Follow Slashdot stories on Twitter

 



Forgot your password?
typodupeerror
×
Mars United Kingdom

UK Nuclear Spacecraft Could Halve Time of Journey To Mars (theguardian.com) 145

British spacecraft could travel to Mars in half the time it now takes by using nuclear propulsion engines built by Rolls-Royce under a new deal with the UK Space Agency. From a report: The aerospace company hopes nuclear-powered engines could help astronauts make it to Mars in three to four months, twice as fast as the most powerful chemical engines, and unlock deeper space exploration in the decades to come. The partnership between Rolls-Royce and the UK Space Agency will bring together planetary scientists to explore how nuclear energy could be used to "revolutionise space travel," according to the government. Dr Graham Turnock, the chief executive of the UK Space Agency, said using nuclear power in space was "a gamechanging concept that could unlock future deep-space missions that take us to Mars and beyond."
This discussion has been archived. No new comments can be posted.

UK Nuclear Spacecraft Could Halve Time of Journey To Mars

Comments Filter:
  • by irchans ( 527097 ) on Wednesday January 13, 2021 @04:32PM (#60939686)

    https://en.wikipedia.org/wiki/... [wikipedia.org]

    Those nuclear rocket engines were much more powerful than chemical rockets - Higher Specific Impulse and Total Impulse.

    My father actually did some work on them.

    • Yes, this is what we should be pursuing for manned missions, not chemical rockets. Cutting travel time in half or more is extremely valuable. Supplies, shelter and tools could be sent on the chemical slow boats years before in preparation for a fast traveling manned mission.

      Also should be researching fission fragment rockets, could power a probe to a few percent of C and get to another star.

      • by K. S. Kyosuke ( 729550 ) on Wednesday January 13, 2021 @09:08PM (#60941194)

        Cutting travel time in half or more is extremely valuable

        It is...except Starship is already being designed with a "three to four months" trip time in mind, and with no nuclear shenanigans to boot.

        • Thanks to refueling. Orbital refueling is more valuable than nuclear rockets, at least for the moment.

          • by K. S. Kyosuke ( 729550 ) on Wednesday January 13, 2021 @10:13PM (#60941390)
            It's not just that. Even refueling at your destination (here, Mars) is easier with Starship. With a nuclear-powered vehicle, from each tonne of extracted water, you'd be able to utilize around 111 kg of it (somewhat more with LANTR, admittedly, but at the expense of greater technical complexity of a hybrid engine), giving you around 1 MNs of impulse per tonne of extracted water. With methalox propulsion, from each tonne of extracted water, you'd be able to utilize around 950 kg, and together with armospheric CO2 extracted, you'd get around 7.7 MNs per tonne of extracted water. This means a significantly better utilization of in-situ resources extracted compared to the nuclear-powered vehicle. Perhaps the proposed CO2 nuclear rocket for orbital ferry applications would be a good idea for the Martian environment, but it has to be developed first.
          • However a nuclear rocket with orbital refuelling would be the absolute killer application.

        • it's a pipe dream, fuel depots everywhere and a fuel production facility on Mars. Nuke rocket doesn't need that.

          • So you replace a pipe dream with an even pipe-ier dream of your own choosing?

            Nuke rocket doesn't need that.

            Nuke rockets don't need working mass? Are you sure?

            • A nuclear rocket can take its working mass from earth for interplanetary round trips. A chemical rocket can't.

              And if a nuclear rocket had liquid or gas core the Ve gets even huger, up to 50 km/sec for gas core. Or beyond that for fission fragment a nice percent of speed of light even.

              Chemical rockets aren't the way.

              • A nuclear rocket can take its working mass from earth for interplanetary round trips.

                None that we have can do that. Solid core NTRs just aren't *that* performant. Gas core NTRs perhaps are but those are a pipe dream, and quite likely to remain so.

                • what we have or did have were engines on test bed; round trip nuke rockets have had some level of design only but of course I could say no chemical rocket infrastructure for Mar round trip exists either.

                  • also should add the nuke rocket gets to cheat, not fired from ground but from being assembled in orbit.. with chem rockets of course

          • A nuke needs fuel as well.
            Or do you think it just flies because ... uh ... oh ... it is a nuke?

    • ...and shit propellant density, so that for your higher total impulse you need implausibly large tankage. Seriously, without LANTR, solid NTRs never had a chance.
      • by quenda ( 644621 )

        ...and shit propellant density, so that for your higher total impulse you need implausibly large tankage.

        Liquid hydrogen. The Space Shuttle managed to get to orbit strapped to that "implausibly large" tank. What's the problem?
        Nobody is suggesting nuclear thermal for boosters, but it works for second stage and excels above LEO.

        We should have had nuclear thermal decades ago for Mars missions, instead of waiting for launch windows on slow-boats every 780 days.
        Now we should be working on nuclear-electric ion drives. One thousandth of a G would be enough for interplanetary flight, say 1000N thrust for a 100 ton

        • Liquid hydrogen. The Space Shuttle managed to get to orbit strapped to that "implausibly large" tank. What's the problem?

          As I said, density. No, that was hydrolox -- not liquid hydrogen -- in that tank. Hydrolox in the tank was five time as dense as hydrogen would have been, and even twice the Isp of nuclear-heated hydrogen wouldn't have been able to get the orbiter to orbit. Delta-v for the Shuttle with 20 tonne payload and the SLWT was around 8.55 km/s. With your hypothetical "nuclear orbiter" and one fifth the mass of propellant, it would have been only 6.75 km/s. Not sure how you'd consider a 1.8 km/s shortfall an improve

          • by quenda ( 644621 )

            With your hypothetical "nuclear orbiter" and one fifth the mass of propellant, it would have been only 6.75 km/s.

            Working? If we convert the Shuttle tank to pure H2, it should hold 150t - OK, that matches your 1/5th. With a reduced launch mass 300t, final mass of 120t and a 9.0km/s impulse, I get 8.4km/s delta-V. But with launch mass well under half that of the hydralox shuttle, there is going to be a much greater delta-V from the boosters. If there is still a shortfall, Kerbal taught me to just strap on more boosters.

            Of course, I've ignored the thrust-to-weight problem, and strapping solid boosters on the side o

            • by quenda ( 644621 )

              Damn! 2 seconds after submit I realise I counted 30t of propellant in the orbiter.
              With a mass ratio of 270/120 tons and 9.0isp I we get 7.3km/s delta V.
                Might need to stretch that tank 25%, but on the plus side, no bulkhead needed and can use thinner walls due to lower propellant mass.

          • The DV is not related to the payload.
            No idea about your tank scenarios, does not mater if you have two taks, one for liquid hydrogen and one for liquid oxygen, or a mixed one.

            (I doubt anyone ever was so braindead to mix liquid hydrogens and oxygen in a tank already, though)

            • I have no idea what you're trying to say here. There is no "mixed tank" or "two tanks" in an NTR scenario outside of LANTR. There's only a hydrogen tank, and that has be significantly upscaled to even keep the existing performance due to low density.
              • The parent said the shuttle had a mixed tank with lox and liquid hydrogen.
                Did you answer to the wrong person?

                NTR scenario outside of LANTR.
                Is it so hard to not use abbreviations everyone has to google?

    • Now suppose you use this tech to go to mars, and back.
      3 main risks
      - exploson of the (conventionnal) launcher on the launchpad or in low athmosphere. Huge quantities of non-activated fuel are dispersed. Very bad.
      - accidental re-entry of the used rocket into mars: activated fuel burns up, extreme contamination of mars
      - accidental re-entry of the used rocket for the back voyage into earth: activated fuel burns up, extreme contamination of earth
      How will we discard and stay away from such extremely dangerous wa

  • Won't happen. (Score:5, Interesting)

    by dunkelfalke ( 91624 ) on Wednesday January 13, 2021 @04:32PM (#60939688)

    Rolls Royce is in serious trouble right now. They are still on the hook for the 787 engine troubles, they don't earn any money with their power by the hour program thanks to the coronavirus, they sold their power generation branch to Siemens, they fell behind technologically compared to GE and have been forced to freeze the development of their next generation ultrafan engine due to a serious lack of funds. I won't be surprised if Rolls Royce wouldn't survive 2021.

    • Re: Won't happen. (Score:3, Insightful)

      by Viol8 ( 599362 )

      The UK government wouldnt let RR fail, it's a major UK defence contractor. And now we're out the EU it can be given state aid or as a last resort nationalised and no one can prevent that.

      • Re: (Score:2, Insightful)

        by dunkelfalke ( 91624 )

        The UK government? You mean Alexander Boris "fuck business" Johnson?

      • And now we're out the EU it can be given state aid or as a last resort nationalised and no one can prevent that.

        You vastly over-estimate the impact of leaving the EU.

        • Not only that, the UK-Japan trade agreement has, in fact, stricter rules on state aid [ft.com] than the EU asked for.

        • Not for state aid my friend.

          • I am just waiting for the screams of outrage from people like you when they realize just how much influence the EU still has over the UK and how little control the UK has now.

            I am also waiting for the outrage when people going on holiday in Spain realize that they have to buy medical insurance.

            And, today, I see that the fisheries deal is making things worse for UK-based boats and may drive many out of business.

          • Not for state aid my friend.

            To address this directly, did you perhaps read the news that Airbus was suing Boeing over state aid to Boeing? Since the USA is not in the EU, please explain how this is possible, but it's not possible for the UK's trading partners to sue over state aid to Rolls Royce?

      • It's going to be like the 1950s all over again.

      • by rnws ( 554280 )
        Well, the USA for one. did you miss that prolonged battled the USA and EU had over "state aid" to Airbus (and Boeing by different means). If Brexistanis want that oft-touted trade deal with the USA, you can be damn sure things like state aid or nationalisation will be a definite deal-breaker for the Yanks.
  • by JonnyCalcutta ( 524825 ) on Wednesday January 13, 2021 @04:36PM (#60939712)

    One thing you Yanks have forgotten is that there are no space dentists on Mars. Doesn't bother us brits.

    As long as we don't run out of space tea and warm space beer.

    • As long as we don't run out of space tea and warm space beer.

      lol -- as long as you don't let Lucas subcontract any of the parts, a brit rocket should be just fine. (We know why you guys like warm beer -- you all have Lucas refrigerators...)

    • Spot on, +1

  • by nospam007 ( 722110 ) * on Wednesday January 13, 2021 @04:38PM (#60939732)

    But not in my neighborhood.

  • We had mission firing duration tested nuclear rocket engines in the late 60s
  • OK, so we have:
    "... British spacecraft could travel to Mars in half the time it now takes by using nuclear propulsion engines built by Rolls-Royce ..."

    Yet the article later specifies:
    '... “This study will help us understand the exciting potential of atomic-powered spacecraft, and whether this nascent technology could help us travel further and faster through space than ever before,” he said.'

    Well, I'd be glad to see some development of nuclear space propulsion, but the headline can clearly stat

  • But incidents do happen at take off time, including explosions. With nuclear propulsion, this would make a kind of dirty bomb, releasing radioactive material in the atmosphere.
    • Not a dirty bomb, reactor doesn't have to be critical before launch, could be non-activated fuel that would only give off alphas. After a reactor is made critical for first time and run in space then yes, fuel becomes a dangerous neutron and gamma emitter even after shutdown. But then no one on the ground needs to care.

    • Dirty bombs aren't a thing. I'm sure they make great plot devices but they are terrible devices for war or terror.

      The more radioactive something is the shorter it's half life. Which means blowing up a dirty bomb involves first accumulating something highly radioactive, which will be highly dangerous to the people making the thing. Then they'd have to attach it to something explosive. That's hard as well because any electronic timers or triggers will be eaten up by the radiation, as will the explosive ma

      • > . Which means blowing up a dirty bomb involves first accumulating something highly radioactive,

        It's the same material as a "clean" bomb. Neutron bombs are typically based on reducing the yield of the weapon, shielding it less effectively and allowing more of the neutrons from the weapon to escape the shielding that helps concentrate the explosion. It's notably _easier_ than an efficient, clean nuclear weapon of maximum yield.

        • A neutron bomb is something different than a dirty bomb. At the core of a neutron bomb is a conventional explosive but it is carefully constructed to trigger a fission explosion, the neutrons are then used to irradiate the area and lead to large numbers of people to get sick and potentially die. A variation on this uses the neutrons to transmute some stable element into some highly radioactive element, which is then spread through the environment by the explosive force of the fission core. This is called

          • I would call a neutron bomb a form of dirty bomb, focused on fallout. I see your point that the Wikipedia definition does not equate them. I'd call the distinction one of degree, not of type, and certainly any fission bomb involves "accumulating something highly radioactive". Either is notably easier to build than a modern atom bomb, and built of much the same materials.

            > a nuclear thermal rocket than undergoes a rapid unscheduled disassembly on lift off will not produce any fission

            Have you seen any nucl

            • I would call a neutron bomb a form of dirty bomb, focused on fallout.

              I guess there's plenty of similarity in their intended result but they are quite different in function.

              certainly any fission bomb involves "accumulating something highly radioactive".

              No, a fission bomb does not involve accumulating highly radioactive material. The uranium and plutonium used in nuclear weapons have half lives in the thousands or millions of years, and the primary decay modes are alpha and beta decay. They pose very little radiation hazard and would be worthless in a dirty bomb.

              Either is notably easier to build than a modern atom bomb, and built of much the same materials.

              A dirty bomb is quite simple to construct, it's just conventional explosives wrapped in some

              • Solar sails could do well, do not require handling nuclear materials in bulk in new environments, and are far safer to test. The low thrust from light pressure and/or solar wind is continuous, and far safer to build, than nuclear engines. There are many good articles about the approach, including:

                https://iopscience.iop.org/art... [iop.org]
                https://ntrs.nasa.gov/citation... [nasa.gov]

                • Solar sails could do well,

                  Obviously not well enough, otherwise nobody would consider nuclear thermal rockets. Solar sails are still theoretical while nuclear thermal rockets use technologies that are well understood and were proven feasible 50+ years ago.

                  do not require handling nuclear materials in bulk in new environments,

                  Irrelevant. Space travel already involves dealing with radiation, nobody is going to care much about radiation from a nuclear thermal rocket engine. What also makes this irrelevant is that any manned mission to Mars is going to have a nuclear reactor for power. They will no doub

                  • Nuclear rockets got significant research because of their military possibilities. A rocket whose energy source could last for years without topping up is appealing. So is a rocker the enemy dare not shoot down without causing nuclear debris. And no, the fuel in a nuclear rocket is _not_ safe. Unless the rocket is very low thrust, it has to have enough fuel concentrated enough to provide chain reactions. Not enough to go critical, but enough to enhance the radioactive output of its core and improve the mass

    • I'd assume they'd be assembled in orbit for just such reasons.

  • I must say that when I read about nuclear engines from Rolls Royce my first thought was Fab-1 [wikipedia.org], the nuclear powered Rolls Royce belonging to Lady Penelope in the TV show Thunderbirds
  • by caseih ( 160668 ) on Wednesday January 13, 2021 @09:24PM (#60941250)

    Scott Manley recently talked about the fascinating nuclear salt water engine: https://www.youtube.com/watch?... [youtube.com]. Also https://en.wikipedia.org/wiki/... [wikipedia.org].

    Fascinating stuff. Unlike most proposals including the idea of detonating nuclear bombs behind the spacecraft, this one is actually feasible. It's a brilliant idea. And it's super efficient. Way more efficient than chemical propulsion. I think it's right up there with ion propulsion, except that it's on a much bigger scale (way more thrust obviously).

    Obviously something like this wouldn't be used in the atmosphere. But out in space it would be just fine.

    Like most nuclear things, though, fear of weapons-grade enriching has and will stifle its development.

    • by vix86 ( 592763 )

      I saw that the other day and when I saw this I immediately wondered if it was great coincidence, but the article is lacking in details in terms of what the UK wants to do.

      I know when I saw Scott's video though, I immediately realized that we'd never be able to reasonably launch these vehicles on Earth. I think its more likely these Nuclear engines are launched from the Moon or maybe a high Earth orbit. Maybe you mine the Uranium on the moon, if there are veins available and build the engines there. Either w

      • by caseih ( 160668 )

        Low earth orbit would be fine. The exhaust has such high velocity that it would leave earth's orbit if what Scott said is true.

    • by lazlo ( 15906 )

      I also really wish that the article had more detail. "nuclear rocket" could mean a whole lot of things, from nuclear thermal rockets, (probably what they're talking about) to nuclear salt water, to Orion, to... technically, if you put an RTG on a craft with an ion thruster, it's a nuclear powered propulsion system, and both of those are currently fielded, though I can't find a single craft that uses both.

  • half is singular and halves is plural. "halve" in its form that you are asking of, is actually a verb. Half is the singular, and halves is the plural. × Mars United Kingdom UK Nuclear Spacecraft Could Halve Time of Journey To Mars

There are two ways to write error-free programs; only the third one works.

Working...