Design of a rapid transit to Mars mission using laser-thermal propulsion
arxiv.org
arxiv.org
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.
Mars could be terraformed (in theory); the Moon never could.
That's not quite true. The Moon definitely has polar ice but it also likely has more water than that [1][2]. Nitrogen seems only to be present in trace quantities [3].
> Mars could be terraformed (in theory); the Moon never could.
Yes and no (on both). People who make this claim often don't understand the magnitude of what they're claiming. Here's just one perspective: molecular velocities in the atmosphere are (of course) a Boltzmann distribution. As such a small percentage of those particles achieve escape velocity and fly off into space (called the Jeans escape energy) in exactly the same way that liquid water cools by evaporation. That amounts to around one million tonnes per year.
Mars has a lower gravity so the loss would be greater at Earth atmospheric pressure and that's just the loss you need to account for and gas that you need to manufacture or produce. Earth's atmosphere has a mass of ~5x10^18 kg. The scale of producing this just in terms of energy consumption is insanely massive.
So when you're talking about this level of energy expenditure it doesn't really matter all that much if you do it on the Moon or Mars.
But what's more, terraforming would necessarily be extremely violent. Do it too fast and you cook the planet. The likely way of getting what you need there is by impacting large bodies from space into the Moon. You probably don't want to live there while doing that. The timescales are likely to be in the thousands of years.
[1]: https://www.nasa.gov/press-release/nasa-s-sofia-discovers-wa...
[2]: https://www.planetary.org/articles/water-on-the-moon-guide
[3]: https://en.wikipedia.org/wiki/Geology_of_the_Moon#Elemental_...
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.
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.
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.
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.
Ultimately: what does Mars offer that you can't get on Earth or the Moon? Is it worth the extra trillions of dollars worth of expense and effort? Even if you're talking about surviving dinosaur-killing asteroid impacts the subterranian or subsea self contained colony offers many advantages over an offworld colony.
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.
That’s a long way down the road, though. Before that, we need to develop a huge amount of infrastructure in space, and doing that will be extremely expensive so long as we have to fight Earth’s gravity well to do so (even accounting for things like cheap reusable rockets).
Either the moon or mars could serve as the “stepping stone”, but I think Mars is better situated for that due to having a wider variety of raw resources available and being overall less harsh than the moon while also having a dramatically weaker gravity well and practically nonexistent (aerodynamically speaking) atmosphere that would allow launching of vastly larger and oddly shaped crafts into orbit. From there, it’s much more feasible to start looking into mining asteroids and building city-ships.
I agree that a Moon colony makes sense, but I think both will happen. What we must see is that our future will take parallel evolutionary paths and that will involve colonisation of planets too, whatever that means. Why not have a permanent settlement on Mars? We have people living in the harshest environments already. It will probably be a good exercise to learn our limits. Maybe we can't have healthy, viable offsprings on Mars and we will settle with cloud cities on Venus.
It's probably not the best idea to pick a winning scenario, let's try everything till we can.
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.
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.
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.
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.
> 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.
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?
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.
First of all, you can’t be positively certain of those. We don’t have access to the reasoning of why the Vikings decided to cross the Artic to America, or Polynesians crossing the Pacific.
Second of all, let’s say they did go to look for food. Are you sure they ran out of land to grow food, or forest for hunting that they had to look for new land? The answer is quite resounding no. Likewise, we don’t have to exhaust all of the resource on Earth before exploring other planets.
Finally, what were those mythological reasons you listed there, if not the desire of human being to explore?
The answer is an absolute and resounding yes, because that's exactly what hunter gatherers do - they move with the herds and where the food is. This isn't just an educated guess, we know this because there are still hunter tribes on Earth right now which do exactly this.
>>Finally, what were those mythological reasons you listed there, if not the desire of human being to explore?
We have historical records of entire tribes moving purely due to religious reasons, either believing that land somewhere else is sacred, or that the land they are on currently is condemned. If you think your deity lives over the horizon, then you get on your boat and go in that direction. Yes ultimately it's a desire to explore, but it's not just because it's "cool".
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.
Mars is just harsher than anywhere on earth. There's less of everything other than space and harmful radiation (and you sort of have to make the space that you want/need when you get there...)
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.
On that part we definitely both agree :)
Although, I would say that developing the tech to colonise Mars can be a useful rallying point for tech useful to Earth (if you can put a city of a million on the red planet, you can also put it in the middle of the Himalayas or Antarctica or the Sahara), in the same way that Tesla is useful as a rallying point for electric cars despite all the people I hear complaining about the build quality.
Plus where does your energy come from? You don't have solar. You need to make your own light to grow food. Geothermal is possible I guess but the ocean is terrible for corrosion and building. The high pressure at the bottom of the ocean makes everything worse.
For instance if people were starving or hiding from fallout, those doomsday shelters the rich are building for themselves would likely be overran by the locals who helped build them or heard all about them from town gossip.
And finally - I hope you aren't suggesting that the base on Mars is a way to escape "8 billion starving people".
Also I really don't like how the arguments so far are about preventing the starving people from coming over and messing things up. It strikes me as very "we need to keep the pleb out" kind of thinking, no different than what some rich people are doing.
Even if the entire surface is irradiated(somehow) you can still launch things into space with underground railguns. It's not what we currently use, but it's easier to imagine this than building a base on Mars with current(or near future) technology.
I would personally love such a habitat, and would market it as a Safe Space for The Curmudgeonly(TM).
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.
We flew to the Moon 50 years ago, logically there would have been human on Mars by now. That didn’t happen, so the next best time is as soon as possible. Like now.
As for limited resources, how much money do you think we spend for space exploration? We waste a lot more money and resource for other things. We should cut down those instead. Let’s take a trivial example. Do you think gaming is a waste of resource? Why don’t we cut down gaming?
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.
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.
To summarize, many of the problems are similar but at much greater scales. I mean, hell we actually put people on the moon. No human has set foot on Mars.
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.
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.
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.
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.
What would we need from Earth? What would be economical to ship from Earth?
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.
Humans can be surprisingly useful still, even if we are very costly to maintain. 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
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.
So if Earth gets a sunshield, it's no more difficult to grow one for Venus. Then eclipsing it and getting it to room temperature would only take a matter of weeks maybe? That would reduce the atmospheric pressure too. Seems like an orders of magnitude easier problem than waiting around for Mars to warm up and pressurize. Although on that note, we could build a giant reflector at the L2 point behind Mars to have room temperature immediately there too.
Looks like a solar sail can be as light as 0.00002 kg/m2, the Earth has a cross section of about 125 million km2, or 1.25e14 m2, so that's 2.5 billion kg or 2.5 million metric tons. Of course there's always a way to make a thinner sail, and we may not need to block all of the light, so I think a million metric tons is a reasonable estimate. Sounds like a lot, but a locomotive is 1000 metric tons, so 1000 train engines or 10,000 heavy launches to save Earth doesn't seem unreasonable. Also we probably only need 1% of that area to have a measurable effect on climate, and that way we wouldn't have to see the shadow either. So we're talking 10 train engines or 100 heavy launches.
IIRC one of the plans for an artificial magnetosphere for Mars only needed a 1 GW supply to the magnetic coil.
Doing a little more reading I came across the superconducting latitudinal "wrap the planet in a solenoid" thing, as well as magnets at L1 etc. I guess that's possible, but that's more of a 2000-years-out sort of set of ideas.
There's a philosophical debate to be had about how far out humans should be thinking when expending resources. If you build for tomorrow, you solve yesterday's problems. If you build for the next millenium, you solve nobody's problems.
Nah, if we really cared we could do either in like a decade or two depending on the Starship timeline.
> If you build for tomorrow, you solve yesterday's problems. If you build for the next millenium, you solve nobody's problems.
Essentially agree; this is why I don’t buy into longtermism: https://kitsunesoftware.wordpress.com/2020/01/08/morality-th...
Thanks for the link to the blog post, I enjoyed it.
See above.
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.
Interesting stuff, more info: https://bigthink.com/hard-science/how-to-colonize-venus/
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.
- 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.