The effects of acoustic levels in manned space vehicles was not thoroughly appreciated until the STS 40 mission, Spacelab Life Sciences 1 (June, 1991). Previous to that mission, waivers were submitted and equipment operated without overwhelming effect on ongoing flight activities. The factors of multiple pieces of noise producing equipment operating simultaneously, operating in the vicinity of crew sleep stations, and operating for this long of a mission (10 days) became relevant in crew tolerance, fatigue, communication, and permanent shifts in hearing thresholds. Because this was a life sciences mission, accurate instrument measurements were obtained of acoustic levels in the middeck, flight deck and spacelab during flight and physiological measurements were obtained from the crew members during all phases of the mission. Due to the STS 40 results, a Spacelab/Payloads Acoustics Working Group (SPAWG) was formed post flight to address acceptable acoustic limits. The charter of this group was to: Identify and assess orbiter, spacelab, subsystems, and experiment hardware with the objective of reducing the overall acoustic levels on the Middeck and within the Spacelab module to acceptable flight levels. Members of the group represented NASA headquarters, field centers, and payload developers.
This paper will briefly address the acoustic impact on crew persons during STS 40, the recommendations of the SPAWG, and current means of addressing acoustic issues within life sciences hardware flown on microgravity missions.