NASA Investigation Board Report On The INITIAL FLIGHT ANOMALIES OF SKYLAB 1

Program Objectives

Skylab missions have several distinct goals: conduct of earth resources observations. advance scientific knowledge of the sun and stars; study the effects of weightlessness on living organisms, particularly man; study and understand methods for the processing of materials in the absence of gravity. The Skylab mission utilizes man as an engineer and as a research scientist, and provides an opportunity for assessing his potential capabilities for future space missions.

Skylab Hardware

Skylab utilizes the knowledge, experience and technical systems developed during, the Apollo program along with specialized equipment necessary to meet the program objectives.

Figure 1-1 shows the Skylab in orbit. Its largest element is the Orbital Workshop (OWS), a cylindrical container 48 feet long and 22 feet in diameter weighing some 78. 000 pounds. The basic structure of the OWS is the upper stage, or S-IVB stage, of the S-IB and S-V rockets which served as the Apollo program launch vehicle. The OWS has no engines, except attitude control-thrusters, and has been modified internally to provide a large orbiting space laboratory and living quarters for the crew. The Skylab 1 (SL-1) space vehicle included a payload consisting of four major units (OWS, Airlock Module (AM)., Multiple Docking Adapter (MDA), Apollo Telescope Mount (ATM)) and a two-stage Saturn-V (S-IC and S-II) launch vehicle as depicted in figure 1-2. To provide meteoroid protection and thermal control, an external meteoroid shield (MS) was added to cover the OWS habitable volume. A solar array system (SAS) was attached to the OWS to provide electrical power.

The original concept called for a "Wet Workshop". In this concept, a specially constructed S-IVB stage was to be launched "Wet" as a propulsive stage on the S-IB Launch System filled with propellants., The empty hydrogen tank would then be purged and filled with a life-supporting atmosphere. A major redirection of Skylab was made m July 22, 1969, six days after the Apollo 11 lunar landing. As a result of the successful lunar landing, S-V launch vehicles became available to the Skylab program. As a result, it became feasible to completely equip the S-IVB on the ground for immediate occupancy and use by a crew after it was in orbit. Thus it would not carry fuel and earned the name of "Dry Workshop".

Skylab Mission Plan

The nominal Skylab-mission (fig. 1-3) called for the launch of the unmanned S-V vehicle and workshop payload SL-1 into a near circular (235 nautical miles) orbit inclined 50 degrees to the equator. Then about 24 hours after the first launch., the manned Skylab 2 (SL-2) launch would take place using a Command Service Module (CSM) payload atop the S-IB vehicle. After CSM rendezvous and docking with the orbiting cluster, the crew enters and activates the workshop; Skylab is then ready for its first operational period of 28 days. At the end of this period, the crew returns to earth with the CSM, and the Skylab continues in an unmanned quiescent mode for some 60 days. The second three man crew is launched with a second S-IB, this time for a 56-day period of manned operation. After return of the second crew to earth, the Skylab again operates in an unmanned mode for approximately one month. The third three-man crew is then launched with the third S-IB for a second 56-day period In orbit after which they will return to earth. The total Skylab mission activities cover a period of roughly eight months, with 140 days of manned operation.

Skylab Program Environment

The Skylab Program Office in the Office of Manned Space Flight in NASA Headquarters is responsible for overall management of the program. The NASA Center responsibilities are as follows:

The major Skylab prime and first tier subcontractors and their. responsibilities are shown in table I-1.

    Figure 1-1   

    Figure 1-2   

    Figure 1-3 - Skylab mission profile