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Design of a rapid transit to Mars mission using laser-thermal propulsion
- jmyeet 5y agoSure let's continue unmanned exploration of Mars but manned exploration let alone colonization makes absolutely zero sense. mars is nothing more than a further, more annoying version of the Moon. Similar gravity, less sunlight (ie further from the Sun), communication latency (~10 minutes vs 1.5 seconds), no magnetosphere (just like the Moon so you'll probably need to live underground) and just enough atmosphere to provide no benefits and be annoying (eg dust storms that obscure the Sun and blow dust all over your equipment). The romantic view of living on an above-ground Martian city is no more realistic than Star Wars. On a side note, laser propulsion is likely the means within reach of interstellar travel. If nuclear fusion is ever viable (and that's still an "if" not a "when") then it could be too. But if you accept that laser propulsion is the only or even just the best means of moving stuff around, it's further rason why a civilization will tend towards building a Dyson Swarm.
- ericmay 5y agoMars has water and more “acceptable” temperatures, I believe. This doesn’t have to be a mutually exclusive endeavor. We can put a base on Luna and colonize Mars. Maybe the Moon is the stepping stone to Mars?
- 0_____0 5y agoThis doesn't answer the question of why you'd want to put people on Mars in the first place.
- ben_w 5y agoDisaster recovery, the penultimate in off-site backups of humanity itself.
- gambiting 5y agoIf that really is your goal then build a colony at the bottom of the ocean or deep under ground here on Earth - at sufficient depth there is literally nothing that could endanger such colony, it's functionally equivalent to being on mars without the idiotic travel cost.
- 0des 5y agoJust put the DC backup in that rack in the corner, should be all we need.
- ben_w 5y agoPlausible, but I remember when I did my degree, one of the examples given about the importance of choosing a good site for “off site backups” was a company whose main site was one of the WTO twin towers, whose off site was the the other tower on the grounds that they couldn’t conceive of anything that would affect both without also destroying civilisation as a whole.
- gambiting 5y agoWell sure, but that's always a question of what are you trying to defend yourself against(what kind of scenario is the backup helping with). Twin towers are probably good enough for any kind of fire/electrical failure/theft/vandalism, but not for a meteor strike, war or as we've seen - terrorism. It's not that people in your example were stupid and didn't see it - just that most likely they didn't consider those dangers as important to have a backup for(if a war breaks out or a meteor strikes New York you probably have bigger problems). It's the same here - most of the "human extinction"-scale events really don't touch a base that's 10km under water or under ground. Nuclear war or meteor strike? nope. Earthquakes? There are places safe from that. Solar flares? Nope. Deadly virus? Quarantine everyone arriving like you would with the journey to Mars. Terrorism remains the main risk, but it would have been the same risk on Mars too. And most importantly - it teaches us how to run an independent colony deep underground, which is important because despite all the Sci-Fi films showing us otherwise, the base on Mars would really have to be underground because of radiation risk. So yeah, sure, run an underground base for a few decades then you can just transplant the technology to Mars - don't start with Mars first.
- ericmay 5y agoWhy do anything?
- gambiting 5y agoThis is a very flippant comment, but I will try to respond anyway - we simply haven't achieved a post scarcity society yet. Maybe we will at some point, but we just aren't there yet. So right now our time, money and natural resources are quite simply limited. So maybe it's not that we shouldn't have a base on Mars - it's just that maybe that shouldn't be the first step in human habitation in space.
- bostonsre 5y agoWhat about motivating humans to strive for greatness? Being curmudgeon underground mole people sounds a lot less likely to inspire the next generation to strive to excel at STEM education. I think even just trying to colonize mars could inspire tens of millions of the next generation when they look up at the sky. A large majority of those won't go into the space colonization field and most will instead contribute to improving our lot and maybe even attempting to get to a post scarcity society.
- thoms_a 5y agoI genuinely had a good laugh at the idea that simply by building an underground colony, the inhabitants would become "curmudgeon underground mole people". I would personally love such a habitat, and would market it as a Safe Space for The Curmudgeonly(TM).
- ericmay 5y agoI don't see how it's any different than the parent comment in terms of being flippant. Should one meet any thing that humans may strive for with "why do that if we haven't done X first"? Why start a new startup if you haven't solved post-scarcity society? We don't need to have a post-scarcity society before progressing science and technology by trying to and succeeding in colonizing Mars. Similarly we create plenty of technology while also not solving the post-scarcity "problem". Adding more resources or more people to solving a problem doesn't mean that it makes the problem easier or more likely to be solved. So you're creating this idea that we can't do X until we've done Y, when the truth is we can do X and Y. Strategically I think we should create an international moon base first before going to Mars, but we can do both.
- dahfizz 5y agoWhy did Homo Erectus leave Africa? Why did early humans cross the land bring into the Americas? What could have possibly possessed the aborigines to cross the ocean to Australia? Because its cool. Because its interesting. Because it is baked into our monkey brains to want to explore. If people want to push the frontier, why are you such a grump about it?
- gambiting 5y agoI'm positively certain that in all of your examples people have pushed into new areas because of food, to find new land to live on, to find riches, to find the promised land or other mythological reasons. Somehow I don't imagine aborigines crossing the ocean because "it's cool". You know what we're going to find on Mars? Rocks. A whole lot of radiation. No breathable atmosphere and freezing temperatures. Imagine the most hellish place on Earth - that's still better for humans than the most pleasant place on Mars. Would it be "cool" to stand on Mars? To stand on another planet? Of course it would. And I firmly believe that we should continue our planetary explanation - but making plans for human habitation on Mars when we haven't even been back to the Moon in 50+ years is literally just stupid. Put a base there, learn how to make it self sufficient and then let's talk about Mars.
- maxerickson 5y agoLike if you could build something awesome on Mars it would pretty much universally be easier to build it in North Dakota.
- ceejayoz 5y agoSure. It's easier to build in North Dakota than it is in the Swiss Alps, too, but people do that in part because they like the Alps. There are going to be people for whom the idea of a frontier life in a place of natural, untouched beauty appeals. We've always had those folks. Some of them find life is harder than they expected; some thrive.
- 5y ago
- jmyeet 5y agoAccording to [1]: > Temperatures on Mars average about -81 degrees F. However, temperatures range from around -220 degrees F. in the wintertime at the poles, to +70 degrees F. over the lower latitudes in the summer. Bear in mind the atmosphere is <1% the pressure of Earth's, basically a vacuum. This actually means you'd barely feel 60mph winds (which, interestingly, was one of several flaws in The Martian book and movie) so hypothermia probably wouldn't be a huge issue from the air but still matters if you contact something solid. It's unclear where the water on Mars is. It's definitely on the poles, which means you're at the lower end of that range, but there may also be water ice in more equatorial latitudes. [1]: https://www.weather.gov/fsd/mars https://www.weather.gov/fsd/mars
- Gravityloss 5y agoWell stated! Humans can be surprisingly useful still, even if we are very costly to maintain. https://en.wikipedia.org/wiki/Moravec%27s_paradox https://en.wikipedia.org/wiki/Moravec%27s_paradox I'm hopeful about artificial magnetic fields - modern superconducting magnets could do wonders in orbit with solar power. Or here's sending ions from Phobos to do it: https://arxiv.org/abs/2111.06887 https://arxiv.org/abs/2111.06887
- ben_w 5y agoEven without superconductors. If I was in change of a lunar colonisation plan, first thing I’d do is send up a rover with some limited ability to process lunar regolith — at a minimum into aluminium, preferably also PV. This rover would slowly crawl around the moon (doesn’t need to be the equator, but at least 5.14+6.68° from the poles to avoid being in darkness at the wrong time of year), leaving a fat conductor behind it. If the rover needs human interaction, it’s only a few seconds of light lag. Once the processing has circumnavigated the moon, the conductor is already in a desiccated vacuum on non-conductive rock, so no extra insulation needed for that to be an HVDC line. Then send some transformers and as much PV and industrial equipment as you want, because now the 14-day-long lunar night is easy to get through. The current going through the conductor gives you a free magnetosphere whose strength goes up the more PV is connected. If you can’t build such a rover, you’re probably not ready to colonise the moon in the first place.
- jmyeet 5y agoI don't disagree with your assessment of building aluminium conductors but my argument is that this isn't even really necessary. Living underground just makes so much more sense and is much, much easier. There is strong evidence of extinct lava tubes on the Moon. Sealing one of those up and pressurizing it is just so much easier, practical and incrementally scalable.
- bbojan 5y agoThe Moon has very little hydrogen, carbon and nitrogen, which Mars has in abundance. These are very important elements both for biology and chemistry. E.g. if you want to have a self-sufficient colony outside Earth, you could do it on Mars but not on the Moon. Mars could be terraformed (in theory); the Moon never could.
- revicon 5y agoWith no magnetosphere would there even be a point to terraforming?
- ceejayoz 5y agoTerraforming is an engineering project on such a scale it's probably reasonable to assume advancements like radiation resistance/repair in humans and artificial magnetic fields. For example, this apparently feasible (but currently batshit crazy) proposal: https://www.universetoday.com/153368/an-absolutely-bonkers-plan-to-give-mars-an-artificial-magnetosphere/ https://www.universetoday.com/153368/an-absolutely-bonkers-p...
- bryanlarsen 5y agoMaintaining an atmosphere is a lot easier than creating it in the first place, and can use the same process and machines. In other words just live with the slow loss and replace the loss gradually.
- revicon 5y agoI think what I meant is with no magnetosphere we would all die of radiation exposure regardless if there was a terraformed atmosphere or not. Without a magnetosphere we'd all be living underground anyway, no point in terraforming.
- nine_k 5y agoA strategically placed powerful magnet outside Mars can protect from the solar wind. There is an orbit that places the orbiting body always on the line between Mars and Sun. Place a superconducting magnet there that generates a few Tesla. Due to the distance from the planet, even though the magnet will deflect more distant particles to relatively small angles, this should still be enough to keep Mars completely in the "shadow". Of course you'll have to and solar-powered thrusters to keep it on the orbit, and fly regular missions to replenish fuel in the ion drives. But thil looks doable even with today's level of technology, given enough money.
- shoulderfake 5y ago
- politician 5y agoThankfully Elon doesn’t need funding from this crowd.
- dang 5y agoWe've banned this account for frequently breaking the site guidelines and ignoring our requests to stop. If you don't want to be banned, you're welcome to email hn@ycombinator.com and give us reason to believe that you'll follow the rules in the future. They're here: https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html.
- slothtrop 5y agoIf terraforming is in the cards, stands to reason it would be first tried in our own backyard. Mars is the best contender for it. Actually it might be useful in other respects than being livable. The vision is far less romantic if you consider it a distant future project.
- 0_____0 5y agoAt least Venus has a magnetosphere. How are you going to terraform a planet that can't retain more than 6.5 millibars worth of atmosphere? Build a big-ass bubble around the planet to deflect solar wind? Nuke the core of the planet to re-melt it and get a magnetic field back?
- politician 5y agoWatch any of the videos on terraforming Venus by Isaac Arthur on YouTube.
- 0_____0 5y agoA brief summary of proposed methods and their feasibility and a link to further literature may do a bit better at getting your point across than the name of a youtube channel that close to 0% of the people reading this are going to seek out at your say-so.
- politician 5y ago> a link to further literature See above.
- ben_w 5y agoNuking the core is neither sufficient nor necessary for the magnetosphere. Not sufficient because all of the nukes together are orders of magnitude too little to melt it, not necessary because a spinning ball of liquid metal is a really inefficient way to make a magnet. IIRC one of the plans for an artificial magnetosphere for Mars only needed a 1 GW supply to the magnetic coil.
- sevenf0ur 5y agoAgreed, if an extinction level event happened on Earth, we'd be better off riding it out underground, than moving off planet.
- Retric 5y agoI agree going to Mars is never going to be a useful for evacuation, but it could help if we where already there. Most plausibility the long duration space flight should prevent the common cold from making the trip which would also prevent many hypothetical super plagues from doing so as well. In theory you could do the same on earth, but it’s unlikely for a self sustaining underground colony to consistently maintain that level of quarantine for new arrivals. However getting a self sustaining population on Mars that could survive indefinitely is currently just science fiction and making the trip is the least difficult hurdle for changing this.
- jmyeet 5y agoTo be clear, off-planet colonization isn't an evacuation strategy. It's a continuation strategy in the event that humanity is wiped off the Earth.
- spywaregorilla 5y agoYou'd probably live underground if on mars anyway.
- slothtrop 5y agoEarth obliteration is a certainty on a long enough timeline, before the Sun goes out. There's no question of riding things out underground at that point. We'd have to be elsewhere.
- jsnodlin 5y ago
- kilroy123 5y agoI strongly disagree and I dare say this is an incredibly short sighted view. Pushing forward to living on Mars will unlock tons of technological and scientific advances that will only help us better live here on Earth, and Mars. The mother of invention will always been necessity. We simply don't need a lot of the tech that will be created, until we try to live off-world. So much technology and scientific know-how, came out of the Apollo program when we pushed towards visiting the Moon. This will be even greater when we move towards colonizing and living off-world rather than just visiting.
- jmyeet 5y agoLet's accept this premise (which amounts to essentially "we don't know what we don't know") and I'll ask a natural follow up question: what is the difference between colonizing the Moon and colonizing Mars in terms of problems we'd need to solve and thus technology we'd likely gain?
- politician 5y agoThe ISRU profiles of both bodies are significantly different and Mars has much higher gravity. The Moon is, first and foremost, a weapons platform, and any every competent military sees it as such. There will never be a functioning colony on the Moon until the Earth is unified under a single government. Mars is far enough away that colonization is possible, and the technology needs are so dramatic that we’ll have to develop a comprehensive deployment plan to bootstrap self-sufficiency from the start. Despite 150 years of industrialization on Earth, we still lack an experimentally tested plan to reboot.
- jmyeet 5y ago> The Moon is, first and foremost, a weapons platform This just isn't true. To quote Isaac Arthur, "there is no such thing as an unarmed spaceship". Kinetic energy is all the weapon you need. Any colony on the Moon or Mars would need to be essentially self-sufficient from day one because the cost of getting payloads to eitehr are so vast to be uneconomical.
- mchusma 5y agoI also think Dyson swarms are the future. But I think the Mars effort is helpful towards getting there. Elon's public motivation for Mars is basically a human backup plan. And for that, it probably may be the best shot of the next 100 years. It seems like a million people living and working on Mars is more likely to survive a worst case scenario that a million people in rotating space habitats.
- jmyeet 5y agoBut how is the Moon not a sufficicent backup plan?
- O5vYtytb 5y agoHow can a moon civilization support itself without the Earth?
- jmyeet 5y agoThe Moon has abundant iron and aluminium. Carbon and hydrogen are possibly an issue but capture a comet or two and that problem goes away. I'm not sure what the state of phosphorus is but luckily we don't need all that much of it. What would we need from Earth? What would be economical to ship from Earth?
- O5vYtytb 5y ago> but capture a comet or two and that problem goes away. So the moon colony needs to be capable of making the things to go and capture a comet, and more comets in the future to replenish supplies, to support itself. That's a very large civilization.
- bostonsre 5y agoThe dust on the moon is extremely abrasive, the temperature fluctuations are more extreme, there is no atmosphere that provides protection against meteorites and high energy particles (not that mars has a thick atmosphere, but it is better than nothing), and the gravity of the moon would be a lot harder for humans to adjust to.
- mrfusion 5y ago
- atonalfreerider 5y agoThere is a future where some scarcely few people set foot on Mars and survive with a fleet of robots. The rest of us can experience Mars through virtually reality. I think this is a likely outcome.
- bayesian_horse 5y agoGravity is higher, which is important for Humans. Also the resources are more diverse. And you can study Mars better from the surface of Mars than from the surface of the Moon (duh...). I'm not a massive fan of Mars colonization. But I do get the appeal of getting manned missions there. Some science really can't be done as well or cheaply by robots alone. Though even with Humans on board, much of the work will be done by robots anyway.
- jvanderbot 5y ago> Some science really can't be done as well or cheaply by robots alone. I'm struggling to imagine how a "lab full of equipment, life support, beds, bathrooms, comms, and return rocketry" doesn't ($-wise) translate much better to "many, many more teleoperated robots with miniaturized labs operated from orbit or Earth with frequent sample return round-trips". Boots on the ground is a moral victory, but I don't see the science victory until you get enough equipment / personnel there to get a thriving ecosystem of thought in-situ. Not to mention: Astronauts are rarely the scientists that study the place they are going. Now an ISS around Mars? That makes a lot of sense to me.
- bayesian_horse 5y agoHumans can get a lot more work done, just by their dexterity, flexibility and ability to learn and adapt. For robots, even simple tasks have to be pre-planned, in this case sometimes years in advance. It is conceivable that you could build a robot/machine that can collect one type of sample and do one type of analysis cheaper and quicker than a Human. However, human astronauts can do multiple types of these, maybe even adapt them on the fly.
- jvanderbot 5y agofor this, teleoperation from orbit seems reasonable. It's not been tried however.
- tiborsaas 5y agoWith this mindset we won't get very far as a species. It was probably already a mistake to climb down from the trees, right? But seriously, what else we should do as humans? I just can't imagine we will sit on our asses because that's a reasonable thing to do. If the benefits of going to Mars only results in a new generation of humans to fall in love with space, that's already good enough. Also don't forget all the cool technology that will spin off from this endeavour. Being able to afford human space exploration is a really good sign since that indicates that we don't have any limiting factors to hold us back. The reverse scenario is way more depressing.
- jmyeet 5y ago> With this mindset we won't get very far as a species. I assume you're saying this in good faith but it's really a straw man argument because it's a false dichotomy. For one there's the obvious: I'm not saying "go nowhere". I'm saying "the Moon makes more sense to colonize than Mars". Also, that doesn't preclude ever colonizing Mars. A Moon-first policy just makes way more sense. Another flaw: why do we even need to colonize a planet? It actually doesn't make much sense if you really think about it. I'm firmly in the camp that thinks humanity's future is in a cloud of orbitals aka an eventual Dyson Swarm. It's way more efficient in terms of living area pre unit mass. It requires no energy tech more sophisticated than solar power. It requires no material that we don't already have. You don't have all the problems with getting into and out of large gravity wells. Gravity (ie spin gravity) can be exactly Earth normal.
- slibhb 5y ago> Another flaw: why do we even need to colonize a planet? It actually doesn't make much sense if you really think about it. I'm firmly in the camp that thinks humanity's future is in a cloud of orbitals aka an eventual Dyson Swarm. It seems odd to quibble about which rock we should colonize when you think this far ahead. Any species that lives in a "cloud of orbitals" or a "Dyson Swarm" is going to have colonized other planets in its solar system, if only as a temporary experiment. The thing to do now is push farther out and explore. Any rock will do but Mars has more romance to it and, for better or worse, that's a requirement.
- bryanlarsen 5y agoIn terms of fuel requirements, Mars and the Moon are about the same distance away, since Mars can utilize aerobraking and the moon has to use fuel to slow down.
- tehsauce 5y ago^This 1000x Almost nobody appreciates how truly inhospitable mars is. human technology is hundreds of years at the least from being able to live there sustainably, if it’s possible at all.
- kitsunesoba 5y ago> mars is nothing more than a further, more annoying version of the Moon. I would say the opposite. Compared to the Moon, Mars has: - A day-night cycle more suited to humans that’s nearly identical to that of Earth (Moon colonies will need to be in polar areas to avoid long stretches of no sunlight) - A more temperate climate with less dramatic temperature swings - Gravity likely high enough for most processes and machines developed on Earth to work correctly - No sharp, statically charged regolith - An abundant, readily available source of Co2 for use in production of fuel, oxygen, and other materials The primary downside is longer transit time, but that can be overcome with smart planning and could be seen as a boon in the long run since it’s a forcing factor in developing self-sustainability — moon colonies will likely remain Earth-dependent for much longer than they need to simply due to how convenient it is to get things shipped from Earth.
- nine_k 5y agoAnother downside of Mars is its having relatively less sunlight. You'll need quite significantly more solar panels to harvest enough power. Even if Mars has enough uranium and thorium, it'll be quite a long time before mining and enriching it would be locally possible so as to power a nuclear reactor. Local production of solar panels looks a bit more feasible.
- kdbeall_ 5y ago> mars is nothing more than a further, more annoying version of the Moon. This is simply wrong. Mars has had the geological processes necessary for ore formation. Whereas the Moon largely lacked those processes. Furthermore, Mars is rich in volatiles. It is likely Mars has everything needed to sustain human civilization. The issue is developing the extraction technologies and proving mineral reserves on Mars.
- bdamm 5y agoWe must go to Mars, if only to convince people on Earth that there really is no second planet.
- tejohnso 5y agoHopefully people start to behave as though there is no second plant long before we go to Mars. Otherwise there will be nobody left to send there.
- stronglikedan 5y agoYup, just like we've been saying for 6,000 years!
- Valgrim 5y agoAs far as we know, humanity is the only example of the universe becoming aware of itself. As far as we know, there isn't / hasn't / won't be anybody else out there, ever. Until we know better, any other presumption must be rejected as wishful thinking. What we DO know is that the conditions that can support life (and consciousness) on Earth rely on an incredibly fragile balance, especially on cosmic timescales. Maybe there's no second planet like earth, but we have a lot to learn if we are to prevent the absolute extermination of consciousness in the universe, so we better get on with it, and fast. Sure we may debate on how we try to achieve this: should we get on the Moon, on Mars, in space habitats, make earth resistant to cosmic catastrophes, transfer our consciousness into computers or teach machines to become conscious in our place? But debating this is actually moot. Billions of people. Massive parallelism. We've been working on all those fronts now for decades, and there's progress. Right now, a company making cheap steel rockets is on it's way to crack cheap space travel. That's a pretty good step for all humanity, in my opinion.
- imglorp 5y agoIf you put the laser in orbit instead of on the ground, you (a) get more solar power to collect there, and (b) don't need to correct for atmospheric distortion and losses on the outgoing beam. And bonus (c) you can point a microwave beam at the ground for more Earth power when you're not using it to sling spacecraft.
- revicon 5y agoI haven't seen it mentioned in this thread, but a much easier place to colonize is the atmosphere of Venus. There's a band of altitude in Venus's atmosphere where it's equal pressure to earth and you'd be able to get out and walk around with a simple oxygen mask. Huge blimps could suspend colonies in this zone (think Bespin from Star Wars). Interesting stuff, more info: https://bigthink.com/hard-science/how-to-colonize-venus/ https://bigthink.com/hard-science/how-to-colonize-venus/
- nine_k 5y agoDepending on what you mean by "colonize". To place a permanent habitat that depends on all solids to be delivered from Earth, certainly. To build something that can grow and develop based on local materials, hardly, I'd say that the most interesting idea would be to grow single-celled organisms which would be able to proliferate in the Venusian atmosphere at these altitudes, completely airborne, and form large reflective clouds to help cool down the planet. Or maybe, help condensate the existing clouds and render the atmosphere transparent, again cooling down the planet.
- kdbeall_ 5y agoThis mission architecture is kinda cool It could fit in neatly with Starship
- nine_k 5y agoLet's not discuss our choice of nearby planets but the paper. It offers: - A light-powered inflatable jet engine with an impressive Isp of 3000 s. - A reusable acceleration block which is laser-powered relatively close to Earth, and then can return back to LEO and attach to another spacecraft. - A way to shoot missions to other destinations using the same tech. - An extreme aerobraking maneuver at Mars, because the acceleration block is not available for slowing down. - A colossal 100 MW laser array on Earth, and the perils of atmosphere compensation. I hope in the future such an array would rather belong to LEO and be solar-powered.
- westurner 5y agoAh, but what if stationary laser L_0 is itself propelled by laser-thermal propulsion laser L_infinity?