The checklist astronaut James Lovell scratched out to calculate his crippled spacecraft’s reentry into earth’s orbit fetched a tidy sum at auction Wednesday. Heritage Auctions, based in Dallas, sold the Apollo 13 artifact to an undisclosed American collector for $388,375. The item was originally valued at $25,000, according to the Telegraph

According to Gizmodo, Lovell scribbled out his calculations of the space craft’s position in space a mere two hours after he famously said, “Houston, we have had a problem.”

A mere 55 hours into the mission, an explosion rocked the Odyssey. The astronauts on board—James Lovell, Jack Swigert, and Fred Haise—had to travel the 200,000 miles back to earth aboard the Lunar module, Aquarius. This document was key in turning the third mission to the moon into “a successful failure,” as it has been called.

“There are few space artifacts as evocative or important as this little booklet,” Michael Riley of Heritage Auctions told the Telegraph. “This checklist may not have made it to the moon’s surface, but it saved the lives of the crew of Apollo 13, captivated the world’s attention and is an amazing artefact {sic} of a moment that was, simultaneously, one of America’s darkest and proudest.” 

Tom Hanks portrayed Lovell in 1995’s Apollo 13. The retired astronaut has homes in Horseshoe Bay and Lake Forest, outside Chicago. Until recently, this artifact was languishing on one of Jim Lovell’s bookcases. Lovell, 83, told Reuters he had “forgotten about the notebook.”

“I was cleaning out some old stuff on a bookcase and found it. My kids took all they wanted and I donated a lot of my collection to museums,” Lovell told Reuters. “I decided to put this up for auction so that someone who is really interested in this piece of history can enjoy it.”

Gizmodos has a large image of the checklist, officially called the Lunar Module Systems Activation Checklist Book, as well as a transcript of the conversation Lovell had with Mission Control about the accuracy of his math.