Page 1 of 5 123 ... LastLast
Results 1 to 30 of 132

Thread: Alternative to chemical rockets

  1. #1
    Join Date
    Nov 2010
    Posts
    3,854

    Alternative to chemical rockets

    Is there anything right now being seriously developed to replace chemical rockets as the primary way to reach orbital velocity and escape velocity from the Earth.

    I've gotten kind of out of touch in recent years with new developments. I know highly efficient ion rockets have been used on long-range long-duation unmanned probes to distant asteroids and comets, but I was wondering if anything big is in the works to transform the space sector in the near to mid range future.

    Is there any serious R&D on electro-magnetic launch, nuclear rockets or anything else?

  2. #2
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    26,185
    Ion drives lack the thrust to launch from Earth's surface.

    The nuclear-pulse Orion would violate nuclear testing bans, no other nuclear launcher is more than a drawing and a theory at this point. The same goes for an orbital elevator. The only ongoing research for a non-chemical lauch that I know of is laser launching, but that's a long, long way from reaching orbit-- a few hundred yards is the max it's reached. Looks like it's conventional rockets for the forseeable future.
    I'm a cynical optimist. I think the only way out is through, but once we get through it'll be better. Very different, but better. Howard Tayler

    It is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that is able best to adapt and adjust. Charles Darwin

    Power, Lord Acton says, corrupts. Not always. What power always does is reveal. Robert A. Caro

  3. #3
    Join Date
    Nov 2010
    Posts
    3,854
    I know there was a nuclear rocket program back in the 1960s that showed promise, I think it used heat from a fission reactor to turn propellant(liquid hydrogen?) into plasma which was then ejected out the exhaust at high speed. But I guess there's still a lot of caution about having radioactive material in close proximity to explosive materials. The thrust to weight ratio for that was impressive.

  4. #4
    Join Date
    Jan 2008
    Posts
    4,209
    NERVA and similar ideas, yes. A closed cycle "nuclear lightbulb" looks promising, but would be a heck of an engineering challenge. But hey, this is rocket science, what part isn't.

  5. #5
    Join Date
    Nov 2010
    Posts
    3,854
    90 minutes of burn time with 250,000 lbs. thrust and thrust to weight ratio of 3 to 4 in tests for the NERVA, too bad nuclear has gotten such a bad name.

    Something like that would start making long range manned missions practical.

  6. #6
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    26,185
    It isn't thrust that keeps long range manned missions from being practical, it's lack of desire; we could use existing launchers to build and fuel a large modular craft, but no one's willing to do it. Threads like this one cover the subject in more detail.
    I'm a cynical optimist. I think the only way out is through, but once we get through it'll be better. Very different, but better. Howard Tayler

    It is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that is able best to adapt and adjust. Charles Darwin

    Power, Lord Acton says, corrupts. Not always. What power always does is reveal. Robert A. Caro

  7. #7
    Join Date
    Nov 2010
    Posts
    3,854
    I guess I'm optimistic that things will change for the better, maybe more international co-operation in space missions leading to less military spending for instance.

  8. #8
    Join Date
    Nov 2005
    Posts
    5,262
    Quote Originally Posted by starcanuck64 View Post
    Is there anything right now being seriously developed to replace chemical rockets as the primary way to reach orbital velocity and escape velocity from the Earth.
    Skylon is a turbojet rocket hybrid. If successful, it would likely replace chemical rockets as the primary way to reach orbital velocity. Of all game-changing space launch technologies, Skylon is easily the one furthest along toward realization (if it will work, of course).

    The Quicklaunch space gun is a light gas gun. If successful, it wouldn't replace chemical rockets for manned missions, but it could replace them for cargo and microsatellites. This one might actually reach realization before Skylon, due to its relatively less radical technology and experience, but it's not a general purpose launcher.

    There is serious ongoing research into space elevators, although I'm personally skeptical that it will pan out.

    Those are the big three, nowadays.

  9. #9
    Join Date
    May 2007
    Location
    New Haven, Connecticut
    Posts
    7,133
    Quote Originally Posted by Noclevername View Post
    Ion drives lack the thrust to launch from Earth's surface.

    The nuclear-pulse Orion would violate nuclear testing bans, no other nuclear launcher is more than a drawing and a theory at this point. The same goes for an orbital elevator. The only ongoing research for a non-chemical lauch that I know of is laser launching, but that's a long, long way from reaching orbit-- a few hundred yards is the max it's reached. Looks like it's conventional rockets for the forseeable future.
    I'd rather not have nuclear rockets launched in my neighborhood, which I would currently define as the Atlantic Ocean and bordering lands and seas. I suspect that most of the population of, say, Florida and California -- where US launches would be most likely -- would tend to agree. I'm old enough to remember above-ground nuclear testing, and old enough to remember that it increased the atmospheric radiation levels enough to make pre-testing steel very desirable for applications that needed low radiation levels.

    I think the most likely, at least for small payloads, is laser launching. While the various gun technologies -- light gas, rail, etc -- show potential, I suspect that the hardening needed would make them less than useful for many orbital applications.
    Information about American English usage here and here. Floating point issues? Please read this before posting.

  10. #10
    Join Date
    Jan 2008
    Posts
    4,209
    The propellants for some rockets, like red fuming nitric acid and dinitrogen tetroxide, are pretty nasty. A closed cycle nuclear rocket would not emit fallout in normal operation. Sure, you don't want it falling on your head, but neither do you want chemical rockets to do that either. We should treat nuclear power like any technology, a tool with potential issues and design accordingly, rather than as a boogyman to be afraid of. Dozens die in the US in coal mining accidents every year, and yet that is apparently an acceptable risk.

  11. #11
    Join Date
    Nov 2005
    Posts
    5,262
    I'm skeptical of Myrabo's lightcraft for various reasons--the main one being the requirements for an extremely powerful pulse laser. That will require an incredible initial investment, which sort of defeats the goal of "cheap" access to space.

    The other noteworthy laser launch system is Kare's heat exchanger laser thermal rocket system. This one also requires a big investment in lasers but at least these are smaller less powerful continuous lasers. Kare's system looks pretty promising, but still...that big expensive array of lasers is a daunting investment.

  12. #12
    Join Date
    Nov 2010
    Posts
    3,854
    From what I understand there's far more radioactivity associated with coal mining/power production than there is with nuclear power, carbon is a great molecular sponge and sops up the uranium and other radioactive elements around it, it's just that nuclear power is new and people haven't learned to accept the risk yet.

    As for something like Orion, I don't think I'd like to be anywhere near one lifting off, but with the containment systems that have been developed for nuclear material and reactors like the US Navy operates, having an nuclear rocket upper stage is probably as safe as a chemical rocket.

  13. #13
    Join Date
    Nov 2005
    Posts
    5,262
    Whether you like it or not, there isn't any active development in nuclear thermal rocketry, and there hasn't been for decades.

  14. #14
    Join Date
    Nov 2010
    Posts
    3,854
    Quote Originally Posted by IsaacKuo View Post
    Whether you like it or not, there isn't any active development in nuclear thermal rocketry, and there hasn't been for decades.
    I'm just spitballing.

    Who knows what changes will take place in the future and nuclear offers some pretty good advantages in energy content over other forms of power.

    Laser is only going to be good for relatively short ranges unless you build a powerful laser in space or on the moon.

  15. #15
    Join Date
    Nov 2005
    Posts
    5,262
    Oh, I have my own ideas of a very good (IMHO) alternative to chemical rockets. However, the question was about alternatives which is currently in the works. Skylon and Quicklaunch are in the works. Space elevators are about as actively developed as you could expect at this stage.

    Laser launch is sort of borderline. Lightcraft was more exciting a decade ago but it seems to have been drifting along since then. Kare's system seems to have more going for it and more momentum, but it's also going to putter out if it doesn't get serious funding when the time comes.

  16. #16
    Join Date
    Nov 2010
    Posts
    3,854
    Thanks, I'll check those out.

  17. #17
    Join Date
    Nov 2010
    Posts
    3,854
    Skylon sounds interesting but the heating issue is challenging, 1000 degrees C at Mach 5.2 at high altitude.

    I guess material science and active cooling technology has come a long way since the SR-71 operating at Mach 3.2+.

  18. #18
    Join Date
    Mar 2004
    Posts
    17,651
    Quote Originally Posted by starcanuck64 View Post
    90 minutes of burn time with 250,000 lbs. thrust and thrust to weight ratio of 3 to 4 in tests for the NERVA, too bad nuclear has gotten such a bad name.

    Something like that would start making long range manned missions practical.
    My recollection was that NERVA, with tanks and fuel, had no hope to have enough thrust to be launched from the surface of the Earth. There were other solid thermal nuclear concepts that might have, but were never developed that far. If you want to send people, they would need to be sufficiently protected from the reactor which is a tricky issue in itself, at the very least requiring a fairly large rocket to give them some distance & shielding from the reactor.

    Anyway, the big issue today are operational costs and I don't see how this could reduce cost to orbit. Actually, I would expect it to be much more expensive. A nuclear rocket would be an expensive proposition, so it would have to be reusable to keep operational costs down, and the safety precautions would be enormous. Launches and safe recoveries would be tricky and a major accident could easily cost hundreds of billions.

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." Abraham Lincoln

    I say there is an invisible elf in my backyard. How do you prove that I am wrong?

    The Leif Ericson Cruiser

  19. #19
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    26,185
    Plus if you even whisper the "nuke" word everyone goes !!!!
    I'm a cynical optimist. I think the only way out is through, but once we get through it'll be better. Very different, but better. Howard Tayler

    It is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that is able best to adapt and adjust. Charles Darwin

    Power, Lord Acton says, corrupts. Not always. What power always does is reveal. Robert A. Caro

  20. #20
    Join Date
    May 2004
    Posts
    292
    Quote Originally Posted by starcanuck64 View Post
    Is there anything right now being seriously developed to replace chemical rockets as the primary way to reach orbital velocity and escape velocity from the Earth.

    I've gotten kind of out of touch in recent years with new developments. I know highly efficient ion rockets have been used on long-range long-duation unmanned probes to distant asteroids and comets, but I was wondering if anything big is in the works to transform the space sector in the near to mid range future.

    Is there any serious R&D on electro-magnetic launch, nuclear rockets or anything else?
    There is a lot of past and current research on gravity shielding by Podkletnov, Modanese and others. Currently with poor results due to lack of realm understanding of the theory and the really large numbers involved. Last research I found was dated 2010 (can't find the link right now).

    I also found this weird unofficial research:
    http://spazio.110mb.com/maxwell.pdf

    If the hypotesis are correct, an at least minimal gravity shielding effect (1/1000 g) should be produceable with "handy" device (some hundred volts, some kilohertz).

  21. #21
    Join Date
    Nov 2010
    Posts
    3,854
    Quote Originally Posted by Van Rijn View Post
    My recollection was that NERVA, with tanks and fuel, had no hope to have enough thrust to be launched from the surface of the Earth. There were other solid thermal nuclear concepts that might have, but were never developed that far. If you want to send people, they would need to be sufficiently protected from the reactor which is a tricky issue in itself, at the very least requiring a fairly large rocket to give them some distance & shielding from the reactor.

    Anyway, the big issue today are operational costs and I don't see how this could reduce cost to orbit. Actually, I would expect it to be much more expensive. A nuclear rocket would be an expensive proposition, so it would have to be reusable to keep operational costs down, and the safety precautions would be enormous. Launches and safe recoveries would be tricky and a major accident could easily cost hundreds of billions.
    In the link from ravens_cry I think the NERVA engine was originally intended to be a third stage on a Saturn 5.

    I think the savings you might be able to get from something like a nuclear rocket operating from high orbit is the longer burn times reducing transit time to Mars or further out and the need for more complex life support systems. But you would need to lift the heavy shielding as well.

    Plus if you even whisper the "nuke" word everyone goes !!!!
    I know, what's with that anyway, don't people know they're surrounded by radiation all the time anyway. If you live or work in a structure that's made from portland cement or cinder blocks you're receiving far more radiation than if you worked in a nuclear power plant.

    edit- Unless you worked at Chernobyl or Fukushima of course, but those were the result of bad design and/or operating precedures. Even Three Mile Island wouldn't have been anywhere near as bad as it was if it weren't for the control room crew misreading the situation because of a lack of instrumentation to read the core temperature.
    Last edited by starcanuck64; 2011-Jun-06 at 01:08 PM.

  22. #22
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    26,185
    Quote Originally Posted by starcanuck64 View Post
    I know, what's with that anyway, don't people know they're surrounded by radiation all the time anyway. If you live or work in a structure that's made from portland cement or cinder blocks you're receiving far more radiation than if you worked in a nuclear power plant.
    Most people are about as ignorant about radiation or nuclear reactors as they are about cosmology. It's some arcane voodoo that they only hear about when it's accompanied by the word "disaster" on the news.
    I'm a cynical optimist. I think the only way out is through, but once we get through it'll be better. Very different, but better. Howard Tayler

    It is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that is able best to adapt and adjust. Charles Darwin

    Power, Lord Acton says, corrupts. Not always. What power always does is reveal. Robert A. Caro

  23. #23
    Join Date
    Jan 2011
    Posts
    54
    There are any number of mechanisms in the area of 'fringe science'. The Dean drive, the EM drive, the Mach Effect drive to name a few. During the close of the twentieth century NASA provided funding for the Breakthrough Propulsion Physics Program (BPP) from 1996 through 2002. This program studied a number of "far out" designs for space propulsion that were not receiving funding through normal university or commercial channels. Anti-gravity-like concepts were investigated under the name "diametric drive". The work of the BPP program continues in the independent, non-NASA affiliated Tau Zero Foundation.

    Beyond that rotating tether propulsion systems called bolos or rotovators may be a way of retiring or at least taming the flaming tiger of chemical rocket propulsion.

  24. #24
    Join Date
    Apr 2007
    Location
    Nowhere (middle)
    Posts
    26,185
    This was the Dean "drive".
    I'm a cynical optimist. I think the only way out is through, but once we get through it'll be better. Very different, but better. Howard Tayler

    It is not the most intellectual of the species that survives; it is not the strongest that survives; but the species that survives is the one that is able best to adapt and adjust. Charles Darwin

    Power, Lord Acton says, corrupts. Not always. What power always does is reveal. Robert A. Caro

  25. #25
    Join Date
    Sep 2009
    Posts
    4,078
    Quote Originally Posted by Noclevername View Post
    This was the Dean "drive".
    This line from the article:

    "stick one of these in a submarine and you have instant spaceship!"
    Probably explains the various sci-fi novels with space going submarines, seriously.

  26. #26
    Join Date
    Jan 2008
    Posts
    4,209
    Orion could basically have launched a submarine into space, but unless we invent fallout free nuclear fusion charges, and maybe not even then, I doubt we will see that concept take flight. Seriously though, what a concept.
    It was daring.
    It was insane.
    And it might have worked.

  27. #27
    Join Date
    Dec 2004
    Posts
    107
    Quote Originally Posted by Noclevername View Post
    Ion drives lack the thrust to launch from Earth's surface.
    More to the point, they will always lack the thrust to launch from Earth's surface. It is inherent in the design. The upper limit on thrust is proportional to the cross-sectional area of the acceleration region and the square of the voltage gradient across the acceleration region.

  28. #28
    Join Date
    Dec 2004
    Posts
    107
    Quote Originally Posted by starcanuck64 View Post
    90 minutes of burn time with 250,000 lbs. thrust and thrust to weight ratio of 3 to 4 in tests for the NERVA, too bad nuclear has gotten such a bad name.

    Something like that would start making long range manned missions practical.
    Sadly, that turns out not to be the case. The only time you need a thrust to weight ratio above 1 is when you are traveling from Earth's surface into orbit. For a long range mission you want a rocket with a high specific impulse, not high thrust.
    NERVA's maximum specific impulse is in the low 800 seconds. A VASIMR can crank out a specific impulse around 30,000 or so.

  29. #29
    Join Date
    Dec 2004
    Posts
    107
    Quote Originally Posted by Garrison View Post
    "stick one of these in a submarine and you have instant spaceship!"

    Probably explains the various sci-fi novels with space going submarines, seriously.
    You betcha!
    http://www.projectrho.com/SSC/submarine.html

  30. #30
    Join Date
    Jan 2008
    Posts
    4,209
    DUMBO, a competing nuclear rocket design to NERVA, did in fact have a thrust to weight ratio of over one, meaning it could have taken off.

Similar Threads

  1. Other chemical elements?
    By Aite1 in forum Science and Technology
    Replies: 14
    Last Post: 2010-May-05, 03:15 PM
  2. Alternative use for rockets?
    By jhwegener in forum Science and Technology
    Replies: 25
    Last Post: 2009-Dec-11, 11:14 PM
  3. Chemical And Ion Propulsion?
    By PraedSt in forum Space/Astronomy Questions and Answers
    Replies: 27
    Last Post: 2008-Nov-24, 11:54 AM
  4. The Generosity Chemical
    By sarongsong in forum Science and Technology
    Replies: 0
    Last Post: 2007-Nov-23, 10:51 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
here
The forum is sponsored in-part by: