NASA Director of Planetary Science visits L.U., discusses possibilities for life beyond Earth
Sam Mathers, News Editor
Dr. James Green, Director of Planetary Science at NASA visited Lakehead University on Wednesday to deliver a presentation called “The Search for Life Beyond Earth in Space and Time.” The ATAC lecture hall filled quickly, with attendees taking seats on the stairs and floor. The presentation was also broadcast by video in two other classrooms to accommodate the massive turnout. The evening began with a light-hearted atmosphere as Dr. Green tossed NASA buttons into the crowd and gave an impromptu talk on Pluto while the other rooms were being set up for the overflow of people. (He still considers it a planet, if you were wondering.) As he prepared to begin his presentation, he set a new tone with these words: “we have not found life beyond this planet. And I’ll make a prediction that in the next ten years we will answer the question: are we alone?”
Before the presentation, Dr. Green sat down with Tamara Spence of The Argus to discuss his work at NASA and his early interest in the field. Born in the Mississippi River town of Burlington, Iowa, His love for outer space began with his high school chemistry teacher, who had the keys to an observatory and taught an after-school astronomy class: “I had the observatory to myself mostly – I shared it with many of the other students, but I just seemed to excel in that.” Dr. Green began doing astrophotography, and built instruments on the back of his telescope that allowed him to capture things like Mercury crossing the sun, Mars getting close to the Earth over time, and the change of the ring plane on Saturn, which were published in the magazine Sky and Telescope.
Dr. Green attended the University of Iowa, where he completed his undergraduate degree, master’s degree and PhD. He says “I got there, and they were working of their 54th space craft… I mean if I wanted to get into this business, that was the place.” As an undergraduate, he worked on a space craft that would be named “Hawkeye” after the university’s mascot, and later analyzed the data when it came in. He became a NASA employee immediately upon leaving the university.
In 2015, Dr. Green consulted on the film The Martian, but says the most exciting part of working at NASA are the scientific discoveries that come in “fast and furious” every day. He says one of the biggest misconceptions about life on other planets is “thinking that this is such a unique environment that… there’s no planets like Earth in the galaxy.”
Habitable places contain three basic things: energy, water, and organics. Earth currently sits in the middle of the habitable zone. The habitable zone refers to the place where, due to the radiant energy of the sun, the water on a planet can exist in the three phases – solid, liquid, and vapour. Over time, the sun gets a little smaller but it’s radiant energy gets a little more intense (increasing 25-30% in the last 4.5 billion years) and over time, the habitable zone moves further away from the sun.
This means that the planets closer to the sun could have existed in the habitable zone at some point in time. This also means that the habitable zone will continue to move further away from the sun, possibly leaving the Earth behind.
Venus orbits the sun in 224 days, and rotates on its axis only 20 or so days further than that – a relatively slow rotation. It is almost tidally locked, meaning it rotates so slowly that one side of the planet never faces the sun. It also rotates in the opposite direction that Earth rotates. The temperature on Venus is hot enough to melt lead at up to 700 Kelvin, and the atmospheric pressure is 90x the atmospheric pressure we feel on Earth. In the 70s and 80s, the Soviets launched a series of space crafts that according to Dr. Green were “unbelievably built like tanks,” which made it to the surface of Venus, but only lasting tens of minutes before being crushed by the atmospheric pressure.
At some point in the past, with the sun’s radiant energy just right, the habitable zone could have maintained Venus in some way. Dr. Green and his team have done extensive modelling, putting water on it in its past and running climate models. The models show that Venus could have looked like Earth, and Dr. Green believes “this is an accurate picture of Venus – it could have been Earth-like for a billion or more years; plenty of time for life to have started on it. So, although we don’t believe life exists on the surface of Venus now because of those extremes, it could have existed on its surface in the past.”
At one time, Mars also looked like Earth – in fact two thirds of its northern hemisphere were under water. In order for it to have looked that way, the planet would have had to have an extensive atmosphere, a magnetic field protector, and a runaway greenhouse effect. There are several landers on Mars, like Curiosity, which sits in the planet’s ancient shoreline – in the area “where water existed and where life may have started.” Dr. Green says they were “absolutely shocked” after drilling below the surface. Normally, Mars looks red, but when they got below the topsoil, Dr. Green says: “it’s grey – it’s a completely different planet than what we’re used to. And in fact, when we bring that in and we test it, its got carbon, hydrogen, oxygen, nitrogen, phosphorous and sulfur, its got all the basic building blocks of life.”
To know for sure if life existed on Mars in the past means finding some sort of fossil – which as Dr. Green says, is extremely difficult on Earth – a place we know for sure has been full of life. As of now, Mars is quite far from the habitable zone. But we know that the habitable zone is slowly moving further away from the sun. Mars has a northern polar cap with a carbon dioxide veneer. Beneath that layer, Dr. Green believes there is a huge amount of water. He says that “over time, the sun’s intensity is going to increase. And there will come a time… the heat from the sun will be so great, that it will sublimate that CO2 veneer. That will dump carbon dioxide into the atmosphere, and that will create a stronger greenhouse effect. What happens next, is that stuff melts. The amount of water that’s in this northern polar cap we estimate to be about one seventh of its former ocean.”
Dr. Green says that “Mercury never had a chance. Its too hot. Venus, we now believe entered the habitable state with all the right stuff but now its popped out, never to return. Earth in its evolution got really close to popping out, but we hung in there, thank goodness, and we’re now well situated in the middle of our habitable zone. Mars looked like Earth in its past, became very arid, became way too cold to its surface, very low pressure, very cold… but in its future, we believe it could pop back into a habitable state. And when that happens, Earth will be here and we as a species better be there.” When asked how long we have, Dr. Green estimates 700 million years, saying, “we’ve got some time… don’t pack yet.”
There are also possibilities for life on the moons of Jupiter and Saturn. Jupiter has a set of moons – Callisto, Ganymede, Europa, and Io, that were all created at the same time but are extremely different. Callisto is furthest away from Jupiter and is completely full of craters. Ganymede is the largest moon in the solar system, and has significantly less craters. Europa has hardly any craters, and Io, which is about the size of our moon, has none. Instead, they found volcanoes. Dr. Green says that “Io is turning itself inside out” as a result of Jupiter’s tidal forces. Io’s orbit is slightly elliptical, so when it gets close to Jupiter, the planet squeezes it, releasing its grip when Io is further away. This causes the heating and melting of the rock. As Dr. Green puts it, “you literally need a new Google map of the surface every 50 to 100 years.”
Europa has an ice shell with twice as much water as there is on Earth underneath it. The tidal forces keep this water just warm enough to maintain it. Europa also has cracks in its surface where massive plumes of water shoot out. These plumes were seen from Earth with the Hubble, meaning they would have to be at least 150 km in height. This is why there are hardly any craters on the surface of Europa. The plumes of water shoot through the cracks, fill in the craters and then freeze, and the craters are gone.
Dr. Green also believes there are hydrothermal vents at the bottom of Europa’s ocean. Dr. Green says that since they were “discovered in 1977, oceanographers have visited about 300 of them, some of them are really hot, some of them are not so hot, some of them are alkaline, some are really acidic; every one of them, teeming with life. Life’s everywhere from these hydrothermal vents. That means our ocean has all the right conditions – has the water, has the energy from the heat, has plenty of organic material and it certainly has had the time to develop it – that condition is most like the bottom of the ocean on Europa.”
Dr. Green says they have been investing in a submarine for 7 or 8 years that they are preparing to make the venture inside one of the cracks. Before that is done, he says “we would probably go in with a lander, sit it on the surface, scrape up material, bring it in, and probably sit underneath a plume and let new material fall on us. And if there’s life in Europa, its probably in one of these interfaces between the water and the ice and we hope that this microbial life, or maybe more complex life will come out, and fall on the lander or be in the region when we can scrape up and analyze, and then really study it. If we get positive indications that there’s life in that ocean, we’re going in a crack.”
One of Saturn’s moons called Enceladus is much smaller than ours, but has large geysers of water pouring out of it. They believe Enceladus has a large ocean, and that these geysers are actually huge cracks. A wall of water that comes out along the crack and forms what they call Saturn’s E ring. Dr. Green says “we have flown through those geysers and we test that water. We understand what’s in it, we measure the organics, we measure the stuff we need – the stuff of life, and we pick up dust. And the dust is coming from the hydrothermal vents. So, all the right conditions are on this body. Already and we know it.”
Titan is another of Saturn’s moon that is of interest to Dr. Green. Larger than the planet Mercury, Titan has liquid on its surface in huge amounts, larger than the Black Sea. But it’s not water – it’s liquid methane. Dr. Green says that “if we want a liquid and we want a solvent – and life needs that, then it’s going to be life like we don’t know it. Its going to be something really different. They actually have a field in astrobiology that there’s research on what we call ‘weird life.’ And they’re studying Titan.”
When asked about contamination and conservation of new discoveries, Dr. Green said there are a set of international rules that state they must reduce their “bio burden,” by cleaning the rovers that are “full of our life.” In terms of conserving any life they find, he says that not enough people are really thinking about that. A lot of people are “rushing to analyze the data,” and Dr. Green says he doesn’t know if “this planet is ready for the discoveries that we’re going to find.”
Arguably the headline of Research and Innovation Week, Dr. James Green’s passion for planetary science did not disappoint. Discussing far more than could be fit into one article, I leave you with Dr. Green on…
The Martian: “The soils have nitrates in it which are great fertilizer, and they’re moist. And so yes. Mark Watney can grow crops on Mars.”
Trappist-1: “It’s a very fascinating solar system because we have discovered 7 terrestrial planets… Out of these seven planets, there’s several of them that are in the habitable zone. And these planets are the size of the earth… this is a small star and these planets are all close to it…They are so close that they are tidally locked… keeping one face toward the sun. So, that’s going to be pretty tough to survive on if you expect life to be there, because the sunlit side is going to be enormously hot, and the night side is going to be enormously cold, and yet it’s going to be hammered by the solar wind. So, we already know this is probably not the best place to look for Earth-like planets. But this is truly a spectacular discovery. And the reason is this: this sun, this dwarf, is only 40 lightyears away… our neighbourhood, it’s about 200 lightyears – 40 lightyears is just around the block. And it has seven planets. And that tells you that there is an enormous amount of planet making material in our neighbourhood. And that means, as we look for more stars in our neighbourhood, we’re going to find those that are more Earth-like well beyond this star.”
U.F.O.s: “So if I was an intelligent being from another planet, I wouldn’t come and go. The distances are so huge, that I would want to know hey, we’ve arrived. So, there’s a paradox called the Fermi paradox. In the 1950’s, Fermi was a very famous scientist that was walking around with some other scientists talking exactly about that issue. Those unidentified flying objects, are they extra terrestrial or not? And Fermi said, well where is everybody?”
Pluto: “Planetary scientists, we couldn’t believe what we saw… that’s a body that’s about 2,000 km in size, and we expected it to look like the moon, full of craters. And there’s huge areas on that body with no craters. It has glaciers and the glaciers move over time and eradicate the surface – clearing out the craters, eliminating the evidence…it’s mostly a Nitrogen glacier… and it moves like toothpaste, just sort of oozes around – its unbelievable. But…there’s some heat inside that body, and it’s heating this material, causing the turnover of this ice. And we call that convection. It’s like you put hot water on the stove and you turn it on and you see bubbles rising; there’s something going on that’s percolating through this heart… So even though the astronomers wanted to throw it out of the solar system, not think it’s a planet, it has so many characteristics of being a planet that we’re gonna tell ‘em: go take a hike. Pluto’s a planet.”
The universe being ‘finely tuned’: “Its certainly playing music to me. I love science. I love how stars come and go, how planets are made, how life started, and whether there’s life beyond earth, and that’s just music to my ears.”