The current cost to send a single person to Mars would be about $10 billion. But that price tag needs to come down to the median cost of a house in the United States if the human species is to survive, according to inventor Elon Musk.

The efficiency needs to improve by a whopping 5 million percent, Musk explains in plans published in the latest issues of the journal New Space, published by Mary Ann Liebert, Inc.

“If things go super well, it might be in the 10-year timeframe, but I do not want to say that is when it will occur,” Musk explains. “There is a huge amount of risk. It is going to cost a lot. There is a good chance we will not succeed, but we are going to do our best and try to make as much progress as possible.”

The piece, written in a conversational tone, is a summarized version of the talk Musk gave in September 2016 at the International Astronautical Congress in Guadalajara. Musk assesses the various extraplanetary colonization options – and settles on Mars as the most feasible.

“If we could warm Mars up, we would once again have a thick atmosphere and liquid oceans,” he writes. “It is a little cold, but we can warm it up.”

The logistics of traveling humans and material are the limiting factor. Methane would be the right propellant to cover the millions of miles to the red planet.

Reusable rockets and space vehicles that would be many times larger than anything yet built would have to be developed to get the best bang for the buck invested, Musk adds.

The one-way trip between the planets would eventually have to be cut down in coming decades to as little as 80 days, he explains.

Building up the infrastructure and the system would take years – and the establishment of a “fully self-sustaining civilization on Mars” would take up to a century, Musk adds.

Scott Hubbard, the Stanford professor who is the editor-in-chief of the journal, said the piece is a way to catalogue the bigger picture of space colonization, he said in a statement released through the publisher.

“In my view, publishing this paper provides not only an opportunity for the spacefaring community to read the SpaceX vision in print with all the charts in context, but also serves as a valuable archival reference for future studies and planning,” said Hubbard.

SpaceX, Musk’s rocket and exploration company, announced in February that their objective was to launch a crewed mission beyond the moon for two private customers for late next year.