What is spacex landing zone 4?

SpaceX landing zone 4 is a concrete pad located at Vandenberg Air Force Base in California, USA. It was constructed specifically for the recovery of Falcon 9 and Falcon Heavy rockets. The landing zone covers an area of approximately 200 feet by 200 feet, and is equipped with hydraulic dampeners and grid fins that help to stabilize the rockets during landing.

SpaceX's first successful landing at Landing Zone 4 was on October 7, 2018, when a Falcon 9 rocket successfully landed after launching the Argentine SAOCOM 1A satellite. Since then, SpaceX has conducted several successful landings at LZ-4, including the first stage of the Falcon Heavy rocket during its STP-2 mission.

SpaceX also has another landing zone, LZ-1, at Cape Canaveral Air Force Station in Florida. Both LZ-1 and LZ-4 are used to recover and refurbish the first stages of their Falcon 9 and Falcon Heavy rockets to help reduce launch costs.