11:15 〜 11:30
[PEM12-08] LAMP1ロケット搭載オーロラカメラの成果とLAMP2ロケット観測検討
キーワード：脈動オーロラ、マイクロバースト、ロケット、中層大気
We report the recent results of a multi-spectral auroral camera AIC on the NASA’s LAMP rocket launched from Poker Flat at 11:27:30 UT on March 5, 2022. The purpose of LAMP rocket mission is to clarify the relationship between pulsating aurora and microbursts. AIC measured two auroral emissions in the E-region at 670 nm (N2 1PG) and mainly in the F-region at 845 nm (OI) using two CMOS cameras called AIC1 and AIC2. Two cameras took images simultaneously with a time resolution of ~10 frame/s. The field-of-view (FOV) of AIC1 was 29 deg x 29 deg directed to the magnetic footprint covering 180 km x 180 km area with a resolution of 3 km x 3 km at the apex altitude (~430 km altitude). FOV of AIC2 was 106 deg diameter circle covering the wide range from nadir to limb of the Earth.
The LAMP rocket was successfully launched into active pulsating auroral patches. AIC worked satisfactorily throughout the flight, and the despun table cancelled the rocket spin correctly. From AIC1 data, we identified significant pulsating auroral patches with sub-second modulations during the flight time of ~160-200 s, ~450-500s, and black arcs at ~600s. We compared auroral images taken by AIC with high-energy electrons (>100keV), low-energy electrons (several to 10 keV) and ground auroral images at Venetie and Fort Yukon, and found good correspondence between them on the main pulsating aurora (~5s) as well as on the sub-second microburst variations.
From the AIC2 data, we estimated the altitude distribution of oxygen 845nm emission with the following three methods. (1) Altitude difference of emission intensities in the direction of the magnetic footprint. (2) Time series of emission intensity in the horizontal direction during the flight. (3) Snapshot of tangential altitude distribution in the limb direction taken above the emission layer. From these analyses, we estimated the emission peaks in the altitude range from 160km to 330km, and emission existed even in the altitude of 100-200 km. The estimated emission altitudes are consistent with the electron precipitation in the energy range of a few keV obtained by EPLAS onboard the rocket.
Although the LAMP/AIC succeeded to observe pulsating auroral continuously, the higher sensitivity and faster imaging are required to resolve the internal modulation (~3Hz) and to observe the faint emission of oxygen 845 nm. For the LAMP2 rocket mission which is planned to be launched in the winter of 2026, we are now developing a new AIC with a sampling of 15 frame/s. We selected a large-sized CMOS (ASI-432MM, 1.1", global shutter) which has higher capabilities than LAMP/AIC (ASI-183MM, 1", rolling shutter). In addition, the selected single board computer NanoPiM4V2 for primary processing of camera data is the same as LAMP/AIC. Using the LED array blinked with an external clock, we examined the timing accuracy of captured image data, and confirmed that the accuracy is sufficient even at 20 fps (50 ms exposure). We also checked that the global shutter characteristics and found that the time difference between top and bottom of image is negligible (3 ms ± 0.9 ms). The case of AIC is now manufacturing, and the electronics will be made in the next fiscal year.
The LAMP rocket was successfully launched into active pulsating auroral patches. AIC worked satisfactorily throughout the flight, and the despun table cancelled the rocket spin correctly. From AIC1 data, we identified significant pulsating auroral patches with sub-second modulations during the flight time of ~160-200 s, ~450-500s, and black arcs at ~600s. We compared auroral images taken by AIC with high-energy electrons (>100keV), low-energy electrons (several to 10 keV) and ground auroral images at Venetie and Fort Yukon, and found good correspondence between them on the main pulsating aurora (~5s) as well as on the sub-second microburst variations.
From the AIC2 data, we estimated the altitude distribution of oxygen 845nm emission with the following three methods. (1) Altitude difference of emission intensities in the direction of the magnetic footprint. (2) Time series of emission intensity in the horizontal direction during the flight. (3) Snapshot of tangential altitude distribution in the limb direction taken above the emission layer. From these analyses, we estimated the emission peaks in the altitude range from 160km to 330km, and emission existed even in the altitude of 100-200 km. The estimated emission altitudes are consistent with the electron precipitation in the energy range of a few keV obtained by EPLAS onboard the rocket.
Although the LAMP/AIC succeeded to observe pulsating auroral continuously, the higher sensitivity and faster imaging are required to resolve the internal modulation (~3Hz) and to observe the faint emission of oxygen 845 nm. For the LAMP2 rocket mission which is planned to be launched in the winter of 2026, we are now developing a new AIC with a sampling of 15 frame/s. We selected a large-sized CMOS (ASI-432MM, 1.1", global shutter) which has higher capabilities than LAMP/AIC (ASI-183MM, 1", rolling shutter). In addition, the selected single board computer NanoPiM4V2 for primary processing of camera data is the same as LAMP/AIC. Using the LED array blinked with an external clock, we examined the timing accuracy of captured image data, and confirmed that the accuracy is sufficient even at 20 fps (50 ms exposure). We also checked that the global shutter characteristics and found that the time difference between top and bottom of image is negligible (3 ms ± 0.9 ms). The case of AIC is now manufacturing, and the electronics will be made in the next fiscal year.