The skylab space station, called Skylab 1, was itself a spacecraft. It was launched into orbit by a two-stage version of a Saturn V rocket. All the main components of the station were integrated into a complete unit which replaced the S-IVB third stage.
The three subsequent missions to the station, Skylab 2, 3 and 4, carried three astronauts each to the station using Apollo Command and Service Modules (CSMs). These were each launched into orbit by a Saturn IB rocket. A proposed Skylab 5 mission and a standby rescue mission would also have used Saturn IB rockets, but were not flown.
Reference: Wikipedia - Saturn V, | Saturn S-IVB | Apollo Command and Service Module, | Saturn IB
The mission of a CSM spacecraft to the station has five main steps:-
The first step is to launch the CSM spacecraft and overcome the Earth's gravity so that it can be placed in a similar orbit to the station. The Apollo Command and Service Modules (CSMs) were each launched into orbit by a Saturn IB rocket.
The Saturn IB was a two-stage rocket. The first stage used eight H-1 engines to lift the weight of the spacecraft, launch vehicle and fuel. When the first stage fuel is used the stage and fuel tanks are discarded to be destroyed. The second stage used 1 J-2 engine to place the CSM into rendezvous orbit.
The rendezvous orbit matches the CSM to the required altitude and speed to catch and dock with the station.
The CSM uses its' own small thruster rocket engines to guide it to the docking point. After initial contact the docking mechanism pulls the craft in and securely locks it to the station with an air tight seal.
Un-docking is the reverse procedure to docking and uses a similar method. After un-docked the CSM uses its thruster to move to a safe distance clear of the station and then uses its 1 x AJ10-137 main engine to slow down for de-orbit. The Service Module and engine are then jettisoned and destroyed on re-entry into the Earth's Atmosphere.
When the spacecraft has slowed sufficiently gravity pulls the Commend Module, containing the crew, into the Earth's atmosphere. It uses its heat shield to slow the decent speed until parachutes are able to be deployed for safe splashdown into the ocean. Ships then recovered the capsule and crew.
Spacecraft missions to the station can be grouped into the following four categories:-
The Skylab station, Skylab 1, was launched as a single unit with its main components already assembled. In orbit the solar arrays and the Apollo Telescope Mount were deployed.
The station crews, Skylab 2, 3 and 4, were transported separately to the station. Each crew returned before the next was launched. Therefore only one docking port was used.
Supplies include all those goods needed to operate, maintain, live in and use the station. Skylab was a habitable station and needed to be repaired and maintained in orbit and provide life support for its crews.
They required consumables such as fuel, water, food, oxygen and spare parts. They were also a working research stations requiring specific equipment and experiment materials from and to the Earth.
Each Skylab crew carried all the necessary consumables, parts and equipment for their mission with them in the CSM. Extra supply missions were therefore not required.
If a failure occurred on the station, which threatened life support, the crew could return to Earth immediately using the docked CSM.
In the event of a failure of a CSM, after docking with the station, it was planned to send a "rescue mission". This would use a CSM modified to carry five astronauts, two going to the station and five returning. a rescue mission was never needed.
The following table lists the spacecraft and carrier rockets used for the Skylab module launch and the crewed missions.
| Statistics | ||||
| Module | Crew Missions | |||
| Skylab 1 | Skylab 2 | Skylab 3 | Skylab 4 | |
| Number of Crew | 0 | 3 | 3 | 3 |
| Spacecraft | Skylab | Apollo CSM-116 | Apollo CSM-117 | Apollo CSM-118 |
| Carrier Rocket | Saturn V AS-513 | Saturn IB SA-206 | Saturn IB SA-207 | Saturn IB SA-208 |