During 2014 and 2015, NASA's Neutron star Interior Composition Explorer (NICER) mission proceeded success- fully through Phase C, Design and Development. An X-ray (0.2-12 keV) astrophysics payload destined for the International Space Station, NICER is manifested for launch in early 2017 on the Commercial Resupply Services SpaceX-11 flight. Its scientific objectives are to investigate the internal structure, dynamics, and energetics of neutron stars, the densest objects in the universe. During Phase C, flight components including optics, detectors, the optical bench, pointing actuators, electronics, and others were subjected to environmental testing and integrated to form the flight payload. A custom-built facility was used to co-align and integrate the X-ray "con- centrator" optics and silicon-drift detectors. Ground calibration provided robust performance measures of the optical (at NASA's Goddard Space Flight Center) and detector (at the Massachusetts Institute of Technology) subsystems, while comprehensive functional tests prior to payload-level environmental testing met all instrument performance requirements. We describe here the implementation of NICER's major subsystems, summarize their performance and calibration, and outline the component-level testing that was successfully applied.
The GOES-12 spacecraft exhibits a loss of heat rejection capabilities over the long term. It also presents a
unique opportunity to evaluate this change at more than one temperature. The Imager and Sounder instruments use
passive radiant coolers to reject heat from their sensors, and operate near 200 Kelvin. The Solar X-ray Imager (SXI)
instrument mirror operates at or above 273 Kelvin. The mass deposition for SXI is substantially less than that of the
Imager and Sounder. The phenomenon is evaluated and reasons for it discussed. This paper follows other descriptions
by the author of the electrostatic return and introduces photolytic interactions at different temperatures.
The reduction in molecular outgassing afforded by the high vacuum degassing of the system components and the expected outgassing of the same when employed under normal ambient pressure and purging are evaluated and discussed. The contaminant deposits that could be expected from the residual outgassing systems are evaluated. A
comparison of the contamination produced by the outgassed and non-outgassed systems has been carried out and is based on the outgassing rate of a combination of devices in the compartment obtained at the end of a reasonable period of outgassing in vacuum and on the rates at the time of employment.
The Geostationary Operational Environmental Satellite (GOES) Sounder instrument uses radiant coolers to reduce the operating temperature of the detectors and filter wheel. GOES resides in an equatorial orbit 36,000 kilometers above the earth, and is stationary with respect to it. During the year, all sides of the spacecraft are exposed to the sun; the filter wheel emitter and detector radiators must be shielded form it to adequately cooled these components for nominal operations.Mirror Optical Solar Reflectors are used too reject sunlight before it can strike the radiators. Molecular outgassing from the Sounder instrument cavity, the filter wheel module, and the Sounder vacuum cooler housing have been demonstrated through mass transport modeling to contaminate the filter wheel sunshield panels during the in- orbit Radiant Cooler bakeout. Excessive molecular and particulate contamination can increase solar energy scatter, increase thermal emittance, and increase solar absorptance; all of which can increase the temperature of the components they serve, thus degrading nominal operations. After the GOES-K spacecraft thermal vacuum test, a haze was observed on and around the entrance aperture, and on the inside faces the filter wheel cooler sunshield. This paper documents the inspections, testing, and analysis used to: a) locate the likely sources for the contaminants, b) predict molecular contaminant accumulation on the filter wheel sunshields during the in-orbit bakeout, c) estimate the thermal effects from molecular build-up, and d) assess proposed hardware modifications and show the selection rationale used to maintain functionality for the GOES-K Sounder instrument.
EOS AM-1 is the first in the series of the EOS spacecraft developed to advance the understanding of the biological and geophysical processes of the Earth's climate on a global basis. The fully integrated spacecraft is EOS AM-1 flight- phase contamination analysis has been performed to verify that the design of the spacecraft is compatible with limiting contamination to the level required for optical instruments and sensor, thermal control surfaces and solar array as well as to identify modifications if needed. This paper summarizes the approach and assumptions used in performing this contamination source and effects analysis for the EOS AM-1 spacecraft. Molecular and particulate contamination potential during the flight segment from launch through completion of orbital mission has been analyzed. Potential contamination sources examined include materials outgassing, instrument and spacecraft bus venting, spacecraft plume and other sources such as mechanisms, moisture absorption, and atomic oxygen. The modeling result have been used to confirm outgassing materials selection, to verify venting designs, and to develop bakeout requirements for components of the spacecraft bus and the instruments.
In preparation for the Hubble Space Telescope (HST) second servicing mission, hardware which was assembled a decade earlier was refurbished and cleaned to meet a requirement more than an order of magnitude cleaner than the original requirement. The fine guidance sensor (FGS) radial bay module is located in ]close proximity to the HST science instruments; therefore the condemnation sensitivity of the second servicing mission science instruments necessitated the establishment of new FGS contamination requirements. These new requirements are based on a critical optics temperature of minus 88 degrees Celsius; the original FGS outgassing requirements were based on protecting the HST primary mirror, which has an average temperature of plus 10 degrees Celsius. A contamination reduction plan was devised, implemented, and refined, resulting in partial deintegration of the FGS, the use of molecular adsorbers, and the use of a bakeout temperature within 1 degree of Celsius of the maximum survival temperature of the hardware. Final contamination measurements are within 3% of the predicted levels and meet the second servicing mission contamination requirements.
The Hubble Space Telescope was designed to be periodically serviced on-orbit during its 15 year mission. Servicing carriers have been designed for these servicing missions and were previously flown during the Hubble Space Telescope Servicing Mission 1, Space Transportation System 61, December 1993. In preparation for the Hubble Space Telescope Servicing Mission 2, the Hubble Space Telescope contamination control philosophy was reviewed to determine its applicability to reflown hardware. The contamination control program currently in place for the Hubble Space Telescope Servicing Mission 2, evolved from the Hubble Space Telescope Servicing Mission 1 contamination control program. The challenge of the Hubble Space Telescope Servicing Mission 2 contamination control program was to maintain the integrity and outgassing certification of the reflown hardware while accommodating configuration changes to the hardware. Environmental control of the hardware, materials screening and outgassing certification of added hardware were the important features of the program.