“The laws of physics are clear,” writes theoretical physicist Michio Kaku; “sooner or later we will face global crises that threaten our very existence.” Whether from our own hand, an asteroid impact, a burst of cosmic rays, or from the inevitable demise of the sun itself, the fate of all life on Earth is extinction. Even the solar system won’t last forever; when the sun’s fuel runs out and it expands into a red giant, the earth will be incinerated in the fireball.
At some point, then, it seems imperative that we move on. Kaku and others concerned with our galactic future advise that we must become “a multiplanet species” if we’re to continue. Yet we haven’t done much about it. “NASA,” he writes, has been “criticized as the ‘agency to nowhere.’ It has been spinning its wheels for decades, boldly going where everyone has gone before.”
That isn’t entirely true. They’ve sent unmanned spacecraft to or past all the planets and even beyond the solar system. Voyager I is now about 13 billion miles (21 billion km) away. Our landers, rovers and flybys have provided data revealing tremendous details about our cosmic neighborhood. Still, it’s been almost 50 years since humans set foot on the moon—a mere 239,000 miles, or 385,000 km, away. Human activity and presence since then has been limited to building and occupying the International Space Station. Although a miracle of imagination and cooperation, the ISS is hardly “getting away.” It orbits above us at roughly the distance of Paris from Lyon, Las Vegas from Los Angeles, or Chicago from Detroit.
We must set our sights higher, Kaku argues. “The goal of terraforming Mars exceeds our capability today,” he notes, “but the technologies of the twenty-second century will allow us to turn this bleak, frozen desert into a habitable world.”
Of course, we have to get there first.
NASA engineer Humphrey “Hoppy” Price has a plan. We won’t be populating Mars anytime soon, he admits, but by 2039 we may be able to video-chat with our children as they inhabit an Antarctic-like outpost on Mars.
Price is chief engineer for NASA’s robotic Mars Exploration Program. He was the project system engineer for the twin GRAIL probes and the configuration engineer for Cassini. He has also managed and performed systems engineering studies for Mars “sample return” technologies as well as for various interplanetary robotic missions. He spoke with Vision science writer Dan Cloer.
DC I noticed that one of the first things mentioned in your Mars exploration proposal is staying within budget. I suppose progress is contingent on expense.
HP For both the manned and planetary explorations projects the budgets have fortunately remained stable over the past 30 years. This has enabled a Mars program with all of its exploratory steps: Sojourner, Spirit, Opportunity, Curiosity and now the 2020 rover, and hopefully we will move on to Sample Return. This has been a long-term, stably funded program. We kept the manned program going with the shuttle for many years. We were able to build the space station over 20 years and keep that going. This is all very positive. We just need to keep moving.
DC The manned exploration of Mars that you outline is built on all of these steps; these accomplishments make the next steps possible. Is the goal to colonize Mars?
HP NASA has not really been thinking about colonization; one of the main thrusts now is the exploration of Mars. Part of this would be setting up a semipermanent base—something like Antarctica, where you have international crews that rotate in and out. But NASA has not been looking at families moving there, having babies and becoming a real colony. When you think about it, not even Antarctica has been colonized yet. There’s a base there, and people live there all the time. But nobody is having babies or raising families.
So just to start the human exploration of Mars under current budget conditions, we developed an example architecture to show that it’s feasible to start sending crews to build up a base over time.
DC Do you see this as a regenerative kind of habitat, a biosphere-like place where food could be grown and materials recycled?
HP NASA has looked at that kind of self-sustaining colony, but that’s not something being actively studied now. We’re more focused on nearer-term exploration. After a few missions we would have built enough surface systems (and have enough confidence in them) that we could have it permanently crewed. It would be more like the space station, where some members stay a long time and others come back more quickly. We might get to the point where there would always be someone on Mars, but no one person would be there permanently; everyone would eventually come back.
We do have plans and experiments for growing food there. That’s one of the first steps—being able to grow food. It would be very important for the morale of the crew to have fresh food and to see things grow; it would be both a psychological and a health benefit.
So NASA does want to get to a point where Mars is permanently occupied, some food is being produced, energy is being produced, and there would be some utilization of local resources—like the carbon dioxide from the atmosphere to make breathing oxygen, and extracting water for drinking, growing plants and making propellant.
DC Has building the International Space Station helped us understand how to accomplish a mission to Mars?
HP Yes, in many ways. For one thing, international cooperation was really important in taking on such a large project. It was built over 20 years and cost the United States alone more than $100 billion, with tens of billions from foreign partners. That’s roughly what it will take for missions to Mars. NASA’s 20-year budget for human spaceflight projects remains about $100 billion—about $5 billion per year. The existence of the space station is evidence that the American public can maintain interest for a long time and continue to financially support the space program.
“We’re still excited about the space station, and missions to Mars would be even more exciting.”
DC There is some concern that when we do get to Mars, we will contaminate the planet with Earth microbes, and this could change its future as well as our understanding of its past. How does NASA see this possibility?
HP There was a lot in the news last year about the selection of a planetary protection officer at NASA, but this is not really anything new as we have had this function for decades. I’m the chief engineer on the robotic Mars exploration program; and for all of our landers we have certain cleanliness requirements. We work with the planetary protection officer to be sure that we’re not contaminating potential Mars life with Earth microbes.
We’re also very serious about managing any Mars microbes we might bring back to Earth. When we do a Mars Sample Return mission, we want to make sure we protect Earth from any possible pathogens that we might bring back from Mars—as remote a possibility as that seems to be.
The rover we’re building now at JPL for the 2020 mission has sterilization measures in place, so that when we take Mars samples, there are no Earth microbes already there. If and when we bring samples back, we’re developing technologies that make sure we break the chain of contamination. This means that the vessel with Mars material that we bring back is completely sealed up in a redundant way and is completely sterile on the outside so that it’s safe. Then it would come to a special facility on Earth that’s able to open it up and protect the material so that none of it could escape to the environment. We’re taking a lot of precautions in our Mars Sample Return plans.
The kind of materials we will actually collect in the 2020 mission has been dry and dead. It’s been blasted by radiation for billions of years from the sun and space. So it’s extremely unlikely that there could be any pathogens in the material we bring back. The dangers, if there are any, would be in areas where there is water ice, or deep underground.
For human missions to Mars, wherever we’re traipsing around in our space suits, our microbes will potentially be released into the environment. But again, it will be on the surface where conditions for life don’t seem possible. So unless those microbes could get to more hospitable places, nothing would happen. We don’t want people to go near these areas anyway.
And when people come back from Mars we’ll want to be sure they aren’t carrying any pathogens with them. So there will be measures in place on Earth—and they will effectively be in quarantine for months on their trip home.
My personal opinion is that the chance of life on the surface of Mars is about the same as the chances on the surface of the moon. We think of it as a kind of self-sterilizing environment.
DC Is the 2020 mission introducing a new way of obtaining samples on Mars?
HP Yes, 2020 actually has a core-sample tube that will drill into rock and soil, which will be packaged in small sterile tubes within the rover. There are several options after this: some of the sample material can be tested by the rover; some tubes could be stored in the rover; and some could be dropped on the surface for a later mission to pick up. It would be a later mission that would collect them off the surface or maybe by meeting up with the 2020 rover and returning the samples back to Earth.
DC What about the prospect of terraforming—to rebuild Mars in the image of Earth? Does NASA work on these ideas of restoring a greenhouse effect, a water cycle on Mars? Or is this just interesting science fiction?
HP That’s a kind of way-out-there science-fiction idea. But NASA does spend a little bit of time doing far-out studies on all these things. These ideas are not part of the main thrust, however, of the human exploration program.
“Realistically, terraforming Mars, even if possible, would take hundreds of years through any kind of mechanism that we can think of.”
The idea of slowly changing the Martian atmosphere—maybe through some type of engineered microorganisms that could grow in the environment over many decades and use some resource from the ground to put into the air—seems farfetched. Some people have proposed a quick fix like setting off hydrogen bombs at the poles and putting a bunch of stuff into the atmosphere to release water and warm the planet. That’s a risky kind of venture; it would be pretty hard to predict what would happen.
A realistic terraforming would be a much slower, well-thought-out, well-researched and well-tested process. I don’t think it’s something we would see in our children’s grandchildren’s lifetime.
DC I understand that Mars lost its original atmosphere. What would make it hold on to a new one?
HP One of the orbiters we have around Mars now, called MAVEN, has done a lot of research into the question of why Mars lost its atmosphere in the first place. Some papers show that it has a hard time holding on to an atmosphere because of its low gravity, and that over time the solar wind tends to blow the atmosphere away.
So it appears that Mars at one time had a thick atmosphere; it was habitable, had water and a higher temperature for maybe hundreds of millions of years. Eventually, though, it lost it. Maybe terraforming could bring it back, and it might be stable again for millions of years, especially if we could come up with a way to counter the rate of loss. But in the long term, Mars does not hold on to its atmosphere by itself. If you don’t keep actively working on it, even a new atmosphere would degrade and disappear.
DC It doesn’t sound like Mars is going to be the lifeboat for the human species.
HP Even if you can’t terraform Mars, you could theoretically build closed environmental systems there using the materials that do exist. The advantage is that there is carbon dioxide, plenty of water in the form of ice, and a day length of about 24 hours like the Earth, which our biology is used to. That’s a big plus. But one of the drawbacks is its low gravity—only about a third of Earth’s.
“A big risk that I don’t think has been explored very much is the problem of gravity and development; can a human embryo develop in 0.3 Earth gravity?”
Look at what happens to astronauts who experience prolonged weightlessness; they have problems with circulation; their eyeballs become deformed because pressures change when gravity isn’t pulling down on the body. All these systems—bone structure, organs, circulatory system—are designed to be in balance at 1 g. At 0.3 g, adults would probably get along okay, but an embryo or a toddler—how would they get along? I don’t think anyone knows the answer.
DC That sounds like a good International Space Station experiment.
HP Yes, but you’d need a new kind of space station with artificial gravity. I don’t think a mammal could develop at all in zero gravity. We need a spinning space station to generate that 0.3 g and then send animals up there and see how they do.
DC What you’re saying just emphasizes the fact that there are many details (which seem obvious once they’re brought up) that are going to make colonizing and actually inhabiting another planet very difficult if not impossible.
HP A really practical approach to exploring Mars is to crawl before you walk, walk before you run, and run before you can drive on Martian speedways. People want to jump ahead—to move off-planet and live on Mars—but there are so many steps that need to happen. The first step is just the basic human exploration of Mars. Then a more permanent base that, like I say, sort of looks like our habitats on Antarctica today. You have to ask yourself, why haven’t we colonized Antarctica? It’s right there; it would be a whole lot easier than colonizing Mars.
DC Sure, but having people there is not going to save us from nuclear annihilation, specicide. If we’re wrecking this planet or bad things are coming (the argument goes), we have to get away from here.
HP But for whatever disastrous scenario you can think of—nuclear war, an asteroid hitting us, some terrible disease that spreads everywhere—you are still going to be a lot better off in some shelter here on Earth, where some people can survive. When it’s done, there will always be a lot more resources on Earth than anywhere else in the solar system.
If you have a safe haven to survive here, after whatever that event is that people are so worried about, you will have air, water, nice temperatures, and 1 g. Everything is going for you here. It seems to me that Earth is the survival place, the lifeboat. For whatever event you postulate, after that event is over, Earth is still going to be the best place to be.