Lightning observations of a small satellite Maido-1 and the study on recorded VHF waveforms

Abstract

This paper reviews developments and lightning observations on a small satellite “Maido-1” and its electromagnetic (EM) payload, the very high frequency (VHF) sensor. Maido-1 satellite was launched on January 23, 2009 and injected into the sun-synchronous polar orbit at an altitude of 660 km. A radio frequency receiver was installed on Maido-1 to examine the feasibility of the space-based digital interferometer receiving lightning EM impulses in VHF band. Through the nine months of the operation period of Maido-1, the VHF sensor conducted 158 lightning observations and recorded about 15,000 VHF EM waveforms around the world. The main achievements of the VHF sensor on Maido-1 are 1) functional confirmation of the sensor manufactured by commercial off-the-shelf products, 2) validation of the sensor sensitivity designed by the numerical estimation for the attenuation in the propagation path, and 3) verification of the available EM noise environment for the lightning observation on the orbit. Characteristics of pulse duration and pulse pair founded in the recoded waveforms are studied using numerical simulation for a layered ionosphere model. This paper also proposes the estimation considering the ionospheric propagation, and its effectiveness is demonstrated.