Most parts of rockets are usually discarded on their way to space, but Elon Musk's SpaceX company has reused parts of an old rocket for another mission.
Recycling rocket components will greatly decrease the cost of launching satellites into space. In 2016 SpaceX showed that used boosters from its Falcon rockets can land safely back on Earth. After the landing, scientists inspected the boosters for several months before confirming they were safe to be used again.
Recycling is good for the planet, so I hope other rocket companies do the same!