William T. Bertrand

Cryogenic quartz crystal microbalance-characterization and calibration for Midcourse Space Experiment (MSX) program

This paper presents the results of an investigation of the operational characteristics of two cryogenically cooled quartz crystal microbalances (CQCM) which are flight units for the Midcourse Space Experiment (MSX) program. The units were operated at temperatures that ranged from 15 K up to 300 K. During the course of this investigation, the CQCMs were temperature cycled over this range for 5 complete warmup/cooldown cycles using warmup rates of 2.5 K/min and 1.0 K/min. There was concern over stop/start operations on orbit wherein the CQCM power could be turned off for some time. The CQCMs were cycled in this manner to determine the return frequency variations after power restoration. A three week drift test at 15 K was carried out to determine the drift in CQCM frequency with time. Temperature effects of the heat sink attached to the CQCM base were also determined by varying this temperature. Finally, films of nitrogen, oxygen, carbon dioxide, and water were deposited at the 15 K base temperature, and a thermogravimetric analysis was done for each of the gases condensed, both for individual gases and for gas mixtures. The results of these analyses will be used to interpret on-orbit analysis of contaminants that are condensed during operation of the SPIRIT III telescope on the MSX satellite.

Quartz crystal microbalance (QCM) flight measurements of contamination on the MSX satellite

The midcourse space experiment (MSX) satellite was launched into a 903 Km, 99.4-deg orbit April 24, 1996. It carries imaging spectrometers and radiometers that operate in the UV, visible, and infrared spectral ranges. In addition, it carries several contamination measuring instruments that are being used to characterize the contamination environment on, in, and around the satellite. Five are quartz crystal microbalances (QCMs), four of which are temperature- controlled (TQCMs). They are located on various external surfaces of the spacecraft and are operating at minus 40 degrees Celsius to minus 50 degrees Celsius to measure the condensation of silicone and organic molecules. One is a cryogenic quartz crystal microbalance (CQCM) which is located adjacent to the SPIRIT III infrared cryogenic telescope primary mirror. Its temperature followed the mirror which cooled from 28 to 20 K during the first week of operation. All QCMs recorded deposition in the 10 - 20 ng/cm

Characterization of Combined Orbital Surface Effects Test Capability at AEDC

2)-day (1-2 angstrom/day) range. Thermo-gravimetric analyses on the QCMs provided insight into the amount and species of contaminants condensed. Data from the QCMs and other instruments in the contamination experiment (CE) suite played an important role in determining when it was safe to open covers on some of the optical instruments.

Update of the midcourse space experiment (MSX) satellite measurements of contaminant films using QCMs

A combined space environment test facility has been created to test spacecraft components and subsystems in a realistic space environment without the expense of flight testing. The facility, developed at the Arnold Engineering Development Center, has the capability to test multiple spacecraft materials in a variety of combined space environments. Simulated environments include any combination of: atomic oxygen, solar ultraviolet radiation, spacecraftinduced contamination, low-energy ions, and spacecraft charging. In addition, total and directional reflectance measurements are performed in-vacuum. A final demonstration test verified combined environment operation and in-vacuum reflectance measurement capability. Future work involves fine-tuning the current system and further expanding the complexity of the simulated environment. Planning is also under way for a scaled-up version of this system that will be capable of testing larger subsystems and full-sized spacecraft.

QCM flight measurements of contaminant films and their effect on midcourse space experiment (MSX) satellite optics

The Midcourse Space Experiment (MSX) satellite was launched on April 24, 1996. This paper provides an update of the quartz crystal microbalance (QCM) data accumulated over these last four years in space. The MSX is the only known experiment that has provided continuous contamination monitoring for such an extended length of time. The five QCMs on board the satellite have provided on-orbit data that have been invaluable in characterizing contamination levels around the spacecraft and inside the cryogenic Spatial Infrared Imaging Telescope (SPIRIT 3). One of the QCMs, the cryogenic QCM (CQCM), located internal to SPIRIT 3, was mounted adjacent to the primary mirror and provided contamination accretion measurements during the 10-month lifetime of SPIRIT 3. Real- time monitoring of contaminant mass deposition on the primary mirror was provided by this CQCM which was cooled to the same temperature as the mirror - approximately 20K. Thermogravimetric analyses (TGAs) on the CQCM provided insight into the amount and species of contaminants condensed on the SPIRIT 3 primary mirror during various spacecraft activities. The four temperature-controlled QCMs (TQCMs) were mounted on external surfaces of the spacecraft for monitoring spacecraft contamination deposition. The TQCMs operated at approximately -50

Updated Version of the NASA SEE Program Spacecraft Contamination and Materials Outgassing Effect s Knowledgebase

DEGC and were positioned strategically to monitor the silicone and organic contaminant flux arriving at specific locations. Updated time histories of contaminant thickness deposition for each of the QCMs are presented. Gradual contaminant thickness increase was observed during the first year in space. During the second year, the QCM frequencies (contaminant film thickness) began to decrease, with the time of onset depending on QCM location. Possible explanationsfor this interesting behavior are discussed.

Space environmental and contamination effects on cryogenic and warm optical surfaces: a review

The Midcourse Space Experiment (MSX) is a Ballistic Missile Defense Organization (BMDO) demonstration and validation satellite program that has both defense and civilian applications. MSX has UV, visible, and infrared instruments including the SPIRIT 3 cryogenic telescope. It also has several contamination measuring instruments for measuring pressure, gas species, water and particulate concentrations and condensable gas species. A cryogenic quartz crystal microbalance (CQCM) and four temperature controlled microbalances (TQCMs) are part of this suite of contamination measuring instruments. This paper describes some of the flight QCM data obtained and analyzed to date. The CQCM is located internal to the SPIRIT 3 cryogenic telescope and is mounted adjacent to the primary mirror. Real-time monitoring of contaminant mass deposition on the primary mirror is provided by the CQCM which is cooled to the same temperature as the mirror -20 K. The four TQCMs are mounted on the outside of the spacecraft and monitor contaminant deposition on the external surfaces. The TQCMs operate at -50°C and are positioned strategically to monitor the silicone and organic contaminant flux arriving at the UV and visible instruments, or coming from specific contaminant sources such as the solar panels. During the first week of flight operation, all QCMs recorded deposition in the 10-20 ng/cm2-day (1-2 A/day) range. These TQCM deposition rates have continuously decreased, and after 270 days mission elapsed time (MET), the rates have fallen to values between 0 and 0. 15 A/day depending on TQCM location. Thermogravimetric analyses (TGAs) on the CQCM and TQCMs have provided valuable insight into the amount and species of contaminants condensed.

Comparison of retro-reflectance and total integrated scatter as a function of angle of incidence based on reflectometer measurements

This paper summarizes and updates new additions and changes to the NASA/SEE Spacecraft Contamination and Materials Outgassing Effects Knowledgebase (SCMOEK). Material outgassing data, optical properties of cryogenic films, round -robin outgassing summary, and space environmental effects library are discussed. Appro ximately 675 material outgassing data files are now included in the Knowledgebase and consists of many of the materials being used for space based applications. The round -robin series of tests were measurements made at 9 facilities throughout the United St ates that have the capability for making these measurements following the ASTM E -1559 Test Method. The optical property portion of the Knowledgebase consists of refractive (n) and absorptive (k) indices for 50

20K-cryogenic-temperature satellite materials outgassing facility for ASTM-E1559 standard

This review paper focuses on measurement techniques and facilities for the study of the contamination and space environment effects on optical and thermal radiative surfaces. Laboratory measurements are reviewed and illustrate how cryogenic and relatively warm surfaces can be affected by contaminants, vacuum, and UV. The laboratory data are used to illustrate the important parameters that require consideration when trying to determine these types of effects on future satellite missions. Optical properties of thin contaminants films, BRDF measurements on cryogenic films, quartz crystal microbalance (QCM) measurements, and UV effects on silicone/hydrocarbon films are presented and discussed relative to their applications to satellite systems. The laboratory data are complemented with flight data from the Midcourse Space Experiment (MSX) satellite. Laboratory results were used to interpret MSX spacecraft flight data. The MSX demonstration and validation satellite program was funded by the Ballistic Missile Defense Organization. MSX had UV, visible, and infrared instruments including the Spirit 3 cryogenic telescope and had several contamination instruments for measuring pressure, gas species, water and particulate concentrations, and condensable gas species. Some of the data collected from the flight QCMs are presented.

Midcourse Space Experiment (MSX) thermoelectric quartz crystal microbalances: calibration and characterization

A laboratory prototype reflectometer with applications in scene content characterization is available at the Arnold Engineering Development Center (AEDC), Arnold AFB. The SCAT/R measures specular, total, and retro-reflectance at five angles of incidence (AOI) scanning from 2.5 to 15 micrometers . Diffuse reflectance, total integrated scatter (TIS), and thermal emittance are calculated from the measurements. Conventional TIS measurements provide a good measure of a surface finish deviation from specularity, but the scatter distribution is not obtainable from a single measurement. By making TIS measurements over a series of AOI, information on the distribution is obtained. For example, a diffuse surface can be evaluated to determine whether the scattering is characterized by a Lambertian distribution. It has been observed that a series of retro-reflectance measurements at various AOI yields similar angle resolved information. In this paper, the relationship between retro-reflectance and TIS as a function of AOI is investigated for various materials using data from SCAT/R scans. The presentation and analysis of the data follow a brief description of the instrument. The SCAT/R thermal infrared data is useful in identifying/cataloging polarization and hyperspectral characteristics of materials and coatings used for camouflage and for other target and background applications.