In every one of its job postings, SpaceX says it's pursuing the "ultimate goal of enabling human life on Mars."
To that end, its website hosts an image of a rusty-red planet morphing into an Earth-like world. The illustration is a nod to a hypothetical and speculative process called terraforming.
Terraforming is a type of climate change, but deliberate and more rapid than the process that's happening on Earth right now.
The idea is that Mars could be transformed into a warm, wet world — one better suited for permanent human colonization — if we can melt the planet's carbon-dioxide-rich ice caps.
In its current state, Mars has less than 1% of the atmospheric density at its surface compared to Earth. (Mars had most of its air blown into space billions of years ago.) That makes it comparable to a vacuum chamber. Under those conditions, harmful space radiation doesn't get blocked, and people couldn't breathe outside of a spacesuit or sealed colony.
It's unknown whether terraforming could be done in a sustainable amount of time on Mars. NASA doubts that it's possible at all, since there may not be enough gases trapped in the poles to feed a cozy planetary atmosphere.
Plus, the effort might require a kind of powerful satellite that could generate a magnetic shield to protect against solar radiation that'd otherwise blow away any human-manufactured atmosphere.
On the flip side, the scenarios researchers have looked into don't really consider water or methane (a potent greenhouse gas) that may be trapped in the Martian ground. They also don't investigate whether any chemical-rich comets and asteroids could be redirected to strike Mars. Musk has even said nuking Mars might help.
Experimenting with terraforming may be only one way to tell if it's possible. Musk, or perhaps his memory and legacy, just might be the impetus that makes it happen in the distant future.