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Comment by gambiting | Hacker News Reader

Seriously, it would be a lot easier to build a colony on the bottom of the ocean or even on the moon - without the incredibly harsh penalty of many months of travel back and forth. There literally doesn't seem to be any benefit to living on Mars except for the romantic notions of it being another planet.

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Mankind undertakes numerous endeavours where the benefits might be non-existent or very indirect. I would argue that when it comes to colonising Mars, we're looking at the latter case.

First rather obvious thing is that building the colony requires a great deal of technological advancement, which in turn creates employment throughout society from research positions to supply chain vacancies. These advancements might also lead to commercial successes which in turn create even more employment and likely an increase in the quality of life.

Second it is a huge inspiration for a lot of people. The very idea that we can conquer space is something that makes me feel shivers. At the same time it is art, testament of the good parts of our species. That romantic notion might end up inspiring many young folk to take careers in fields that contribute to the betterment of mankind.

No I totally get that. My point is if we want to get to that lofty goal of space exploration and colonisation, then our own Moon really is the obvious choice. The supply chains, the technology, the achievement is no smaller than it would be on Mars. For some reason people threat it as almost "too easy" which is obviously completely nonsense. We should built and maintain a permanently inhibited base(colony?) on the Moon before venturing out all the way to Mars. Surely having a visible colony so close to us would be a huge uplifting achievement to all of mankind.

The bottom of the ocean is perhaps less glamorous, but it's no less technically challenging - the risks of having a permanent base on the bottom of the Mariana Trench would be huge, but we could try living there permanently, growing our own food, conduct research etc - it many ways it's more similar to space exploration than many people think.

You raise a good point. Start with the low hanging fruit before leaping to the apex. Walk before sprinting.

The Moon is very difficult as the long days result in extreme temperatures. Daytime temperatures can reach 253.4 degrees Fahrenheit (123° C). Covering a large area in a reflective surface can dramatically lower that, but the Apollo missions only worked because they stayed for a few days near lunar dawn.

There are ways around this, but the moon is a harsh mistress.

Make the first colony one thin, long pipe across the entire surface. The difference in temperature would provide a steady flow of air at the average temperature.

This is probably completely ridiculous for reasons obvious to someone who knows what they're talking about.

From a pure technology standpoint an under sea mining colony seems like a better first step. Like Mars internal combustion engines are useless and constant supplies of oxygen are required. Resource wise the ocean covers more land than the surface of Mars or the moon and it’s within shipping distance.

Ok, so... we've been doing all that for a hundred years, and the result is we turned our planet into an unlivable oven.

It requires some amazing mental gymnastics to call global warming the "result" of going to space. Exploring space has given us plenty of real word benefits, like communication links and weather satellites

Good.

And where are you supposed to go from the bottom of the ocean? From the Moon or Mars, access to the whole solar system is easier than from Earth's surface.

Again, as I said in my other comment - the bottom of the ocean is increadibly challenging in itself. The need to build habitats that could permanently withstand tonnes of pressure is not that far off from habitats needing to survive the harshness of space. We could learn how to build those, how to live in them, how to grow food and obviously conduct science. Those findings would be valuable outside of our planet too.

And importantly, when people say that they want to go to Mars in order to secure the future of our species - the bottom of the ocean is protected form nearly every natural or human made catastrophe imaginable. Even if the surface of the earth was vaporised in nuclear fire, 10km under the surface of water nothing would touch such a colony.

But of course, please don't misunderstand me - of course a Moon colony would be far more preferable.

It is more a necessity than "romantic".

Living on a single planet is a single point of failure for humanity. A nuclear war, an asteroid impact or a super vulcano eruption and we are done.

(Living in a single solar system is still dangerous, as a gamma ray burst directed at the solar system would still wipe us all out. Leaving the solar system is a lot further out than (trying to) colonize other locations in the solar system.)

And like I said in the other comment - colony at the bottom of the ocean would protect us from nearly anything, while simultaniously giving us opportunity to develop, test and perfect habitats for harsh environments. If it could become truly independent then that's your goal fully achieved and many technologies would transplant directly into space colonization. It's truly incredible what 10km of water can protect you from. The entire surface of Earth could be destroyed be it by nuclear war or an asteroid strike, and a colony on the bottom of the ocean would barely notice.

Both types of colonies could (and should) be pursued, but for self-sustaining colonies, the isolation that spaces colonies provide is an actual advantage. There's no incentive for self-sustainability with ocean colonies, because they can easily obtain what they need from the surface. Space colonies have clear incentives, because help would always be 6-12 months away (for Mars colonies).

A colony on the bottom of the ocean won't protect us from overpopulation or from exhausting the Earth's resources. On a long enough timescale, we'll have to stop the population from growing or find somewhere else to live.

I'm not sure the Moon would be that much easier than Mars. It's far enough that any transfer of anything needs a lot of planning. And no atmosphere. Mar's thin atmosphere means you can get some materials just by pumping air, which is a lot easier than mining.

Also no atmosphere = micrometeoroids striking directly the surface (and possibly you). On Mars the atmosphere takes care of burning up any meteoroids and Mars Climate Orbiters before they can hit you.

That’s a double-edged sword. Yes, Mars’s atmosphere can protect you from micrometeoroids, but it also makes it absolute hell to land anything there. The atmosphere is thick enough to burn up any spacecraft you try to land there but nowhere near thick enough to use a parachute. The moon, on the other hand, is much easier to land on using only retro rockets as brakes.

Sure, but you need to break all your speed at arrival with rocket engines. Not a big difference for regular trips from Earth - no need to make these more quickly than the regular few days.

But say you are coming back from Mars and want to land on a Moon base or even just dock to a lunar space station. Now you have to brake all the excess interplanetary speed with your engines! And that might be quite a lot, especially if you opted for going faster to reduce the transit time.

But if you are arriving with the same speed at Mars, you can use the atmosphere for aerocapture first without having to brake all that speed with engines. And people might do that for Moon bound trips as well - first do an aerocapture to an excetric Earth orbit using Earths atmosphere and only then adjust the resulting orbit for Moon encounter. That should reduce the raking requirements quite a lot.

For that reason I can imagine future interplanetary ships always having a degree of aerodynamic capability, so they can make use of the atmosphere to slow down when needed. Even if they are not really made to land on a body with atmosphere.

Aerocapture with the thin Martian atmosphere is much riskier than aerobraking [1]. Since you’re trying to bleed off all of your delta-v in one pass, your margin for error is much lower due to the high energies involved. Aerobraking is much less risky but way slower, taking months to decelerate and so much less feasible with human passengers.

For landing on earth you only need aerobraking and parachutes. For the moon all you need are the retro rockets (we’ve already done it). To send humans to Mars you need retro rockets, a heat shield, and a parachute. The combination of systems makes the whole procedure a lot more complicated and error prone, increasing risk.

[1] http://sicsa.egr.uh.edu/sites/sicsa/files/files/projects/dec...

Fair enough - and indeed, the Lunar delta-v needed is usually quite small. Apparently Chang'e 5 sample module needed just 1,67 km/s to reach lunar orbit for example.

Still, I think there are definitely cases where atmosphere helps (even if it causes issues elsewhere).

So even if you used propulsive breaking to get captured into orbit of a body with atmosphere for safety reasons, you can still capture into a very eccentric orbit & then carefully use aerobraking (as demonstrated many times at Mars already) to lower and circularize your orbit before landing. And with a bit better aerosurfaces you could even use the atmosphere to tune your orbits inclination as needed.

The Moon is indeed the best place to "learn the ropes" before setting out further out.

But it does not attract the same level of excitement as Mars does for some reason. We're already been there so it seems it's been ticked off the list...

I've always hoped that by the time I am old I can look up at the moon at night and see lights on it's surface.

The Moon is indeed the best place to "learn the ropes" before setting out further out.

It is not because there is less in-situ there. Dr Robert Zubrin makes this case in his books.

I believe that our understanding of lunar surface resources has changed significantly since those books. We now know there is more water than we ever suspected. We also have found what look like lava tubes that form natural ice traps. Being about a week from Earth also means we can iterate a lot faster and the 2 second delay makes remote controlled exploration a lot simpler.

At least one reason would be to win internet arguments with people that say the high price of housing is due to there being a finite amount of land on earth.

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