Question: did the robinsons make it back to earth

Answer: No, In early 1968, while the final third-season episode ``Junkyard in Space'' was in production, the cast and crew were informally made to believe the series would return for a fourth season. Allen had ordered new scripts for the coming season. A few weeks later, however, CBS announced a list of television series they were renewing for the 1968--69 season, and Lost in Space was not included. Although CBS programming executives failed to offer any reasons why Lost in Space was cancelled, there are at least five suggested reasons offered by series executives, critics and fans, any one of which could be considered sufficient justification for cancellation given the state of the broadcast network television industry at the time. As there was no official final episode, the exploring pioneers never made it to Alpha Centauri nor found their way back to Earth.