Fluorescence-based thin film measurements using the vpcarwater recovery system in lunar and microgravity

Nancy Hall*, Michael Perez, Eric Litwiller, Michael Flynn, Jeffrey Mackey

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

3 Scopus citations


Due to the impracticality of storing large quantities of fresh water in NASA long-term exploration missions, a Vapor Phase Catalytic Ammonia Removal (VPCAR) system was refined for the purpose of purifying water from wastewater products in low gravity environments. Major modifications were performed on the diagnostic measurement systems, which included fiber-coupled photomultiplier tube assemblies and camera systems. Ground testing and calibration were performed to determine fluorescent dye/water solution evaporation rates for future heated VPCAR operations and to obtain accurate calibration curves for both the camera-based and photomultiplier tube (PMT) based film measurements. Testing was then conducted in September of 2007 aboard the NASA C-9B Reduced Gravity Aircraft platform simulating both lunar gravity and microgravity levels with the purpose of quantifying the low-gravity performance of thin film measurement subsystem modifications made to the VPCAR water recovery system after its previous reduced gravity aircraft flight in October 2006. Four reduced gravity aircraft flights were conducted in September 2007 in which testing employed the use of two fiber-coupled PMT systems and one camera system to detect fluorescence intensity levels that were proportional to the film thickness. A second camera system was used to detect the difference in water spray levels occurring from the wiped film rotating disk (WFRD) in lunar gravity and microgravity. The PMT light collecting fiber tips were mounted using a new custom made mount located in a position near the hub of the rotating disk distillation component of the VPCAR system on the opposite side from the wiper. In order to more accurately quantify film thickness, the fiber mount was equipped with a new splash guard reducing dye/water spray accumulation near the fiber tips. This paper presents VPCAR film measurement systems design and calibration, fluorescent dye/water evaporation test results and film thickness measurement results in earth, lunar and microgravity operations.

Original languageEnglish (US)
Title of host publication46th AIAA Aerospace Sciences Meeting and Exhibit
StatePublished - 2008
Externally publishedYes
Event46th AIAA Aerospace Sciences Meeting and Exhibit - Reno, NV, United States
Duration: Jan 7 2008Jan 10 2008

Publication series

Name46th AIAA Aerospace Sciences Meeting and Exhibit


Other46th AIAA Aerospace Sciences Meeting and Exhibit
Country/TerritoryUnited States
CityReno, NV

ASJC Scopus subject areas

  • Aerospace Engineering


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