|"An overhead view of the Skylab space station cluster in Earth orbit as photographed from the Skylab 4 Command and Service Modules (CSM) during the final fly-around by the CSM before returning home." Feb. 8, 1974 NASA photo|
“All things must pass away.” -George Harrison, “All Things Must Pass”
According to the NASA History book Living and Working in Space: The NASA History of Skylab, Skylab 4’s commander, Gerald Carr, boosted the space station’s orbit by firing the Apollo spacecraft’s attitude-control thrusters for three minutes at the end of his crew’s 1973-1974 mission. It was then expected that the space station might remain in orbit for another nine years, through 1983. By 1977, that expectancy shifted to 1980, the solar maximum year. But in early 1978, it was clear that Skylab might come down even sooner than expected. Solar activity had been the highest ever recorded by modern instruments, and this factor increased drag on the space station.