Senior scientist at NASA's
Planetary Systems Branch
McKay's research focuses on the evolution of the solar system and the origin of life. McKay is currently involved in planning future Mars missions and has authored a number of studies on terraforming Mars as well as geo-engineering Earth.
When Elon Musk launches his rocket out to retire onto the possibly-habitable wilds of Mars, one can safely assume that you and I and everyone we know will not be on that flight.
Nor will estimated millions of climate change refugees, like the people of the Carteret Islands, whose home is expected to go completely underwater this year. If it's possible to alter an entire planet's climate to make it habitable, then why doesn't our news feed fixate on renovating Earth? Amongst armageddon prophecies of climate change's global environmental destruction, is our desire to start over on Mars– terraforming an entire planetary atmosphere from scratch– a basic concession that Earth's non-super rich are evolution's losers?
In the past few years, science has lurched closer to envisioning habitable Mars, though at the moment estimates for creating breathable oxygen range from hundreds to 100,000 years in the future, the soil is currently toxic to astronauts, and travel is so unwieldy that scientists have proposed "printing" humans on Mars. Meanwhile, I wondered why not make Earth's increasingly inhospitable deserts greener.
We talked to NASA scientist Christopher McKay, who has written a number of studies and articles on geo-engineering and terraforming. This includes co-authoring an early influential article "Making Mars Habitable," which was released two years before Kim Stanley Robinson's Mars Trilogy captured the public's imagination. Below, we discuss renegade attempts to fertilize the ocean, plans to spray aerosols into the atmosphere, the delicate balance of climate alterations, as well as a realistic timeline for blue Mars.
Hopes&Fears: Five years ago, the public probably would have laughed off the idea of somebody like Elon Musk, for example, saying "I'd like to retire on Mars.” Have you seen a major shift in people's ideas about how seriously they should take terraforming? And how feasible it actually could be to intentionally design a planet's atmosphere?
Chris McKay: Well, on Earth, geo-engineering is taken very seriously. As you may remember, there was a group up in British Columbia that tried to take geo-engineering into their own hands by dumping a lot of iron in an attempt to fertilize the ocean. It is certainly feasible, and, as some would argue, it's desirable.
From a scientist's point of view, there's no difference between physics of doing something unintentionally or intentionally. From a public policy point of view, there's a big difference, obviously. That is where the debate is focusing– should we take up geo-engineering as a matter of policy?
Somebody saying "I want to go live on Mars" was just silly ten years ago– how are you going to get there? Musk, by himself, has made it credible. His company has done things that previously were considered only doable by nation states, for example, putting a capsule in orbit around the Earth and bring it safely back. John Glenn got a ticker tape parade for doing that. Yuri Gagarin and Sputnik, that was all he did: get launched, go around the Earth a few times, and land on land, and it revolutionized the world. The Chinese did it a few years ago, to much fanfare. Orbiting and safely returning a capsule was always considered an entry-level move by a nation as it develops its space capability. To everyone's surprise, Elon Musk, a single individual, formed a private company, and he did it in just a few years with spectacular success.
Nobody laughs anymore at Musk saying "I'm going to go retire on Mars," because he is doing what previously we thought only national programs could do.
— Spraying atmospheric aerosols has been compared to the cooling effects of aerosols emitted by volcanos. The eruption of Mount Pinatubo in 1991 created a stratospheric aerosol layer which caused a global cooling.
H&F: About the idea of moving to Mars– because of the chemical perchlorate, the soil on Mars would be considered toxic if it were on Earth. That makes me wonder how much more possible it would be to make the Sahara, for example, a thriving rainforest versus terraforming all of Mars? Is it possible to terraform locally?
Chris McKay: Well, first of all, perchlorate in the soil makes it toxic, but I don't think it ends the discussion of terraforming. It just adds both challenge and an opportunity. I co-authored a research paper in which we found that though it would be hazardous to astronauts, it could be an important source of oxygen.
In answer to your question about terraforming locally, it is possible to go to Mars and create a large scale ecosystem in a jar, like Biosphere 2 in Arizona. That's sort of an obvious thing to do– build a greenhouse on Mars and live inside of it. That's not terraforming, or even related to terraforming. That's just biologically-based life support.
The other point about the Sahara is, it's possible to do regional climate change, but it's very difficult to do it without affecting other regions. So, yeah, I guess in principle, one could change climate on Earth so that the Sahara was no longer a desert, but by doing so, you would certainly change the climate elsewhere. You might turn Europe into a desert, because the entire Earth, of course, is a very interactive complex system. You can't change it in one way without affecting things elsewhere. No one would support a program that sets out to change the Sahara into a tropical rain forest because of the side effects that might result to the rest of the Earth's climate.
— In 2010, the Haida Salmon Restoration Corp. undertook a rogue mission to dump 100 tons of iron-rich dust into the ocean, in an attempt at ocean fertilization– resulting in a phyto-plankton algae bloom which traps atmospheric carbon. The act was condemned by the United Nations' International Maritime Organization for lack of oversight.
H&F: Right. Are people considering making biospheres on Earth and isolating regions to preserve, instead of fix, climate if it comes to that?
Chris McKay: People have made biospheres on Earth. There was an experimental one made in the late '80s in Arizona, Biosphere 2. It was made as a way of demonstrating that it was possible. People have also talked about preserving seed banks and things like that. I'm not aware of anybody who's talking about building a habitat as a way of preserving an ecosystem against climate change, though. It's an interesting idea.
H&F: You’ve mentioned a few major geo-engineering proposals in your studies, like iron fertilization of the ocean, and spraying stratospheric aerosols. Is there a geo-engineering scenario on Earth, which is, in your opinion, most effective?
Chris McKay: I think the two you just mentioned. Iron fertilization of the ocean and putting aerosols in the atmosphere. Those seem to be the most plausible. I would imagine that if we decide to do experiments that one or the other will be taken up.
H&F: We're losing so many species, and there are so many climate-related problems that are the side effects of side effects. Do you think that geo-engineering could save species from extinction, or will species stay on that track, no matter what?
Chris McKay: It's tough doing anything ecological on Earth. There are so many of us, and Earth is so delicately interwoven. When I'm talking to students, I draw the analogy between humans on Earth and a bull in a china shop. No matter what we do, we're breaking something. But on Mars, we’re like a bull in an empty field. Anything the bull leaves behind is positive. It's a whole different paradigm.
Directly to your question, can we mitigate climate change and stop the destruction of habitat and species? Eventually, I think we will. Geo-engineering may be one part of the solution.
What I can really say, though, is that the problem on Earth is tied to all sorts of problems, like the fact that we've built all our cities on the coast, and so if the sea level rises, that's not a big problem for the biosphere. The alligators aren't going to care that the sea level is rising ten meters– they'll just move inland a little bit. But the cities of Miami and New York are going to care. I don't have an easy path forward for the Earth, except to say that eventually, we're going to have to learn how to do geo-engineering. In the long term, it's not an option, it’s mandatory.
H&F: Back to what you were saying about the bull in the empty field–scientists are predicting that it’ll be much more practical to create an atmosphere for carbon-breathing life forms on Mars. You’ve written and said that all forms of life on Mars would be good, empirically, even if Mars were never habitable for humans. Why?
Chris McKay: The point here is that it's possible to restore Mars to the conditions it once had early in its history. The change is actually straightforward: just warm up Mars, it will get a thick atmosphere and thick carbon dioxide, water, and nitrates from the soil. That will be habitable for life, and it will be very much like Earth, early in its history. We have this romantic view of Earth that it was made exactly for us, and it's always been just fine for humans. That's not true at all. If you were to randomly appear on Earth at any time in Earth's history, chances are better than even you'd step out of your spacecraft or time machine and you would not be able to breath the air because there wouldn't be enough oxygen in it.
It turns out that the easiest way to terraform Mars is for plants, insects, and maybe some animals...the naked mole rat, for example, doesn’t need much oxygen...but not for humans. It wouldn't be an environment suitable for humans to walk around naturally like they do on Earth. When we say make Mars a home to life, we really mean us. We have this conceit that we are life.
NASA spending on Mars Missions:
1964-1972 Mariners 1-9:
1975-1982: Viking 1 and 2:
roughly $1 billion
1992 Mars Observe:
1996-2004 The Mars Global Surveyo, over seven years:
(roughly $521 million*)
1997 Mars Pathfinder
1998 Mars Climate Orbiter
1999 Mars Polar Lander
1999 Deep Space 2 Probes
2001 Mars Odyssey
2003 Mars Exploration Rover- Opportunity
2005 Mars Reconnaissance Orbiter
2007 Phoenix Mars Lander
2011-Current Mars Rover (Mars Science Laboratory):
estimated $2.47 billion
2013 Mars Atmosphere and Volatile Evolution
*adjusted for inflation
Humans have launched 40 spacecraft to Mars
That, then, goes back to the literal meaning of the word “terraform.” Are we literally trying to make Mars a duplicate of Earth, or are we just trying to make Mars a planet rich in life? Turns out making Mars a planet that's rich in life isn't so hard, but that life would be mostly trees, insects and small animals. Making Mars a duplicate of Earth would be very hard. It may be possible, but it's much, much harder because of the hard step of making enough oxygen. That took billions of years on Earth, and it would probably take at least hundreds of thousands of years on Mars.
H&F: You’ve written that fully terraforming could theoretically be possible within 17 years if operating at a rate of 100% energy efficiency and 100% efficiency of transforming carbon into oxygen. Realistically, you found that the energy efficiency would optimistically be at about 10% and efficiency for transforming carbon at 0.01%.
Chris McKay: Right.
← A proposal for "cloud seeding" by Stephen Salter and John Lathan of NASA. The concept entails spraying ocean water into the atmosphere so that salt particles make clouds thicker and more reflective.
Source: S.Salter/J. MacNeill via nature.com
H&F: Do you think, if Elon Musk develops some crazy unimaginable technology, it could be possible to make terraforming a reality on a human timeline? Or do you think it's just too enormous of an undertaking to do that?
Chris McKay: That's a good question. Let me phrase it precisely in terms of efficiency. If you had 100% efficiency of converting sunlight energy into oxygen, you could make enough oxygen for humans to breath in twenty years or so. Twenty years is a very short time, but 100% efficiency is unrealistic. What's realistic right now is the efficiency of Earth's biosphere. The efficiency of Earth's biosphere for producing oxygen from sunlight is about one hundredth of a percent. That's one part in ten thousand. Instead of taking twenty years, it would take twenty times ten thousand years, or about a hundred thousand or two hundred thousand years.
The obvious question is, then, can we improve the efficiency of ecosystems? Instead of one hundredth of a percent, maybe we could get them up to ten percent or even one percent. That's not something that's in the scope of science right now, but you could imagine not too far down the road, synthetic biology, et cetera, being able to do that sort of thing.
Instead of a hundredth of a percent, it gets up to one percent. Then, instead of two hundred thousand years, it's two thousand years. Still a long time, two thousand years, but it's not inconceivably long any more. If you really got optimistic, you could say, well, let's get synthetic biology to crank the efficiency all the way up to ten percent. Then you've got it down to two hundred years. That's short. Two hundred years, that's easy to imagine. People often say, as well, why do we even bother using plants [to terraform]? Why don't we just use a machine? The advantage of plants is that they could, in principle, cover and harvest sunlight from the whole planet.
If you use machines, you've got to figure out how to power them, and you're going to have to spread these machines all over the whole planet. Then you might as well do it with plants.
H&F: There are rumors that there are weather modification programs already in place. Do you know of any?
Chris McKay: On the Earth?
H&F: Yeah. Any official program, either government or corporate?
Chris McKay: No. I know of two things. One is that geo-engineering research is being done. Pilot projects are being proposed, but none has been approved yet. One almost got approved in the UK. At the last minute, it got cancelled. It's just too delicate. No official government project from any government that I'm aware of, has done even a pilot study, although many projects are doing conceptual studies.
— According to the National Oceanic and Atmospheric Administration, March 2015 was the warmest March (on Earth) since record-keeping began in 1880. 2014 was the hottest year.
At the unofficial level, there have been attempts to do geo-engineering by dumping iron in the ocean, like that private group in British Columbia that I’d mentioned earlier...it generated a lot of flak.
H&F: Do you see there being an ethical code being put into place? Do you see any policy makers getting closer to actually approving these things?
Chris McKay: On Earth or on Mars? Or both?
H&F: I guess on both, actually.
Chris McKay: On Mars, I don't think there's going to be any pressing need to have any sort of regulations any time soon because no one's in a position to do anything. Governments don't want to generate regulations against a hypothetical. Until Elon Musk is on Mars and starts thinking about doing something, then the governments will react.
On Earth, I definitely see there being codes put in place. When things like that British Columbia project are happening, people realize that they need agreements and policies. There will be international agreements, I think fairly quickly, on geo-engineering research and experiments. In fact, the National Academy of Science of the US has already published a position paper on how it should be regulated. That’s going to affect much more than just science and biology.