Chemical rockets will not be enough for civilizations around low-mass stars

Habitable exoplanets around low-mass stars could be the most common type of habitable planets. Chemical rockets could be inadequate for many of these exoplanets.

Researchers suggest that a “reasonable” cutoff for interstellar travel is given by m0/mf ≈ 1000. In this case, a payload with mass comparable to that of the Apollo mission (∼ 45 tons) would require a fuel mass that is one-fifth the mass of the Sears tower.

In other words, it will not be easy for technological species orbiting low-mass M-dwarfs, such as Proxima Centauri and TRAPPIST-1, to undertake interstellar travel by means of chemical rockets. Consequently, these species may opt for alternative means of propulsion such as light sails, which have the added advantages of dispensing with carrying the fuel and achieving relativistic speeds.

57 thoughts on “Chemical rockets will not be enough for civilizations around low-mass stars”

  1. Well, the real problem is going to be finding a habitable planet around a low mass star. There is a reason why we find ourselves with a star that is above the 88th percentile in star masses. Smaller stars have much wilder flares and, combined with the fact any planet in their Goldilocks zone would have to be much closer, this would pretty much eliminate any possibility of being habitable. To make it worse, however, these planets would almost invariably be tidally locked, and only an amazing amount of sophistry can overcome the arguments against them being habitable. Additionally, as I said, the Goldilocks zones would be much smaller than around a star like our own, and planets don’t stay the same distance from their star forever. A smaller zone would likely see a planet drift out of the zone that much sooner and, considering it probably takes billions of years to make a planet like Earth, there goes your habitability. Although it doesn’t really pertain to its mass, it’s also good to keep in mind that the Sun has very little variability and, unlike most stars, is a singleton, with no companions to help mess up planetary orbits.

  2. Well, bummer, they will have to develop something better then. We know that chemical rockets aren’t a good option for interstellar travel either, even if we can launch stuff with solar escape velocity more easily. We have only used them for throwing relics into interstellar space without any plans for reaching other stars and do something useful once there. So, the problems any hypothetical low mass star planet inhabitants would face are just slightly harder than those we will.

  3. In other words, it will not be easy for technological species orbiting low-mass M-dwarfs, such as Proxima Centauri and TRAPPIST-1, to undertake interstellar travel by means of chemical rockets. ” Edited to remove alliterative cussing. Seriously, somebody had to write a paper on this?

  4. Well the real problem is going to be finding a habitable planet around a low mass star. There is a reason why we find ourselves with a star that is above the 88th percentile in star masses. Smaller stars have much wilder flares and combined with the fact any planet in their Goldilocks zone would have to be much closer this would pretty much eliminate any possibility of being habitable. To make it worse however these planets would almost invariably be tidally locked and only an amazing amount of sophistry can overcome the arguments against them being habitable.Additionally as I said the Goldilocks zones would be much smaller than around a star like our own and planets don’t stay the same distance from their star forever. A smaller zone would likely see a planet drift out of the zone that much sooner and considering it probably takes billions of years to make a planet like Earth there goes your habitability. Although it doesn’t really pertain to its mass it’s also good to keep in mind that the Sun has very little variability and unlike most stars is a singleton with no companions to help mess up planetary orbits.

  5. Well bummer they will have to develop something better then.We know that chemical rockets aren’t a good option for interstellar travel either even if we can launch stuff with solar escape velocity more easily. We have only used them for throwing relics into interstellar space without any plans for reaching other stars and do something useful once there.So the problems any hypothetical low mass star planet inhabitants would face are just slightly harder than those we will.

  6. In other words it will not be easy for technological species orbiting low-mass M-dwarfs such as Proxima Centauri and TRAPPIST-1″ to undertake interstellar travel by means of chemical rockets. “”Edited to remove alliterative cussing. Seriously”””” somebody had to write a paper on this?”””

  7. Earth had life like around 1b years after formation right? Just correcting. It’s probably possible. I don’t think even a solar flare aimed directly at a planet is a guaranteed global extinction event. Undersea life might be ok. I’m not saying civilizations would do all that well, but life itself may be able to tolerate that kind of environment.

  8. You beat me to it. Dumbest premise to start from. Why would we be shocked if civs from low mass stars can’t use chemical rockets for IS propulsion if we’re not even entertaining the thought? The launch mass would be absurd.

  9. You don’t need to stumble across transuranic elements to discover radioactivity. It was an inevitability of the discovery of the electron, the Michelson-Morley experiment and the development of quantum mechanics. We would have and could have discovered radioactivity and started artificially creating uranium and plutonium without having had access to natural radioactive ores.

  10. Why are we debating the use of chemical rockets for interstellar travel specifically for civilizations around low mass stars? It’s not feasible for us, and we’ve known this for a long time. The launch mass is impractically enormous. Nobody, literally nobody, in the futurism/interstellar community, has realistically considered chemical rockets as a propulsion system since… 1960.

  11. Hypothetically, they were in a system without much in the way of really heavy elements, and so never developed nuclear power? Nuclear fission is kind of the door to higher physics; On a planet not gifted, like ours, with radioactive elements, an intelligent species could be very slow about getting past chemistry.

  12. Earth had life like around 1b years after formation right? Just correcting. It’s probably possible. I don’t think even a solar flare aimed directly at a planet is a guaranteed global extinction event. Undersea life might be ok. I’m not saying civilizations would do all that well but life itself may be able to tolerate that kind of environment.

  13. You beat me to it. Dumbest premise to start from. Why would we be shocked if civs from low mass stars can’t use chemical rockets for IS propulsion if we’re not even entertaining the thought? The launch mass would be absurd.

  14. You don’t need to stumble across transuranic elements to discover radioactivity. It was an inevitability of the discovery of the electron the Michelson-Morley experiment and the development of quantum mechanics. We would have and could have discovered radioactivity and started artificially creating uranium and plutonium without having had access to natural radioactive ores.

  15. Why are we debating the use of chemical rockets for interstellar travel specifically for civilizations around low mass stars? It’s not feasible for us and we’ve known this for a long time. The launch mass is impractically enormous. Nobody literally nobody in the futurism/interstellar community has realistically considered chemical rockets as a propulsion system since… 1960.

  16. Hypothetically they were in a system without much in the way of really heavy elements and so never developed nuclear power?Nuclear fission is kind of the door to higher physics; On a planet not gifted like ours with radioactive elements an intelligent species could be very slow about getting past chemistry.

  17. Should note that no civilization will be travelling interstellar space using chemical rockets. And that solar sails don’t work that great for Low Mass Stars. Until you can build fusion rockets you should stay home. You are not ready to leave kindergarten.

  18. Should note that no civilization will be travelling interstellar space using chemical rockets. And that solar sails don’t work that great for Low Mass Stars. Until you can build fusion rockets you should stay home. You are not ready to leave kindergarten.

  19. If they are living around a functioning star they will discover fusion at least. Of course, we have yet to see if fusion is actually a usable road to small (

  20. If they are living around a functioning star they will discover fusion at least.Of course we have yet to see if fusion is actually a usable road to small (

  21. I dunno – I tried plugging in some numbers to their equation, and for a stellar mass of 0.2 I only get a mass ratio of about 95, not 1000… Anyone else get what they show in their chart?

  22. I dunno – I tried plugging in some numbers to their equation and for a stellar mass of 0.2 I only get a mass ratio of about 95 not 1000… Anyone else get what they show in their chart?

  23. It seems our own interplanetary future is going towards the chemicalpunk, though. That technology is enough to get us out of Earths gravity well, and the new societal and market organization of commercial space would probably take us there in numbers, besides of allowing us to place a lot more machinery and automated infrastructure in space. Quaint, inefficient but working rockets beat awe inspiring but insanely dangerous or nonexisting technologies.

  24. If this had been about the difficulty of interPLANETARY travel, there would have been a point to this. Planets in the habitable zone of a low mass star are moving faster around their star than the Earth around the sun, so the delta-V for Hohmann transfer orbits are greater. Getting into orbit around their planet would be no harder than for earth, but once in orbit getting to another planet would require something better than chemical rockets.

  25. It’s true that, eventually, they’ll discover fusion. So far the only way we’ve found to make fusion work involves transuranic elements… But I suspect that a civilization without transuranics will skip right from chemical to solar power, and use beamed propulsion with solar power satellites, because nuclear will be so underdeveloped and inconvenient.

  26. Basically, this paper is a refutation of the nascent xeno chemicalpunk movement. All of our geeky fanboy dreams of interstellar alien retro chemical rocket civilizations are duly crapped upon. But I maintain that multiplanet chemicalpunk civilizations can still exist, in systems with multiple planets in the habitable zone, perhaps orbiting a gas giant.

  27. It seems our own interplanetary future is going towards the chemicalpunk though.That technology is enough to get us out of Earths gravity well and the new societal and market organization of commercial space would probably take us there in numbers besides of allowing us to place a lot more machinery and automated infrastructure in space.Quaint inefficient but working rockets beat awe inspiring but insanely dangerous or nonexisting technologies.

  28. If this had been about the difficulty of interPLANETARY travel there would have been a point to this.Planets in the habitable zone of a low mass star are moving faster around their star than the Earth around the sun so the delta-V for Hohmann transfer orbits are greater. Getting into orbit around their planet would be no harder than for earth but once in orbit getting to another planet would require something better than chemical rockets.

  29. It’s true that eventually they’ll discover fusion. So far the only way we’ve found to make fusion work involves transuranic elements… But I suspect that a civilization without transuranics will skip right from chemical to solar power and use beamed propulsion with solar power satellites because nuclear will be so underdeveloped and inconvenient.

  30. Basically this paper is a refutation of the nascent xeno chemicalpunk movement. All of our geeky fanboy dreams of interstellar alien retro chemical rocket civilizations are duly crapped upon. But I maintain that multiplanet chemicalpunk civilizations can still exist in systems with multiple planets in the habitable zone perhaps orbiting a gas giant.

  31. It seems our own interplanetary future is going towards the chemicalpunk, though.

    That technology is enough to get us out of Earths gravity well, and the new societal and market organization of commercial space would probably take us there in numbers, besides of allowing us to place a lot more machinery and automated infrastructure in space.

    Quaint, inefficient but working rockets beat awe inspiring but insanely dangerous or nonexisting technologies.

  32. If this had been about the difficulty of interPLANETARY travel, there would have been a point to this.
    Planets in the habitable zone of a low mass star are moving faster around their star than the Earth around the sun, so the delta-V for Hohmann transfer orbits are greater. Getting into orbit around their planet would be no harder than for earth, but once in orbit getting to another planet would require something better than chemical rockets.

  33. It’s true that, eventually, they’ll discover fusion. So far the only way we’ve found to make fusion work involves transuranic elements…

    But I suspect that a civilization without transuranics will skip right from chemical to solar power, and use beamed propulsion with solar power satellites, because nuclear will be so underdeveloped and inconvenient.

  34. Basically, this paper is a refutation of the nascent xeno chemicalpunk movement. All of our geeky fanboy dreams of interstellar alien retro chemical rocket civilizations are duly crapped upon.

    But I maintain that multiplanet chemicalpunk civilizations can still exist, in systems with multiple planets in the habitable zone, perhaps orbiting a gas giant.

  35. I dunno – I tried plugging in some numbers to their equation, and for a stellar mass of 0.2 I only get a mass ratio of about 95, not 1000…
    Anyone else get what they show in their chart?

  36. If they are living around a functioning star they will discover fusion at least.

    Of course, we have yet to see if fusion is actually a usable road to small (< yottawatt) controlled power outputs.

  37. Should note that no civilization will be travelling interstellar space using chemical rockets. And that solar sails don’t work that great for Low Mass Stars. Until you can build fusion rockets you should stay home. You are not ready to leave kindergarten.

  38. Earth had life like around 1b years after formation right? Just correcting. It’s probably possible. I don’t think even a solar flare aimed directly at a planet is a guaranteed global extinction event. Undersea life might be ok. I’m not saying civilizations would do all that well, but life itself may be able to tolerate that kind of environment.

  39. You beat me to it. Dumbest premise to start from. Why would we be shocked if civs from low mass stars can’t use chemical rockets for IS propulsion if we’re not even entertaining the thought? The launch mass would be absurd.

  40. You don’t need to stumble across transuranic elements to discover radioactivity. It was an inevitability of the discovery of the electron, the Michelson-Morley experiment and the development of quantum mechanics. We would have and could have discovered radioactivity and started artificially creating uranium and plutonium without having had access to natural radioactive ores.

  41. Why are we debating the use of chemical rockets for interstellar travel specifically for civilizations around low mass stars? It’s not feasible for us, and we’ve known this for a long time. The launch mass is impractically enormous. Nobody, literally nobody, in the futurism/interstellar community, has realistically considered chemical rockets as a propulsion system since… 1960.

  42. Hypothetically, they were in a system without much in the way of really heavy elements, and so never developed nuclear power?

    Nuclear fission is kind of the door to higher physics; On a planet not gifted, like ours, with radioactive elements, an intelligent species could be very slow about getting past chemistry.

  43. Well, the real problem is going to be finding a habitable planet around a low mass star. There is a reason why we find ourselves with a star that is above the 88th percentile in star masses. Smaller stars have much wilder flares and, combined with the fact any planet in their Goldilocks zone would have to be much closer, this would pretty much eliminate any possibility of being habitable.

    To make it worse, however, these planets would almost invariably be tidally locked, and only an amazing amount of sophistry can overcome the arguments against them being habitable.

    Additionally, as I said, the Goldilocks zones would be much smaller than around a star like our own, and planets don’t stay the same distance from their star forever. A smaller zone would likely see a planet drift out of the zone that much sooner and, considering it probably takes billions of years to make a planet like Earth, there goes your habitability.

    Although it doesn’t really pertain to its mass, it’s also good to keep in mind that the Sun has very little variability and, unlike most stars, is a singleton, with no companions to help mess up planetary orbits.

  44. Well, bummer, they will have to develop something better then.

    We know that chemical rockets aren’t a good option for interstellar travel either, even if we can launch stuff with solar escape velocity more easily.

    We have only used them for throwing relics into interstellar space without any plans for reaching other stars and do something useful once there.

    So, the problems any hypothetical low mass star planet inhabitants would face are just slightly harder than those we will.

  45. “In other words, it will not be easy for technological species orbiting low-mass M-dwarfs, such as Proxima Centauri and TRAPPIST-1, to undertake interstellar travel by means of chemical rockets. ”

    Edited to remove alliterative cussing. Seriously, somebody had to write a paper on this?

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