What event is referred to as a "blast off"?

"Blast off" refers specifically to the moment when a spacecraft is launched into space. This term vividly captures the explosive release of energy and thrust that occurs at the start of a launch, allowing the vehicle to overcome Earth's gravitational pull. During this event, powerful rocket engines ignite, propelling the spacecraft into the atmosphere.

The other choices, while related to space exploration, do not encapsulate the same immediacy or context as "blast off." Satellite deployment typically occurs in orbit after a spacecraft has already launched, while aerospace experiments can take place during testing or research phases but do not have the dramatic connotation of launch. Rocket recovery involves the retrieval of a rocket after it has completed its mission and does not denote the initial launch phase. Thus, "blast off" is distinctively and appropriately associated with spacecraft launches.