This week in rocket history we’re looking back at the first crewed mission to the USA’s first space station: Skylab 1. Or two, depending on who you ask. The first crewed mission to Skylab was originally called Skylab 1 and then retroactively changed to Skylab 2. Some sources still call it Skylab 1. The Rocket Roundup team was highly annoyed so to keep the confusion to a minimum, we’ll refer to it as the first crewed Skylab mission.

Skylab the space station was a converted Saturn V third stage fitted out on the ground and launched on another Saturn V. The original plan was to launch Skylab as an active “wet” workshop where it would launch as the second stage of the much smaller Saturn 1B rocket and insert itself into orbit and be converted to a space station there. Yes, that means they were going to fill the second stage with fuel and some internal bits, launch it into space, drain the remaining fuel, and convert the now-empty second stage to a space station on orbit.

After Apollo 18 through 20 were cancelled, the concept switched to a “dry” workshop launched on one of the now spare Saturn Vs.

Skylab was launched on May 14, 1973, and suffered some damage on the way up. During launch, the station’s micrometeoroid shield (which protects the pressurized space from impacts with debris) separated early. The errant shield took one of the two solar arrays with it. This caused a lot of problems, most importantly making the station too hot to enter safely, over 54 degrees Celsius or about 130 degrees Fahrenheit. All other aspects of launch were normal. The Apollo Telescope Mount with its smaller solar panels were deployed, giving the station a small amount of power. This was clearly a major problem, and NASA set to work on a repair to be implemented by the first crewed mission a week later.

This made that first crewed mission to the space station a very critical one.

In order to make the needed repairs, NASA first needed to know the extent of the damage. A highly classified National Reconnaissance Office Keyhole-8 (Gambit 3) film camera reconnaissance satellite was tasked with taking pictures of the damaged station to assist with the repair plan. The satellite was launched on May 16, Skylab was imaged on May 19t and the photo was returned to the ground (along with pictures of targets in the Soviet Union, its primary mission) on May 20.

Following the rushed design and build of an expandable sunshade in seven days, the crewed Skylab mission was launched on May 25, 1973, at 13:00 UTC. The three crew members were Pete Conrad as Commander, Paul Weitz as Command Module Pilot (CMP), and Joseph Kerwin as Science Pilot. They launched in an Apollo Command Module carried to orbit on a two stage Saturn 1B. Because of the low Earth orbit destination and the capabilities of the launch vehicle, the Service Module was loaded with much less fuel than for a lunar mission.

The launch of the first crewed Skylab mission was nominal, and on its fifth orbit, it successfully rendezvoused with Skylab the space station. Command Module Pilot Weitz flew the Apollo around the station and inspected the damage before docking, which turned out to be very difficult — it took eight attempts to achieve a hard dock. As soon as they docked with the space station, it was time to get to work.

The crew attempted an Extra Vehicular Activity (spacewalk) to free the stuck solar panel with Weitz standing up in the Apollo and pulling on the debris that was keeping the solar panel stuck using a cable cutter on a three-meter pole while Conrad flew the spacecraft. This first attempt was unsuccessful.

The crew boarded the station, and on the second day of flight they absolutely had to do something about the temperature. Remember, it was over 54 degrees Celsius inside the station. So the sunshade was deployed by the astronauts from inside the station by using the science airlock in the Apollo Telescope Mount. Once the sunshade was finally deployed, the temperature in the module immediately dropped, at a rate of 18C or 64F per hour. It stabilized at a much more reasonable 23C (74F).

With the interior now at a comfortable temperature, the next step was to free the solar panel. This was successfully completed on the second spacewalk of the mission on June 7, which was conducted from the airlock onboard Skylab, a Gemini spacecraft hatch built into the structure. The EVA was not without problems, however, as Kerwin and Conrad found that the actual station differed from the mockup they had trained on, and at the moment the solar panel was freed, the two astronauts were flung off the structure by the force. They remained attached through their tethers, and the shaken astronauts were able to return to the inside of the station.

The rest of the astronauts’ 28 total days in space were much less eventful. On June 19, Conrad and Weitz performed the third and final EVA of the mission. This one was completely nominal: the two spacewalkers used handrails to move around and a pulley system to remove film canisters and space environment samples from around the module. They also cleaned the outside of one of the telescopes and performed percussive maintenance – yes, they hit it with a hammer – to reopen a stuck circuit breaker preventing all the power generated by the module from going to Skylab proper.

Altogether, the crew performed 392 hours of scientific experiments, including observing two major solar flares with the telescopes. They also conducted further investigations into the human body’s reaction to weightlessness, made possible by that vast, converted fuel tank that formed Skylab’s pressurized module. Some of the equipment included a rotating chair and a zero-g treadmill to gauge the ability of a human body to do physical work in space.

The Apollo capsule carrying the first astronauts to Skylab splashed down in the Pacific ocean 1,320 kilometers west of San Diego, California at 13:49 UTC on June 22, 1973. The USS Ticonderoga, an Essex class aircraft carrier, handled the recovery.

More Information

Concept to Design: Defining the Workshop (NASA History)

Chapter 5: Years of Uncertainty, 1967-1969 (NASA History)

Skylab 2: “We can fix anything!” (NASA)

Those magnificent spooks and their spying machine: The spies help rescue Skylab (The Space Review)

More Details for 1973-05-26 (Astronautix)

Skylab 2 (Astronautix)

Skylab 2 (Space Facts)