Natural and Induced Space Environments Effects on the International Space Station
- Paper number
IAC-05-B4.2.07
- Author
Mr. Carlos Soares, Boeing Integrated Defense Systems, United States
- Coauthor
Mr. Ronald Mikatarian, Boeing Integrated Defense Systems, United States
- Coauthor
Dr. William Schmidl, Boeing Integrated Defense Systems, United States
- Coauthor
Courtney Pankop, The Boeing Company, United States
- Coauthor
Dr. John Alred, Boeing Integrated Defense Systems, United States
- Coauthor
Mr. Paul Boeder, Boeing Integrated Defense Systems, United States
- Coauthor
Mr. Gregory Pilkinton, Boeing Integrated Defense Systems, United States
- Coauthor
Dr. Steven Koontz, National Aeronautics and Space Administration (NASA)/Johnson Space Center, United States
- Year
2005
- Abstract
Space environments disciplines are an essential component of anomaly resolution activities and flight operations on the International Space Station (ISS). The interactions with the natural and induced space environments play a critical role in ISS mission operations. The lessons learned and processes developed for ISS are applicable to the design, assembly, and operations of long-duration space systems including new space station designs and missions to the Moon and Mars. The ISS Environments Team is responsible for multiple disciplines within the ISS Program, including external contamination, ionizing radiation, neutral atmosphere and solar ultraviolet radiation, plasma effects and acoustics. The Team is involved in many aspects of flight operations and supports anomaly resolution and risk mitigation activities. This paper discusses some of those activities. These include imaging, venting and thruster operations, optical property degradation, science operations, ionospheric plasma charging effects, natural environment effects, and noise control in habitable areas. Imaging is a critical resource used to record the condition of ISS surfaces, and it aids in the identification of surface degradation, contamination and plasma effects. Comprehensive image surveys are performed during Shuttle missions and on an on-going basis with the ISS robotic arm and truss-mounted cameras. Venting operations are an integral part of ISS operations. The vehicle has 33 active vents (this figure excludes contingency vents) that vent gases and liquids to space. Depending on the effluent, vent exhausts can produce contamination, erosion (direct impact) and violations of the molecular column density requirement. Thruster operations happen during approach and separation from visiting vehicles, reboost and attitude control, desaturation of Control Moment Gyros (CMGs), etc. Thruster firings induce contamination and erosion on ISS sensitive surfaces. Thruster induced contamination produces optical property degradation and hazards to extra-vehicular activity (EVA) as the fuel/oxidizer reaction products contain toxic byproducts. Thruster induced erosion can cause excessive damage to the solar cells’ anti-reflective coating. Optical property degradation models, drawing on data from both on-orbit and ground-based experiments, were developed to support ISS operations, and are continuously updated as new data become available. The predictive capability of this model has been used to extend the life of orbital replacement units (ORUs) and decrease operational constraints through relief of thermal environment predictions. The Environments Team also supports science operations. As an example, studies were conducted to develop flight rules needed to protect the U.S. Lab window from induced contamination with its shutter. The ISS, because of its large structure and high voltage solar arrays, has a complex plasma interaction with the ionosphere in low Earth orbit (LEO). This interaction of the ISS US Segment photovoltaic (PV) power system with the LEO ionospheric plasma produces floating potentials on conducting elements of the ISS structure relative to the local plasma environment. To control the ISS floating potentials, two Plasma Contactor Units (PCUs) are installed on the Z1 truss. Atomic oxygen, solar ultraviolet radiation and electron radiation can have a significant effect on the performance of select types of materials exposed to the external space environment. Changes in material properties are not always well characterized prior to use of the materials on-orbit. The ISS vehicle contains a significant amount of hardware susceptible to ionizing radiation induced single event effects (SEE). As of Flight/Stage 11, the US segment of ISS contains over 600 SEE susceptible avionics boxes and 3000 devices susceptible to SEE induced functional interrupt. Crew exposure to noise is a consistent concern among flight doctors. Most of the internal ISS hardware produces noise, or unwanted sound. Whether it’s due to fans, pumps, or motors, the noise can approach unacceptable levels. Unlike a normal worker, a crewmember cannot go somewhere to get out of the environment. The noise must be continuously monitored to protect the astronauts from hearing damage. Immediate response is necessary in case of a noise anomaly.
- Abstract document
- Manuscript document
IAC-05-B4.2.07.pdf (🔒 authorized access only).
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