Final answer:
The astronaut associated with Apollo 18 who never flew again due to budget cuts is Harrison Schmitt, the only scientist who walked on the Moon during Apollo 17. The Apollo missions were stopped abruptly after Apollo 17, although future lunar exploration and scientific interest does continue.
Step-by-step explanation:
The individual associated with Apollo 18 who never flew again after the Apollo program was terminated is Harrison Schmitt. Schmitt was an astronaut-scientist who walked on the Moon during the Apollo 17 mission and was scheduled to go back with the planned Apollo 18. Unfortunately, due to budgetary constraints, the funding for additional missions were cut, and the program ended after Apollo 17, making that the last manned lunar mission. As a result, Schmitt never had the opportunity to return to the Moon.
The cost of the entire Apollo program was relatively modest by today's standards—only about $100 per American over a decade, roughly equal to the cost of a large pizza per year. Despite the affordability, the program was not able to escape political and economic pressures, leading to its premature end. Subsequently, massive Apollo rockets were left to languish, although some have since been moved to museums. Interest in lunar exploration has persisted, with spacecraft from various countries continuing to visit the Moon's orbit or surface in the past two decades. While Apollo 18 and subsequent missions were cancelled, the fascination with Moon landings as a pivotal moment in the 20th century remains.