Venus: Death of a Planet

From the fires of a sun’s birth, twin planets emerged. Venus and Earth. Two roads diverged in our young solar system. Nature draped one world in the greens and blues of life. While enveloping the other in acid clouds, high heat, and volcanic flows. Why did Venus take such a disastrous turn? And what light can Earth’s sister planet shed on the search for other worlds like our own? For as long as we have gazed upon the stars, they have offered few signs that somewhere out there are worlds as rich and diverse as our own. Recently, though, astronomers have found ways to see into the bright lights of nearby stars. They’ve been discovering planets at a rapid clip, using orbiting observatories like NASA’s Kepler space telescope, and an array of ground-based instruments. The count is almost a thousand and rising. These alien worlds run the gamut, from great gas giants many times the size of our Jupiter, to rocky, charred remnants that burned when their parent star exploded. Some have wild elliptical orbits, swinging far out into space, then diving into scorching stellar winds.

Still others orbit so close to their parent stars that their surfaces are likely bathed in molten rock. Amid these hostile realms, a few bear tantalizing hints of water or ice, ingredients needed to nurture life as we know it. The race to find other Earths has raised anew the ancient question, whether, out in the folds of our galaxy, planets like our own are abundant, and life commonplace? Or whether Earth is a rare Garden of Eden in a barren universe? With so little direct evidence of these other worlds to go on, we have only the stories of planets within our own solar system to gauge the chances of finding another Earth. Consider, for example, a world that has long had the look and feel of a life-bearing planet. Except for the moon, there’s no brighter light in our night skies than the planet Venus, known as both the morning and the evening star. The ancient Romans named it for their goddess of beauty and love. In time, the master painters transformed this classical symbol into an erotic figure, then a courtesan.

It was a scientist, Galileo Galilei, who demystified planet Venus, charting its phases as it moved around the sun, drawing it into the ranks of the other planets. With a similar size and weight, Venus became known as Earth’s sister planet. But how Earth-like is it? The Russian scientist Mikkhail Lomonosov caught a tantalizing hint in 1761. As Venus passed in front of the Sun, he witnessed a hair thin luminescence on its edge. Venus, he found, has an atmosphere. Later observations revealed a thick layer of clouds. Astronomers imagined they were made of water vapor, like those on Earth. Did they obscure stormy, wet conditions below? And did anyone, or anything, live there? The answer came aboard an unlikely messenger, an asteroid that crashed into Earth.

That is, according to the classic sci-fi adventure, “The First Spaceship on Venus.“ A mysterious computer disk is found among the rubble. With anticipation rising on Earth, an international crew sets off to find out who sent it, and why. What they find is a treacherous, toxic world. No wonder the Venusians want to switch planets. It was now time to get serious about exploring our sister planet. NASA sent Mariner 2 to Venus in 1962, in the first-ever close planetary encounter. Its instruments showed that Venus is nothing at all like Earth. Rather, it’s extremely hot, with an atmosphere made up mostly of carbon dioxide. The data showed that Venus rotates very slowly, only once every 243 Earth days, and it goes in the opposite direction. American and Soviet scientists found out just how strange Venus is when they sent a series of landers down to take direct readings. Surface temperatures are almost 900 degrees Fahrenheit, hot enough to melt lead, with the air pressure 90 times higher than at sea level on Earth.

The air is so thick that it’s not a gas, but a “supercritical fluid.” Liquid CO2. On our planet, the only naturally occurring source is in the high-temperature, high-pressure environments of undersea volcanoes. The Soviet Venera landers sent back pictures showing that Venus is a vast garden of rock, with no water in sight. In fact, if you were to smooth out the surface of Venus, all the water in the atmosphere would be just 3 centimeters deep. Compare that to Earth, where the oceans would form a layer 3 kilometers deep. If you could land on Venus, you’d be treated to tranquil vistas and sunset skies, painted in orange hues. The winds are light, only a few miles per hour, but the air is so thick that a breeze would knock you over. Look up and you’d see fast-moving clouds, streaking around the planet at 300 kilometers per hour. These clouds form a dense high-altitude layer, from 45 to 66 kilometers above the surface. The clouds are so dense and reflective that Venus absorbs much less solar energy than Earth, even though it’s 30% closer to the Sun. These clouds curve around into a pair of immense planetary hurricanes as the air spirals down into the cooler polar regions.

Along the equator, they rise in powerful storms, unleashing bolts of lightning. Just like earth, these storms produce rain, only it’s acid rain that evaporates before it hits the ground. At higher elevations, a fine mist forms, not of water but of the rare metal tellurium, and iron pyrites, known as fool’s gold. It can form a metallic frost, like snowflakes in hell. Scientists have identified around 1700 major volcanic centers on Venus ranging from lava domes, and strange features called arachnoids or coronae, to giant volcanic summits. The planet is peppered with volcanoes, perhaps in the millions, distributed randomly on its surface. Venus is run through with huge cuts thousands of kilometers long that may well be lava channels. Our sister planet is a volcanic paradise, in a solar system shaped by volcanism. The largest mountain on Earth, Hawaii’s Mauna Kea volcano, measures 32,000 feet from sea floor to summit.

Rising almost three times higher is the mother of all volcanoes: Olympus Mons on Mars. Jupiter’s moon Io, is bleeding lava. It’s produced deep underground by the friction of rock on rock, caused by the gravitational pull of its mother planet. Then there’s Neptune’s moon Triton, with crystals of nitrogen ice shooting some 10 kilometers above the surface. Saturn’s moon Titan, with frozen liquid methane and ammonia oozing into lakes and swamps. On our planet, volcanoes commonly form at the margins of continents and oceans. Here, the vast slabs of rock that underlie the oceans push beneath those that bear the continents. Deep underground, magma mixes with water, and the rising pressure forces it up in explosive eruptions. On Venus, the scene is very different. In the high-density atmosphere, volcanoes are more likely to ooze and splatter, sending rivers of lava flowing down onto the lowlands. They resemble volcanoes that form at hot spots like the Hawaiian islands.

There, plumes of magma rise up from deep within the earth, releasing the pressure in a stream of eruptions. To see a typical large volcano on Venus, go to Sappas Mons, at 400 kilometers across and 1.5 kilometers high. The mountain was likely built through eruptions at its summit. But as magma reached up from below, it began to drain out through subsurface tubes or cracks that formed a web of channels leading onto the surrounding terrain. Is Venus, like Earth, still volcanically active? Finding the answer is a major goal of the Venus Express mission, launched in 2005 by the European Space Agency. Armed with a new generation of high-tech sensors, it peered through the clouds. Recording the infrared light given off by several large mountains, it found that the summits are brighter than the surrounding basins. That’s probably because they had not been subject to as much weathering in this corrosive environment.

This means that they would have erupted sometime within the last few hundred thousand years. If these volcanoes are active now, it’s because they are part of a deeper process that shapes our planet as well. On Earth, the release of heat from radioactive decay deep in its mantle is what drives the motion of oceanic and continental plates. It’s dependent on erosion and other processes associated with water. With no water on Venus, the planet’s internal heat builds to extreme levels, then escapes in outbreaks of volcanism that may be global in scope. This may explain why fewer than a thousand impact craters have been found on Venus. Anything older than about 500 million years has literally been paved over. So why did Venus diverge so radically from Earth when it was born in same solar system and under similar circumstances? There is growing evidence, still circumstantial, that Venus may in fact have had a wetter, more Earth-like past.

One of the most startling findings of the early Venus missions was the presence of deuterium, a form of hydrogen, in Venus’ upper atmosphere. It forms when ultraviolet sunlight breaks apart water molecules. Additional evidence recently came to light. Venus Express trained its infrared sensors on the planet’s night side, to look at how the terrain emits the energy captured in the heat of the day. This picture is a composite of over a thousand individual images of Venus’ southern hemisphere. Higher elevation areas, shown in blue, emit less heat than the surrounding basins. That supports a hypothesis that these areas are made not of lava, but of granite. On Earth, granite forms in volcanoes when magma mixes with water. If there’s granite on Venus, then there may well have been water. If Earth and Venus emerged together as twin blue marbles, then at some point, the two worlds parted company.

Earth developed ways to moderate its climate, in part by removing carbon dioxide, a greenhouse gas, from its atmos phere. Plants, for one, absorb CO2 and release oxygen in photosynthesis. One square kilometer of tropical jungle, for example, can take in several hundred tons of co2 in just a year. That’s nothing compared to the oceans. In a year’s time, according to one recent study, just one square kilometer of ocean can absorb 41 million tons of CO2. Earth takes in its own share of CO2. When rainfall interacts with rocks, a chemical reaction known as “weathering” converts atmospheric CO2 to carbonate compounds. Runoff from the land washes it into rivers and the seas, where they settle into ocean sediments. With little water and no oceans, Venus has no good way to remove CO2 from its atmosphere. Instead, with volcanic eruptions adding more and more CO2 to the atmosphere, it has trapped more and more of the sun’s heat in a runaway greenhouse effect. Venus is so hot that liquid water simply cannot survive on the surface. Nor, it seems, can it last in the upper atmosphere.

The culprit is the Sun. The outer reaches of its atmosphere, the corona, is made up of plasma heated to over a million degrees Celsius. From this region, the sun sends a steady stream of charged particles racing out into the solar system. The solar wind reaches its peak in the wake of great looping eruptions on the surface of the Sun, called coronal mass ejections. The blast wave sweeps by Venus, then heads out toward Earth. Our planet is fortified against the solar blast. Plumes of hot magma rise and fall in Earth’s core as it spins, generating a magnetic field that extends far out into space. It acts as a shield, deflecting the solar wind and causing it to flow past. It’s this protective bubble that Venus lacks. Venus Express found that these solar winds are steadily stripping off lighter molecules of hydrogen and oxygen.

They escape the planet on the night side, then ride solar breezes on out into space. All this may be due to Venus’ size, 80% that of Earth. This prevents the formation of a solid iron core, and with it the rising and falling plumes that generate a strong magnetic field. There may be another reason too, according to a theory about the planet’s early years. A young planet Venus encountered one or more planet-sized objects, in violent collisions. The force of these impacts slowed its rotation to a crawl, and reversed it, reducing the chances that a magnetic field could take hold. This theory may have a surprising bearing on Earth’s own history. Scientists believe the sun was not always as hot as it is. In fact, going back several billion years, it was cool enough that Earth should have been frozen over. Because it was not, this is known as the faint young sun paradox. Earth’s salvation may well be linked to Venus’ fate.

The idea is that the Earth occupied an orbit closer to the Sun, allowing it to capture more heat. The gravity of two smaller planets with unstable orbits would have gradually pushed it out to its present orbit. The pair would eventually come together, merging to form the Venus we know. As dead as Venus is today, it has brought surprising dividends in the search for life. On its recent crossing between Earth and the Sun, astronomers were out in force. In remote locations where the viewing was optimal, such as the Svalbard islands north of Norway. The data gathered here would be added to that collected by solar telescopes on the ground and in space. To object for most was to experience a spectacle that will not occur again till the year 2117. It was also to capture sunlight passing through Venus’ atmosphere.

Today, the Kepler Space Telescope is searching for planets around distant stars by detecting dips in their light as a planet passes in front. Telescopes in the future may be able to analyze the light of the planet itself. If elements such as carbon or oxygen are detected, then these worlds may well be “Earth-like.” Venus provides a benchmark, and some valuable perspective. So what can we glean from the evolution of planet Venus? As we continue to scan the cosmic horizons, the story of Venus will stand as a stark reminder. It takes more than just the right size, composition, and distance from the parent star, for a planet to become truly Earth-like. No matter how promising a planet may be, there are myriad forces out there that can radically alter its course. For here was a world, Venus, poised perhaps on the brink of a glorious future.

But bad luck passed its way. Now, we can only imagine what might have become of Earth’s sister planet? 8.

Top 10 Recently Discovered Earth Like Planets

Welcome to Top10Archive! The longer we stay on Earth, the more apparent it becomes that maybe we should have a backup plan should we live long enough to completely dry ‘er up. On our quest to find the perfect place to call Second Home, we’ve come across these incredible exoplanets. Factoring in the Earth Similarity Index or ESI, we’ve compiled the Top 10 Earth-like planets discovered over the past decade. 10. Kapteyn B In June of 2014, the High Accuracy Radial Velocity Planet Searcher discovered the potentially habitable exoplanet Kapteyn B. Found to reside in a system estimated at over 11 billion years old, about 7 billion years older than our own solar system, Kapteyn B orbits the red subdwarf star Kapteyn and is 12.8 light-years away from Earth. Kapteyn B has an ESI of .67 and, while found within a habitable zone capable of liquid water, is believed to have a temperature of approximately -91° F or roughly -68° C and, therefore, too cold to sustain water in a liquid form, but with enough C02 in its atmosphere, this may not even be a factor.

Working against the argument of habitability is the fact that some researchers, such as Paul Robertson at Penn State University, think Kapteyn B may not even exist and may just be a starspot mimicking a planetary signal. 9. Gliese 667 Cc Orbiting around the red dwarf star Gliese 667 C some 23 light years away, the exoplanet Gliese 667 Cc is within the habitable zone and has an ESI of .84. In November of 2011, astronomers noticed the super-Earth and started to find similarities to our own planet. The habitability of Gliese 667 Cc depends on where you’re aiming to terraform as the two hemispheres display complete opposite properties. One side is completely shrouded in permanent darkness while the other is constantly facing towards the red dwarf. It’s believed that, between these hemispheres, there is a sliver of space that may experience temperatures suitable for human life. There is, however, a possibility of extreme tidal heating upwards of 300 times that of Earth, calling into question whether, at times, if Gliese 667 Cc may be a little too hot for habitation.

8. Kepler 442b Launched in 2009, NASA’s Kepler space observatory has succeeded on numerous occasions in its mission to find Earth-sized planets. Announced in January of 2015, alongside the discovery of Kepler-438b, 442b has an ESI of .83 and a radius of 1.34 radians, quite a bit larger than Earth’s radius of .009 radians. While located within the habitable zone and deemed one of the most Earth-like planets in regards to temperature and size, life would be quite a bit different on 442b. For instance, a year would only be 112.3 days long and we’d experience only 70% of the sunlight that we’re used to receiving on Earth. Since the axial tilt is believed to be fairly small, we also shouldn’t expect to enjoy the quarterly change in seasons that we’re accustomed to. 7. Proxima B With an ESI of .87, Proxima b may be one of the most Earth-like exoplanets to date, but that doesn’t mean it’s the greatest candidate for habitability.

Though it shares many characteristics with Earth and touts a higher ESI, if you haven’t noticed yet, that’s not a guaranteed proponent of habitability. In fact, Proxima b, which is only 4.2 light-years away, is likely uninhabitable due to incredibly high stellar wind pressures. Compared to Earth, Proxima b is thought to be subjected to pressures of more than 2,000 times what we experience. Coupled with the radiation from its host star, it’s possible that the exoplanet would have no atmosphere to sustain life. In October of 2016, researchers at the National Center for Scientific Research in France hypothesized a chance for surface oceans and a thin atmospheric layer, though proof has yet to be discovered. 6. Kepler 438b In January of 2015, the newly found Kepler 438b, located 470 light years away, was deemed one of the most “Earth-like” planets ever discovered, making it an incredible candidate for the potential of life. Though it has a potential ESI of .88 and still carries similarities to our home world, research later that year determined that, while still “Earth-like,” 438b may be missing qualities needed for habitation – such as an atmosphere.

The planet’s nearby star emits flares 10 times more powerful than the Sun, leading to the possibility of a stripped atmosphere. There’s still hope that Kepler-438b, which is 12% larger and receives 40% more light than Earth, may be usable if it has a magnetic field like our own. 5. Wolf 1061 c At an ESI of .76, Wolf 1061 c is a potentially rocky super-Earth exoplanet discovered in December of 2015, some 14 light-years away from Earth. Orbiting Wolf 1061 at .084 AU, the exoplanet is closer to the inner edge of the habitable zone and is believed to be tidally locked. With one side permanently fixated on its star, the possibility of an extreme difference in temperatures on either side of the planet is incredibly likely. On the warmer side, liquid water may be sustainable, though it’s hypothesized to have an icy equilibrium temperature of -58° F or about -50° C, that could be offset by a thick atmosphere that allows for a transfer of heat away from the side of the planet facing Wolf 1061. 4. Kepler 62 e A Super-Earth found within the habitable zone of the Kepler 62 star, this exoplanet, which was discovered in 2013, has an ESI of .

83 and has some of the imperative qualities of potentially livable planets. On top of being rocky, the planet is also believed to be covered in an extensive amount of water. One factor working against 62 e as a habitable zone is the 20% increase in stellar flux from what we experience on Earth, which can trigger temperatures as high as 170° F or about 77 ° C, and start a detrimental greenhouse effect. In relation to Earth, 62 e is 60% larger and orbits the Kepler 62 star 243 days quicker and receives 20% more sunlight than Earth does. 3. Kepler 62f Kepler 62 f may only have an ESI of .67, but this super-Earth, discovered at the same time as 62e at about 1,200 light-years away from Earth, poses one of the best scenarios for habitability.

Where the exoplanet may fall short in its ability to sustain life is its possible lack of an atmosphere, which would lead to any surface water to be ice. At 1.4 times larger than Earth and with an orbital period of 267 days, life on 62f would be fairly similar to life on Earth – that is, of course, if its atmosphere were similar to that of our own. As of now, much remains unknown about the theoretically habitable planet, including whether or not it’s mostly terrestrial or predominantly covered in water. 2. Kepler-186f Kepler 186f of the Kepler 186 system may only have an ESI of .61, but the 2014 discovery is the first Earth-like exoplanet to have a radius similar to Earth’s – measuring in at about 10% larger. Found 500 light-years from Earth in the Cygnus constellation, 186f has an orbital period of 130 days and only receives 1/3 the energy from its star that Earth receives from the Sun. In terms of livability, 186f is within the habitable zone, but unknown atmospheric factors make how habitable it may be impossible to determine.

Like Kepler 442b, 186f has a low obliquity that keeps it from experiencing seasons like Earth. Of the four other planets in the Kepler system, 186f is believed to not be tidally locked like its neighbors and may be the only one far enough away from the Kepler star to sustain water. 1. Kepler 452b Also known as Earth 2.0, the discovery of Kepler 452b by the Kepler space telescope was announced in July of 2015. Found 1,400 light-years away from Earth, the super-Earth, which has an ESI of .83, was located in the habitable zone of a G-type star that shares a very similar mass and surface temperature of our Sun. While 452b’s smaller radius indicates it may have a rocky, terrestrial surface, the habitability of the exoplanet remains widely unknown, though it is believed to be subjected to a runaway greenhouse effect. The exoplanet is approximately 60% larger than Earth and has a year that’s only 5% longer than our own, earning it the title of Earth’s Cousin.

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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).

Earth in 1000 Years

Ice in its varied forms covers as much as 16% of Earth’s surface, including 33% of land areas at the height of the northern winter. Glaciers, sea ice, permafrost, ice sheets and snow play an important role in Earth’s climate. They reflect energy back to space, shape ocean currents, and spawn weather patterns. But there are signs that Earth’s great stores of ice are beginning to melt. To find out where Earth might be headed, scientists are drilling down into the ice, and scouring ancient sea beds, for evidence of past climate change. What are they learning about the fate of our planet, a thousand years into the future and even beyond? 30,000 years ago, Earth began a relentless descent into winter, Glaciers pushed into what were temperate zones. Ice spread beyond polar seas. New layers of ice accumulated on the vast frozen plateau of Greenland.

At three kilometers thick, Greenland’s ice sheet is a monumental formation built over successive ice ages and millions of years. It’s so heavy that it has pushed much of the island down below sea level. And yet, today, scientists have begun to wonder how resilient this ice sheet really is. Average global temperatures have risen about one degree Celsius since the industrial revolution. They could go up another degree by the end of this century. If Greenland’s ice sheet were to melt, sea levels would rise by over seven meters. That would destroy or threaten the homes and livelihoods of up to a quarter of the world’s population. These elevation maps show some of the areas at risk. Black and red are less than 10 meters above current sea level. The Southeastern United States, including Florida, And Louisiana.

Bangladesh. The Persian Gulf. Parts of Southeast Asia and China. That’s just the beginning. With so much at stake, scientists are monitoring Earth’s frozen zones, with satellites, radar flights, and expeditions to drill deep into ice sheets. And they are reconstructing past climates, looking for clues to where Earth might now be headed, not just centuries, but thousands of years in the future. Periods of melting and freezing, it turns out, are central events in our planet’s history. That’s been born out by evidence ranging from geological traces of past sea levels, the distribution of fossils, chemical traces that correspond to ocean temperatures, and more. Going back over two billion years, earth has experienced five major glacial or ice ages. The first, called the Huronian, has been linked to the rise of photosynthesis in primitive organisms. They began to take in carbon dioxide, an important greenhouse gas. That decreased the amount of solar energy trapped by the atmosphere, sending Earth into a deep freeze.

The second major ice age began 580 million years ago. It was so severe, it’s often referred to as “snowball earth.” The Andean-Saharan and the Karoo ice ages began 460 and 360 million years ago. Finally, there’s the Quaternary, from 2.6 million years ago to the present. Periods of cooling and warming have been spurred by a range of interlocking factors: volcanic events, the evolution of plants and animals, patterns of ocean circulation, the movement of continents. The world as we know it was beginning to take shape in the period from 90 to 50 million years ago. The continents were moving toward their present positions. The Americas separated from Europe and Africa. India headed toward a merger with Asia. The world was getting warmer.

Temperatures spiked roughly 55 million years ago, going up about 5 degrees Celsius in just a few thousand years. CO2 levels rose to about 1000 parts per million, compared to 280 in pre-industrial times, and 390 today. But the stage was set for a major cool down. The configuration of landmasses had cut the Arctic off from the wider oceans. That allowed a layer of fresh water to settle over it, and a sea plant called Azolla to spread widely. In a year, it can soak up as much as 6 tons of CO2 per acre. Plowing into Asia, the Indian subcontinent caused the mighty Himalayan Mountains to rise up. In a process called weathering, rainfall interacting with exposed rock began to draw more CO2 from the atmosphere, washing it into the sea. Temperatures steadily dropped.

By around 33 million years ago, South America had separated from Antarctica. Currents swirling around the continent isolated it from warm waters to the north. An ice sheet formed. In time, with temperatures and CO2 levels continuing to fall, the door was open for a more subtle climate driver. It was first described by the 19th century Serbian scientist, Milutin Milankovic. He saw that periodic variations in Earth’s rotational motion altered the amount of solar radiation striking the poles. In combination, every 100,000 years or so, these variations have sent earth into a period of cool temperatures and spreading ice. Each glacial period was followed by an interglacial period in which temperatures rose and the ice retreated. The Milankovic cycles are not strong enough by themselves to cause the shift.

What they do is get the ball rolling. A decrease in solar energy hitting the Arctic allows sea ice to form in winter and remain over summer, then to expand its reach the following year. The ice reflects more solar energy back to space. A colder ocean stores more CO2, which further dampens the greenhouse effect. Conversely, when ocean temperatures rise, more CO2 escapes into the atmosphere, where it traps more solar energy. With so many factors at play, each swing of the climate pendulum has produced its own unique conditions. Take, for example, the last interglacial, known as the Eemian, from 130 to 115,000 years ago. This happened at a time when CO2 was at preindustrial levels, and global temperatures had risen only modestly. But with higher solar energy striking the north, temperatures rose dramatically in the Arctic. The effect was amplified by the lower reflectivity of ice-free seas and spreading northern forests.

There is still uncertainty about how much these changes affected sea levels. Estimates range from a 5 to 9 meters, levels that would be catastrophic today. That’s one reason scientists today are intensively monitoring Earth’s frozen zones, including the ice sheet that covers Greenland. Satellite radar shows the flow of ice from the interior of the island and into glaciers. In the eastern part of the island, glaciers push slowly through complex coastal terrain. In areas of higher snowfall in the northwest and west, the ice speeds up by a factor 10. The landscape channels the ice into many small glaciers that flow straight down to the sea. In the distant past, the center of the island may have been drained by a giant canyon, recently discovered. Scientists found that it’s 550 kilometers long and up to 800 meters deep.

It leads from Greenland’s interior to one of today’s most volatile glaciers. This is the Petermann Glacier in Northwest Greenland. Amid unusually warm summer temperatures in 2012, satellites tracked a giant iceberg as it broke off and moved down the glacier’s outlet channel. At about 31 square kilometers, this island of ice stayed together as it floated along. After two months, it finally began to fragment. The Jakobshavn glacier on Greenland’s west coast flows toward the sea at a rapid rate of 20 to 40 meters per day. At the ice front, where the glacier meets the sea, Jakobshavn has been retreating as it dumps more and more ice into the ocean. You can see it in this map. In 1851, the front was down here. Now it’s 50 kilometers up. One reason, scientists say, is that water seeping down into its base is acting like a lubricant.

Another is that as the glacier thins, it’s more likely to break off, or calve, when it interacts with warmer ocean waters. Scientists are tracking the overall rate of ice loss with the Grace Satellite. They found that from 2003 to 2009, Greenland lost about a trillion tons, mostly along its coastlines. This number mirrors ice loss in the Arctic as a whole. By 2012, summer sea ice coverage had fallen to a little more than half of what it was in the year 1980. While the ice rebounded in 2013, the coverage was still well below the average of the last three decades. Analyzing global data from Grace, one study reports that Earth lost about 4,000 cubic kilometers of ice in the decade leading up to 2012. Sea levels around the world are now expected to rise about a meter by the end of the century. What will happen beyond that? To gauge the resilience of Greenland’s great ice sheet, scientists mounted one of the most intensive glacial drilling projects to date, the North Greenland Eemian Ice Drilling Project, or NEEM. The ice samples they obtained from the height of Eemian warming told a surprising story.

If you were a visitor to Northern Greenland in those times, you would have stood on ice over two kilometers thick. Temperatures were warmer than today by about 8 degrees Celsius. And yet, the ice had receded by only about 25%, a relatively modest amount. That has shifted the focus to Earth’s other, much larger ice sheet, on the continent of Antarctica. Antarctica contains 90% of all the ice, and 70% of all the fresh water on the Earth. Scientists are asking: how dynamic are its ice sheets? How sensitive are they to melting? Data from Grace and other satellites shows that this frozen continent overall has lately been losing as much ice as it gains. The vast plateau of Antarctic ice is one of the driest deserts on Earth. What little snow falls, remains, adding to the continent’s mass. You can see evidence of this in the snow and ice that piles up at the South Pole research station. This geodesic dome was built in the 1970s.

By the time it was decommissioned in 2009, the entrance was nearly buried. With a thickness of up to 4 kilometers, the ice on which this outpost sits will not melt easily. That’s true in part because of the landmass below it, captured in an extraordinary radar image. The eastern part of the continent, the far side of the image, is a stable foundation of continental crust. In contrast, the western side dips as much as 2500 meters below present day sea level. Along the Amundsen Sea Coast, the ice is disappearing at an accelerating rate. Inland ice streams are moving toward the ocean at at least 100 meters per year. They end up in floating ice shelves that extend hundreds of miles into the ocean. This region is the greatest source of uncertainty about global sea level projections. When ice shelves like this grow, they become prone to fracturing. A giant crack, for example, recently appeared in the Pine Island Glacier. Within two years, a 720 square kilometer iceberg had broken off.

But the scientists are more concerned about what’s happening below the surface. In recent times, the Southern ocean that swirls around the continent has been getting warmer, at the rate of .2 degrees Celsius per decade. That has affected ice shelves like Pine Island by melting them from below. In a comprehensive survey of the continent, scientists concluded that this process was responsible for 55 percent of the mass lost from ice shelves between 2003 and 2008. It’s also been blamed for one of the more puzzling twists in the story of climate change, the spread of sea ice all around Antarctica. One possibility is that ramped up winds, circling the pole, are pushing the ice into thicker, more resilient formations. Another is that the melting of ice shelves has spread a layer of cold, fresh water over coastal seas, which readily freezes.

A team of researchers has come to the Pine Island Glacier to try to monitor the melting in real time. After five years of preparation, they drilled through 500 meters of ice to begin measuring ice volume, temperature, salinity, and flow. In some places, they found melt rates of about 6 centimeters per day, or about 22 meters in a year. Because ice shelves hold back inland glaciers, the melting could trigger larger changes. That’s likely what happened to the Larsen ice shelf on the Antarctic Peninsula in the year 2002. It’s thought to have been stable since the last interglacial. Warmer ocean waters had been eating away at Larsen’s underside. By early February of 2002, the shelf began to splinter into countless small icebergs. By March 7th, when this picture was taken, it had completely collapsed, forming a vast slush that drifted out to sea. Without the shelf’s buttressing effect, a series of nearby glaciers picked up speed, dumping an additional 27 cubic kilometers of ice into the ocean per year.

Evidence from the last interglacial, the Eemian, brings an ominous warning of what could lie ahead. It’s based on the height of ancient coral reefs, which grow to a depth relative to the sea level above them. Based on reefs along the Australian coast, a recent study published in the journal Nature showed that sea levels remained stable for most of the Eemian, at 3-4 meters above those of today. But the authors found that in the last few thousand years of the period, starting around 118,000 years ago, sea levels suddenly shot up to 9 meters above today. The authors concluded, in their words, that “a critical ice sheet stability threshold was crossed, resulting in the catastrophic collapse of polar ice sheets.” Looking ahead, uncertainties about the future of our climate abound. According to one study, the long cool down to the next glacial period is due to start in the next 1500 years or so, based on the timing of Milankovic cycles. But for this actually to happen, the study says, enough new ice would have to form to get the ball rolling. CO2 would have to retreat to below pre-industrial levels.

Instead, it appears that a warming climate is becoming a fact of life. The danger is that if the melting gains a momentum of its own, even reducing CO2 emissions may not be enough to stop it. The still unfolding story of Earth’s past tells us about the mechanisms that can shape our climate. But it’s the unique conditions of our time that will determine sea levels, ice coverage, and temperatures. What’s at stake in the coming centuries is the world we know, the one that has nurtured and sustained us. The Earth itself will go on, ever changing on short and long time scales, a dynamic living planet 1.