Crystalline emiristol
Crystalline emiristol was a type of low-technology solid propellant used as a fuel.

The Kataan probe, launched from Kataan in the 14th century, used crystalline emiristol as a propellant. This left behind a radioactive trail that the  could trace back to its home star system in 2368, using a probe. ()

Materials

it:Emiristolo cristallino