50 years ago: Skylab launches towards near disaster

May 14, 1973: Skylab, America’s first space station, lifts off cleanly on the last Saturn V. But a minute later . . .


Welcome aboard Skylab, America’s first space station.  Our target no longer the moon.  Our target is the Earth.  The sun, too.  Our target envelopes the spaces above the sky and a large spaces within the shell of what once was a Saturn third stage.  

There on Pad 39-A a space station sits in place of Saturn V number 513, the last of the big boosters scheduled to fly, awaiting launch this afternoon, May 14, 1973.  There the converted moon rocket sits, like a rifle cartridge pointed at the sky, the nose of the station enclosed in an aerodynamic shroud.  Here it is, real after years of delay and doubt, the overlooked stepchild of the Apollo program.  Skylab, the last remnant of the ambitions of the mid-sixties called Apollo Application Program that would have expanded upon the lunar program in a variety of projects in earth orbit and on the moon.  This is all that survived the budget cuts that began after the Apollo fire in 1967.

Picture it as it soon will be in orbit, liftoff set for 1:00 p.m. EDT.  See yourself approaching the massive station in a modified Apollo, as we will tomorrow, our liftoff aboard the smaller Saturn IB set for  1:30 p.m.  

See us approaching the station.  Its sheer bulk grows larger and larger, demanding attention, yet the Apollo Telescope Mount (ATM) draws out eyes, riding perpendicular to the station on a crisscross of trusses.  The eight instruments for studying the sun are housed the hexagonal box.  It measures 13.2 ft. long and 11 ft. across.   Four windmill-like solar power arrays, long and narrow, extend from ATM in an X pattern, spanning 98 ft. along each direction.  They can generate up to 10.480 watts of power.  

They provide not even half of the Skylab’s power.  Two solar wings will extend from opposite sides of the converted stage, called the Orbital Workshop, which makes up the main part of the space station.  These panels, measuring 27 ft. by 31 ft. each, will provide 12,400 watts of power.

The Multiple Docking Adapter pokes from under the truss of beams holding ATM.  This cylinder is a remnant of an early version of the APP station, the “wet” workshop.  In the original concept the actual second stage (S-IVB) of a Saturn IB booster would after use be converted.   Astronauts would have docked with the stage at the Multiple Docking Adapter (MDA), which would have featured several docking ports for adding experimental modules, including an ATM telescope housed in a converted Lunar Module.  When, in 1969, tests showed that converting the interior of the tank into a habitat posed too many problems, the project switched to a “dry” workshop, launched already outfitted on a Saturn V taken from the Apollo project.

The MDA retained the main docking port at its long end, and just a single backup radial (side) port.  Apollo spacecraft, modified versions of the ones that took astronauts to the moon, will ferry crews to the station, docking to the main port.   The module measures 10 ft. in diameter and 17 ft. long, with a working volume of 1,140 cubic ft., (compared to 210 cubic ft. for the Apollo command module).  That space is now used to house many experiment systems, such as those for Earth sensing instruments and the control panel for the solar telescopes.  An experiment in itself, the module was not laid out with a a floor/walls arrangement to give a visual “up” and “down.”  Equipment is located around the circular interior of the cylinder.  Actually, the arrangement, while somewhat confusing, poses no problem. The human eye carries its own reference of up and down.  The module, loaded, weighs 13,800 lb.

It leads to a smaller cylinder, the Airlock Module, partially nested in a ring extending from the converted S-IV stage where the forest of struts holding the telescope mount is anchored.  At the MDA end, it maintains the 10-ft. inside diameter, then narrows to 5.5 ft. at the forward airlock hatch.  At the side of this tunnel, a Gemini hatch provides the exit for spacewalks.  The sole task envisioned for spacewalks involves changing film used by the ATM telescopes. The airlock module is 17.5 long in total, with a volume of 624 cubic ft.  It weighs 14,500 lbs.  A hatch at the aft ends opens to the forward dome of the Orbital Workshop, the main body of the station.  The circular hatches are nearly 4 ft. in diameter.

The workshop is built in the interior of what would have been the hydrogen tank of the S-IVB stage.  It is 48 ft. long. and 21.67 ft. in diameter, yielding a habitable volume of 9,550 cubic ft.  The workshop weighs 78,000 lbs.  The upper dome is ringed with stowage lockers and water tanks

The massive interior space below the dome is divided into two levels by an open grid serving as floor and ceiling.  The large open space of the top floor is set aside for experiments, such a test flying a version of a maneuvering backpack, a prototype for ones to be used on spacewalks in the future.  In addition to experiment equipment, it also contains a film vault, food lockers and even a food freezer.

The lower level, with much less ceiling height, is divided into several “rooms.”  One section contains three sleeping berths with privacy curtains.  They are oriented vertically, as if the occupant in a sleeping bag was hanging on the wall.  It’s one of two exceptions to the “up” and “down” orientation of the workshop.  

A “waste management” compartment is wedged between the sleeping births and a wardroom.  It contains a water dispenser and a toilet that, in the absence of gravity, operates using air currents to draw away feces into a collector.   It is mounted on the wall, the other exception to the vertical orientation of the workshop.

The wardroom forms another room, s place for the crew to gather.  It’s centerpiece is three food warming trays like the petals of a flower around a central stem.  It is a room with a view.  A large circular observation window, a rather late addition to the design, opens the space inside the “can” to the space around the Earth.

The largest area of the lower level forms an experiments area.  It contains a lower body negative pressure device, an experiment to see if low pressure exerted on the legs will keep blood from pooling in the upper body.  Many of the medical experiments will be conducted in the area.  It’s equipped with a rotating chair to be used to spin a subject to investigate vestibular disturbances in weightlessness.  And contains a stationary bicycle, ergometer, to test changes in lung function — and provide exercise.

At the center of the lower level, a lid opens to a trash airlock.  Bagged trash will be drawn into the empty, unpressurized volume of what was the S-IVB oxygen tank. Overall, the station measures 118 ft. long.

There you have it — everything needed to sustain our three crews is loaded on one vehicle, the 333-ft.-tall two-stage version of the Saturn V.  That includes about 2,000 lbs. of food in eleven lockers, 12,000 gal. of water, and 450 pieces of clothing.  About 1,800 items are stowed in 400 locations, all carefully inventoried. 

Oh, yes, one other structure:  A micrometeoroid shield of thin metal wrapped tightly around the belly of the workshop for launch.  Once on orbit, by means of tension bars, it will be extended 5 in. above the hull, braking and breaking apart any micrometeoroids that strike the station.  It also is covered in patterned gold paint which protects against and balances the extreme heat of the sun. 

The Skylab program costs $2.6 billion.  The station itself, about the size of a two-bedroom home, is pegged at $294 million, all riding on one shot.


All is ready for launch at 1 p.m. EDT.  We, the three crews who with inhabit Skylab in missions of 28, 56, and 56 days over an 8-month period are present to witness the launch.  The weather is cooperating, thunderstorms staying off the the west, although the sky is partly cloudy. 

The last Saturn V (outside of museums) is ready to take to the sky.  At T – min. 8.9 sec., the five first stage engine begin their start sequence, building to 7.6 million lbs. of flaming thrust.  T – zero, release and liftoff.  

“We have a liftoff.”  Rising slowly, the stack leans away from the launch tower for safety.

“Skylab has cleared the tower.”

“Houston is now in command.”  The vehicle makes its pitch and roll maneuver to cock it on the proper heading for a high-inclination orbit tilted 50 degrees to the equator.   Thirty seconds since launch — the stack passes in and out of clouds.  “Good thrust on all five engines.”   At about 45 sec., Skylab passes punches into a solid cloud layer, lost to tracking cameras.

Sixty seconds — the vehicle goes supersonic, 10 sec. from “Max Q” where the combined forces of air pressure and velocity places the maximum stress on the structure.  

At 1 min. 30 sec., the call comes from Mission Control, “Passed through Max Q.  Still looking good.”


Stop right there.  Up there in the sky, unseen beyond the clouds, something has happened, something hinted at by just a few real-time telemetry readings received in Mission Control.

Rewind the clock to one minute in the climb beyond the clouds.  At 60.12 sec. after launch, torsion rod #7 of the micrometeoroid shield, shifted toward deployed.  The rod, one of eight sets of two, is located near an auxiliary tunnel running up the side of the workshop.  The tunnel runs between two panels of the shield, containing a smaller tunnel through containing the wiring for the thruster system.  Due to poorly fitting seals — and two missing ones — air is ramming into the tunnel, spilling under the nearby shield panels made of thin aluminum.  The upper edge of the micrometeoroid shield near the tunnel likely began to come loose at this time.  

At 61.78 sec., the vehicle’s roll rate decreased slightly.  Tension rod #7 continued to release, with pressure increasing under the meteoroid shield.  At 62.75 sec., sensors inside the station registered an unusual vibration quickly followed by sudden increase in the vehicle’s roll rate, caused by the air flow venting through hinges in the meteoroid shield.  The shield begins to be peeled from the hull of the workshop, wrapping around solar wing #2 and tearing free.  The force, at about 62.85 sec., breaks the wing’s tiedowns.  Wing #2 is unlatched and loose.  

The meteoroid shield continues to unwind.  At 63.17 sec., a large vibration is recorded as a piece of the shield strikes the interstage between the workshop and the Saturn’s second stage.  At 63.70, panels of the shield, still peeling away, reach solar wing #1, and wrap around the wing.  The remainder of the shield tears loose, some of the straps pulled over the still-latched wing. 

Roll rates and readings return to normal.  As if nothing had happened above the clouds. 


“Roll program complete.”  We’ve  reached 1 min. 30 sec.  “Passed through Max Q.  Still looking good,” Houston says.  Now 1 min. 45 sec.  “All sources continue to look good.”

At 2 min. 18 sec.    “Coming up on center engine shutdown.  On time.”  Followed by:  “Standing by for first stage shutdown.  First stage shutdown, on time.  Show good ignition of all five second stage engines.”


At 9 min. 49 sec. since launch, shutdown of the second stage.  The orbit is nearly perfect at 171 mi. altitude.  And three seconds later, four-solid fueled rockets on the spent stage fire to separate it from Skylab and push it away.  A few seconds later telemetry shows an unusual wobble that quickly dampens out.  But everything appears to be going fine.  The steps ahead to transform Skylab into its orbital configuration are all conducted automatically.

The nose of the vehicle, still encased in the large launch shroud, pitches down towards Earth in what is called a gravity gradient attitude, where gravity keeps the position stable.  And 15 min. 40 sec. after launch, pyrotechnics blow away the four clamshell panels of the shroud, exposing the front end of the space station.  The telescope mount rides at the tip, in front of the docking adapter.  At 16 min. 39 sec., electric motors pivot it on its truss arms 90 degrees from the long axis of the station.  The ATM locks into place in less than 4 min.  Eight minutes later the automatic system begins deploying its four “windmill” solar arrays.  Most of these steps occur out of communications range of the network of 11 ground stations around the world, supplemented by a tracking ship and aircraft.

Next comes deployment of the two big solar wings on the body of the workshop.  This process begins 41 min. after launch as the long booms containing the arrays are to swing out perpendicular to the station.  Then 11 min. later, the three panels of each wing, folded accordion style in the booms, are commanded to unfurl.


Let’s back up again — to the moment the second stage separated from Skylab.  The plume of the retrorockets blasted against the unlatched solar wing #1, opening it with such a force that it snapped away.  Gone.


Two minutes after the solar wings are commanded to unfurl, 54 min. since launch, Skylab comes into range of the Carnarvon, Australia.  Telemetry indicates the wings have not deployed.   Near the end of the first orbit, Skylab comes into contact with the Goldstone and Texas tracking stations, at which time deployment of the micrometeoroid shield is due.  Telemetry shows “no joy” — no deployment.  They also receive an indication of a short in relay used to deploy the workshop’s wings.  All other systems show green . . . except for one other oddity.  Solar wing #1 on the workshop is producing 25 watts of power.  The two wings should be producing 6 kW.  On the second orbit, backup commands to deploy the shield are sent.  No joy.   And temperatures begin to fluctuate and rise.  

Three hours into the flight, controllers realize the meteoroid shield had torn away at launch.  They soon realize that solar wing #2 is missing.  And wing #1 appears to be stuck against the side of the station, open just a crack, enough to provide a trickle of power.

Obviously our launch aboard the Apollo ferry cannot take place on schedule.  Power is the main concern at this point.  Supplementing the ATM windmill arrays with power from the Apollo’s fuel cells, might yield enough power to run the workshop and its experiments for a couple weeks or so.  And maybe a flight could be stretched for a 28 day with minimal power.  With this hope, launch is reset for May 20.

Not so fast, however:  Temperatures quickly rise to 100 degrees (F) in the workshop.  The exposed outer skin of the station could reach 325 degrees (F) in the sun.  Indeed, interior temperatures in places reach to as much as 170 degrees (F).  Skylab is cooking to death.

No launch will be possible even on the 20th.  Time is needed to devise a rescue plan, improvise some sort of sunshield.  The Skylab astronauts return to Houston on the morning of the 15th, the entire project in jeopardy.  Pete Conrad, commander of the first flight, says, “About all I can say is we’ve come home to regroup.”

Time is everything. 

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