What changes has Obama made to NASA?

[Andy Resnick]

What? Are you sure about that? My main point was not that technology per se has advanced greatly, but that the cost has been reduced, maybe more mundane materials and technology.

The entire U.S. manned lunar program cost roughly $100 billion. There is no good reason why we cannot complete one lunar mission in a relatively short amount of time at a "reasonable" cost. We would not be starting from scratch.

I am sure. Computer components follow a mil-spec type of standard, and mission-critical components are held to an even higher standard.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040014965_2004000657.pdf
http://www.cti-us.com/pdf/HistoryEEESpacePartsinUSA.pdf
http://aero-defense.ihs.com/collections/nasa/nasa-standards-14.htm
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/36804/1/01-1236.pdf
http://misspiggy.gsfc.nasa.gov/tva/meldoc/docs4/docs4.pdf

http://sunland.gsfc.nasa.gov/smex/wire/mission/cdhsw/wirrqtop.htm
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880004514_1988004514.pdf
http://www.aspera-3.org/idfs/APAF_SRS_V1.0.pdf

The full NASA motto is "Fast, Better, Cheaper: pick two."

 

[Norman]

I am sure. Computer components follow a mil-spec type of standard, and mission-critical components are held to an even higher standard.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040014965_2004000657.pdf
http://www.cti-us.com/pdf/HistoryEEESpacePartsinUSA.pdf
http://aero-defense.ihs.com/collections/nasa/nasa-standards-14.htm
http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/36804/1/01-1236.pdf
http://misspiggy.gsfc.nasa.gov/tva/meldoc/docs4/docs4.pdf

http://sunland.gsfc.nasa.gov/smex/wire/mission/cdhsw/wirrqtop.htm
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19880004514_1988004514.pdf
http://www.aspera-3.org/idfs/APAF_SRS_V1.0.pdf

The full NASA motto is "Fast, Better, Cheaper: pick two."

I can second Andy's statement here. There is a lot of testing that goes into any piece of hardware that flies for NASA. I am not directly involved in testing, but I have done initial radiation exposure estimates for some upcoming missions to help define likely dose rates for electronics.

You cannot simply take your refurbished Dell laptop up on the ISS. It dies very quickly. Never mind something that is going to get flown to Jupiter or Saturn and is mission critical. The assumptions about how advanced our every day electronics are has absolutely no direct correlation on the availability and quality of space quality electronics.

 

[D H]

The full NASA motto is "Fast, Better, Cheaper: pick two."

"Faster, better, cheaper" was one of NASA's dumber ideas. The 2003 Columbia disaster, along with the 1999 losses of the Mars Climate Orbiter and the Mars Polar Lander, put the nix on that idea (for example, see http://www.spaceref.com/news/viewnews.html?id=864).

Perhaps we will now do the right thing with regard to human spaceflight. As Churchill noted, we Americans always do do the right thing -- but only after we have tried everything else. The Obama budget for FY2012 has $850 million going to commercial space. Congress however has other thoughts; congressional budget meddling is an ongoing issue with any technology project. Key congresscritters still want NASA to build a new human-capable rocket by 2016 on a paltry budget and using existing technology (read: high-cost contractors, lots of marching armies). NASA this time around finally had the cajones to tell Congress that what those congresscritters want cannot be done within the proscribed budget. NASA is not fighting the concept of commercial space. Congress is.

 

[Shackleford]

155 billion in 2010 dollars, and we would be pretty much starting from scratch. Most of that money was spent on procurement and operations. R&D was a small part of the total budget.

Obama's proposed budget for NASA is $18.7 billion for 2012, less than that ($18.0 billion) in 2013 and 2014. About 1/3 of NASA's expenditures go to human space flight, not all of which will go to your back to the future / redo Apollo program. Even if we splash the ISS, kill the JWST, its hard to see more than 6 billion a year going into developing, procuring, and operating a new (old) rocket. We maybe we could redo Apollo in 20 years or so.

Are you saying we would need $6 billion/year for 20 years? $1 billion is a lot of money. You can get a lot done with $1 billion. I don't understand why it takes so much money, especially now that we've "been there and done that." We already know the appropriate performance requirements of the systems and materials and so forth. I'm asserting here that NASA is grossly inefficient and that you could probably get away with spending a lot less with the right management of the program(s). Given our modest technological advancements, scientific understanding, and experience, with the right management and leadership, we should be able to make one trip to the Moon at a cost less than the relative 1960s cost.

 

[D H]

Are you saying we would need $6 billion/year for 20 years?

Yes, I am. That comes out to $120 billion, or $35 billion less than the cost of the Apollo program. You apparently are thinking that because we have "been there, done that" that the cost will be a lot less. What makes you think that? Most of the cost of the Apollo program was for procurement and operations, not R&D. To make matters worse, twenty years is a very suboptimal time frame for such an endeavor. Finally, spending $6 billion per year on this would entail spending all of the human spaceflight budget on this (i.e., we would need to scrap the ISS, and that ain't going to happen).

The only way to make such an endeavor cost less than $100 billion would require
1. Doing it in significantly less than 20 years and
2. Drastically reducing the cost of getting into orbit.

Item 1 would require Congress to up the ante on NASA's budget. This will not happen any time soon given the immense downward pressure on non-defence discretionary spending. Item 2 is possible if Congress stops meddling with NASA's budget.

 

[Shackleford]

Yes, I am. That comes out to $120 billion, or $35 billion less than the cost of the Apollo program. You apparently are thinking that because we have "been there, done that" that the cost will be a lot less. What makes you think that? Most of the cost of the Apollo program was for procurement and operations, not R&D. To make matters worse, twenty years is a very suboptimal time frame for such an endeavor. Finally, spending $6 billion per year on this would entail spending all of the human spaceflight budget on this (i.e., we would need to scrap the ISS, and that ain't going to happen).

The only way to make such an endeavor cost less than $100 billion would require
1. Doing it in significantly less than 20 years and
2. Drastically reducing the cost of getting into orbit.

Item 1 would require Congress to up the ante on NASA's budget. This will not happen any time soon given the immense downward pressure on non-defence discretionary spending. Item 2 is possible if Congress stops meddling with NASA's budget.

I agree with 2. We should focus on that instead of cobbling together slightly more-advanced rockets. What about trans-atmospheric flight?

When I think the cost should be less, I think that the appropriate materials might now be more prevalent and thus lower in cost; that the computing power allows us to more efficiently and quickly design the appropriate systems and requirements; that we know what to expect in the flight, and so forth. Is this any of this correct?

Aren't the Air Force rockets better and cheaper?

 

[Norman]

I agree with 2. We should focus on that instead of cobbling together slightly more-advanced rockets. What about trans-atmospheric flight?

What exactly do you mean by trans-atmospheric flight? If I take the phrase at face value, it seems like all space-bound rockets are "trans-atmospheric"

When I think the cost should be less, I think that the appropriate materials might now be more prevalent and thus lower in cost; that the computing power allows us to more efficiently and quickly design the appropriate systems and requirements; that we know what to expect in the flight, and so forth. Is this any of this correct?

DH mentioned this above (twice I think). The huge price tag on going to the moon is due to procurement- or the acquisition of the actual vehicles, rockets, hardware, etc. The things you mention above have to do with R&D (mainly). The materials we use for spaceflight are largely unchanged. The only thing I could see making a noticeable difference is a system engineering perspective on the overall design.

 

[Shackleford]

What exactly do you mean by trans-atmospheric flight? If I take the phrase at face value, it seems like all space-bound rockets are "trans-atmospheric"



DH mentioned this above (twice I think). The huge price tag on going to the moon is due to procurement- or the acquisition of the actual vehicles, rockets, hardware, etc. The things you mention above have to do with R&D (mainly). The materials we use for spaceflight are largely unchanged. The only thing I could see making a noticeable difference is a system engineering perspective on the overall design.

Oh. I didn't know that. I thought we've made a bit of advancement in materials science and engineering in the last 42 years.

Of course, I knew the bulk of the cost would be procurement and "buying" everything we need. I just thought, from an economic standpoint, the cost might have been reduced over the years for whatever reason.

 

[twofish-quant]

Oh. I didn't know that. I thought we've made a bit of advancement in materials science and engineering in the last 42 years.

At some point you run into basic physical limitations. It turns out that for launching people into space "big and dumb" is the way to go which is why the Russians are good at it.

 

[twofish-quant]

Are you saying we would need $6 billion/year for 20 years?

Yes.

$1 billion is a lot of money.

In 2011 dollars, a billion is not that much money. A $1 billion is the cost of one Manhattan skyscraper or the budget of a large university for one year, and the programs that I work on routinely process several tens of billion dollars in transactions each evening.

I'm asserting here that NASA is grossly inefficient and that you could probably get away with spending a lot less with the right management of the program(s).

I don't think that you can. Once you start pushing efficiency past a certain point, it makes things more inefficient.

Also, the question becomes efficient for what? Astronomers for example have figured out that manned space flight is useless for astronomy, so $1 spend on manned space flight turns out to be "inefficient."

Given our modest technological advancements, scientific understanding, and experience, with the right management and leadership, we should be able to make one trip to the Moon at a cost less than the relative 1960s cost.

I don't think so. Some things have gotten a lot cheaper since 1960 (computer technology). Some things haven't (plumbers). You also have to realize that we have costs that didn't exist in the 1960's. One is that we don't have the technology infrastructure that we did in the 1960's and we have to rebuild that from scratch.

 

[twofish-quant]

Then there's the whole problem with astronauts- they need to eat and poop fairly regularly. That hasn't changed since 1969, and the technology to deal with that hasn't changed much, either.

Whereas robots have gotten a lot cheaper. This is why astrophysicists tend to be extremely strongly against astronauts in space. People haven't changed much since 1969, but computers have.

Also a lot of the technology that has made things cheaper since 1969 really doesn't help you. The big problem with manned space flight is that you don't want a rocket to blow up with a human being on top, and a lot of things that are cheap are cheap at the expense of reliability. I can get a really cheap cell phone. If it stops working, I get a new one. If a cheap part on a rocket fails, someone dies. You do have computers that have been rated for manned aerospace, but those are *enormously* expensive.

NASA did try to do "faster and cheaper" with unmanned spacecraft . The trouble was that spacecraft started failing left and right. If you have political backing so that spacecraft *can* fail left and right, and you get more money to "try again" that's great. Except that you just can't do that with people.

 

[twofish-quant]

I agree with 2. We should focus on that instead of cobbling together slightly more-advanced rockets. What about trans-atmospheric flight?

You mean like the space shuttle...

The trouble is that when you have massive budget cuts, that's a bad time to fund breakthrough technologies. There are a *lot* of technologies on the drawing board that could potentially reduce the cost of LEO. The trouble with those technologies is that you need to fund them to see if they work, and when you work on experimental technology and find out that most of them *don't* work (and most of them won't), the budget hawks scream at you for wasting tax payer money, and those programs get canned.

When I think the cost should be less, I think that the appropriate materials might now be more prevalent and thus lower in cost; that the computing power allows us to more efficiently and quickly design the appropriate systems and requirements; that we know what to expect in the flight, and so forth. Is this any of this correct?

No. Part of the reason it isn't is that we haven't really done much research in manned space flight since the 1960's because there isn't money there.

Aren't the Air Force rockets better and cheaper?

Air Force contracts rockets to the same aerospace companies that NASA does.

 

[D H]

What about trans-atmospheric flight?

Trans-atmospheric vehicles / aero-space planes are just one of many technologies that are at a perpetually low technology readiness level (TRL). What about space elevators? Launch loops? Fusion rockets? Laser launch systems? Any other technology out of the world of sci-fi?

"Trans-atmospheric vehicle" is an old 1980s-era term for a single stage to orbit (SSTO) vehicle, typically one that uses an air-breathing engine for a good part of the flight through the atmosphere. SSTO, regardless of propulsion technique, is for now a pipe dream, and has been one for 40-50 years. The term "trans-atmospheric vehicle" is one of several reincarnations of the SSTO concept. National aero-space plane is another later reincarnation. There have been many others.

That it is a pipe dream does not mean that the concept is necessarily wrong or wrongheaded. NASA and the Air Force should continue to do research into alternative propulsion / flight technologies such as scramjets.

What is wrongheaded is pinning ones hopes on a specific technology that has remained at a low TRL for decades. Let's suppose we arbitrarily pick one of the myriad of perpetually TRL 1-3 technologies as the one and only hope of the future, sinking billions of dollars into bringing this technology X from the realm of sci-fi to engineering reality. The most likely outcome is abject failure, with billions of dollars down the drain and no aero-space plane / fusion rocket / scramjet vehicle / launch loop / space elevator / whatever to show for the expenditure.

Aren't the Air Force rockets better and cheaper?

Better? What's your metric?

Cheaper? Both NASA and the Air Force have a lot of hopes pinned on SpaceX and other commercial space ventures because United Launch Alliance tends to offer vehicles that are expensive to assemble, expensive to launch, and expensive to operate.

The ULA vehicles used by the Air Force are not human-rated. Making them human-rated is one of several CCDev 2 proposals (http://en.wikipedia.org/wiki/Commercial_Crew_Development#CCDev_2) that NASA is considering right now.

 

[D H]

Also, the question becomes efficient for what? Astronomers for example have figured out that manned space flight is useless for astronomy, so $1 spend on manned space flight turns out to be "inefficient.".

Whereas robots have gotten a lot cheaper. This is why astrophysicists tend to be extremely strongly against astronauts in space. People haven't changed much since 1969, but computers have.

Astrophysicists and astronomers can be rather dumb at times. Those who think this way (and there are several) are not thinking.

Let's suppose that Congress completely eliminated NASA's human spaceflight programs. What would be the outcome? Space-based scientists would like to think that all of those monies currently directed toward human spaceflight would go to space science. That is not what would happen. What would happen is that those monies would go elsewhere, or nowhere given our current budget crisis.

Another thing that would happen is that a lot of the monies currently allocated to space-based science would also go elsewhere, or nowhere. Space-based science would have to stand on its own against other sciences. Just as space scientists look jealously at the billions spent on human spaceflight, there are lots of other scientists who look jealously at the billions spent on space science. While robotic space missions are cheap compared to human space missions, those robotic space missions are extremely expensive when compared to science done on the Earth.

Space scientists have seen their wish for drastically reductions in spending on human spaceflight come true at least three times in the past. The outcome has been the same each time. The end of the Apollo era saw drastic reductions in spending on human spaceflight and on space science. The same thing happened in Russia. Russia spent a lot on space exploration in the 1960s, and spent a lot on space science as well. The Russian space program, manned and unmanned, saw drastic reductions post-Apollo.

Neither the US nor Russia completely canceled their human spaceflight programs. Great Britain did. Great Britain's space scientists successfully petitioned Parliament to ban all spending on human spaceflight. Those space scientists won the battle but lost the war. After decades of ever dwindling expenditures on space science, Britain's remaining few space scientists petitioned Parliament to lift the ban on human space exploration a year or so ago.

 

[Andy Resnick]

Whereas robots have gotten a lot cheaper. This is why astrophysicists tend to be extremely strongly against astronauts in space. People haven't changed much since 1969, but computers have.

Also a lot of the technology that has made things cheaper since 1969 really doesn't help you. The big problem with manned space flight is that you don't want a rocket to blow up with a human being on top, and a lot of things that are cheap are cheap at the expense of reliability. I can get a really cheap cell phone. If it stops working, I get a new one. If a cheap part on a rocket fails, someone dies. You do have computers that have been rated for manned aerospace, but those are *enormously* expensive.

NASA did try to do "faster and cheaper" with unmanned spacecraft . The trouble was that spacecraft started failing left and right. If you have political backing so that spacecraft *can* fail left and right, and you get more money to "try again" that's great. Except that you just can't do that with people.

What your (well-considered) comments come back to is essentially asking "what is the proper mission for NASA?" Answers can range from "launch stuff into space", to "manned exploration", and everything in between.

And that's the problem- NASA has not had a well-defined mission since the end of Apollo in the early 1970s. There was a huge explosion in activity- space shuttle, 2 space stations, space-based telescopes across the entire EM spectrum, "mission to planet Earth"...

And then the whole *other half* of NASA- the Aeronautics side: Wing design, engine design, de-icing, civil aviation safety and systems ...

What this led to was a defocused, diffuse agency that has the symptoms of ADHD: extreme short-term focus on a succession of unlinked concepts. There was never a coherent research program to develop next-generation rockets/engines/systems for anything beyond low Earth orbit.

Additionally, NASA has to deal with a never-ending supply of wingnuts who contact their congressperson (or the science deputy for said congressperson) claiming they have all kinds of ideas to 'help' NASA: Alcubierre warp drives, space elevators, zero point energy, Podletnikov gravitational shielding... The congressperson, not knowing anything about science, calls NASA HQ and says "I have a constituent, he's a scientist, and he wants to know if you have thought about [insert dumb idea here]." NASA, being a political organization, commits time and money to 'study' the idea:

http://www.nasa.gov/centers/glenn/technology/warp/possible.html

All that wasted effort only serves to *further* dilute any semblance of a coherent mission. But wait, there's more...

Saint Al Gore, he-who-invented-the-interwebnet, issued OMB Circular A-76 back in 1992 as part of "reinventing Government", which defined "inherently governmental activities". Most people have never heard of this document, which says something, considering it's impact.

In brief, "scientific research", "research and development" and the like are *not* inherently governmental activities. Thus, government employees cannot perform those functions.

Specifically, "A commercial activity is a recurring service that could be performed by the private sector and is resourced, performed, and controlled by the agency through performance by government personnel, a contract, or a fee-for-service agreement. A commercial activity is not so intimately related to the public interest as to mandate performance by government personnel. Commercial activities may be found within, or throughout, organizations that perform inherently governmental activities or classified work."

NASA proper- the civil servants- are explicitly prohibited from doing the very research needed to develop better spaceflight systems- it has to be contracted out. And we are back to dealing with the wingnuts, who feel their pet ideas need to be developed and (successfully) lobby for earmarks to get money.

It's not clear how to get out from this vicious cycle. Partly there needs to be a clear, unambiguous goal set for NASA to accomplish, and that goal (and funding) has to be kept constant for 10-20 years. That requires leadership. Personally, I think a reasonable goal is to establish a permanent base on the moon- it's possible to make concrete from materials on the lunar surface, and so a base could be established that can provide radiation shielding for the crew. Having a base on the moon would provide a testbed for technologies required to get humans to Mars, should we then decide to set that as the next goal.

 

[Shackleford]

Personally, I think a reasonable goal is to establish a permanent base on the moon- it's possible to make concrete from materials on the lunar surface, and so a base could be established that can provide radiation shielding for the crew. Having a base on the moon would provide a testbed for technologies required to get humans to Mars, should we then decide to set that as the next goal.

Are you aware of how much it would cost to simply establish the mining operation? Instead of mining on Earth, let's go to the Moon instead! It would cost too much just to get the necessary equipment up there. I've heard it costs $20K/pound to get into orbit.

You work on making getting into orbit as cheaply as possible. Then, the Moon, Mars, aren't that far away.

I agree NASA does need a clear, reasonable goal.Throwing money at something doesn't make it better. My vote is for propulsion and transatmospheric vehicles.

However, it seems the Air Force is already well-ahead of NASA.

http://www.rand.org/pubs/monograph_reports/MR890.html

 

[D H]

Throwing money at something doesn't make it better. My vote is for propulsion and transatmospheric vehicles.

Those two sentences are in direct contradiction with one another.

However, it seems the Air Force is already well-ahead of NASA.

http://www.rand.org/pubs/monograph_reports/MR890.html

That document is from 1995. Some questions:

1. What makes you think that NASA was not a part of those efforts?
2. Has a viable trans-atmospheric vehicle been developed in the 15 years that have passed since the publication of that document?
3. What makes you think that trans-atmospheric vehicles are the one and only answer to the problem of access to space?
   4. What if the apparently insurmountable problems that make the answer to question #2 "no" are just that, insurmountable problems?

 

[Shackleford]

Trans-atmospheric vehicles / aero-space planes are just one of many technologies that are at a perpetually low technology readiness level (TRL). What about space elevators? Launch loops? Fusion rockets? Laser launch systems? Any other technology out of the world of sci-fi?

"Trans-atmospheric vehicle" is an old 1980s-era term for a single stage to orbit (SSTO) vehicle, typically one that uses an air-breathing engine for a good part of the flight through the atmosphere. SSTO, regardless of propulsion technique, is for now a pipe dream, and has been one for 40-50 years. The term "trans-atmospheric vehicle" is one of several reincarnations of the SSTO concept. National aero-space plane is another later reincarnation. There have been many others.

That it is a pipe dream does not mean that the concept is necessarily wrong or wrongheaded. NASA and the Air Force should continue to do research into alternative propulsion / flight technologies such as scramjets.

What is wrongheaded is pinning ones hopes on a specific technology that has remained at a low TRL for decades. Let's suppose we arbitrarily pick one of the myriad of perpetually TRL 1-3 technologies as the one and only hope of the future, sinking billions of dollars into bringing this technology X from the realm of sci-fi to engineering reality. The most likely outcome is abject failure, with billions of dollars down the drain and no aero-space plane / fusion rocket / scramjet vehicle / launch loop / space elevator / whatever to show for the expenditure.

Better? What's your metric?

Cheaper? Both NASA and the Air Force have a lot of hopes pinned on SpaceX and other commercial space ventures because United Launch Alliance tends to offer vehicles that are expensive to assemble, expensive to launch, and expensive to operate.

The ULA vehicles used by the Air Force are not human-rated. Making them human-rated is one of several CCDev 2 proposals (http://en.wikipedia.org/wiki/Commercial_Crew_Development#CCDev_2) that NASA is considering right now.

I hope you don't think I was equating RLVs with space elevators. I was under the impression that Transatmospheric flight was not a pipe dream, e.g. cold fusion, and that the Air Force is actively involved in R&D.

 

[Shackleford]

Those two sentences are in direct contradiction with one another.



That document is from 1995. Some questions:

1. What makes you think that NASA was not a part of those efforts?
2. Has a viable trans-atmospheric vehicle been developed in the 15 years that have passed since the publication of that document?
3. What makes you think that trans-atmospheric vehicles are the one and only answer to the problem of access to space?
   4. What if the apparently insurmountable problems that make the answer to question #2 "no" are just that, insurmountable problems?

I'll admit I'm new to the term. The document from 16 years ago and an even earlier one I found gave favorable conclusions to the technology. If that was 16+ years ago, is it reasonable to assume advancements have been made?

 

[D H]

I hope you don't think I was equating RLVs with space elevators. I was under the impression that Transatmospheric flight was not a pipe dream, e.g. cold fusion, and that the Air Force is actively involved in R&D.

Both the Air Force and NASA spend some R&D money on truly nutty ideas, some of which even violate the laws of physics. The rationale behind investing R&D money in nutty ideas is that even though the odds of success are extremely small, the payback will be truly immense if the ideas do somehow pan out.

NASA and the Air Force have been putting sometimes small, sometimes large amounts of money into an SSTO vehicle for a long, long, long time, at least since the 1960s. The concept of an SSTO vehicle has long had a small coterie of aficionados. They even managed to convince Ronald Reagan to announce in his 1986 State of the Union address a desire to create "a new Orient Express that could, by the end of the next decade, take off from Dulles Airport, accelerate up to 25 times the speed of sound, attaining low Earth orbit or flying to Tokyo within two hours." This led to an eight year boondoggle, the National Aero-Space Plane. The idea keeps coming back because even though the odds of success are extremely small the potential for payback is immense.

Do note the similarity in phrasing between the last sentences of the first and second paragraphs.

I'll admit I'm new to the term. The document from 16 years ago and an even earlier one I found gave favorable conclusions to the technology. If that was 16+ years ago, is it reasonable to assume advancements have been made?

Tiny steps? Yes. Meaningful steps? No. An SSTO vehicle is still a pipe dream. While investing small amounts of R&D money in a pipe dream is not necessarily a stupid idea, pinning ones hopes on a pipe dream is a very stupid idea.Edit
I see that you have not yet answered any of the questions I raised in post #67.

 

[Shackleford]

Both the Air Force and NASA spend some R&D money on truly nutty ideas, some of which even violate the laws of physics. The rationale behind investing R&D money in nutty ideas is that even though the odds of success are extremely small, the payback will be truly immense if the ideas do somehow pan out.

NASA and the Air Force have been putting sometimes small, sometimes large amounts of money into an SSTO vehicle for a long, long, long time, at least since the 1960s. The concept of an SSTO vehicle has long had a small coterie of aficionados. They even managed to convince Ronald Reagan to announce in his 1986 State of the Union address a desire to create "a new Orient Express that could, by the end of the next decade, take off from Dulles Airport, accelerate up to 25 times the speed of sound, attaining low Earth orbit or flying to Tokyo within two hours." This led to an eight year boondoggle, the National Aero-Space Plane. The idea keeps coming back because even though the odds of success are extremely small the potential for payback is immense.

Do note the similarity in phrasing between the last sentences of the first and second paragraphs.
Tiny steps? Yes. Meaningful steps? No. An SSTO vehicle is still a pipe dream. While investing small amounts of R&D money in a pipe dream is not necessarily a stupid idea, pinning ones hopes on a pipe dream is a very stupid idea.

Hm. What makes the technology a pipe dream? What do you think is the next revolutionary propulsion technology? Is there even one on the horizon?

 

[Shackleford]

EditI see that you have not yet answered any of the questions I raised in post #67.

That document is from 1995. Some questions:

1. What makes you think that NASA was not a part of those efforts?

I don't. I'm sure NASA was involved.

2. Has a viable trans-atmospheric vehicle been developed in the 15 years that have passed since the publication of that document?

Isn't there currently an Air Force or DARPA test vehicle out there?

3. What makes you think that trans-atmospheric vehicles are the one and only answer to the problem of access to space?

I don't. I don't know of anything else, other than the ion-propulsion technology.

4. What if the apparently insurmountable problems that make the answer to question #2 "no" are just that, insurmountable problems?

Well, if I knew what they were, I'm sure I'd agree with you. Clearly, I'm not all that informed in this area. I've heard a few things here and there from someone who was in the military and is currently at NASA.

...

 

[D H]

Hm. What makes the technology a pipe dream? What do you think is the next revolutionary propulsion technology? Is there even one on the horizon?

Just as a starter,

1. Shock layer heating. One of the unfortunate side effects of traveling at Mach 5 is that the vehicle has a tendency to melt. Orbital speed is Mach 25.
2. The rocket equation. A chemical SSTO rocket that goes into orbit and that carries its own fuel and oxidizer has to be 96% or more fuel and oxidizer. That 4% that is not fuel includes fuel tanks and rockets.
3. There is one way out of this morass: Get the oxidizer from the atmosphere, the way a normal jet aircraft does. There is a problem with this concept. Blow on a candle and it goes out. A scramjet engine is a candle being blown on by a wind in excess of Mach 5. Orbital speed is Mach 25.
4. The highest speed that has been attained is Mach 5 by the X-51 for a total of 200 seconds by a tiny little vehicle. X-51 is intended to get to Mach 6. Orbital speed is Mach 25.
5. Getting past Mach 17 is not even in the realm of sci-fi. It is in the realm of fantasy.
6. Just in case you didn't notice it before, orbital speed is Mach 25.

 

[Shackleford]

Just as a starter,

1. Shock layer heating. One of the unfortunate side effects of traveling at Mach 5 is that the vehicle has a tendency to melt. Orbital speed is Mach 25.
2. The rocket equation. A chemical SSTO rocket that goes into orbit and that carries its own fuel and oxidizer has to be 96% or more fuel and oxidizer. That 4% that is not fuel includes fuel tanks and rockets.
3. There is one way out of this morass: Get the oxidizer from the atmosphere, the way a normal jet aircraft does. There is a problem with this concept. Blow on a candle and it goes out. A scramjet engine is a candle being blown on by a wind in excess of Mach 5. Orbital speed is Mach 25.
4. The highest speed that has been attained is Mach 5 by the X-51 for a total of 200 seconds by a tiny little vehicle. X-51 is intended to get to Mach 6. Orbital speed is Mach 25.
5. Getting past Mach 17 is not even in the realm of sci-fi. It is in the realm of fantasy.
6. Just in case you didn't notice it before, orbital speed is Mach 25.

Okay. I didn't know its performance was that far short.

What do you think is the next revolutionary propulsion technology? Is there even one on the horizon?

 

[D H]

What do you think is the next revolutionary propulsion technology?

There are lots of things in the pipeline. Scramjets are one. VASIMR, solar sails, rail launchers: All are being researched. Which one will come out the winner, no telling. Picking a winner from the slew of technologies being researched by the Air Force, DARPA, and NASA before it is ready is a dumb idea.

Is there even one on the horizon?

VASIMR looks very promising as a technique for keeping the ISS in orbit. However, VASIMR is useless as a launch technology and is of limited use as a means of getting people beyond low Earth orbit. Beyond that, it depends on what you mean by horizon. If you mean something that could be put into use now to get people into space or beyond low Earth orbit, absolutely not.

 

[Shackleford]

There are lots of things in the pipeline. Scramjets are one. VASIMR, solar sails, rail launchers: All are being researched. Which one will come out the winner, no telling. Picking a winner from the slew of technologies being researched by the Air Force, DARPA, and NASA before it is ready is a dumb idea.


VASIMR looks very promising as a technique for keeping the ISS in orbit. However, VASIMR is useless as a launch technology and is of limited use as a means of getting people beyond low Earth orbit. Beyond that, it depends on what you mean by horizon. If you mean something that could be put into use now to get people into space or beyond low Earth orbit, absolutely not.

So, then it's still sci-fi at this point.

 

[D H]

All of those perpetually low TRL technologies are sci-fi at this point. Something will pop up, but what that something is, nobody knows. Picking a winner prematurely is not the answer because the odds are that in reality that winner is a loser. A lot (and I mean a lot; tens of billions) has been spent on trans-atmospheric flight with nothing to show. The same goes for fusion rockets and, to a lesser extent, laser-powered propulsion. Each of those represents a technology chosen prematurely because they have powerful constituencies behind them.

 

[Shackleford]

All of those perpetually low TRL technologies are sci-fi at this point. Something will pop up, but what that something is, nobody knows. Picking a winner prematurely is not the answer because the odds are that in reality that winner is a loser. A lot (and I mean a lot; tens of billions) has been spent on trans-atmospheric flight with nothing to show. The same goes for fusion rockets and, to a lesser extent, laser-powered propulsion. Each of those represents a technology chosen prematurely because they have powerful constituencies behind them.

Because of this thread, an article on this caught my attention. Of course, now, I'm skeptical.

http://www.spacedev.com/spacedev_advanced_systems.php

 

[D H]

Because of this thread, an article on this caught my attention. Of course, now, I'm skeptical.

http://www.spacedev.com/spacedev_advanced_systems.php

That is nothing like the trans-atmospheric vehicles you wrote about earlier. This is old-style stuff. It uses a commercial rocket for launch, a heat shield for reentry, and a lifting body for descent and landing. No scramjets, no SSTO. This is similar to the Shuttle system, which also uses disposable rockets for launch, a heat shield for reentry, and a lifting body for descent and landing.

Unlike the side-mounted Shuttle, this vehicle is perched atop the launch vehicle. The Columbia disaster was a consequence of the Shuttle's side-mount configuration. Unlike the Shuttle, this vehicle does not have a 1000 km cross-range capability. In other words, the Dream Chaser will not be able to launch from Vandenburg, snatch a Russian spy satellite out of its orbit, and return to Vandenburg one rev later with no one the wiser as to what happened. That is not a big loss.

 

[MattRob]

I think if NASA was a little larger than we'd be doing a lot more in space. In TEN YEARS, we went from no human having ever gone into space, to landing on the moon. Just two years before that decade, 1957, the first satellite went in orbit. Twelve years before then, the first intercontinental missiles were launched from Peenemünde, the V-2's at Great Britain. We went from liquid-fueled rockets being a fancy but useless system, a "pipe dream", in 1930, to the first practical guided, space-fairing rockets in 1942, to the first "pipe dream" satellite in orbit in 1957, to the "pipe dream" of meeting another vehicle IN ORBIT in 1965 with Gemini, to perhaps the most ludicrous, monstrous "dumb, pipe dream" of sending a 33-story, multi-million pound, 3-staged rocket, (5 stages if you count the vehicles as stages), take three men into space in two separate vehicles, which re-oriented and docked en route, entered orbit, landed on the moon, lifted off, and docked in Lunar orbit, and returned to Earth. And then we did it SIX more times. I never want to hear "pipe dream" again. All it takes is willpower. If we had this kind of willpower to get an Orbital Elevator working, it would be working. If the nation were this united to make an SSTO, we would have an SSTO. It seems all imagination (which now carries a negative connotation) and vision have been completely stripped from American society, perhaps because we don't have something like Apollo anymore to prove what's possible. Because Congressmen have decided that making some vision and real hope for Americans isn't even worth HALF OF ONE PERCENT of their budget.
</rant>

Just as a starter,

1. Shock layer heating. One of the unfortunate side effects of traveling at Mach 5 is that the vehicle has a tendency to melt. Orbital speed is Mach 25.
2. The rocket equation. A chemical SSTO rocket that goes into orbit and that carries its own fuel and oxidizer has to be 96% or more fuel and oxidizer. That 4% that is not fuel includes fuel tanks and rockets.
3. There is one way out of this morass: Get the oxidizer from the atmosphere, the way a normal jet aircraft does. There is a problem with this concept. Blow on a candle and it goes out. A scramjet engine is a candle being blown on by a wind in excess of Mach 5. Orbital speed is Mach 25.
4. The highest speed that has been attained is Mach 5 by the X-51 for a total of 200 seconds by a tiny little vehicle. X-51 is intended to get to Mach 6. Orbital speed is Mach 25.
5. Getting past Mach 17 is not even in the realm of sci-fi. It is in the realm of fantasy.
6. Just in case you didn't notice it before, orbital speed is Mach 25.

Personally, I don't see why there's so much fuss against scramjets. From what I understand, they can produce more thrust than drag from mach 4 up, and involve no moving parts aside from fuel injectors. (No fans, etc.). From what I understand of the Scramjet, the issue it faces is that shock layer heating. It requires too much speed for a given dynamic pressure, and current heat shielding technology can't handle it. But this is what gets me. Ablative heat shields have survived re-entry on JUPITER at 230 G's, I hardly see how we can't handle mach 4 even at sea level. Maybe ablative heat shields aren't reusable but surely they can be made for more than one use, and a 2-3 use scramjet sled with a Specific Impulse of 20,000-40,000 all the way to whatever speed you want with hardly any moving parts is bound to be far cheaper than a 750-ton LH2/LOX External Tank and 3 SSME's.
(Sled? I meant booster.)

And I've never heard of the "blowing out the candle". I always thought the heat for ignition came from the mach 4 shockwaves in the engine, so the fuel was constantly lit.

My main concern is a lot of the arguments seem to be applicable to ALL space vehicles (1,4,5,6). And space vehicles CERTAINLY are NOT impossible. It's interesting that no matter how many times people think something is ridiculous, mock it, and are proven wrong by time, people keep doing it. Sure some things really are crazy, but I think mockeries are thrown around a bit too lightly. After all, we did land on the moon...

So what about now? The thread topic is NASA's current future, I highly doubt my obscure post on Physics Forums will drive NASA to investigate ideas seriously and develop a cheap system, last I heard it's going to be 5 years for Dragon 9 to be man-rated.

My rant for manned spaceflight will come tomorrow when I'm not so tired and my thoughts are better organized...

 

[twofish-quant]

What do you think is the next revolutionary propulsion technology? Is there even one on the horizon?

Going low tech.

The US has this fascination with gee-whiz, revolutionary technology. Sometimes you are lucky and those technologies allow for basic breakthroughs in some areas. The trouble is that it appears that getting stuff into LEO cheaply isn't one of those areas, which is why the Russians and Chinese seem to be better at this.

There's nothing fundamentally revolutionary about what the Russians and Chinese are doing, they are just taking technology that has been around for the last fifty years and making it work. Same with the commercial space ventures. SpaceX is out to make a profit, and in some areas, you make profits by using boring technology that has been around for the last fifty years.

 

[twofish-quant]

All it takes is willpower. If we had this kind of willpower to get an Orbital Elevator working, it would be working.

You can't get around basic laws of physics through willpower. You can sometimes get around a basic law of physics through clever engineering, but that's something different.

Because Congressmen have decided that making some vision and real hope for Americans isn't even worth HALF OF ONE PERCENT of their budget.

Hardly. The problem isn't lack of vision. The problem is that different people have different visions. If you ask most astrophysicists, they'd prefer if the US gets totally out of the manned space flight business, because robots are *MUCH* more effective at doing science.

Personally, I don't see why there's so much fuss against scramjets.

Laws of physics and that sort of thing.

Maybe ablative heat shields aren't reusable but surely they can be made for more than one use, and a 2-3 use scramjet sled with a Specific Impulse of 20,000-40,000 all the way to whatever speed you want with hardly any moving parts is bound to be far cheaper than a 750-ton LH2/LOX External Tank and 3 SSME's.

It turns out that most of the expense of space flight is in fixed costs, particularly labor. You can dramatically reduce costs by setting up an assembly line with cheap labor and then cracking out rockets by the truckload (i.e. stuff that China and Russia are good at). That works in favor of throwaway boosters and against anything reusable. If you go high tech, then the skill level of the people that are working on the rockets go up, and you can't get a community college level educated person to put wire A into part B.

It's interesting that no matter how many times people think something is ridiculous, mock it, and are proven wrong by time, people keep doing it.

Sometimes the naysayers are right.

 

[D H]

If you ask most astrophysicists, they'd prefer if the US gets totally out of the manned space flight business, because robots are *MUCH* more effective at doing science.

Read post #64, please.

 

[Shackleford]

Going low tech.

The US has this fascination with gee-whiz, revolutionary technology. Sometimes you are lucky and those technologies allow for basic breakthroughs in some areas. The trouble is that it appears that getting stuff into LEO cheaply isn't one of those areas, which is why the Russians and Chinese seem to be better at this.

There's nothing fundamentally revolutionary about what the Russians and Chinese are doing, they are just taking technology that has been around for the last fifty years and making it work. Same with the commercial space ventures. SpaceX is out to make a profit, and in some areas, you make profits by using boring technology that has been around for the last fifty years.

Then the most efficient way to get someone into orbit is also the most inefficient way, by just blasting through the atmosphere.

I'm curious if it's any more efficient to go up through a low-pressure system in the atmosphere?

 

[twofish-quant]

Read post #64, please.

I tend to agree with you, but in the interests of giving astrophysicists who hate manned space program a far hearing then...

1) A lot of the animus is not directed at manned space flight in general, but specifically project Constellation. The problem is that Constellation is a budgetary train wreck. If NASA funding is constant and if Constellation goes through according to 2008 plans, then by 2020, Constellation will eat up all of NASA's budget, and at that point the belief is that Constellation will try to kick unmanned space programs and science out of the boat. A healthy manned space program may increase funding for science, but no one thinks Constellation with current funding is viable. If you look ahead at the most likely outcome, you'll have a budgetary train wreck in 2020 and the only two politically viable options would be to squeeze out unmanned space flight or stop Constellation, and astrophysicists would rather have that conversation now.

Conversely, I don't know of any astrophysicist that is against the SpaceX program. The reason being is that if that program falls apart it's not going to have any impact on unmanned spacecraft .

2) Astrophysicists aren't experts at politics. Lobbyists, marketers, and politicians are. There may be (and I think there are) great political reasons for manned space flight. However, those political reasons have to take into account that if the question is how much astronomy can be done for how much money, then the answer is "don't use people." That might not be the right question, but it's the question that astrophysicists have the most expertise in.

3) A great manned space program may help astronomy, but we don't have a great manned space program, and astronomers are still smarting over the Hubble fiasco. The problem with Hubble was that it was designed with the assumption that routine manned space flights were possible, and when that turned out not to be true, it put to whole program in danger. It's not so much jealousy that motivates astrophysicists, but rather fear and anger.

Personally, I don't think that you can come up with an argument that makes astrophysicists strong supporters of manned space flight. What I think is possible is to turn them from being highly negative to somewhat negative or neutral. If you set up the budgets so that manned space flight cannot have negative impacts on unmanned space flight (perhaps by moving the costs into a separate line item) then you've changed the situation.

 

[twofish-quant]

Then the most efficient way to get someone into orbit is also the most inefficient way, by just blasting through the atmosphere.

Define efficient. If you define it in $$$$ terms, then you'll find that in 2011, trying to build a air-breathing spacecraft is an extremely bad idea.

Ironically, this is the sort of thing that killed the central planned economies of Russia and China. Without market prices, you have no way of even measuring economic efficiency, and so you end up with projects that just eat up huge amounts of resources that could have been used for other things.

If you are talking physics, then it turns out that rockets are more "efficient" than air-breathers since you go straight up out the atmosphere, whereas if you have an air-breather, you have to take a trajectory that keeps you in the atmosphere for much longer. Then there is gravity. While you are in a suborbital trajectory, you have to expend energy to keep from falling down. You minimize those losses by going straight up as quickly as you can.

 

[MattRob]

You can't get around basic laws of physics through willpower. You can sometimes get around a basic law of physics through clever engineering, but that's something different.

True, but there's nothing fundamentally impossible with some of these concepts. We're not trying to rewrite physics, we're building an orbital elevator. I don't think there're any equations which clearly state that that's impossible. Sure it takes some really advanced materials and a LOT of them (skyrocketing the costs through the thermosphere, literally), but fundamentally possible. But "willpower" on part of the population, means much more funding, which means many more resources, engineers, and possibly even better engineers.

Laws of physics and that sort of thing.

Okay, what laws of physics? Heat + Oxygen + Fuel = Combustion. Heat is shockwaves in the engine, fuel is injected, oxygen is in the atmosphere. The air heats up and expands in the engine, causing it to leave faster than it entered, causing a net gain in velocity as it travels outwards, and law of conservation of momentum accelerates vehicle forward. How is this impossible?

It turns out that most of the expense of space flight is in fixed costs, particularly labor. You can dramatically reduce costs by setting up an assembly line with cheap labor and then cracking out rockets by the truckload (i.e. stuff that China and Russia are good at). That works in favor of throwaway boosters and against anything reusable. If you go high tech, then the skill level of the people that are working on the rockets go up, and you can't get a community college level educated person to put wire A into part B.

Can't argue with that. But you can only cheap down space launch so much. And, like I said, if a fully reusable system with a short turnaround time can be developed, then because the supply of lifting ability is going to go so far up, it's going to get a lot cheaper. There's a gruesome limit on turnaround time when you have to re-build the entire, or even just part of, the rocket every time. I'm no expert, but I think I can say just from basics that if a system has a turnaround time of less than a week, it would lower prices drastically, if it has any meaningful lift capacity at all. This is why I like the idea of scramjets so much. With that you simply don't need staging or a huge mass ratio. And the simplicity of the engine means not a lot of maintenance, though the cooling system is a whole different story.

What about something like the White Knight/Spaceship One - type "mothership" configuration? Make a "carrier" aircraft with LOX-RP1 rockets, after MECO it detaches, "orbiter" ascends to orbit, mothership switches to turbofan engines to allow it to fly back to the launch site.
Two stages, though both aren't just reusable, but airplane-like. Perhaps even a practical turnaround time less than three weeks if engineered correctly? Have the orbiter attach to the bottom. No cranes, no V.A.B. assembly, no launchpad, even. Just some maintenance, fill the tanks, line up on a runway and it's ready to fly again, just like that. Forget the idea of big, cylindrical, take-it-around-on-a-crawler rocket that needs a launch tower and launchpad. All that only increases turnaround time and maintenance. What's wrong with making the first stage really airplane-like? A Me-163 with modern fuels and a juiced-up mass ratio? With the orbiter simply having to attach to the underside like an MXY-7, drastically reducing time and complexity of assembly. Except, as opposed to the early rocket-planes, use modern fuels such as LOX-LH2 and/or LOX-RP1. Heck, I just worked out the math and the mass ratios wouldn't have to be far above 3 if it DID use LH2/LOX. About half of the Space Shuttle+ET assembly! With RP-1/LOX it would have to be a little above 7.

- Not a big fan of LH-2. I think it's just crazy to use something that cold. Isn't that a source of a lot of the maintenance needed for the Shuttle, because it has to work with something that incredibly cold? And the Columbia incident was because of the insane insulation needed to keep it at -424 *F!
(meanwhile LOX at -298 *F and RP1 at room temperature.)

 

[chiro]

two-fish I'd like to ask you a question.

Space-ships rely on the simple principle of having a net directed force that is in the direction of space. Its simple physics 101. You exert a net-force on an object that is greater than the natural forces holding that something in place (ie gravity) and your vehicle then heads in the direction of the net-force. (I know its simplified but I just wanted to get the main idea across).

Now with the definition of energy and work we need a mechanism to provide that force. Without getting into the details of energy conversion and associated mechanisms (like thermodynamics), we know that if we can get some device to take some energy source and convert it into force, then we have liftoff.

Now currently we are stuck in an energy stoneage with oil based energy. But why does that have to be a restriction of "the laws of physics"? Do you believe that we won't discover other forms of energy generation in the future that can give us our "net-force" in ways that are better than the standard "oil" route?

If a new energy source and utilization process is found it won't break "the laws of physics". The laws of physics don't say that we have to use "oil" as our energy reservoir.

Now to get to my question. Do you really think the laws of physics forbid us to discover a better energy source that is cheaper, abundant, more efficient, and portable to allow mankind to overcome the current barriers in space-travel?

 

[MattRob]

I'm not Two-Fish but I'll reply, or at least comment, anyways. We're not entirely dependent on oil for all our power. There's Nuclear energy, hydroelectric energy, coal power, natural gas, and of course the less mainstream but ever present solar and wind power. Just to name a few. I highly disagree with saying we're in an "energy stoneage", nuclear power is quiet an accomplishment, and we're on the brink of harnessing FUSION power, that can power a city with the hydrogen in a bucket of water. Cars run on "Oil", a highly processed hydrocarbon solution known as Gasoline, by chemically reacting with oxygen to produce heat and drive an amazingly intricate piston engine, an invention I believe was many, many decades ahead of it's time. In principle, a car engine is far more complicated than a rocket engine. (Though that's hardly true in practice, but it is true for certain rockets.) And, interestingly enough, a piston engine relies on a combustible fuel, so it doesn't have to be a hydrocarbon, it's just those are the most cheap and easily available. Cars (Piston engines) could, theoretically, run on any combustible fluid. Alcohol could be an option. And I'm sure there're more non-oil based combustibles than that, that's just off the top of my head.

A Rocket engine does not use "oil", or any form of hydrocarbon, for it's energy reservoir, unless it's a LOX-RP1 engine (Liquid Oxygen, Rocket Propellant One, a type of Kerosene made specifically for rockets), which is used in cheaper, less complicated launch systems. The Space Shuttle, for instance, uses Liquid Hydrogen and Liquid Oxygen, so did the upper stages of the Saturn-V. The engines in-orbit use a hydrazine/nitrogen-oxide combination. (To be specific, Monomethylhydrazine/Dinitrogen-Tetroxide, used on Space Shuttle Orbital Menuvering engines and the Apollo's Command Module SPS orbital menuvering engine.) The Earliest liquid-fuelled rockets ran on Alcohol or Hydrogen peroxide. Solid Rockets run on ammonium perchlorate, though that's certainly not the only option. By far, in terms of performance, LOX/LH2 is the best oxidizer/fuel combination. In terms of price efficiency... Maybe, maybe not. I don't know and I don't know if anyone knows. If someone knew then I assume every engine would use one or the other, but some engines use one and some engines use the other. LOX/RP-1 has lower performance but is much easier to handle and work with, hence, cheaper. Though because it has lower performance it requires a bigger rocket with more fuel.

I'm sorry, but buzzwords annoy me, and with the whole "green" movement going on, "Oil-based society" and "energy stoneage" really seem more political than scientific.

Now, to reply, we don't use "oil" as our energy reservoir in rockets. Only a very specific fuel out of many different options available use oil, and there's no reason to think of hydrocarbons as low-tech. They're a readily available, cheap, abundant, efficient and portable source of power. Though you're right in that they don't provide as much power as we'd like, though we could always want more power, though spaceflight is very demanding.

Sorry, I'll let Two-Fish answer now...

 

[Shackleford]

Define efficient. If you define it in $$$$ terms, then you'll find that in 2011, trying to build a air-breathing spacecraft is an extremely bad idea.

Ironically, this is the sort of thing that killed the central planned economies of Russia and China. Without market prices, you have no way of even measuring economic efficiency, and so you end up with projects that just eat up huge amounts of resources that could have been used for other things.

If you are talking physics, then it turns out that rockets are more "efficient" than air-breathers since you go straight up out the atmosphere, whereas if you have an air-breather, you have to take a trajectory that keeps you in the atmosphere for much longer. Then there is gravity. While you are in a suborbital trajectory, you have to expend energy to keep from falling down. You minimize those losses by going straight up as quickly as you can.

I think it was the entire Communist-flavored iteration of Marxism that killed the economies of Russia and China, but I'm sure we're diametrically opposed on this point.

I was talking about physics. Is it actually more efficient in terms of energy? There's an incredible amount of friction from the atmosphere when you plow straight through it at those tremendous speeds. Still, you would have to do a lot of work against the gravitational force with the air-breathers.

 

[Ryker]

I think it was the entire Communist-flavored iteration of Marxism that killed the economies of Russia and China, but I'm sure we're diametrically opposed on this point.

So if you disagree with twofish, what feature of communism was it that killed the economies then? Because you do realize he did mention one such feature of the "communist-flavored iteration of Marxism", right? You seem to be just tossing the word around without any substance behind your "arguments", and I find it very odd that people in this day and age still see the world as "red" and the rest. I guess the conservative US propaganda really does still hold sway over the fears of Americans.

 

[twofish-quant]

True, but there's nothing fundamentally impossible with some of these concepts.

Fundamentally impossible no. Fundamentally extremely difficult requiring large amounts of expensive research to figure out ways around those issues, yes. For example SSTO is limited by the rocket equation which means that given a specific impulse, you need fraction X of weight in the rocket and fraction Y in fuel.

Sure it takes some really advanced materials and a LOT of them (skyrocketing the costs through the thermosphere, literally), but fundamentally possible.

Which requires $X billion in research with probability Y of success.

But "willpower" on part of the population, means much more funding, which means many more resources, engineers, and possibly even better engineers.

Which then requires an economic system to generate the wealth necessary to get things done.

Okay, what laws of physics? Heat + Oxygen + Fuel = Combustion. Heat is shockwaves in the engine, fuel is injected, oxygen is in the atmosphere. The air heats up and expands in the engine, causing it to leave faster than it entered, causing a net gain in velocity as it travels outwards, and law of conservation of momentum accelerates vehicle forward. How is this impossible?

It's not. Jet aircraft do it all the time. However if you want to go to Mach 25, then you run into the amount of energy that is in the fuels, and then you run into frictional heating. Also, to tell if something is impossible or not, you have to run numbers. In the case of SSTO spacecraft , you have to have materials with a certain level of energy content, a certain weight, and certain structural characteristics.







Can't argue with that. But you can only cheap down space launch so much. And, like I said, if a fully reusable system with a short turnaround time can be developed, then because the supply of lifting ability is going to go so far up, it's going to get a lot cheaper. There's a gruesome limit on turnaround time when you have to re-build the entire, or even just part of, the rocket every time. I'm no expert, but I think I can say just from basics that if a system has a turnaround time of less than a week, it would lower prices drastically, if it has any meaningful lift capacity at all. This is why I like the idea of scramjets so much. With that you simply don't need staging or a huge mass ratio. And the simplicity of the engine means not a lot of maintenance, though the cooling system is a whole different story.

What about something like the White Knight/Spaceship One - type "mothership" configuration? Make a "carrier" aircraft with LOX-RP1 rockets, after MECO it detaches, "orbiter" ascends to orbit, mothership switches to turbofan engines to allow it to fly back to the launch site.
Two stages, though both aren't just reusable, but airplane-like. Perhaps even a practical turnaround time less than three weeks if engineered correctly? Have the orbiter attach to the bottom. No cranes, no V.A.B. assembly, no launchpad, even. Just some maintenance, fill the tanks, line up on a runway and it's ready to fly again, just like that. Forget the idea of big, cylindrical, take-it-around-on-a-crawler rocket that needs a launch tower and launchpad. All that only increases turnaround time and maintenance. What's wrong with making the first stage really airplane-like? A Me-163 with modern fuels and a juiced-up mass ratio? With the orbiter simply having to attach to the underside like an MXY-7, drastically reducing time and complexity of assembly. Except, as opposed to the early rocket-planes, use modern fuels such as LOX-LH2 and/or LOX-RP1. Heck, I just worked out the math and the mass ratios wouldn't have to be far above 3 if it DID use LH2/LOX. About half of the Space Shuttle+ET assembly! With RP-1/LOX it would have to be a little above 7.

- Not a big fan of LH-2. I think it's just crazy to use something that cold. Isn't that a source of a lot of the maintenance needed for the Shuttle, because it has to work with something that incredibly cold? And the Columbia incident was because of the insane insulation needed to keep it at -424 *F!
(meanwhile LOX at -298 *F and RP1 at room temperature.)[/QUOTE]

 

[twofish-quant]

Now currently we are stuck in an energy stoneage with oil based energy. But why does that have to be a restriction of "the laws of physics"?

That's not the problem. If you restrict yourself to any sort of chemical rocket, then you can get a specific impulse of at most about 450 seconds. If you start working on solid nuclear rockets, then you can get Isp up to 1200. With air breathing spacecraft you can get Isp up to 2500 seconds.

Once you have the number of the specific impulse, then you plug those numbers into the rocket equation, and that gives you the limits for what your fuel fraction is, and at that point you start figuring out what you make the rocket out of.

Now you can get rid of the problem by putting the source of the power on the ground. The trouble with that is that we have done enough research in jets and rockets to know what the basic problems are. We haven't done that research in laser powered boosters.

If a new energy source and utilization process is found it won't break "the laws of physics".

The two sources right now are chemical and nuclear fission.

Do you really think the laws of physics forbid us to discover a better energy source that is cheaper, abundant, more efficient, and portable to allow mankind to overcome the current barriers in space-travel?

In the next two decades, yes. If there is some source of energy outside of chemical and nuclear that we don't know about, it's going to be really subtle, and if we haven't found it yet, we aren't going to find it anytime soon.

And if there are no sources of energy, then there are no sources of energy.

Now if you think that the laws of themodynamics don't hold them all bets are off.

 

[chiro]

I'm not Two-Fish but I'll reply, or at least comment, anyways. We're not entirely dependent on oil for all our power. There's Nuclear energy, hydroelectric energy, coal power, natural gas, and of course the less mainstream but ever present solar and wind power. Just to name a few. I highly disagree with saying we're in an "energy stoneage", nuclear power is quiet an accomplishment, and we're on the brink of harnessing FUSION power, that can power a city with the hydrogen in a bucket of water. Cars run on "Oil", a highly processed hydrocarbon solution known as Gasoline, by chemically reacting with oxygen to produce heat and drive an amazingly intricate piston engine, an invention I believe was many, many decades ahead of it's time. In principle, a car engine is far more complicated than a rocket engine. (Though that's hardly true in practice, but it is true for certain rockets.) And, interestingly enough, a piston engine relies on a combustible fuel, so it doesn't have to be a hydrocarbon, it's just those are the most cheap and easily available. Cars (Piston engines) could, theoretically, run on any combustible fluid. Alcohol could be an option. And I'm sure there're more non-oil based combustibles than that, that's just off the top of my head.

A Rocket engine does not use "oil", or any form of hydrocarbon, for it's energy reservoir, unless it's a LOX-RP1 engine (Liquid Oxygen, Rocket Propellant One, a type of Kerosene made specifically for rockets), which is used in cheaper, less complicated launch systems. The Space Shuttle, for instance, uses Liquid Hydrogen and Liquid Oxygen, so did the upper stages of the Saturn-V. The engines in-orbit use a hydrazine/nitrogen-oxide combination. (To be specific, Monomethylhydrazine/Dinitrogen-Tetroxide, used on Space Shuttle Orbital Menuvering engines and the Apollo's Command Module SPS orbital menuvering engine.) The Earliest liquid-fuelled rockets ran on Alcohol or Hydrogen peroxide. Solid Rockets run on ammonium perchlorate, though that's certainly not the only option. By far, in terms of performance, LOX/LH2 is the best oxidizer/fuel combination. In terms of price efficiency... Maybe, maybe not. I don't know and I don't know if anyone knows. If someone knew then I assume every engine would use one or the other, but some engines use one and some engines use the other. LOX/RP-1 has lower performance but is much easier to handle and work with, hence, cheaper. Though because it has lower performance it requires a bigger rocket with more fuel.

I'm sorry, but buzzwords annoy me, and with the whole "green" movement going on, "Oil-based society" and "energy stoneage" really seem more political than scientific.

Now, to reply, we don't use "oil" as our energy reservoir in rockets. Only a very specific fuel out of many different options available use oil, and there's no reason to think of hydrocarbons as low-tech. They're a readily available, cheap, abundant, efficient and portable source of power. Though you're right in that they don't provide as much power as we'd like, though we could always want more power, though spaceflight is very demanding.

Sorry, I'll let Two-Fish answer now...

Thanks for the reply.

I didn't mean to generalize oil as the only source of energy, I was simply trying to point out that the "laws of physics" don't prevent us from overcoming current limitations that we may have.

In terms of the word "energy stoneage", I qualify that with the point that the energy "age" is rather young in our history and for the most part we are at the start of it. I imagine in another hundred years we will look back at the energy "stoneage" just like we look back at the tractors that use oxen to operate.

Also I never mentioned any "green" forms of energy. Personally I think things like biofuels are a joke.

Also what is wrong with "oil based society"? Most of the energy we need comes from oil. Fair enough it doesn't power space vehicles leaving earth, but it damn well powers most of the stuff right here on earth. How the hell is that a buzzword? There are reasons why countries guard their oil and why wars are fought over resources.

Also the truth is that even with technological developments in utilizing oil in more effecient ways, most of the energy in your typical car engine is wasted.

The nuclear fission methods and hopefully the fusion methods is kinda what I'm getting at. Truly in the context of energy with reference to "traditional" forms of energy, you can see the kind of context of talking about when I remark about the "energy stone-age".

 

[twofish-quant]

I think it was the entire Communist-flavored iteration of Marxism that killed the economies of Russia and China, but I'm sure we're diametrically opposed on this point.

Which part of Marxism? Russia in 1950 had state-owned enterprise reacting to centrally planned resource allocations. The US had private enterprises reacting to market prices. Is the problem the state ownership or the centrally planned resource allocations or something else?

Personally, I think that it's the centrally planned resource allocations, which means that you can avoid the problems if you have market prices, even if the corporations are state owned. Which has been the experience of China.

I was talking about physics. Is it actually more efficient in terms of energy? There's an incredible amount of friction from the atmosphere when you plow straight through it at those tremendous speeds. Still, you would have to do a lot of work against the gravitational force with the air-breathers.

The thing about rockets is that you don't have high speeds until you get out of the atmosphere. By the time you are at Mach 10, you pretty much already in a vacuum, which means that you don't have to worry about hypersonic aerodynamics.

 

[twofish-quant]

I was simply trying to point out that the "laws of physics" don't prevent us from overcoming current limitations that we may have.

In what? There are no energy limitations that I can think of in generating a mass consumption society, but we are talking about getting payload into LEO, and in that case you are running against some pretty fundamental constraints. You can think of ways around those constraints, but you can't ignore them.

Also what is wrong with "oil based society"?

The problem is that the supply of crude oil is finite. We've already used all of the "easy oil". We are just going to have to find something else in the next fifty years. No real choice in that. The good news is that there are huge amounts of coal lying around, and if we can figure out a way of having coal power a car, we are set, and we are really close to that. (Burn the coal in power plant, have said power plant power a battery.)

Coal will last us for a few more hundred years, which is enough time to get solar power satellites up, and that will last us until the sun burns out.

 

[D H]

In TEN YEARS, we went from no human having ever gone into space, to landing on the moon. Just two years before that decade, 1957, the first satellite went in orbit. Twelve years before then, the first intercontinental missiles were launched from Peenemünde, the V-2's at Great Britain.

Just because some things were easy in retrospect does not mean everything is easy. You are doing exactly the same thing here as people who say "if we could put a man on the Moon we should be able to do X" (substitute favorite pet project for "X").

I never want to hear "pipe dream" again. All it takes is willpower.

All of the wishing, willpower, and money in the world do not make an idea that is inherently unfeasible, impractical, or uneconomical suddenly become feasible, practical, and economical.

But this is what gets me. Ablative heat shields have survived re-entry on JUPITER at 230 G's, I hardly see how we can't handle mach 4 even at sea level.

The Galileo atmospheric probe was a capsule. It wasn't even a lifting body like the X-38 or SpaceDev's proposed Dream Chaser or Orbital Science's proposed Prometheus vehicle. Even the Shuttle (a delta wing) enters the atmosphere more like a lifting body than like a jet.

Heating of the nose in a hypersonic vehicle is a huge problem. The nose on the X-51 will get up to 1480 °C, and that is for a vehicle whose top speed is "only" Mach 6 (orbital speed is Mach 25). The Shuttle, along with those lifting body reentry vehicles, solve this problem by flying belly-first rather than pointy-end first. This solves two problems: Dumping excess speed, and avoiding having the nose melt off. That is not an option for a vehicle that intentionally flies pointy-end first.

Specific Impulse of 20,000-40,000

Whoa there! what units (is this 20,000-40,000 ft/sec?), and what speed (Isp for an air-breathing vehicle decreases markedly with speed).

After all, we did land on the moon...

Stop that.

 

[Shackleford]

In what? There are no energy limitations that I can think of in generating a mass consumption society, but we are talking about getting payload into LEO, and in that case you are running against some pretty fundamental constraints. You can think of ways around those constraints, but you can't ignore them.
The problem is that the supply of crude oil is finite. We've already used all of the "easy oil". We are just going to have to find something else in the next fifty years. No real choice in that. The good news is that there are huge amounts of coal lying around, and if we can figure out a way of having coal power a car, we are set, and we are really close to that. (Burn the coal in power plant, have said power plant power a battery.)

Coal will last us for a few more hundred years, which is enough time to get solar power satellites up, and that will last us until the sun burns out.

I thought they don't know exactly how crude is formed, that it might not be a "fossil" fuel but rather formed through some other geologic process. It seems to me that the rock cycle would recycle many desirable minerals and possibly even generate crude somehow. If not, they don't know how much crude is actually out there. You don't know if we've used up all the "easy oil." Also, that's the thing - technology dictates what is "easy."

http://www.chron.com/disp/story.mpl/ap/business/7420991.html

D H,

I'm curious. What's your background?

 

[D H]

I tend to agree with you, but in the interests of giving astrophysicists who hate manned space program a far hearing then...

1) A lot of the animus is not directed at manned space flight in general, but specifically project Constellation.

There was a lot of animus within the human spaceflight community against Constellation: Against NASA headquarters for a perceived railroading through of what some thought was a poor design, against Bush for underfunding the program, and against Congress for micromanaging the program and dictating suboptimal approaches.

That said, Bush's initial Vision for Space Exploration concept to get back in the business of sending people beyond low Earth orbit, along with the shift in policy direction from space science back to human spaceflight, was widely perceived in a very positive light throughout the human spaceflight community. "About @#$% time" was the general consensus.

Conversely, I don't know of any astrophysicist that is against the SpaceX program. The reason being is that if that program falls apart it's not going to have any impact on unmanned spacecraft .

They need to rethink that posture for at least two reasons. One is that in the minds of many of the politicians who ultimately fund the space program, the justification for doing space science is that this space science is a precursor for human space activities. The other is that they are looking at the wrong thing. They are doing science, so they should look at how expensive their pet projects are compared to other science programs. Space science comes up very short in this regard. It is very expensive and has a limited return on investment. It is a vibrant human spaceflight program that justifies those expenses.

Astrophysicists aren't experts at politics.

Politics isn't rocket science. It's harder. That's why rocket scientists (and astrophysicists) make such lousy politicians.

Personally, I don't think that you can come up with an argument that makes astrophysicists strong supporters of manned space flight.

They should read history lest they be doomed to repeating it.

 

[elfboy]

nasa is the only hope for space discovery
private sector lacks the funding, safety standards