On the plus side (for plants), the Martian atmosphere is about 95% CO2. Even though the total pressure of the atmosphere is much less than our own, the partial pressure of CO2 is still about 20 times higher (erring a bit on the generous side).
On the other hand, Mars is about 1.5 times as far from the sun, so the intensity of sunlight is less than half, and temperatures are correspondingly colder. Then again, if we're going to support human colonists, we probably need a nuclear power source anyway. So let's assume we rig up bright lighting to grow our plants.
There's some uncertainty about the soil, but at least some studies suggest that it could support life. There's probably frozen water there, so we'll use the spare heat from our nuclear reactor to melt some.
Humans need approximately 30g of Oxygen per hour, which is roughly 1 mole. A fast-photosynthesising plant can produce 30 umol/m2/s. Running the numbers, you'd need 9 square metres of leaf area photosynthesising at that rate per person - assuming it could carry on 24 hours a day. To supply food, you'd need rather more, because not all of the carbon fixed goes into edible parts.
This is actually a lot more feasible than I initially thought. You'd probably want to send robots ahead to construct the base and plant the plants, though. And you still have the problem of life support for the journey, which would be several months.
The experiment was a closed biosphere life support system, 36m^2 involving two subjects for 30 days. The article mentions the moon and mars. As I understand it, this thing would be a sealed capsule that you bring with you. This forms part of the ongoing field of CLESS (controlled ecological life support systems). All the references I've seen point to the Russian Bios-3 project as being the first public example of this.
I am also interested to hear more about your ideas regarding the feasibility of martian agriculture :)
I guess you'd fill the capsule with 'locally sourced' air and soil, though, perhaps supplemented with some nutrients brought from earth.
A sealed chamber could be pumped up to around earth pressure, making it easier for the astronauts to go in - although with high CO2, they'd still need oxygen tanks. On the other hand, the pressure difference would require a much stronger capsule, so perhaps farmers in spacesuits is the way to go.
Although if you've got water (and there is water on the moon) and a nuclear powerplant generating loads of electricity, getting oxygen's not a problem.
It appears that you don't have much carbon, though (see 'Lunar regolith' on Wikipedia). So once you've got your oxygen generator set up, you may have to fly coal up there to burn for CO2. Once you're set up, though, you should be able to keep the carbon in a closed loop between humans, the encapsulated air and the plants.
If the plant material to support each person is drawing down 2 moles CO2 per hour (doubled from earlier calculations, because not all the carbon ends up in edible parts), then a tonne of carbon should supply the plants needed for 5 people for a year. By the end of the year, you've probably closed the loop, so the fixed carbon is returning to the air.
On the moon, you'd have to run pretty much ecological "closed system", perhaps with oxygen and water supplemented by industrial processes. However, rapid resupply is possible, and non-fatal mistakes correctable.
On mars you could get away with a lossier system (seems to me, easier access to outside air, water, nutrients), but resupply is so much harder...
I suspect you're right, but I think the biggest factor is simply getting the humans there in the first place. The journey to Mars would take much longer - meaning the ship has to carry much more food, and more capacity to produce heat and regenerate oxygen. Crews do stay a few months on the ISS, but they can be resupplied from Earth.
It's just ("just") a six-month trip. If you want to break things into smaller shipments, launch them directly to the Mars surface.
Even better, this means you can get a significant portion of your mission hardware (including your return vehicle) ready and waiting on the Martian surface, having survived what is probably the most dangerous part of the mission (landing) before your humans launch.
(Two year launch window gives you time to make sure everything is working, and also gives various in-situ fuel production methods a chance to run their course.)
The only real place besides the surface of either planet where you would want to "dock" with something is the orbit of either planet.
What I was thinking of was sending something out on a slower path, maybe back past Earth or something and then sending the main craft at a faster speed to meet somewhere along the way.
You are right it probably isn't needed, was more just wondering if it were possible or would the speed differences make docking too hard. I guess the slower moving craft would run through a lot of fuel to bring its speed up enough when close to docking.
If order to meet, they would need to match both position and velocity. Meaning whatever history they had gone through, they both had to get to that position-and-vector.
There are some faster and slower paths. More missions to Mars have taken an 8-month-or-so journey because it's easiest and lowest power, and all unmanned cargo are probably going to take that route.
But by using just a bit more energy, you can cut the travel time down to about 6 months.
Most Mars missions involve launching stuff to land on the Mars surface (or maybe in orbit) that would take the slower path while the humans take the faster path.
(If you really want a bigger craft than you can launch from Earth at one time, just link up in LEO.)
If you have a nuclear reactor or extensive solar panels, you may just as well use it to split CO2 into O2 and CO (monoxide gas can also burned as fuel). Plant photosynthesis is rather inefficient if your goal is a breathable atmosphere. If the goal is biomass for food, then just call up Monsanto for a few space-dense crops.
It would probably easier to oversize the powerplant (to generate oxygen, growlights, melt water, treat air and waste) than to try to bring along a whole biological ecosystem. On the first few trips at least...
The advantage with the powerplant approach is that you can live anywhere with rock and ice in the soil (most airless planetoids) or CO2 and water in the atmosphere (Venus, Mars or the gas giants).
I agree, but I think it's still interesting from the point of view of food. As it takes months to get there, and months to get back, you probably want astronauts to be staying there for at least a few months.
Resupply from Earth is slow and expensive - especially when Mars is at the far end of its orbit. And as far as I know, we can't synthesise food artificially. Even if we could make some simple sugars, that will hardly keep the astronauts healthy. So I think growing plants would start to look quite inviting.
But I think the bigger challenge is getting anyone there in the first place. They'd need life support for months. I suspect you'd have to assemble something about the size of the ISS in Earth orbit, then send it across to Mars, and deploy landers to reach the surface.
It may be useful as fuel for a mars vehicle or for rockets (electric vehicles will take you not very far and it's hard to strap the nuclear reactor to it). CO is easier to store than hydrogen. Of course, if you have a steady supply of ice you can make methane/methanol which is better for that purpose. But to extract ice you will need heavy mining machinery, earth-moving etc...
CO + O2 fuel would make more sense on Venus, where water would be more scarce (water is present in thin clouds of sulphuric acid in about 25% concentration). The surface, however, is another business.
Also I'm not sure how useful CO fuel would be if you had electrical power already. Maybe splitting CO2 into CO and O2 only to later recombine could make sense as power storage? Maybe if you are using solar power and regular batteries aren't feasible for some reason, or maybe in a vehicle?
There might be uses for burning CO on Mars, but not as the byproduct of CO2 splitting for breathable oxygen.
Mars is about 1.5 times as far from the sun, so the intensity of sunlight is less than half
Don't break out the nukes yet…
No cloud cover is going to push up the average insolation, plus a thinner atmosphere will absorb less. Dust will bring it back down some amount.
Temperature could be handled with insulation. Aerogel might be good here. A thin layer of glass sufficiently hard to survive the blowing dust and then a layer of aerogel to retain heat but still pass most of the light.
I think the light would be sufficient for plants, but I don't think insulation would be enough without a heat source. Now, you could lug loads of chemical fuel all the way from earth, or...
Hmm and RTG like the one Curiosity is using could be used to charge batteries at night and then run growlights during the day. Excess heat could be captured to keep the temperature up. There is a the radiation hazard of course.
A simpler solution is something like that setups that the aquaponics folks run. [1] Basically if you've got electricity (nuclear power) and water (from the soil/ice) you can build pressurized grow room to make food. It would be interesting for these guys to build such a system underground to get an idea of how much external electricity it needed to function.
> So let's assume we rig up bright lighting to grow our plants.
Sorry, but this is missing the point in as big a way as possible if you are using a nuclear plant. Even providing half intensity sunlight for large scale agricultural purposes is not feasible from an economic standpoint. Use the intensity of sunlight that's there. You just have to accept higher acreages and longer growing times. That would still enable civilization.
I wonder what types of plants would be most amenable to growing on Mars. The environment could be simulated in greenhouses (red houses ;) on Earth to cultivate successful plants (genetically-engineered or bred the old fashioned way).
I don't think any earth plant could survive 1% standard pressure. I have read papers on what genes would be interesting to splice here and there to make plants that could survive that, though.
It's odd that any mention of Elon Musk colonizing Mars results in rapturous worship.
Other efforts, China in particular, seem to attract scorn. Especially in light of the fact that Elon Musk's original plan was to send a greenhouse with plants to Mars.
Perhaps this has something to do with China's absolutely atrocious record regarding:
1) The environment
2) The rest of the world
3) Human rights
--
Is it really that difficult to understand that some of us have the foresight to realize that China's method of interfacing with its environment is not something that we want to see tarnishing a yet-untarnished planet?
1) The environmental burden is simply offshored from the West to China along with offshore manufacturing. The environmental impacts are also offshored since they suffer the majority of them. It's ludicrous for someone enjoying the fruit of globalization along with clean air and clean water to blame China for destroying the environment. No, you are the one destroying it since you are part of the globalization. You are the one allowing the multinationals to skew local environment laws by offshoring, in the guise of capitalism. You are the enabler of the environment problems.
2) What is China's absolutely atrocious record against the rest of the world?
Get over yourself. The US had a terrible environmental record until recently, and most conservatives want to see the EPA abolished; the US has been at least as expansionist as China internationally, if not more so; our human rights record is also atrocious. I don't mean just in historical terms, but in the ongoing travesty that is our prison-industrial complex.
This is not to excuse China's poor record by any means, but your sanctimony is unwarranted.
The human rights record of the USA is not reasonably comparable to that of China.
I basically agree that the USA shouldn't be on a high horse with China regarding environmentalism, since China is doing precisely what the USA did when it originally industrialized. That doesn't make China's environmental travesties OK, but it does rob them of some moral impact, at least from Americans.
I probably agree with the principle behind your comment, but:
* Those incarceration numbers come from the Chinese government and haven't been audited by any third party (a perennial complaint about Chinese prison statistics)
* They don't necessarily capture every form of detention present in China, including forced labor camps, administrative detention, house arrest, and pre-trial holding.
* Speaking of which, Chinese police can (according to HRW) send people to "Reeducation Through Labor" camps for up to three years without trial.
* Something like 650MM Chinese live in rural poverty in the countryside; China also has a concomitantly low crime rate for its population. Another way to say this is that there are effectively two Chinas in a way there aren't two Americas.
* Not all incarceration is intrinsically bad. For instance, a recent survey of Cook County found violent domestic assaults made up a huge component of all offenders. China has rampant, endemic violent domestic abuse issues. If China is incarcerating fewer people in part because it's doing a worse job of protecting helpless people, that's not a great thing either.
* And of course, China imprisons people for political speech; it imprisons defense attorneys (for "obstructing justice") even in nonpolitical cases; it executes more of its citizens and for a much larger diversity of crimes; its citizens have far fewer due process protections (they can be held effectively indefinitely prior to trial even after recent reforms, they have no right to refuse interrogation, etc); it forcibly sterilizes women in prison; it harvests the organs of prisoners.
We should indeed imprison fewer people and of course end the war on drugs (already, we're seeing sharp drops in the number of people incarcerated for simple possession of cannabis) and our for-profit prison administration is fraught.
But let's keep perspective. It is ultimately pointless to compare criminal justice between a country that has the rule of law (even when that law is unjust) and one that simply doesn't have that. A comparison between the US and China is, unfortunately for both countries, unhelpful.
We won't settle this here, although I'd like to offer lots of coutnerexamples. As I said earlier, it's not that I think China is so great as that I'm deeply disturbed by the flaws in the US criminal justice system. Maybe we should pick this up via email?
Funny, but I think the actual concerns are more along the lines of "What happens if it works?"
If they accidentally unleash an Earth origin extremophile, it would have the potential to taint any any life that may already exist on Mars. This hypothetical life on Mars probably isn't of any real use to us, obviously it isn't megafauna or something, but it would be of unspeakable scientific importance. The chance to study live from an independent instance of abiogenesis.. I just can't find the words to describe how important that would be.
We know all that. That's why we're being cautious about exploring it now; but we should be able to get a definitive answer on the presence or absence of Martian life within a decade or two. If there is life there, we'd be better off studying it iin situ than trying to transport it back and forth.
Present or not, we need to have some kind of strategy for how to survive there on a long term basic, either for a small-scale scientific mission or on a larger scale to terraform.
Besides, there are several other places in the solar system that have the potential to host life, such as Europa. I don't want we should spend so long sitting on our hands that another generation or more has to die without seeing the human race explore further. It irritates me that it's already 40 years since the last moon landing: http://xkcd.com/893/
Oh certainly, I feel the same way. We are definetly going to put humans on Mars eventually, and better sooner rather than later, but I think that it is something that needs to be done with an incredible amount of caution. There are definitely concerns about contamination that need to be considered carefully when planning such missions.
That is certainly a possibility. However contamination of Mars will make coming to that conclusion, if the evidence points to it, a great deal harder.
(Well, obviously contaminating Mars is itself panspermia, but not really of the interesting sort. A confirmed instance of "natural" panspermia would tell us a lot about what we can expect about the distribution of life throughout the universe.)
Is it really that difficult to understand that some of us have the foresight to realize that China's method of interfacing with its environment is not something that we want to see tarnishing a yet-untarnished planet?
What does it mean to "tarnish" a lifeless planet? Or even Earth for that matter? Every single kilogram of hazardous material on Earth was here long before humans evolved; all we're doing is moving around what occurs naturally. In the worst case, the same would be true of Mars.
I think the thing most likely to give America a swift kick in the back of their pants about their space program is hearing that China is going to do it first.
There's a whole lot to be skeptical about here, but even rumors can kick off a space race.
Perhaps NASA will get more funding for Mars missions as a result of this. Everybody wins long-term.
It's a shame that it takes a threat of one-upmanship to get people off their asses rather than doing it for the sake of scientific endeavour, but that's human nature.
I see mixed opinions whenever Elon Musk comes up. Perhaps your sample size of comments for both Elon Musk and China is insufficient. Indeed, when you posted your comment in this thread, there were less than 10 other comments.
It works like this: Grade school kids running around have puns pop into their heads, so by the time they get to high school, they're over the obvious ones. However this only works for their native language.
This is why translated puns can sound very stupid. It's also why you're likely to sound stupid when you try to pun in Chinese.
But the costs are also vastly larger, and the payoffs likely smaller.
And prestige? 1/3 of the Earth's land surface is covered by desert. If you could suddenly transform that from a life-hostile to a life-flourishing environment, you'd win as many Nobel Peace Prizes as they can possibly stamp out.
Transforming the desert into a life flourishing environment is really easy, you just have to add enough water. I believe that's how they do agriculture is large parts of Africa. It's of course quite expensive to do so if you can't get the water from, say, an aquifer. Sometimes you can even flood the whole area, if you want to
That's an interesting link, but it doesn't really discuss the ecological effects of such a project regarding human habitablity in surrounding areas. I'm more hopeful for something like the Green Wall of China[1], but aggressive enough to actually reclaim desert rather than merely halt its advance. It's also a plus if it works on a timescale of less than a century. :)
Though we should also note that turning desert into (ideally) arable land could have disastrous unforeseen effects; consider how much of the Amazon is fertilized by the Sahara.[2]
Transforming a desert into a life flourishing environment will also potentially affect rainfall patterns and climate in general all over the globe. Can't find the source right now, but fine dust from one particular desert provides large portion of condensation kernels in the world.
Far from. It takes nearly 2 years just to get to Mars.
Also, China tends to be a fast copier, not a leader. They seem to leave the bulk of development costs to someone else. So I think it's unlikely that they will front the resources it'll take to make a Mars mission possible.
What a huge generalisation. This appears to be true in the consumer electronics world perhaps, but look outside of that and it's harder to justify.
For example, China has been building a lot of infrastructure in the past few decades, including the longest and highest bridges in the world[0][1]. There was a story on HN a few days ago about a Chinese company's plans to build what will be the tallest building in only 90 days[2].
Granted there is a lot of press about these bridges falling down, and maybe their rocket will blow up half way to Mars. But you can't say that they aren't pushing things themselves.
I actually think that it's quite fair to criticize a "leading" achievement that falls apart or otherwise fails soon after.
For an achievement to "count", I'd make the bold claim that it has to actually work.
* However, I do agree that often to make progress you absolutely have to push your engineering "comfort zone" and try dangerous things, in order to learn from your mistakes. But this does not change my definition of "success", it just acknowledges realities of R&D.
Also, China tends to be a fast copier, not a leader.
You could have said the same thing about the US in the first half of the 19th century, and look how innovative we ended up being by the start of the 20th. Or about Japan later on. Societies that are able to copy innovations quickly seldom have trouble generating innovations when they run out of things to copy.
Wasn't there a famous Chinese guy who said something like "never underestimate your adversary".
In the past that might have been true, but things change. Just one example A lot of people have been educated in the US, and are going back to china to start companies.
That's true for gadgets and some other industries, engineering of some things that makes the world go on, like container ships and cars are another matter in which the West has long ceased to be the sole leader, even in design.
Aerospace and software are industries the West still dominates though. Since HN tends to focus on those this is a common impression for people here, it's not in some other industries.
I think the PRC do have technology and money to put things in outerspace in the near future, what they do not have yet is the know-how.
I hate to knee-jerk this one, but my first reaction to this is that it's probably propaganda. In the States a few years ago, there was an effort to create a self-contained ecosystem and it failed no matter how hard the engineers behind it tried. That China can suddenly say "Yo guys, we got it to work" out of the blue is suspicious at best.
Not to say they haven't got something half-functional. I'm just very skeptical that it's as great as they say it is.
Since soil samples on mars seem to be strongly oxidizing, even containing perchlorate, the vegetables are likely to catch fire upon touching martian soil.
Mix the soil with fine grained coal and water, and the oxidizing power disappear. The remaining coal can be used as a fertilizer. (I'm not sure if this is the more economical recipe.)
And growing vegetables on the moon is far too expensive to be practical - moon rocks cost thousands of dollars per gram!
EDIT: OK, for the benefit of whoever didn't have a sense of humor, I was suggesting that the astronauts might be planning on bringing some soil with them.
Yep. It gets kind of interesting though when you think about the challenges.
You could have a really good plan to convert martian soil for plant use, but then again, that might fail. This obviously means you can't depend on your garden. Also, what you would have would be a laboratory, not a garden. You would spend a lot more time analysing the food than eating it.
On the other hand, you could carry out a sample return mission, bring some mars dust back, run tests, and land with a solid plan. Only thing is, sample return from mars would make moon rocks look cheap.
Finally, bringing the soil with you would be the most reliable method. It's moon rocks in reverse though! That soil would be, kilo for kilo, the most expensive soil in the history of mankind.
Ship the conversion equipment and laboratory first, remotely operated and mostly autonomous. Send mice second. Send people only when you know your garden is working and producing edible (or good enough that it's an acceptable risk) food.
This might require slightly better AI than currently exists, and a lot of patience from telepresence operators, but it seems achievable in the near future.
I'm all for this, the current policy of "don't contaminate Mars with organic materials" brings us nowhere, let's put some life on there and see what happens!
I'd be a big fan of sending loads of bacteria with the potential to survive, and some water and stuff, to Mars. Just to see what happens. Hey, the Martian environment would be a "gross evolutionary pressure", right? :)
It's a worthwhile goal but the preparing is a poor choice of words because it sounds like it's happening next week. You prepare yourself for work in the morning. You prepare for going to the supermarket. You prepare to take a dump by making sure toilet paper is present. You prepare for a trip. You research growing plants on Mars for many years and eventually stage operations on the Moon. Finally, when the day comes, you prepare for the first mission to Mars.
But this cannot be of much use, even if they can make an atmosphere somehow, they would need an active core for magnetic field to protect from solar particles/radiation.
Their experiment was using a closed biosphere, so they're bringing the atmosphere with them.
Really, I think the original article was terrible; it omitted important details to make the whole thing sound more silly. Closed biological systems are an interesting field of research.
I'm not sure about radiation levels on a mars mission, but if we can solve the problem for humans, it should be solvable for plants/algae.
My impression was that Curiosity's sensors have shown that the presumed danger of Martian radiation has been greatly overestimated. Unfortunately, I can't remember the sources, but I've read it in multiple places.
The magnetic field on Earth is not what protects you from radiation. It's the thickness of the atmosphere. Lots of radiation is uncharged particles which don't care at all about a magnetic field.
There's a lot of thinking in the comments here which is good for what it is, but which lags far behind engineers and scientists who have thought about it for years.
These are very good news indeed. I started to wonder what good Elon Musk's colonists and tourists will do on Mars upon arrival. And it appears that they shall be able to buy some grocery! Isn't that wonderful?
"During the experiment, four kinds of edible vegetables, namely lettuce, leaf lettuce, gynura bicolor and sonchus oleraceus, were planted in a 36-square-meter area to absorb the carbon dioxide exhaled by the two astronauts and provide them with oxygen and 30-50 grams of fresh vegetables per meal per person."
Google tells me you need 1 ton of soil to cover 30m^2 to a depth of 25cm. So now I'm interested to know if/how they're optimising for mass efficiency.
I don't thing the GP was worried about the amount of sunlight needed to grow food, but rather pointing out that Icarus's downfall was flying too close to the sun.
On the plus side (for plants), the Martian atmosphere is about 95% CO2. Even though the total pressure of the atmosphere is much less than our own, the partial pressure of CO2 is still about 20 times higher (erring a bit on the generous side).
On the other hand, Mars is about 1.5 times as far from the sun, so the intensity of sunlight is less than half, and temperatures are correspondingly colder. Then again, if we're going to support human colonists, we probably need a nuclear power source anyway. So let's assume we rig up bright lighting to grow our plants.
There's some uncertainty about the soil, but at least some studies suggest that it could support life. There's probably frozen water there, so we'll use the spare heat from our nuclear reactor to melt some.
Humans need approximately 30g of Oxygen per hour, which is roughly 1 mole. A fast-photosynthesising plant can produce 30 umol/m2/s. Running the numbers, you'd need 9 square metres of leaf area photosynthesising at that rate per person - assuming it could carry on 24 hours a day. To supply food, you'd need rather more, because not all of the carbon fixed goes into edible parts.
This is actually a lot more feasible than I initially thought. You'd probably want to send robots ahead to construct the base and plant the plants, though. And you still have the problem of life support for the journey, which would be several months.