delay going to the moon again by 2020 is the fact that congress has no intention whatsoever of paying for that, and no one, not even Bush takes the program seriously.
Why are they wasting money on programs that are going to be thrown right out the window, never to be heard of again, as soon as the next president takes office?
Nuclear Rockets (Score:5, Interesting)
Check out this interesting article [nuclearspace.com], part 10 of a series, about a hypothetical design for a non-polluting, 100% reusable nuclear rocket based on the Saturn V form factor. Using existing engineering apart from the gaseous core reactor, it could lift 1000 tons of payload into orbit (6 times the capacity of the proposed single-use Ares 5 cargo rocket, and 30 times that of the shuttle), and then return 1000 tons of cargo to a powered vertical landing. No expendable fuel tanks, no solid booster recovery, just a big old Flash Gordon style rocketship. This is heavy lifting power that could take up a space hotel or moon base in one shot. It could power enormous ships to Mars in 3 months, not merely to explore but to colonize, carrying hundreds of people at a time, hundreds of tons of equipment and supplies, and highly effective radiation shielding.
I know it's the "N" word, but this rocket wouldn't be a nuclear disaster waiting to happen. If such a ship crashed or exploded and released its entire nuclear fuel load into the atmosphere, the nuclides released would be 1% of what came out of a single 1950s bomb test (and there were many of those).
political reality calling... (Score:3, Insightful)
Let's however get back from engineering dreamland and take a cold hard look at political reality. Anything with the word "nuclear" in it scares the shit out of the vast majority of people. Most people seem to be convinced that every nuclear device is a potential nuclear weapon waiting to go off, and that any nuclear accident will inevitably result in thousands of deaths and an area the size of Texas rendered uninhabitable.
I am perfectly well aware that
Thoughts from an aerospace engineer (Score:3, Insightful)
http://www.transterrestrial.com/archives/010396.html#010396 [transterrestrial.com]
What exactly is the issue? The problem is that any structure has a resonant frequency at which it naturally vibrates. If you excite the structure at that frequency, you can develop a positive-feedback system that will literally shake it apart (the Tacoma Narrows Bridge is the classic example).
Solid rocket motors don't run particularly smoothly (compared to well-designed or even poorly designed liquids) and large solid motors provide a very rough ride. Everyone who has ever ridden the Shuttle to orbit has commented on how much smoother the ride gets after staging the SRBs.
Now, one way to mitigate this is to damp it out with a large mass. The Shuttle does this by its nature, because even though it has two of the things, they are not directly attached to the orbiter--they are attached to a large external tank with one and a half million pounds of liquid propellants in it, and it can absorb a lot of the vibration. Moreover, the large mass has a frequency that doesn't resonate with the vibration.
As I understand it (and I could be wrong, and I'm not working Ares, but this is based on discussions, many off the record and all on background with insiders on the program), there is a very real concern that the upper stage on top of the SRB in "the Stick" will be excited at a resonant frequency, but that even if not, the stage will be too small to damp the vibrations of the huge SRB below.
If this is the case, there is no simple solution. You can't arbitrarily change the mass of the upper stage--that is determined by the mission requirement. Any solution is going to involve damping systems independent of the basic structure that are sure to add weight to a launch vehicle that is already, according to most reports, underperforming. Or it will involve beefing up the structure of the upper stage and the Orion itself so that they can sustain the acoustic vibration loads. In the case of the latter, it is already overweight, with low margins.
So this constitutes a major program risk, that could result in either cancellation, or a complete redesign (that no longer represents the original concept, because the problem is fundamentally intrinsic to it).
Now, let's take apart the response a little:
Thrust oscillation is...a risk. It is being reviewed, and a mitigation plan is being developed. NASA is committed to resolve this issue prior to the Ares I Project's preliminary design review, currently scheduled for late 2008.
The problem is that NASA can "commit" to resolve it until the cows come home, but if it's not resolvable, it's not resolvable. They can't rescind the laws of physics, and we're approaching a couple of anniversaries of times when they attempted to do that, with tragic results.
Now this next part is (to put it mildly) annoying:
NASA has given careful consideration to many different launch concepts (shuttle-derived, evolved expendable launch vehicle, etc.) over several years. This activity culminated with release of the Exploration Systems Architecture Study in 2005. Since then, the baseline architecture has been improved to decrease life cycle costs significantly.
NASA's analysis backs up the fact that the Ares family enables the safest, least expensive launch architecture to meet requirements for missions to the International Space Station, the moon and Mars. NASA is not contemplating alternatives to the current approach.
The problem is that NASA didn't give "careful consideration" to the previous analyses after Mike Griffin came in. As far as can be determined, all of the analysis performed under Admiral Steidle's multiple CE&R contracts, performe
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Re:Nasa (Score:5, Informative)
Bill
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Re: (Score:3, Informative)
Re: (Score:3, Insightful)
I see the problem here being one of opportunity cost.
This of course assumes the technology would never have been discovered if we didn't spend the initial investment; but by beating the would-be discoverer to the punch, we get the return sooner
But what technologies are discovered later because we are inefficiently allocating resources via NASA? You can say that solar cells, fuel cells, and velcro came sooner because NASA helped invent them. But NASA has been wasting money for decades. You don't see what's missing.
Re:Nasa (Score:5, Interesting)
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Re:Second Post (Score:5, Funny)
Management....wants....a....launch....so....shut....the....fuck....up, Scotty!
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