Statistics – Applications
Scientific paper
Dec 1996
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996esasp.392..125o&link_type=abstract
Environment Modelling for Space-based Applications, Symposium Proceedings (ESA SP-392). ESTEC Noordwijk, 18-20 September 1996. E
Statistics
Applications
Scientific paper
Six INTELSAT VIII/VIIIA satellites currently under construction at Lockheed Martin Astrospace facilities in Princeton, New Jersey, USA, will be equipped with electrostatic charge sensors and associated equipment in order to monitor external and internal charging via normal spacecraft telemetry measurement. This paper will describe the design, implementation, measurement strategy, deployments plans associated with the two types of sensors to be installed on these satellites. The discharge threat model which will use the sensor telemetry data as input will also be described. The planned utilization of near real time charge distribution predictions as determined from this model versus the detection and mitigation of the internal and surface electrostatic discharge threat will be discussed. The first INTELSAT VIII satellite equipped with these sensors is planned to be launched in early 1997 and the following five satellites are planned to be launched four months apart following the first. Two types of sensors are planned to be installed on each INTELSAT VIII/VIIIA satellite. The first type of sensor is called "Surface Charge Monitor" which consists of a 2x2 inch alluminum plate painted with Chemglaze dielectric paint and bonded to the spacecraft structure with a non-conductive adhesive. It is designed to measure charging by magnetospheric plasma electrons with energies from 5 keV to 20 keV and with worst case current density from 0.1 to 1 nA/cm2. This range was chosen because it has the probability of occuring of 99%. The charge monitor will indicate when such an environment is present at the spacecraft's orbital location. Two of these units, one on the anti-earth panel another on either the north or south transponder panel, are being mounted onboard each INTELSAT VIII/VIIIA satellite. The second type of sensor is called "Dosimeter/Internal Charge Monitor" consisting of a sensor housing plate equipped with four identical radiation sensitive p-FET device each shielded with a different thickness Kovar lid. The shield thickness on each device were selected by trading FET lifetime versus sensitivity to dose. The dosimeter was designed to monitor flux of, and total dose imparted by, electrons with energies from 200 keV to 6 MeV. This detector will indicate when such an environment is present at the spacecraft's orbital location and will measure the flux of these electrons at two predetermined locations inside the spacecraft structure. The key component of dosimeters are designed, fabricated and tested by the Center for Space Microelectronics Technology, Jet Propulsion Laboratory of the California Institute of Technology. Support electronics are provided with the sensors in order to meet the spacecraft mechanical and electrical interface requirements. Analog telemetry is available from both the Surface Charge Monitors and the Dosimeters to provide in-orbit data via Redundant Telemetry Modules. Actual engineering data from both sensors are obtained by utilizing calibration curves in ground data processing. Detailed models of the Internal and External Sensor Assemblies will be constructed. These models will subsequently be integrated with the existing INTELSAT VIII/VIIIA spacecraft model, which will be then used for the total dose and charge distribution calculations described below:
The NOVICE programs will be used to calculate the total dose expected at the sensor, using an adjoint Monte-Carlo method of radiation transport. The integral electron/proton spectrums used as input to these calculations will be varied, depending on the specific longitudinal positions of the INTELSAT VIII/VIIIA spacecraft. Total dose results will be used to establish an expected correlation between dosimeter/readings. electron/proton spectrums, time in orbit, and spacecraft location. Results will be compared with other measurements made and data available at GEO altitude.
Future utilization plans of INTELSAT VIII/VIIIA electrostatic charge sensors include correlation of measured data with ESD events at GEO orbit, plasma propagation and impact studies and other ESD threat parameters for the geostationary communication satellites.
Bowman C.
Liu Danmin
Ozkul A.
Scali F.
No associations
LandOfFree
Design and operational characteristics of electrostatic charge measurement onboard Intelsat VIII & VIII-A communication satellites does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Design and operational characteristics of electrostatic charge measurement onboard Intelsat VIII & VIII-A communication satellites, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Design and operational characteristics of electrostatic charge measurement onboard Intelsat VIII & VIII-A communication satellites will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1499870