While manned outposts on other planets still remain the premise of bold science fiction, NASA’s retiring chief scientist, James Green, suggested that making Mars habitable may be deceptively straightforward.
In 2017, Greene brought up the prospects of terraforming Mars at the NASA Planetary Science Vision 2050 Workshop, arguing that a “magnetic shield” could protect the Red Planet from high-energy solar particles and prevent the solar wind from stripping the Martian atmosphere, a move that would improve the climate.
“The solar system is ours, let’s take it,” he said at the time. “And that, of course, includes Mars. But for humans to be able to explore Mars, together with us doing science, we need a better environment.”
In a recent interview with The New York Times, Green also observed that the task of terraforming Mars is “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,” he said. “When the pressure goes up, the temperature goes up.”
Greene noted that being able to walk on the planet’s surface without a spacesuit would afford humans “flexibility and mobility”, while increasing the atmospheric pressure and temperature would enable humankind to “begin the process of growing plants in the soils.”
He acknowledged, however, out that the “first level of terraforming”, which he set at 60 millibars – “the Armstrong limit, where your blood doesn’t boil if you walked out on the surface” – is still “a factor of 10 from where we are now.”
The retiring scientist also speculated that another planet in our solar system, Venus, could be terraformed as well, with the help of a “physical shield that reflects light”, which would lower the second planet's extremely high atmospheric temperature.