A small shuttlepod of the Enterprise-D, named after the astronaut Ellison Onizuka, which Data flew to Tau Cygni V and Geordi La Forge took towards Risa.
The Onizuka was a two-seat shuttlepod carried by the Enterprise-D. Its name honours Ellison Onizuka, who died in the Challenger accident of 1986.
In The Ensigns of Command, hyperonic radiation around Tau Cygni V makes transporters useless and is deadly to humans, so Data goes down alone in the Onizuka to persuade the colonists to leave before the Sheliak arrive.
In The Mind's Eye, Geordi La Forge sets out in the same pod for a conference on Risa. A Romulan warbird intercepts it on the way. La Forge is taken aboard and conditioned as an assassin while a double goes on to Risa in his place, and he is returned to the Enterprise with no memory of the abduction.