Creating 'Planet B' in Earth's image

Remaking Earth on another planet is likely not possible, and experts say the current talk about it perpetuates a problematic idea that we could one day leave Earth's problems behind.

Driving the news: SpaceX founder Elon Musk yet again waded into the world of terraforming — transforming a planet to make it like our Earth. He declared on Twitter that a series of nuclear explosions above Mars could create "artificial suns" to warm the world and make it habitable.

Musk has long said he hopes to help humanity become a multiplanetary species, insulated from catastrophes that would make Earth uninhabitable for humans.

• Terraforming Mars could be one avenue that would lead to humans living on another world for the long term.
• “We have a small team engaging the broader scientific community on how best to enable a self-sustaining civilization on Mars, and we welcome the efforts of others who share this goal," a SpaceX spokesperson told Axios via email.

Background: Scientists and science fiction writers alike have been drawn to the idea of finding ways to thicken Mars' atmosphere and make the planet habitable.

• Carl Sagan, for example, speculated about terraforming Mars in a 1971 paper, and in 1991, NASA scientists published a study in the journal Nature looking at ways to make Mars livable.
• Scientists now are also thinking about terraforming on a smaller scale using a lightweight material known as aerogel to create zones of habitability.

But, but, but: The best available data today shows that attempting to terraform the entirety of Mars would be prohibitively expensive and may not work at all.

• According to a study published in 2018 in the journal Nature Astronomy, Mars doesn't actually have enough easily accessible carbon dioxide to be able to create an atmosphere hospitable to humans.
• Musk has floated the idea of reflecting light at Mars using orbiting satellites, but that would require millions of mirrors and the logistics would be extremely complicated, experts told Axios.

If somehow those problems could be overcome, terraforming an entire world could take hundreds of years, according to some estimates, and it would likely require hundreds of billions of dollars.

• Even if scientists were able to create a habitable Mars, it wouldn't necessarily stay that way forever.
• Due to Mars' small size, whatever atmosphere is created around the planet will likely dissipate after hundreds of thousands of years.

There are also ethical questions about whether humans should endeavor to fundamentally change Mars on such a grand scale.

• If life is found on the red planet, explorers and researchers would need to be careful not to disturb it, experts say, and that could make terraforming or even living on Mars in habitats very difficult.

The bottom line: Musk's focus on terraforming is entertaining for his followers on social media, but some scientists are frustrated that he perpetuates the idea that there is a "Planet B" that we could create for ourselves.

• "Frankly, it’s more dangerous to imagine that Mars could serve as a backup planet," Bruce Jakosky, a Mars researcher at the University of Colorado, Boulder, told Axios via email. "It might make us collectively less concerned with taking care of our home planet."

Editor's note: This story has been updated to include a comment from a SpaceX spokesperson.