Elon Musk, the CEO of both Tesla and SpaceX, is taking on a new project.

He is writing a book for Penguin.

We're told it's a book about Earth and Mars. It will be half about the issues facing us on Earth — sustainability issues in particular.

The second half will be about the idea of a multiplanetary existence — about what's possible, about the adventure of experience.

Musk's literary agent is Jennifer Rudolph Walsh, an agent at William Morris.

Walsh invited a group of publishers to hear a pitch on the book. All of them bid. Musk narrowed the field down to two. Penguin flew someone out to meet with Musk at SpaceX's California headquarters. They won the deal.

Multiple sources say Musk will make more than $3 million on the deal. We heard $3.5 million a couple times. One source close to the deal says that's low.

Musk told a source of ours that he plans to write the book all by himself, without a ghost writer, and that he is ready for it to take a while, perhaps a couple of years.

That's good news for Bloomberg Businessweek's Ashlee Vance, who has a highly anticipated book about Musk coming out in a few months.

Musk has a grand vision for the book's launch, a source tells us. He hopes to launch it across the globe in multiple languages on the same day. Many in the publishing industry will laugh at the absurdity of that idea — but then again, none of them have launched any rockets or built any electric-car companies lately.

Correction: An earlier version of this story said that Jennifer Walsh run an agency called Worldwide Literary Department. She does not. She is an agent at William Morris, where, according to LinkedIn, she is "EVP and Co-Head" of its Worldwide Literary Department. We apologize for this mistake.