The Air On Mars Has A Mysterious Glow. Here’s Why

With a rarified (or super thin) atmosphere looking at the stars from Mars must be incredible! But at night on Mars, there's also another source of light … the atmosphere of the Red Planet is literally glowing! Howdy glow worms, this is DNews, and I'm Trace. Nightglow is the tendency for the atmosphere of a planet to glow in complete absence of external light. This bizarre effect was spotted in mid-2016 by MAVEN. The Mars Atmosphere and Volatile EvolutioN mission was sent to orbit Mars to ascertain how Mars was stripped of its ancient atmosphere. But, while analyzing ultraviolet pictures scientists spotted this nightglow in the swirling high-altitude air of our rust-colored neighbor… Okay first, MAVEN has found that the sun's constant barrage of energy from it's nuclear reactions have slowly stripped the atmosphere of the planet to it's current level, 100 to 150 times thinner than our on Earth.

That same stripping of the atmosphere is causing the nightglow that MAVEN spotted! When ultraviolet light from the sun hits the "leading edge" of the planet the energy in the particles break down carbon dioxide, nitrogen and oxygen which are all floating around in the Martian sky. This is called photodissociation. The now-broken-up particles, are then carried on high altitude winds all around the planet. Once they reach the nightside of Mars (away from UV light), those free nitrogen and oxygen atoms interact — combining to form nitric oxide between 60 and 100 kilometers above the dusty surface [. When they do that, they release energy, causing this nightglow! It's basically the same idea used for glow-in-the-dark toys or glowsticks! Scientists are excited because it's very difficult to map the movement of the Martian atmosphere! Taking "pictures" of this glow can help scientists determine what's happening down there throughout the Mars year.

They can see how air moves in different Mars seasons, better understand the planet's cloud formations, and thanks to ozone formation, find water molecules. To be honest, nightglow is completely normal, and Mars isn't the only planet that has it… it's been seen on Venus, and a little planet you may have heard of, Eeeahhrth?! Just like on Mars, Earth's nightglow is caused by chemical reactions in the upper atmosphere, between 85 and 95 kilometers up. And just like on Mars this glow is very faint; NASA's Earth Observatory says the glow on our planet is about a billionth as bright as sunlight. So, it's very hard to see, but it's not invisible. A 2005 study in Astroparticle Physics found about 564 photons per meter squared, per second, over the Mediterranean Sea. And, if you were on the International Space Station looking sideways at the atmosphere you can see a faint glow… that's Earth's nightglow! We know a bit more about our own nightglow — for example, just like on Mars, the solar wind photo dissociates molecules in our upper atmosphere, and when they recombine they release energy as green, blue, yellow, and red light: oxygen glows green or blue, sodium yellowish, and hydroxls, or OH molecules glow red.

Science is beautiful, ain't it? Nightglow is just another byproduct of the sun's neverending assault on our atmosphere, and the atmosphere of other planets in our solar system. What a warm nuclear ball of awesome. Worried that the constant barrage of solar energy is actually going to steal our atmosphere? Can we run out of oxygen!? Check out this video with my girl Julia for more on that. And what is your favorite science topic? Space? Environment? Animals? Physics?! Tell us in the comments. Thanks for watching! Please subscribe so you get more DNews..

Sending Humans to Mars: How Will We Do it? | Nat Geo Live

Why are we so fascinated with Mars? There's this visceral connection that we have. It's been a constant steady light in the night sky for us. You and I can go outside tonight on a clear night, look towards the southwestern sky, and see a bright orange star, the Red Planet. (audience applauding) Looking at Mars, it's also of interest because it is within what we call the Habitable Zone around the sun. And so we're going to be exploring tonight a little bit more. I'd like to ask our guests here, our experts on a little bit about that. And let's get into the challenges and what it really takes to get to Mars. – Mars is incredibly difficult to get onto, because you have to go through the atmosphere.

And the atmosphere is not your friend, because it swells up because of dust. When there's a lot of dust in the atmosphere, it shrinks. There are lateral winds, although the atmosphere is thin. But it is a scientific bonanza once you're on the surface. It has ancient rivers and ancient lakes, hydrothermal systems. All the evidence is there, the geologic evidence. It's from the first half of geologic time. So early in geologic time, Mars was warm and wet, and the international exploration of Mars robotically is all focused on if it was habitable and whether or not life got started and evolved and is still there. – That's amazing. So let's look at some of the technology. Let's talk about this character here. He's making a lot of buzz in the media, right? Elon Musk, he's the head of SpaceX, and his true love and passion is space exploration. And his vision is to send humans to Mars. So NASA isn't really alone.

They have partnerships. Is that… – Right. – [Andrew] Really going to be integral now? – Yes, so NASA historically has partnered with people, has consulted and contracted with organizations all over the country. And so as we're looking into this next phase, this going to Mars, there are still going to have to be these partnerships. As you say, Elon Musk is one, but there are others that are going to help us do the important work of figuring out what, exactly, the best technology is. But it is definitely something that we're going to have to do together. – It's not an easy thing. – No. – Right, so take a look at this. – [Male] T-minus four minutes. – [Peter] We've reached a tipping point. Thousands of years from now, whatever we become, whoever we are, we'll look back at these next few decades as the moment in time that we are moving off this planet as a multi-planetary species. – [Male] BC and DC verify F9 and Dragon R at startup. – [Male 2] F9 is in startup. – And SpaceX stands as nothing less than a massive game changer.

– [Male 3] Stage One, Stage Two present for flight. – [Stephen] Elon Musk says the only reason that I founded this company is to get human beings to Mars. – [Male 4] LC, LD go for launch. – The key to making Mars economical is the reusability of rockets. – [Male5] T-minus one minute. – I just don't think there's any way to have a self-sustaining Mars space without reusability. Getting the cost down is really fundamental. If wooden sailing ships in the old days were not reusable, I don't think the United States would exist. – [Male 5] T-minus 30 seconds. – And if they nail this ability to land a rocket any way they want on Earth, then they can nail doing it on Mars. – [Male 5] T-minus 15. – This flight is a huge deal.

We haven't yet landed the rocket. So this is going to be hopefully our first successful landing. – [Male 5] T-minus 10, nine, eight, seven six, five, four, three, two, one, zero. We have liftoff of Falcon 9. (spectators cheering and applauding) (dramatic music) – [Male 6] Vehicle's reached maximum aerodynamic pressure. – [Male 7] Stage 1 propulsion is still nominal. Altitude 32 kilometers. Speed at one kilometer per second. Downrange distance 13 kilometers. (explosive sounds) (slow dramatic music) – [Casey] Space is defined by the strange relationship between failure, risk and innovation, which is you can take risks. You can try something very innovative. But you're more likely to fail. – So what was it supposed to look like? Well, you'd have the booster going up, and what I'm showing you here is going to be a composite, a long exposure photograph.

What it's supposed to have looked like, and then the booster coming back down. And what you see on your right hand side of the screen is the booster that came down back onto the launchpad. And what I want to know, Jedidah, is why is it so important to have reusability? I'm talking about Mars, going to Mars. Why is that so important? – Yeah, over the long term, the hope is that if you can reuse something, it's cheaper, right? You want it to be cheaper and more efficient. It's sort of your workhorse that you just continue to use. It's not always the case that things are cheaper when you reuse them, but you want something that you can use, rinse, recycle, reuse. That's rinse, repeat, that's what you want. The other thing is, you want to be able to use that piece of technology as scaffolding for the next thing you do.

Maybe you use a piece of your booster to build the first structure, right? Maybe you recycle it in that way. So you hope, first, that there's a cost savings. You hope that there's a sort of efficiency that you can build in. And third, that you can use it as a scaffolding for the next thing. – Let's look at the idea of the timeline. What is it, like seven months to get there, right? Just to get there. So we need to, right now, start building up on that, and one of the most recent attempts at that is the year-long mission that both the U.S. and the Russians took part in. U.S. astronaut Scott Kelly, you can see here in this image, spent a whole year, coming back in March, exploring this whole concept of what happens to human body being exposed to microgravity for long durations? So we're starting to work on those aspects. And I'd like to know, I mean, what toll does it take on the human body? What does space travel, long term space travel, do to a human body? – The truth is we don't really know, right? We've never done this before.

Commander Scott Kelly and his colleagues were sort of the first to stay in space as long as they did. And even there, they had a lot more protection from Earth, from the sort of microgravity. Also, we were still in the magnetosphere, so they had protection from radiation. Still, more radiation than they'd have if they were where we are, but we don't know what's going to happen when you put a person in sort of interstellar, interplanetary travel for seven months. We don't know. We know already that you lose bone mass. We know that you've got these radiation effects. We have no idea about the psychological impact. So these are all things that we're still trying to understand, and his mission, their mission is critical to understanding at least step one in the process. So there's a lot to be understood.

– When we get there, I'd like to know how are we going to choose the landing sites? Now, what I've got here for you is the map of Mars, and these are potential landing sites that we have. What goes in, Ray, maybe you can speak to this, about choosing… – Well, there are engineering aspects. There are science aspects. You want to go to a place that's scientifically interesting. Could be layer deposits that represent kind of ancient riverbeds or lakes. It could be ancient hydrothermal deposits from volcanoes, or whatever it turns out to be. But you also need to land in a place that you can get back out of. And that's the plus or minus 50. It's relatively easy to go back into orbit. And not too cold, because Mars is cold to begin with. It's way below freezing on average. And if you go to the high latitudes, it's super cold. – You know, the ultimate goal is to send humans.

So what I'd like to know is what do you guys think in terms of the specialties? What kind of people should we be sending to Mars? – It's an important point to recognize that going to Mars is going to be what they call sociotechnological. It is not just going to be the technical that takes us there. It's not just going to be the sociological or the psychological. It is going to be the interaction of those two things, the optimization of those two things, that makes it happen. So, yeah, you want people that have skills that are technical. You want them to be able to fix things and create experiments. Physicians, you need someone there in case you have medical emergencies. But you also want the kind of mental stamina to be able to deal with all of the conditions that you're going to be sort of faced with.

So as I look at it, I think about not just your skills in terms of what you've been educated to do, I think of a variety of perspectives, of life experiences, of outlooks on life, because all of those things are going to be necessary to make this work. So we need an inclusive environment and an inclusive set of people. – [Andrew] I guess growing food is going to be important, isn't it, Jedidah? – Yeah, so it's this idea of being able to reuse and create a sense of self-sufficiency, right? We cannot haul all the food we'll ever eat to Mars if we go, if we stay. All of these questions. You just can't bring it. You've got to create self-sufficiency and food security there. So the idea is that you'll want to figure out ways to grow things on Mars. And not just for food, which is going to be important, but again towards that social component. You'll want something to do that brings you closer to nature.

We've seen Mars is an arid place. There's not much happening there, as we can see so far. So you want some green. You'll want to get your hands in the dirt. You'll want to grow something, see it progress over time. So there's that mental sort of restorative piece of going and being out in nature, even on Mars. – I mean, that's interesting, but when we're talking about going to Mars, to me this looks like a candy wrapper. I don't know, but there's trash on Mars right now already. – Already. – Right? There's trash. I mean, we're already… – What can you do? I mean, it's probably a piece of the sky crane. – Right, but we're not living there. Humans aren't there yet. We're sending our stuff there. And then we're already altering Mars, right? There's already alterations of Mars, and there's talk about how humans will be altered by Mars as well.

There's a lot of talk about that. And I want you guys to check this little video out. This whole idea of altering Mars and stuff. It's really fascinating. – Terraforming Mars is not a small job. This is a massive project. This is a bigger project than anything humanity has ever attempted. – Terraforming is taking an environment such as Mars and making it more Earthlike. – Terraforming is like super science fictiony right now. I don't think people understand how big planets are, so terraforming one is a ludicrous task. – You solve all the problems except breathing. So once Mars is terraformed and made more Earthlike, you're still going to have to wear a helmet on your head of some sort or some kind of breathing apparatus. – Might we have the urge to tinker with our DNA, such that you don't need a spacesuit on Mars? – We are on the edge right now of being able to change our own genome and our own genetics in our own bodies in real time. – Our ability to control DNA, the programming language of life, helps us open up Mars.

What happens if there is a virus that drives some kind of a flu and knocks out a large population or large percentage of your group? You can actually sequence the virus, send it back to Earth to analyze, and you can send back from Earth an upgraded T-cell. – If you do interfere with our genome so that you can survive on Mars, you're pretty much going through a one-way door and saying, I will never go back to Earth. – We might very well have a future in which you have different kinds of humans that look very different from each other. – Once we get computers that are smarter than humans at thinking about stuff and coming up with stuff, we can ask them to figure out how to cure viruses. – We can kind of tell them, look, we want to explore, and this is what we'd like to do. And then the robots, either the rovers or the helicopters or the balloons can make their own judgement and actually do the exploration. – So ultimately we're going to need things like machines that can make machines if we want to have a solar system civilization.

– Well, future technologies that we're developing on Earth now, like 3D printing and electric cars, can actually be extremely useful to us in creating an outpost of civilization on Mars. – Imagine being able to send a 3D printer to the Martian surface that sort of pulls the soil out, adds some water, adds some binder, and is sitting there 3D printing shelters in advance of a community coming. And you've got your homes pre-built waiting for you right there. – So Jedidah, this is all nice, but what happens if we find life on Mars? Will our plans be altered? – I think they should be, right? Because now we've got to understand and figure out what's happening, try not to completely decimate their way of being and life in terms of, probably, microbial structures and such. Also just small tidbit, no terraforming.

– No terraforming. Interesting. Why is that? – It's a stupid idea. – Okay. Why? – It's out of equilibrium. I mean, Mars is cold and dry today for a reason. Early in geologic time, there were volcanoes. There was a massive amount of greenhouse warming from the gases coming up. Because it's small a planet relative to Earth, it stopped its internal activity sooner than the Earth. So the gases in the atmosphere were on a one-way trip to be oxidized and placed into minerals. So if you increase the amount of sunlight with mirrors, or whatever, you can sublimate, get more water vapor in the atmosphere, more rain. But what's going to happen? It's going to react with the rocks and go back down into the subsurface eventually.

There's a famous reaction that was codified by Harold Urey. He's a very distinguished Nobel Prize winning chemist. And it's the way the Earth stays more or less the way we like it. Sometimes it goes into deep freeze. Sometimes it's really warm. But what happens is, is the volcanoes pump up the gases that keep us warm. But the hydrologic cycle consumes those gases, as carbonic acids, CO2 goes into the water, and it reacts and forms limestones. But the limestones go back downstairs, get decomposed, and the gases come back up as greenhouse gases through volcanoes. If you stop the internal engine, you go in the one-way deep freeze. It's what happened to Mars, because it's smaller than the Earth. So terraforming can increase the temperature of the surface, but you can get some gas out. But it will eventually get corroded and put back down into the subsurface in a one-way trip. So it may work for a couple decades, but over longer time, it's bogus, in my opinion. – And also would decimate whatever is there that we don't know yet.

– Yeah, there's a very important paradigm that all the nations are following called Planetary Protection. So you sterilize spacecraft before they're on the surface, because the worst thing to have happen is to go to Mars in the future and find ourselves. – All right, I have a question. One last question. If you could take anything from Earth, any physical object on Earth, what would it be, and you take it to Mars. Wouldn't you want to take something to Mars? What would one thing be? – I'm going on my 47th wedding anniversary, and I really like my wife, so she would go with me. (audience applauding) – Nice. You get points. You get points for that. – That's videotaped. – Is this being taped? – Yes it is. (audience laughing).

The Earth: Crash Course Astronomy

The Earth is a planet. That’s a profound statement, and one that’s not really all that obvious. For thousands of years, planets were just bright lights in the sky, one-dimensional points that wandered among the fixed stars. How could the Earth be one of them? With the invention of the telescope those dots became worlds, and with spacecraft they became places. The Earth went from being our unique home in the Universe to one of many such…well, planets. The Earth is the largest of the terrestrial planets, the four smaller, denser, rocky worlds orbiting close in to the Sun. It’s about 13,000 kilometers across, and has a single, large Moon which we’ll learn a lot more about next week. Unlike the other three terrestrial planets, Earth has something very important: Water. Or, more specifically, liquid water on its surface, where it can flow around, evaporate, become clouds, rain down, and then mix up chemicals so they can do interesting, complex things—like support life.

Earth’s ability to sustain life depends on that water. It also depends on Earth’s atmosphere, of course—breathing has its advantages—and both, weirdly enough, depend on Earth’s magnetic field to exist. And that, in turn, depends on what’s going on deep inside our planet. So, let’s take a look. Like the Sun, the Earth is a many-layered thing. At its very center is the core, which actually has two layers, the inner core and the outer core. The inner core is solid, and made mostly of iron and nickel. These are heavy elements, and sank to the center of the planet when it was forming, leaving lighter elements like oxygen, silicon, and nitrogen to rise to the surface. The solid inner core is about 1200 kilometers in radius, or about 10% the radius of the Earth. The outer core is also mostly iron and nickel, but it’s liquid. The material in it can flow. It’s about 2200 kilometers thick. The temperature in the Earth’s core is tremendously high, reaching 5500° C. The pressure is huge as well, as you might expect with the weight of an entire planet sitting on top of it. You might think at such a high temperature, iron would be a liquid, but iron can stay solid if the pressure is high enough.

In the inner core, the pressure is extremely high, and even though it’s hot, iron is solid. In the outer core, where it’s still hot, but the pressure is a little bit lower, iron is a liquid. Above the core is the mantle.It’s about 2900 kilometers thick. The consistency of the mantle is weird; most people think it’s like lava, but really it’s like very thick hot plastic. It behaves more or less like a solid, but over long periods of time, geologic periods of time, it can flow. We’ll get back to that in a sec. On top of the mantle is the crust, a solid layer of rock. The overall density of the rock in the crust is less than in the mantle, so in a sense it floats on the mantle. There are two types of crust on Earth: Oceanic crust, which is about 5 kilometers thick, and continental crust, which is a much beefier 30-50 kilometers thick. Still, the crust is very thin compared to the other layers. The crust isn’t a solid piece, though; it’s broken up into huge plates, and these can move.

What drives the movement of these plates is the flow of the rock in the mantle, and that, in turn, is powered by heat. The core of the Earth heats the bottom of the mantle. This causes convection; the warmer material rises. It’s not exactly a speed demon, though: The rate of flow is only a couple of centimeters per year, so it takes about 50 or 60 thousand years for a blob to move a single kilometer. The hot material rises toward the surface, but it’s blocked by the crust. The magmatic rock pushes on the plates, causing them to slide around very slowly. Your fingernails grow at about the same rate the continents move. Over millions of years, though, this adds up, changing the surface geography of the Earth—where you see continents now is not at all where they were millions of years ago. In some places, generally where the plates come together, the crust is weaker.

Magma can push its way through, erupting onto the surface, forming volcanoes. Other volcanoes, like Hawaii or the Canary Islands, are thought to be from a plume of hotter material punching its way right through the middle of a continental plate. As the plate moves, the hot spot forms a linear chain of volcanoes over millions of years. Volcanoes create new land as material wells out, but they also pump gas out of the Earth too. A large part of Earth’s atmosphere was supplied from volcanoes! The interior of the Earth is hot; in the core, it’s about as hot as the surface of the Sun! Where did that heat come from? Most of it is leftover from the Earth’s formation, more than 4.5 billion years ago. As rock and other junk accumulated to form the proto-Earth, their collisions heated them up. As the Earth grew that heat built up, and it’s still toasty inside even today. Also, as the Earth formed and gained mass it began to contract under its own gravity, and this squeezing added heat to the material. Another source is elements like uranium deep inside the Earth, which add heat as the atoms radioactively decay.

And a fourth source of heat is from dense material like iron and nickel sinking to the center of the Earth, which warms things up due to friction. All of these things add up to a lot of heat, which is why, after all these billions of years, the Earth still has a fiery heart. The outer core of the Earth is liquid metal, which conducts electricity. The liquid convects, and this motion generates magnetic fields, similar to the way plasma in the Sun generates magnetic fields. The Earth’s rotation helps organize this motion into huge cylindrical rolls that align with the Earth’s axis. The overall effect generates a magnetic field similar to a bar magnet, with a magnetic north pole and south pole, which lie close to the physical spin axis poles of the Earth. The loops of magnetism surround the Earth, and play a very important role: They deflect most of the charged particles from the solar wind, and they trap some, too. Without the geomagnetic field, that solar wind would hit the Earth’s atmosphere directly.

Over billions of years, that would erode the Earth’s air away, like a sand blaster stripping paint off a wall. Mars, for example, doesn’t have a strong magnetic field, and we think that’s why its atmosphere is mostly gone today. But we do have an atmosphere, and it’s more than just air blowing around. Earth’s atmosphere is the layer of gas above the crust. Because it’s not solid, it doesn’t just stop, it just sort of fades away with height. By accepted definition—and by that I mean it’s not really science, it’s more of a “Eh, let’s just do it this way” kind of thing—the line between Earth’s atmosphere and space is set at 100 kilometers up. This is what’s called the Kármán line, and if you get above it, congratulations! You’re an astronaut. The atmosphere is, by volume, about 78% nitrogen, 21% oxygen, 1% argon of all things, and then an assortment of trace gases. There’s water vapor, too, almost all of it below a height of about 8-15 kilometers. This part of the atmosphere is warmest at the bottom, which means we get convection in the air, creating currents of rising air, which carry water with them, forming clouds, which in turn is why we have weather. At a height of about 25 kilometers on average is a layer of ozone, a molecule of oxygen that’s good at absorbing solar ultraviolet light.

That kind of light can break apart biological molecules, so the ozone layer is critical for our protection. Incidentally, the Earth’s magnetic field does more than trap solar wind particles; it also channels some of them down into the atmosphere, where they slam into air molecules about 150 kilometers up. This energizes the molecules, which respond by emitting light in different colors: Nitrogen glows red and blue, oxygen red and green. We call this glow the aurora, and it happens near the geomagnetic poles—far north and south. The lights can form amazing ribbons and sheets, depending on the shape of the magnetic field. I’ve never seen an aurora. Some day. You may not be aware of the atmosphere unless the wind is blowing, but it’s there. It exerts a pressure on the surface of the Earth of about a kilogram per square centimeter, or nearly ten tons per cubic meter! There’s roughly ton of air pushing down on you right now! You don’t feel it because it’s actually pushing in all directions—down, to the sides, even up—and our bodies have an internal pressure that balances that out. The Earth also has liquid water on its surface, unique among the planets.

The continental crust is higher than oceanic crust, so water flows down to fill those huge basins. The Earth’s surface is about 70% covered in water. Most likely, some of this water formed when the Earth itself formed, and some may have come from comet and asteroid impacts billions of years ago. The exact proportion of locally sourced versus extraterrestrial water is still a topic of argument among scientists. Earlier, I mentioned trace molecules of gas in the atmosphere. One of these is carbon dioxide, which only constitutes about 0.04% of the lower atmosphere. But it’s critical. Sunlight heats the ground, which emits infrared light. If this infrared light were allowed to radiate into space, the Earth would cool. But carbon dioxide traps that kind of light, and the Earth doesn’t cool as efficiently.

This so-called greenhouse effect warms the Earth. Without it, the average temperature on Earth would be below the freezing point of water! We’d be an iceball. This is why climate scientists are concerned about carbon dioxide. A little is a good thing, but too much can be very dangerous. Since the Industrial Revolution, we’ve added a lot of the gas to our atmosphere, trapping more heat. By every measure available, the heat content of the Earth is increasing, upsetting the balance. It’s melting glaciers in Antarctica and Greenland, as well as sea ice at the north pole. Sea levels are going up, and some of the extra CO2 in the air is absorbed by the oceans, acidifiying them. There’s an old concept in science fiction called terraforming: Going to uninhabitable alien planet and engineering it to be more Earthlike. I don’t know what the opposite process would be called, but it’s what we’re doing to Earth right now.

The Earth is the only habitable planet in the solar system. And you know what? We should keep it that way. Today you learned that the Earth is a planet, with a hot core, a thick layer of molten rock called the mantle, and a thin crust. The outer core generates a strong magnetic field, which protects the Earth’s atmosphere from the onslaught of the solar wind. Motion in the mantle creates volcanoes, and the surface is mostly covered in water. The Earth’s atmosphere is mostly nitrogen, and it’s getting warmer due to human influence.