It’s Noisy Out In Space

“Before breakfast, FE-2/SO Don Pettit unstowed and prepared the personal acoustic dosimeters, including changing the batteries, to be carried by each crewmember for the periodic noise dosimetry. [Tonight, after about 15 hours of measurements, data from each dosimeter will be recorded and the hardware power-cycled.]”

“After wake-up at 1:00am EST and the daily morning inspection, CDR Ken Bowersox set up the SLM (sound level measurement) audio dosimeters for another noise survey in the station, tracking today’s crew ops acoustically.”

“At various times during the day, FE-1 Nikolai Budarin conducted acoustic measurements in the station to characterize acoustic noise in SM crew cabins;  Results of these measurement results are required to develop noise countermeasures for the crew quarters. [Acoustic survey was taken with nominally installed cabin doors open and closed, and with certain suspected sources of high noise in the cabins turned On and Off. Nikolai first installed cabin doors for the right and left crew quarters, then took measurements with the Russian noise meter with various noise-generating systems On and Off, finally downloading the data to Laptop 3. Measurement conditions were: Only continuously functional on-board systems were to be On, no intermittent noise, including conversation, short noise generated by Vozdukh scrubbing system valve state changes. For in-cabin measurements the microphone was to be positioned 1.5 m off the floor in the cabin center. The crewmember was to be in the cabin as far as possible from the microphone, maintaining the same body position throughout the series of measurements. Microphone not in the way of heavy airflow.]”

“Treschev also spent about an hour in the SM taking noise level readings with the “Shumometer” sound level meter. [Purpose of the periodic activity is the characterization of the potential sources of excessive acoustic noise in the SM cabins and above the treadmill (ventilation fans located in the RO work compartment). Only the continuously running vehicle systems in operation are recorded, with a step-by-step deactivation of individual ventilation fans. Results of the sampling will be used in the development of noise reduction measures and in the validation of the ground acoustic testing of the main noise sources on RSC-Energia’s SM simulator in KIS-416.]”

“Today’s timeline called for OHA (on-orbit hearing assessment) by all three crewmembers, last time done two months ago. After Carl Walz set up the necessary equipment, the OHA acoustic countermeasure assessment was completed by Yuri, Dan and himself. For the periodic hearing tests, the crew is using special EarQ software on their medical laptop, individually molded Prophonics ear plugs, Bose ANR (acoustic noise reduction) headsets, and a sound meter for background measurements.”

Editor’s note: Last Spring, during testing at KSC, the US Lab Module “Destiny” was found to be in violation of ISS program noise requirements. The noise level inside the US Lab exceeds the “NC-50” noise requirement (a weighted-average thing that comes out roughly 50 dB). A requirements change, CR3361, was promptly generated to relax the requirement. The CR appears to be on a fast track to approval since the usual “Technical Coordination Meeting” that is held to discuss a proposed change has been “bypassed” because it has been “sufficiently coordinated with the affected parties.”

The rationale given for requesting acceptance of this Change Request is ” The USL acoustic environment has been reduced during development by addition of mufflers, wrapping noise sources
with quieting materials, lining rack interiors with foam, and close-outs of acoustical openings. Additional reduction of acoustical
noise would result in unacceptable schedule delays and excessive cost. Program management has indicated that additional quieting
and operational constraints, if implemented, will be accomplished on-orbit. Noise levels higher than the specification are accepted
based on short operational duration or crew operations. Detailed technical rationale is documented in NCR-ISS-5A-022, Stage 5A
Integrated Acoustic Non-Compliance”

Included in the Adobe Acrobat file are:

• CR3361, “Exception to US Lab Acoustics NC50 Requirement”
  
• The TCM bypass notification for CR3361
  
• An extract from SSP41162, the specification for the US segment of ISS, with: the noise specification for the US segment and the existing waiver for Node 1
  
• An extract from SSP50005B (Space Station Flight Crew Integration Standard), section 5 (Natural and Induced Environments) with the NC-50 requirement and associated weighting curve).
  

Node 1 encountered the same situation. After testing, Node 1 was noisier than the requirement, but it was launched anyway. This is apparently symptomatic of what some people in the ISS program refer to as an “overall ISS bottom-up engineering philosophy”, which basically says “Boeing builds what it builds, and if it doesn’t meet the requirements (part of its contract with NASA), we’ll change the requirements.”

This, of course, can also be applied to Russia.

Editor’s note: This CR (Change Request) is working its way through the system. It would seem that the Service Module is not the only ISS element with partially addressed noise problems – problems that may only be resolved after the element is in orbit.

“Rationale: The USL acoustic environment has been reduced during
development by addition of mufflers, wrapping noise sources with quieting
materials, lining rack interiors with foam, and close-outs of acoustical
openings. Additional reduction of acoustical noise would result in
unacceptable schedule delays and excessive cost. Program management has
indicated that additional quieting and operational constraints, if
implemented, will be accomplished on orbit.”

Title: Russian Segment Acoustic Noise Violations

Number: 3774

Description: Russian Segment (FGB and Service Module) exceeds noise requirements

Full Text of Risk Summary: [Word] [Acrobat]

“(1) 2A.2 and 3A provides for relatively short noise exposure in the FGB (3A Crew does not go into SM). Shuttle flight rules on Acoustics are applicable for 10 – 14 day missions, and therefore can be applied to the FGB Prior to permanent crew habitation. (2) Quieting provisions were installed in the FGB on 2A.1 lessening the acoustical levels. Following completion of the acoustics data assessments from 2A.1, additional noise abatement measures may be required.”

NASA Watch Note: The following ISS Program Risk Summaries describe some of the current technical risks associated with Russia’s participation in the ISS program – and the methodical steps being taken to alleviate each of these problems. Each Risk Summary describes the problem and its potential impact on the program and safety, a designated point of contact, a ROM (Rough Order of Magnitude) cost estimate, an estimated closure date, an Abatement Plan Overview, Closure / Acceptance Criteria, and a listing of major actions taken to date. Each report is presented here in Word and Adobe Acrobat formats.

The sum of the listed ROM (Rough Order of Magnitude) costs for these 7 risk summaries (several of them list no cost impacts), estimated when the summaries were first written, was $3.096 billion. These costs represent the threat to the ISS program in a worse case scenario if the issues remained unresolved. As these issues were pursued towards resolution, these estimated cost impacts decreased.

• Russian Segment Acoustic Noise Violations
  
• Soyuz Launch Vehicle Upgrade
  
• Progress Supportability
  
• Russian Windows
  
• SPP Berthing Feasibility
  
• SPP Schedule & Funding
  
• Depressurization of the Russian Segment