The story of the Skylab space station, 50 years on

Fifty years since from its launch, we look back at the troubles and triumphs of the USA’s trailblazing space station.

By Jane Green

Published: Sunday, 14 May 2023 at 12:00 am

Skylab 1 was America’s first long-duration orbiting laboratory.

Crewed between May 1973 and February 1974, it was the ‘great uncle’ of Mir and the International Space Station, engineered from the shell of a redundant rocket stage (part of an earlier epic space programme).

Transformed with additional modules and structures, Skylab became an unmitigated success.

With humans now scheduled to return to the Moon in the near future, it’s time to celebrate this venerable one-of-a-kind space station.

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The Skylab space station in orbit. Credit: NASA

Early beginnings

Skylab was ultimately the result of Cold War political hostility between the Soviet Union and the United States, known as the Space Race.

When Russia launched its first artificial satellite, Sputnik, in October 1957 – aboard an R-7 rocket designed by Russian Sergei Korolev – the United States was worried.

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Sputnik 1 – the satellite that launched the Space Race. Credit: NASA

The race between these two superpowers for the domination of space began in earnest. Their next target? The Moon.

Having already sent astronauts into orbit during Project Gemini, on 20 July 1969 the Moon race was won by the USA when Apollo 11’s Neil Armstrong and Buzz Aldrin took humankind’s first footsteps in the lunar dust.

The next goal was to achieve a lasting presence in space: Skylab.

Reusing Apollo hardware

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A Saturn V S-IVB stage, modified to create an orbital workshop – later renamed Skylab – is unloaded at Redstone airfield, Alabama, 1968. Credit: NASA/MSFC

With the Apollo programme in the 1970s cut short, NASA began the Apollo Applications Program, its remit to adapt redundant hardware and systems developed for the lunar landing.

Needing to keep his staff employed, famed Apollo rocket engineer and head of NASA’s Marshall Flight Center, Wernher von Braun, advocated launching an orbiting workshop using two-stage Saturn IB rockets.

The hydrogen tank of the S-IVB stage would have ample room for what would be known as a ‘wet’ workshop.

It could be launched loaded with liquid oxygen and liquid hydrogen, functioning as the rocket’s second stage in ascent.

Once in orbit, any residual fuel and oxidiser could be vented and the oxygen tank pressurised to give astronauts a breathable atmosphere.

Pre-installed fittings could be made to the floors and walls – an aluminium grid structure with plentiful openings for fuel flow – enabling equipment to be mounted and experiments conducted.

On top of the S-IVB stage could be a Multiple Docking Adaptor (MDA) with two docking ports – a prime axial one and back-up radial one – for the Apollo Command and Service Modules (CSM) ferrying crews and supplies.

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A masterpiece of recycling, the station repurposed launch and flight vehicles from the Apollo era

In the event of a spacecraft being disabled, a second two-person crewed Apollo CSM capsule could rescue resident crew, enabling all five astronauts to safely return to Earth.

But concerns arose about the time required for astronauts, working in zero-G, to unload copious equipment from the MDA and install it in this ‘wet’ workshop.

By 1969, and with unused Apollo 18, 19 and 20 Saturn V rockets waiting in the wings, the decision was made to switch Skylab’s launch from the smaller Saturn IB rocket to the much larger Saturn V.

The greater capacity of the Saturn V meant that the S-IVB no longer needed to function as a rocket stage during launch.

This ‘dry’ Orbital Workshop (OWS) could be outfitted on the ground, the hydrogen fuel tank serving as the main living quarters, with exercise equipment, a galley, zero-gravity shower system and the necessary instruments for scientific experiments.

The liquid oxygen tank could be utilised as a waste facility.

Launch time for Skylab

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14 May 1973: the uncrewed Skylab is launched aboard a modified Saturn V rocket from NASA’s Kennedy Space Center

On 8 August 1969, after years of development and workshops, the McDonnell Douglas Corporation was awarded the contract to create an orbital workshop out of two existing S-IVB stages.

The unpiloted Skylab (SL-1) – weighing 77,088kg and the only space station built and operated solely by the USA – was launched on a two-stage Saturn V rocket (SA-513) on 14 May 1973 from Kennedy Space Center’s Pad 39A.

Shortly after lift-off, a large micrometeoroid shield – installed to deflect debris and act as a thermal blanket – structurally failed. Within seconds, aerodynamic forces ripped it from the station.

One of the two main solar array wings, designed to deploy in space, also partially deployed.

Several minutes later, after the rocket’s second stage burn, retro rockets fired, separating the booster from the station.

Their exhaust hit the partially deployed solar array and tore it off.

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Seamstresses stitch together a sun-shade for the Skylab Orbital Workshop. Credit: NASA

Later, in orbit, it was discovered that the other solar array had been tangled in debris and failed to deploy.

With the micrometeoroid shield missing, the station was exposed to extreme levels of solar radiation – a withering 52°C (126°F).

Mercifully, four solar arrays on the Apollo Telescope Mount (ATM) deployed as planned, giving sufficient power for Marshall Space Flight Center controllers to stabilise the station until repairs could be made.

On 25 May, after a delay for tools to be modified and techniques developed, and after subsequent crew training, Skylab 2 (SL-2) launched on a Saturn IB rocket (SA-206) carrying the first Skylab crew: commander Charles ‘Pete’ Conrad, pilot Paul Weitz and science pilot Joseph Kerwin.

On their second day in orbit, in searing temperatures, they deployed a 6.7m x 7.3m ‘parasol’ – a solar shade – through an airlock in the side of the OWS. Made of woven nylon, mylar and aluminium it instantly reflected sunlight and made the inside temperature bearable.

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Skylab 4 commander Gerald Carr balances fellow astronaut William Pogue, the mission’s pilot, upside down on his finger. Credit: NASA

Stabilising Skylab for operations

Along with the Orbital Workshop (OWS) and Multiple Docking Adaptor (MDA), there was the Airlock Module (AM), which could be sealed off and depressurised, enabling astronauts to exit via a large hatch to conduct spacewalks for changing camera film, performing experiments and doing routine maintenance.

On 7 June, the crew used this facility to release the jammed solar array and deploy it fully, increasing the available power.

Also key was the octagonal Apollo Telescope Mount (ATM) to which three control moment gyroscopes (CMGs) were attached, stabilising the entire station.

The ATM housed the four solar arrays and a battery of solar instruments.

Inside, a cylinder, divided into four quadrants and gimballed to enable exquisite pointing control, provided mounting points for X-ray and hydrogen-alpha telescopes, a spectroheliograph, spectrographs, a spectroheliometer, cameras and a white-light coronagraph.

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Astronaut Owen Garriott retrieves an image experiment from the Apollo Telescope Mount during a spacewalk on the second crewed Skylab mission. Credit: NASA

Working at a complex control console, astronauts viewed and studied our nearest star in X-ray, extreme ultraviolet, ultraviolet and hydrogen-alpha wavelengths – an operation, according to commander Charles Conrad, akin to “playing three 88-keyboard pianos at the same time”.

Solar flares, filaments, coronal holes, coronal mass ejections and even a comet – Kohoutek – were observed and imaged with hitherto unrivalled clarity.

These lengthy solar observations across the electromagnetic spectrum, above Earth’s atmosphere, vastly increased our knowledge of the Sun and the heavens.