payload

A payload is usually what's being carried or transported by a vehicle or spacecraft. For example, a plane might carry cargo as its payload.

The word "payload" often comes up when talking about space exploration. When a rocket blasts off into orbit, it's carrying a payload of instruments and equipment to study the stars or take pictures of distant planets. Sometimes scientists pack a lot of heavy gear on board, like solar panels or communication devices, which become part of the payload. In other cases, the payload might be something smaller, like a tiny robot designed to explore a new world.