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Characterizing ISS Charging Environments with On-Board Ionospheric Plasma MeasurementsCharging of the International Space Station (ISS) is dominated by interactions of the biased United States (US) 160 volt solar arrays with the relatively high density, low temperature plasma environment in low Earth orbit. Conducting surfaces on the vehicle structure charge negative relative to the ambient plasma environment because ISS structure is grounded to the negative end of the US solar arrays. Transient charging peaks reaching potentials of some tens of volts negative controlled by photovoltaic array current collection typically occur at orbital sunrise and sunset as well as near orbital noon. In addition, surface potentials across the vehicle structure vary due to an induced v x B (dot) L voltage generated by the high speed motion of the conducting structure across the Earth's magnetic field. Induced voltages in low Earth orbit are typically only approx.0.4 volts/meter but the approx.100 meter scale dimensions of the ISS yield maximum induced potential variations ofapprox.40 volts across the vehicle. Induced voltages are variable due to the orientation of the vehicle structure and orbital velocity vector with respect to the orientation of the Earth's magnetic field along the ISS orbit. In order to address the need to better understand the ISS spacecraft potential and plasma environments, NASA funded development and construction of the Floating Potential Measurement Unit (FPMU) which was deployed on an ISS starboard truss arm in August 2006. The suite of FPMU instruments includes two Langmuir probes, a plasma impedance probe, and a potential probe for use in in-situ monitoring of electron temperatures and densities and the vehicle potential relative to the plasma environment. This presentation will describe the use of the FPMU to better characterize interactions of the ISS with the space environment, changes in ISS charging as the vehicle configuration is modified during ISS construction, and contributions of FPMU vehicle potential and plasma environment measurements to investigations of on-orbit anomalies in ISS systems.
Document ID
20090007706
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Minow, Jospeh I.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Craven, Paul D.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Coffey, Victoria N.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Schneider, Todd A.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Vaughn, Jason A.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Wright Jr, Kenneth
(Alabama Univ. Huntsville, AL, United States)
Parker, Paul D.
(Jacobs Engineering Group, Inc. Huntsville, AL, United States)
Mikatarian, Ronald R.
(Boeing Co. Houston, TX, United States)
Kramer, Leonard
(Boeing Co. Houston, TX, United States)
Hartman, William A.
(Boeing Co. Houston, TX, United States)
Alred, John W.
(NASA Johnson Space Center Houston, TX, United States)
Koontz, Steven L.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
September 29, 2008
Subject Category
Space Sciences (General)
Report/Patent Number
MSFC-2021
Meeting Information
Meeting: 59th International Astronautical Conference
Location: Scotland
Country: United Kingdom
Start Date: September 29, 2008
End Date: October 3, 2008
Sponsors: British Interplanetary Society
Distribution Limits
Public
Copyright
Other

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