Jim Green, NASA’s Retiring Top Scientist, Says We Can Terraform Mars

Yeah, it’s doable. Stop the stripping, and the pressure is going to increase. Mars is going to start terraforming itself. That’s what we want: the planet to participate in this any way it can. When the pressure goes up, the temperature goes up.

The first level of terraforming is at 60 millibars, a factor of 10 from where we are now. That’s called the Armstrong limit, where your blood doesn’t boil if you walked out on the surface. If you didn’t need a spacesuit, you could have much more flexibility and mobility. The higher temperature and pressure enable you to begin the process of growing plants in the soils.

There are several scenarios on how to do the magnetic shield. I’m trying to get a paper out I’ve been working on for about two years. It’s not going to be well received. The planetary community does not like the idea of terraforming anything. But you know. I think we can change Venus, too, with a physical shield that reflects light. We create a shield, and the whole temperature starts going down.

In 2015, NASA approved the Europa Clipper mission to search for signs of life on Jupiter’s moon Europa, set for launch in 2024, following the detection of plumes erupting from its subsurface ocean in 2013. Did you want to see that mission happen sooner?

Oh, yeah, I would love to have seen it earlier, but it wasn’t going to happen. There are certain series of missions that are so big they’re called strategic missions. For them to actually happen, the stars have to align. You have to propose it, have a solid case work, go to the NASA administration and then pitch it to Congress. Every year, I proposed a Europa mission. Every year. The administration was not interested in going to Europa.

The plumes on Europa are what made the Europa mission happen. I was at an American Geophysical Union meeting in 2013. Several of the scientists were going to give a talk on finding a plume with Hubble on Europa, and I go, “Oh, my God.” I said this is fantastic, I want to do a press conference. I call back to NASA headquarters, and they pulled it off. I took that information back with me to headquarters and added that into the story of Europa. That really turned the corner. They said, “Wow, maybe we should do this.”

Congress decided against putting a lander on the mission. Did you want one?

I would love a lander, but it’s not in the cards. It makes the mission too complicated, but everything we do on Clipper feeds forward to a lander. I insisted that we had a high-resolution imager to the point whereas we fly over certain areas, we’re going to get the information we need to go, “Let’s land right there, and safely.” Europa has got some really hazardous terrains, so if we don’t get the high-resolution imaging, we’ll never be able to land.

You want to take a step, but not a huge step. You fail when you do that. Viking is that example, where we took too big a step. We didn’t know where to go, we didn’t know enough about the soils or the toxins in the soils. We hadn’t really gotten a good idea where water was on the planet in the past. There were 10 things we should have known before we put the two Vikings on the surface.

Are you still going to work on scientific papers in your retirement?

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