Are plants really that inefficient? They're basically solar-powered nanomachines that release oxygen from carbon. Wikipedia reports "an overall photosynthetic efficiency of 3 to 6% of total solar radiation".
It's also important to remember that plants evolved to reproduce and spread as effectively as possible, not to be as photosynthetically efficient as possible. Engineered machines, however, can be designed with energy efficiency as the main goal.
Apparently the first stage of photosynthesis effectively does convert sunlight to electricity and does that with 90% efficiency, which is far beyond what our technology can achieve.
The potential economic value for space exploration comes from satellites orbiting earth (communication, sensors), mining near earth asteroids for rare and expensive minerals and possibly even energy generations. Moon is possible destination because it could serve Earth.
From the point of financing the effort Mars is just a sink. First spend hundreds of billions to start it, then billions per year to maintain it.
People don't spend their wealth to permanently reduce their living standards and the change for survival of their children. Permanently breathing bottled air inside a housing in a desert planet, having reduced lifespan etc. is not fun. All the space exploration romantics goes away in few years and people lose the interest.
If you want to colonize Mars permanently, first create (de facto) post scarcity economy on the Earth. Before that' there is no change for permanent colonization. Research settlement in Mars is possible.
As the article describes, mining asteroids for rare and expensive minerals is more viable from Mars.
Earth is in an incredibly deep gravity well: it's remarkable that we made it out with just chemical rockets, an Earth just 1.5x larger in diameter would need a stack of something like 20 Saturn Vs to get one ton to LEO, instead of the 120 tons that a single rocket could do on Earth.
Mars is half the diameter of Earth. To lift fuel to an asteroid from Mars takes a rocket 1.7% the size of an equivalent rocket from Earth.
Asteroid miners will need fuel, water, food, metals, and other supplies that could be manufactured on Mars. It is many, many times cheaper to launch these from the surface of Mars than to do so from the surface of Earth.
You end up with a three-way triangle of trade between high-tech components like microchips and turbopumps from Earth, supplies from Mars, and precious metals aerobraking down into Earth's gravity well.
> Moon is possible destination because it could serve Earth.
I don't want to mirror previous stupid decisions on Earth of undervaluing potential colonies, but the Moon has very little it can offer Earth...the geology can't support the production of fuel, water, food, and metals like Mars is capable of.
AFAIK it makes even more sense to try and lift manufacturing out to LEO and beyond, rather than sending raw resources downwell. Earth has plenty of natural resources that aren't extracted because there's no need, but which would be still cheaper to tap into than having them sourced from space.
This is why it's fashionable now to talk about "cislunar economy". Instead of sending raw material planetside, you'd "reinvest" extracted metals and volatiles into supporting and expanding space-based capability, ultimately leading to a small and somewhat self-sustaining economy, which could then maybe trade with Earth, offering products that benefit from being manufactured in microgravity (optical fiber is one example of such product today). I imagine such space-based economy would end up being the primary trade partner for Mars, just by virtue of being upwell.
> I don't want to mirror previous stupid decisions on Earth of undervaluing potential colonies, but the Moon has very little it can offer Earth...the geology can't support the production of fuel, water, food, and metals like Mars is capable of.
Not like, but enough to matter, at least in term of fuel and raw resources. Food, well... we have to figure out how to grow it in space anyway, so this doesn't make Moon farm any less likely than an orbital farm. Point being, Moon is a pretty useful destination. It's close and has resources, which puts it in a position of being key element in expanding space-based manufacturing and operations.
Asteroids near earth provide wast quantities of water and there is cheap energy available (the Sun). Asteroids also have hydrocarbons. Asteroid mining would serve earth. Mining mars would not be competitive source of minerals for Earth.
Asteroid mining is easier to automatize. Move them even closer to earth and use partial automation and remote control.
The metals in asteroids are easier to mine because usually they have not been oxidized like they are on the Earth or in the Mars, nor are they buried deep in the ground. It's possible that there are just nodules to pick up.
Mars has low gravity, but the delta-v that determines the cost is still huge compared to asteroids. Delta-V to nearest asteroids from LEO is ~3.3. Delta-v from LEO to Mars is 9.3.
Access to Mars is also technically more challenging (Mars landers fail often. The few asteroid that have been done have been a success).
Move them with what fuel?
Also, the Martian missions have been far more ambitious than the asteroid missions.
Before people go they should live on a submarine for a couple years to see how they like it.
> Last week, a Nature paper (https://www.nature.com/articles/s41550-018-0529-6) was published by Jakosky and Edwards arguing that, based on data from more recent orbiters, the total near-surface reserves of CO2 are much too low to built up the atmosphere enough for terraforming. What a bummer!
He describes some of the back-and-forth dispute, but ultimately comes down pretty pessamistic on Mars terraforming.
And expansion and sustainance would be very capital intensive, due to a lack of a breathable atmosphere requiring heavy duty habitats and lack of vegetation/fauna that can be harvested.
As for costs, dropping them is precisely the goal SpaceX is based around. The BFR isn't just meant to enable transport of people - it also aims at being able to move a lot of mass to Mars for cheap.
To get to the point where a Mars colony is self-sufficient in producing things like heavy-duty construction equipment and solar panels could require obscene capital expenditures.
Not saying that it wouldn't be worth doing - imagine just all the technological spin-offs that would come from overcoming the challenges of creating a self-sustaining settlement on another planet, not to mention making an entire planet's worth of resources accessible to us - just that the scope of what it would require to pull off should be appreciated.
>>The BFR isn't just meant to enable transport of people - it also aims at being able to move a lot of mass to Mars for cheap.
I agree. The BFR will be a game-changer.
Also, solar panels I place in the list of high-tech components that would need to be imported. Curiously though, I recall reading that wind power could be used on Mars. A wind plant could be mostly fabricated from local material, with only electrical components sourced from Earth, and apparently wind power is competitive with solar on Mars - the atmosphere is less dense, but solar panels also provide less due to R^2 drop in power per unit of area with distance.
I agree it won't be easy - or cheap - but both the prospect of a colony and all the potential spin-offs make it worth it.
I suspect that the development will occur before the initial buildings. The political/social/economic risk environment just doesn't include the option of sending mavericks up to see if they can figure out something that works.
The rovers we have now and the rovers we are building/will build are pretty good at identifying what we have to work with, and it's comparatively easy to test a material process or construction technique on Earth before trying it while wearing a spacesuit.
At the very least, I expect we'll have a viable base of initial buildings and a fuel/oxidizer depot set up before the first astronauts arrive.
I agree about desert trials (or better yet, somewhere dry and cold near the pole). I'm not sure why this isn't done - whether it's just a money issue, or there's less benefit to be had from such test than we think?
I think NASA will do them but their dates for such a mission are decades away. Others who want to do this earlier are probably just not serious. With current tech this would be a suicide mission. Any little problem will kill the settlers.
This seems .. incredible. Do we have a different understanding nowadays? (The paper is 20 years old)
If EOS can raise $4 billion over a year-long token sale, we could surely raise a few billion for a Mars colony that could change the destiny of the human species.