In an essay published Tuesday on CNN’s website, President Obama renewed his call for American astronauts to visit Mars.

“We have set a clear goal vital to the next chapter of America’s story in space: sending humans to Mars by the 2030s and returning them safely to Earth, with the ultimate ambition to one day remain there for an extended time,” he wrote.

The plan is not new: The president laid out the same goal in 2010 during a speech at NASA’s Kennedy Space Center in Florida.

But the column on Tuesday, along with a joint blog post by senior White House and NASA officials, offered new details on how the United States expected to reach the red planet.