Buzz Aldrin on the moon
U.S. astronaut Buzz Aldrin stands beside a solar wind experiment next to the Lunar Module spacecraft on the surface of the moon after he and fellow astronaut Neil Armstrong became the first men to land on the moon during the Apollo 11 space mission, July 20, 1969. Reuters/Neil Armstrong/NASA/Handout

Buzz Aldrin may have been the second man to walk on the moon but he's almost certainly the first person to pose for a photo at Stonehenge wearing a T-shirt that says, “Get Your Ass To Mars.” That's exactly the image Aldrin posted on Twitter as part of his argument that NASA should spare no expense to make the journey to the red planet.

With his hands pulling open an outer shirt, Aldrin, 85, stood in a Superman-like pose near the ancient British rock formation to reveal the T-shirt he's now made famous. Aldrin has worn the “Get Your Ass To Mars" shirt while making appearances on behalf of his ShareSpace Foundation, the organization he founded to advocate for science and math education in the U.S. (His effort is also represented by the hashtag #GYATM on Twitter.)

The T-shirt is available for sale in a range of colors, but it's clear that Aldrin is in it for more than the money. He previously suggested colonizing Mars with a one-way trip, with the first humans there ultimately starting a settlement that others can visit later. He addressed the issue, and the idea of entrepreneur Elon Musk's SpaceX making the first trip, during a Reddit Ask-Me-Anything session last year.

“Tourism trips to Mars and back are just not the appropriate way for human beings from Earth -- to have an individual company, no matter how smart, send people to Mars and bring them back, it is VERY expensive. It delays the obtaining of permanence, internationally,” Aldrin wrote before addressing the Reddit user who asked the initial question.

“Your question referred to a monumental achievement by humanity -- that should not be one private company at all, it should be a collection of the best from all the countries on Earth, and the leader of the nation or the groups who make a commitment to do that in 2 decades will be remembered throughout history, hundreds and thousands of years in the future of the history of humanity, beginning, commencing a human occupation of the solar system.”