Human Spaceflights

International Flight No. 44

Skylab 2

USA

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Launch, orbit and landing data

Launch date:  25.05.1973
Launch time:  13:00:00.53 UTC
Launch site:  Cape Canaveral (KSC)
Launch pad:  39-B
Altitude:  415 - 424 km
Inclination:  50.04°
Docking Skylab:  26.05.1973, 21:56:00 UTC
Undocking Skylab:  22.06.1973, 08:55 UTC
Landing date:  22.06.1973
Landing time:  13:49:49 UTC
Landing site:  25° 45' N, 127° 2' W

walkout photo

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alternate crew photo

alternate crew photo

alternate crew photo

alternate crew photo

Crew

No.   Surname Given names Position Flight No. Duration Orbits
1  Conrad  Charles, Jr. "Pete"  CDR 4 28d 00h 49m 48s  404 
2  Kerwin  Joseph Peter  SPT 1 28d 00h 49m 48s  404 
3  Weitz  Paul Joseph  PLT 1 28d 00h 49m 48s  404 

Crew seating arrangement

1  Conrad
2  Kerwin
3  Weitz

Backup Crew

No.   Surname Given names Position
1  Schweickart  Russell Louis "Rusty"  CDR
2  Musgrave  Franklin Story  SPT
3  McCandless  Bruce II  PLT

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Support Crew

  Surname Given names
 Crippen  Robert Laurel "Crip"
 Truly  Richard Harrison "Dick"
 Hartsfield  Henry Warren, Jr. "Hank"
 Thornton  William Edgar

Flight

Launch from Cape Canaveral (KSC); landing 1320 km southwest of San Diego in the Pacific Oecean.

The Skylab (SL) was a manned, orbiting spacecraft composed of five parts, the Apollo telescope mount (ATM), the multiple docking adapter (MDA), the airlock module (AM), the instrument unit (IU), and the orbital workshop (OWS). The Skylab was in the form of a cylinder, with the ATM being positioned 90 deg from the longitudinal axis after insertion into orbit. The ATM was a solar observatory, and it provided attitude control and experiment pointing for the rest of the cluster. It was attached to the MDA and AM at one end of the OWS. The retrieval and installation of film used in the ATM was accomplished by astronauts during extravehicular activity (EVA). The MDA served as a dock for the command and service modules, which served as personnel taxis to the Skylab. The AM provided an airlock between the MDA and the OWS, and contained controls and instrumentation. The IU, which was used only during launch and the initial phases of operation, provided guidance and sequencing functions for the initial deployment of the ATM, solar arrays, etc. The OWS was a modified Saturn 4B stage suitable for long duration manned habitation in orbit. It contained provisions and crew quarters necessary to support three-person crews for periods of up to 84 days each. All parts were also capable of unmanned, in-orbit storage, reactivation, and reuse. The Skylab itself was launched on May 14, 1973.

The Command Module (CM) was a conical pressure vessel with a maximum diameter of 3.9 m at its base and a height of 3.65 m. It was made of an aluminum honeycomb sandwhich bonded between sheet aluminum alloy. The base of the CM consisted of a heat shield made of brazed stainless steel honeycomb filled with a phenolic epoxy resin as an ablative material and varied in thickness from 1.8 to 6.9 cm. At the tip of the cone was a hatch and docking assembly designed to mate with the lunar module. The CM was divided into three compartments. The forward compartment in the nose of the cone held the three 25.4 m diameter main parachutes, two 5 m drogue parachutes, and pilot mortar chutes for Earth landing. The aft compartment was situated around the base of the CM and contained propellant tanks, reaction control engines, wiring, and plumbing. The crew compartment comprised most of the volume of the CM, approximately 6.17 cubic meters of space. Three astronaut couches were lined up facing forward in the center of the compartment. A large access hatch was situated above the center couch. A short access tunnel led to the docking hatch in the CM nose. The crew compartment held the controls, displays, navigation equipment and other systems used by the astronauts. The CM had five windows: one in the access hatch, one next to each astronaut in the two outer seats, and two forward-facing rendezvous windows. Five silver/zinc-oxide batteries provided power after the CM and SM detached, three for re-entry and after landing and two for vehicle separation and parachute deployment. The CM had twelve 420 N nitrogen tetroxide/hydrazine reaction control thrusters. The CM provided the re-entry capability at the end of the mission after separation from the Service Module.
The Service Module (SM) was a cylinder 3.9 meters in diameter and 7.6 m long which was attached to the back of the CM. The outer skin of the SM was formed of 2.5 cm thick aluminum honeycomb panels. The interior was divided by milled aluminum radial beams into six sections around a central cylinder. At the back of the SM mounted in the central cylinder was a gimbal mounted re-startable hypergolic liquid propellant 91,000 N engine and cone shaped engine nozzle. Attitude control was provided by four identical banks of four 450 N reaction control thrusters each spaced 90 degrees apart around the forward part of the SM. The six sections of the SM held three 31-cell hydrogen oxygen fuel cells which provided 28 volts, two cryogenic oxygen and two cryogenic hydrogen tanks, four tanks for the main propulsion engine, two for fuel and two for oxidizer, and the subsystems the main propulsion unit. Two helium tanks were mounted in the central cylinder. Electrical power system radiators were at the top of the cylinder and environmental control radiator panels spaced around the bottom.
This spacecraft was almost identical to the command and service module used for Apollo missions. Modification was made to accomodate long-duration Skylab missions and to allow the spacecraft to remain semi-dormant while docked to the Skylab cluster. A crew of three men and their provisions were carried. The mission of this spacecraft was to ferry a crew of three to the Skylab complex and return them to Earth.

This mission carried out the first crew of the Skylab space station. The flight became a "rescue mission" for the overheated space station, which had been damaged at its launch. Launched on May 25, 1973, the first Skylab crew's most urgent job was to repair the space station. Skylab's meteorite-and-sun shield and one of its solar arrays had torn loose during launch, and the remaining primary solar array was jammed. Without its shield, Skylab baked in the sunshine. The crew had to work fast, because high temperatures inside the workshop would release toxic materials and ruin on-board film and food

The first EVA, in fact a SEVA, was performed by Paul Weitz on May 25, 1973 (0h 40m). The astronauts moved the Skylab 2 CM close to the jammed array. Paul Weitz then stood with his upper body through the hatch and assembled a 4.5-m (15-ft) pole with a shepherd's hook on the end from three 1.5-m (5-ft) sections handed to him by Joseph Kerwin. He hooked and pulled on the array while Joseph Kerwin gripped his legs. Charles Conrad had to hold the CM steady because Paul Weitz's efforts pulled it toward the workshop. Paul Weitz replaced the hook with a universal prying tool when the strap did not budge, but to no avail. Their efforts thwarted, the astronauts docked with Skylab and closed out a 22-hour day.

On June 07, 1973 the second spacewalk occurred (3h 25m). Joseph Kerwin and Charles Conrad rehearsed the planned EVA inside Skylab, and on this date depressurized the Skylab Airlock Module, which was made cramped by their burden of tools. Charles Conrad left the airlock through its surplus Gemini hatch and stepped into the Pressure Garment Assembly foot restraint at the Fixed Airlock Shroud work station. Joseph Kerwin passed him six 1.5-m (5-ft) poles, helped him assemble the cable cutter assembly, then moved to the discone antenna using the ATM girders and other projections in the EVA Bay as mobility aids. Charles Conrad handed him the cable cutter assembly, then moved to the discone antenna carrying the BET. The plan called for Joseph Kerwin to hook the cable cutter assembly on the strap holding wing 1 closed. Charles Conrad would then crawl down the assembly to wing 1 and attach the BET. However, Joseph Kerwin had difficulties finding a firm foothold near the discone because Skylab unexpectedly differed from the mockup in the tank in Huntsville. He was forced to hold on with one hand while attempting to position the pole with the other. After a frustrating half hour, Joseph Kerwin shortened his 1.8-m (6-ft) tether by doubling it. This held him more firmly against Skylab and allowed him partial use of his other hand. He finally succeeded in hooking the aluminum strap. Charles Conrad attached the BET large hook to the discone antenna, then climbed along the cable cutter assembly pole. He attached one of the two BET small hooks to bolt holes on wing 1. Again the flight Skylab differed from the ground mockup; the second small hook would not fit. Joseph Kerwin tightened the BET at the discone end using a cleat, then cut the strap holding the array closed. Charles Conrad placed the BET over his shoulder, put his feet against the workshop's hull, and strained against the BET to pull open the array. Joseph Kerwin joined him. Finally the hydraulic damper holding the array closed gave way.

For the final EVA Charles Conrad and Paul Weitz left the Skylab station on June 19, 1973 (1h 36m). The first part of the EVA was very similar to the EVA as planned pre-flight. The astronauts removed film from the ATM solar telescopes for return to Earth and replaced the film. This required a fraction of the time planned. Four of Skylab's five EVA work stations were positioned to restrain the astronaut during film changeout. The Fixed Airlock Shroud (FAS) station, the main EVA work station, was located next to the external airlock hatch. The FAS station was the "base camp" for ascending the ATM. The astronauts moved between the work stations via the Deployment Assembly route, or "EVA Trail." The route consisted of single and dual handrails, the latter resembling ladders without rungs. According to the Skylab astronauts, the single handrails worked well, while translation using the dual rails was as easy as "driving on the freeway." All handrails were painted blue for visibility and provided with "road signs" - alphanumeric designators. The blue faded rapidly in the strong sunlight of space, however, and the designator labels proved difficult to see. ATM film cassettes were moved in a device called a film tree. The primary method of moving the trees was by three extendible booms located in the EVA Bay within reach of FAS. Controls for the motorized booms were located next to the EVA hatch. The booms could be manually operated if necessary, and "clotheslines," pulley-type devices, provided a backup film transport method. Their film changeout tasks completed, Charles Conrad and Paul Weitz removed space exposure samples launched on the workshop's exterior to accompany them back to Earth. Paul Weitz and Charles Conrad then moved on to tasks added after the successful wing 1 deployment on EVA 2. They used a brush to clean the White Light Coronograph occulting disk, which was producing glare. Charles Conrad then moved to Circuit Breaker Relay Module 15. Acting on instructions from the ground, he hit it with a hammer to free a stuck relay. This low-tech solution succeeded and soon the module was feeding electricity into the Skylab power system again. The EVA brought the total for Skylab 2 to more than 5 hours, twice what was originally planned.

For nearly a month they made further repairs to the workshop, conducted medical experiments, gathered solar and Earth science data, and performed a total of 392 hours of experiments. The mission tracked two minutes of a large solar flare with the Apollo Telescope Mount; they took and returned some 29,000 frames of film of the sun. The Skylab 2 astronauts spent 28 days in space, which doubled the previous U.S. record.

The recovery ship was the USS Ticonderoga.

Photos / Graphics

Apollo CSM
Skylab
crew in training
crew in training Conrad in training
Earth observation
 

more Earth observation photos


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Last update on May 01, 2017.