Final answer:
The next NASA project after the Apollo missions was Skylab, America's first space station, followed by the Space Shuttle program.
Step-by-step explanation:
After the Apollo missions ended, NASA shifted its focus to low Earth orbit projects, leading to the development of Skylab, America's first space station. Skylab was launched by NASA in 1973 and was used for various scientific experiments and observations of the Sun and Earth until its decommission in 1979. Following Skylab, NASA embarked on the Space Shuttle program, which began flights in 1981 and continued for thirty years, fostering advancements in space exploration, science, and international cooperation. The Space Shuttle program operated from 1981 to 2011 and had a total of 135 missions. It was an important part of human spaceflight for several decades and played a significant role in the construction and maintenance of the International Space Station.