The phrase "blast off" refers to launching a spacecraft or missile, and therefore the concept of antonyms for this phrase might seem difficult to comprehend. However, if we look at it in a broader sense, we can come up with some antonyms that describe the opposite of launching or taking off. Words like "land," "descend," "touch down," or "settle" could be seen as antonyms, as they all describe the process of lowering or reaching a surface, instead of ascending or rising. Other potential antonyms for "blast off" could be "disembark," "unload," or "deactivate," as they all suggest the opposite of initiating an action or starting a journey.