An entire copy of Wikipedia etched on to nickel disks in microscopic font could be on the moon.
The 30-million pages were created for the Arch Lunar Library and put on Israel's failed Beresheet Mission.
However, the items were designed to be indestructible and the creators believe they could have survived.
Unfortunately, where they are on the moon is anyone's guess with speculation they were flung away from the crash site.
A Tweet from Arch Mission Foundation said: "The landing was a little bumpier than expected, but airplane black boxes survive stronger impacts, and our disc is less breakable.
"Small, light objects, like our 100 gram library, do better in impacts. It was probably thrown a few km away - a 30 million page frisbee on the moon."
As well as the Wikipedia contents there were also 30,000 books and other facts of human existence.
Nova Spivack, one of those involved in the project, tweeted: "When you look at the Moon from now on - realise there is a lost library there - containing Wikipedia, 30,000 books, 5000 languages, the history of the world, David Copperfield’s secrets, and much more."
Arch is now appealing for help to work out where the items might have landed.
The robot craft Beresheet, built by non-profit SpaceIL and state-owned Israel Aerospace Industries (IAI), crashed on its final descent on Thursday.
This dashed Israel's hope of becoming the fourth country to manage a controlled lunar landing.
However, it is now planning another attempt.
