Concept information
Preferred term
LPT
Definition
- LPT is a detection unit of JAXA (Japan Aerospace Exploration Agency), Tokyo, Japan. LPT complements the radiation measurements of Carmen-2. In June 2006, JAXA and CNES signed a MOU (Memorandum of Understanding) with the intent to load the JAXA instrument LPT (Light Particle Telescope) onto the Jason-2 spacecraft of CNES. 19) LPT consists of two units, which are LPT-E and LPT-S. Figure 14 shows the external views of LPT-E (left) and LPT-S (right). A block diagram of LPT is shown in Figure 15. LPT-E is mounted inside of the satellite and LPT-S is outside. LPT-E provides functions of the electrical I/F with the Jason-2 satellite system. It receives primary power supply from satellite system and provides sensors and electrical circuits with secondary power. It also receives telecommands and sends telemetry data via the MIL-1553B bus using protocols specified by the PROTEUS standard satellite bus which is used for the Jason-2. LPT-S consists of four sensors. Specifications of each sensor are shown in Table 6. Each sensor counts number of interesting particles irradiated from inside of the view angle with the specific energy of each channel every one second (time resolution). The LPT-S device has a FOV in the zenith direction; it is accommodated on the outside of the spacecraft. The LPT-E device is installed inside of Jason-2. LPT-S consists of 4 sensor units; ELA-A, ELS-B for counting electrons, APS-A and APS-B for protons. Each unit includes a set of radiation detectors, their preamplifiers, high voltage supplies, analog and digital board for data processing and analyzing. They measure energies of incident particles and identify particle species by the ΔE x E method. The counts of each particle are accumulated for a second and transmitted to LPT-E. There is an electrical interface between LPT-S and the satellite bus system. LPT-E includes a CPU board for data handling, receiving commands, and transmitting telemetry data in order to control the LPT-S according to a command. LPT-E also supplies LPT-S with power. 20) Each sensor has 2 measurement modes. The nominal mode is called “count mode”, which obtains count data in energy bins for each particle. Another “list mode” transmits analog-to-digital converted data indicating energy of incident particles. The list mode is used for checking health and gain drift of the detector and electronics while the volume of data to be transferred is limited. Initial performance check: LPT was initially checked out from June to November 2008 and the LPT was working correctly. The electrical noise was measured for ELS-A, APS-B and APS-A using regular test pulses. The full width of half maximum (FWHM) derived from the test pulses corresponded to 16.3 keV for ELS-A. For APS-A and APS-B, the electrical noise was smaller than a digit of the ADC (Analog–to-Digital Converter) in LPT. Those FWHMs are consistent with the technical requirement. A world flux map for electrons measured by ELS-A in the 400 – 490 keV energy range is shown in Figure #. The map shows averaged data for 4 months from November 2008 to February 2009. It is easily found that the border of SAA (South Atlantic Anomaly) at that altitude of 1336 km is extended from the middle of Indian Ocean to the western edge of Pacific Ocean. The slot region between the inner radiation belt and the outer radiation belt is also seen clearly. The observational data of LPT helps to improve the radiation environment knowledge and characterize the local radiation environment to evaluate errors of other mission instruments. An improved LPT device will be also onboard JASON-3 which has the same orbit as JASON-2. (en)
Broader concept
- JRE (CARMEN-3 + LPT) (en)
Change note
- 2018-04-25 12:45:03.0 [mmorahan] Insert Concept add broader relation (LPT [b7c3f2fb-0fdd-465d-9107-f1c7369c72f2,367563] - JRE (CARMEN-3 + LPT) [4fd10be3-7cd3-4f49-810e-61924a2453a4,367555]);
- 2018-04-25 12:50:00.0 [mmorahan] insert AltLabel (id: null category: primary text: Light Particle Telescope language code: en); insert Definition (id: null text: LPT is a detection unit of JAXA (Japan Aerospace Exploration Agency), Tokyo, Japan. LPT complements the radiation measurements of Carmen-2. In June 2006, JAXA and CNES signed a MOU (Memorandum of Understanding) with the intent to load the JAXA instrument LPT (Light Particle Telescope) onto the Jason-2 spacecraft of CNES. 19) LPT consists of two units, which are LPT-E and LPT-S. Figure 14 shows the external views of LPT-E (left) and LPT-S (right). A block diagram of LPT is shown in Figure 15. LPT-E is mounted inside of the satellite and LPT-S is outside. LPT-E provides functions of the electrical I/F with the Jason-2 satellite system. It receives primary power supply from satellite system and provides sensors and electrical circuits with secondary power. It also receives telecommands and sends telemetry data via the MIL-1553B bus using protocols specified by the PROTEUS standard satellite bus which is used for the Jason-2. LPT-S consists of four sensors. Specifications of each sensor are shown in Table 6. Each sensor counts number of interesting particles irradiated from inside of the view angle with the specific energy of each channel every one second (time resolution). The LPT-S device has a FOV in the zenith direction; it is accommodated on the outside of the spacecraft. The LPT-E device is installed inside of Jason-2. LPT-S consists of 4 sensor units; ELA-A, ELS-B for counting electrons, APS-A and APS-B for protons. Each unit includes a set of radiation detectors, their preamplifiers, high voltage supplies, analog and digital board for data processing and analyzing. They measure energies of incident particles and identify particle species by the ΔE x E method. The counts of each particle are accumulated for a second and transmitted to LPT-E. There is an electrical interface between LPT-S and the satellite bus system. LPT-E includes a CPU board for data handling, receiving commands, and transmitting telemetry data in order to control the LPT-S according to a command. LPT-E also supplies LPT-S with power. 20) Each sensor has 2 measurement modes. The nominal mode is called “count mode”, which obtains count data in energy bins for each particle. Another “list mode” transmits analog-to-digital converted data indicating energy of incident particles. The list mode is used for checking health and gain drift of the detector and electronics while the volume of data to be transferred is limited. Initial performance check: LPT was initially checked out from June to November 2008 and the LPT was working correctly. The electrical noise was measured for ELS-A, APS-B and APS-A using regular test pulses. The full width of half maximum (FWHM) derived from the test pulses corresponded to 16.3 keV for ELS-A. For APS-A and APS-B, the electrical noise was smaller than a digit of the ADC (Analog–to-Digital Converter) in LPT. Those FWHMs are consistent with the technical requirement. A world flux map for electrons measured by ELS-A in the 400 – 490 keV energy range is shown in Figure #. The map shows averaged data for 4 months from November 2008 to February 2009. It is easily found that the border of SAA (South Atlantic Anomaly) at that altitude of 1336 km is extended from the middle of Indian Ocean to the western edge of Pacific Ocean. The slot region between the inner radiation belt and the outer radiation belt is also seen clearly. The observational data of LPT helps to improve the radiation environment knowledge and characterize the local radiation environment to evaluate errors of other mission instruments. An improved LPT device will be also onboard JASON-3 which has the same orbit as JASON-2. language code: en);
URI
https://gcmd.earthdata.nasa.gov/kms/concept/b7c3f2fb-0fdd-465d-9107-f1c7369c72f2
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