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Mars Express gets festive: A winter wonderland on Mars
- pseudolus 8y agoThat's quite probably the most impressive picture of 2018. For a long time there was a belief that earth was singular in possessing an abundance of water and now spectroscopy has revealed the presence of water on other planets and fly-bys by probes show geysers erupting from the surfaces of moons. Science advances even if it's not always at the pace we would like.
- danbruc 8y agoHydrogen and oxygen are the most (~75%) and third most (~1%) abundanten elements in the universe and this has been known for quite some time, so it does not seem that unexpected that water is not especially rare. But maybe the formation of water from gases requires conditions that are at least somewhat rare in the universe.
- pseudolus 8y agoTrue enough, but if you are old enough to remember the 1960's and early 1970's the belief, at that time, in the presence of water on other bodies in our solar system was never a given.
- imglorp 8y agoWell, now we know where to land the first fleet of robotic air and fuel factories.
- curtis 8y agoGeoffrey Landis made a proposal for a polar landing site for the first manned mission to Mars back in the 90s. One of the clear advantages is that you don't need to bring hydrogen with you for the return trip, but instead you can just make it from the ice. Landis proposed the mission for northern hemisphere summer so that solar power would be constantly (or nearly constantly) available. One thing Landis didn't mention but is worth considering is that ice could be used for radiation shielding, either by tunneling into it or by melting it and reforming it into a surface structure. However, landing on the polar ice cap has some downsides, not least of which is it would be the most boring place on the whole planet to land. Korolev crater might make a good alternative site since you could conceivably land near a substantial amount of easily accessible water ice while still retaining easy access to terrain that is not ice-covered. [1] http://www.geoffreylandis.com/pole.html http://www.geoffreylandis.com/pole.html
- maxxxxx 8y ago" you can just make it from the ice" I always read this but do we really have the tech to this without needing big and heavy equipment and a lot of energy? Why don't we "just" do this on the South Pole?
- Sharlin 8y agoBecause there’s no pressing need for hydrogen and oxygen on the South Pole. On Mars we’d need both. A serious Mars mission would almost certainly include a small nuclear reactor for power.
- maxxxxx 8y agoYou also need to cool down and liquify the hydrogen. That doesn't seem simple.
- Sharlin 8y agoNot if you feed it to a Sabatier [1] reactor to produce methane, which is what most ISRU-based mission designs call for. A LH2 based return vehicle would indeed make things considerably trickier. [1] https://en.wikipedia.org/wiki/Sabatier_reaction https://en.wikipedia.org/wiki/Sabatier_reaction
- arijun 8y agoMost plans that use water to make fuel on Mars don't use liquid hydrogen at all. The two most well known plans are the BFR/SSH and Zubrin's Mars Direct, both of which use liquid methane. You still have to cool it, but not nearly as much, and it doesn't come with the other problems of hydrogen like embrittlement.
- trhway 8y agoMethane can also be used to make food https://www.newscientist.com/article/2112298-food-made-from-natural-gas-will-soon-feed-farm-animals-and-us/ https://www.newscientist.com/article/2112298-food-made-from-... Thus no need to grow potatoes :)
- sidcool 8y agoImages like this one give me goosebumps. It's another planet!
- starbeast 8y agoI got the shivers from this as well. It is not only absolutely fucking stunning in and of itself but considering what it took to be able to see this image, all of the people responsible are utterly magnificent bastards. Also I have had a thoroughly shit week, so I wish them extra thanks for gifting me a bit of optimism, which I sorely needed. Awe is an overused term, but here it genuinely applies.
- beart 8y agoFor anyone skipping the article - This is actually a composite image and not a single photo.
- jessriedel 8y agoIts not a composite photo either. It's a fully artificial visualization based on real topographical and composition data. EDIT: nope, I was wrong, it's actually based on a real satellite photo that was then stretched to give the illusion of a perspective from low altitude: https://www.esa.int/spaceinimages/Images/2018/12/Plan_view_of_Korolev_crater https://www.esa.int/spaceinimages/Images/2018/12/Plan_view_o...
- jonknee 8y ago> artificial visualization based on real topographical and composition data Yes, that's what they mean by a composite.
- jessriedel 8y ago"Composite photo" means "multiple photos combined together" not "artificial picture generated from information on chemical composition".
- jonknee 8y agoThey used topographic data and visual imaging to create the "composite" image, that's accurately described as a composite in my book. Similar to zooming around a city in Google Earth. Here's the top down view (still quite spectacular!): http://www.esa.int/spaceinimages/Images/2018/12/Plan_view_of_Korolev_crater http://www.esa.int/spaceinimages/Images/2018/12/Plan_view_of...
- seiferteric 8y agoTFA mentions that the air above it gets cold and sinks creating a cold air layer, presumably it is more dense. Any idea how dense this air would be?
- jstanley 8y agoI don't think it would be particularly dense, it's just denser than the other air on Mars. Mars's gravity is less than Earth's, so the air will probably be less dense than the air over the arctic. EDIT: According to https://en.wikipedia.org/wiki/Mars https://en.wikipedia.org/wiki/Mars , typical atmospheric pressure on the surface is about 0.6 kPa, compared to about 100 kPa on Earth. That's a bigger difference than would be explained by gravitational differences alone, so probably the fact that there is just much less atmosphere is more important. Either way, it's substantially less dense than any air you're likely to encounter on Earth.
- remcob 8y agoGravity on Venus is 0.9 that of Earth, but it's atmosphere on the surface is 90 times as dense. Surface gravity doesn't say much about atmospheric density (the mass of the atmosphere does).
- nabla9 8y agoOn earth you get atmospheric pressure 0.6 kPa around 35 km altitude. It's very low pressure.
- donpdonp 8y agoI'm a bit confused - werent the NASA landers looking at the Martian dirt for microscopic traces of evidence of water in the past? or perhaps digging for some sign of water? and the NSA probe just flys by and says hey look out the window, there's a entire lake of frozen water, sitting on the surface, that noone has ever observed before.
- Retra 8y agoI believe the landers were looking for historical traces of liquid water. Mars has a significant amount of frozen water around the poles, as has been known for a while, and this is just one example of some of it.
- rory096 8y agoWe've long known (since Mariner 9 spectroscopy in 1972) that Mars' polar ice caps consist of a combination of water and dry ices and grow & shrink each season through direct deposition of water vapor from the atmosphere (sublimating back into water vapor in the spring, with no liquid phase). Mars Phoenix (which landed in the upper northern hemisphere and dug for soil samples) was intended to figure out whether the ground environment near the ice cap was conducive to life. It found that the soil does contain water ice distributed throughout it, but also contains hostile perchlorates. More recently, satellite imagery has found evidence of liquid water, both in seasonal flows on mid-latitude slopes (as a briny mixture with low freezing temp), and in underground lakes beneath the south polar ice cap. tl;dr: This Korolev crater pic is a fun pretty-picture post offering an opportunity to educate readers with a seasonal twist. No new science here.
- borkt 8y agoTheyve been looking for water (liquid H2O). We have known about the caps well back, at least the 70s.
- jessriedel 8y agoThis image is digitally generated from topographical maps collected by satellite. There are no probes on Mars that are located in a place where they could actually take a picture like this. EDIT: My first sentence was wrong. As finnh points out, it's actually based on a real satellite photo that was then stretched to give the illusion of a perspective from low altitude.
- AtHeartEngineer 8y agoSnowboarding on Mars anyone?
- sempron64 8y agoIt's an interesting question whether this would work. A lot of the low-friction properties of snow are due to pressure-based melt. I wonder if skis or a snowboard would slide well in this crater, both due to the low gravity and extremely low temperature. Maybe with size adjustments to optimize surface area and pressure for an adult human weight it might work, but I have no idea where to even start this calculation.
- ddingus 8y agoThis is simple, but how many of you want to go there? Pictures like this make me want it. To stand somewhere on the ice, maybe brush a little snow around and see the rim all around... it's like a little island, delicate. We are living in fantastic times!