Overview

Hodoyoshi-2 or Rapid International Scientific Experiment Satellite (RISESAT) is a 50kg experimental earth observing and research satellite launched by JAXA. One of its payloads is the Very Small Optical TrAnsponder (VSOTA) developed by NICT. It was launched on January 18th, 2019 aboard the Epsilon-4 launch vehicle at JAXA Uchinoura Space Center located on the southern tip of Japan. [1]

VSOTA is a dual-band (980nm/1550nm) laser signal transmitter without a gimbal or internal fine pointing mechanism. Primary testing is to be with the NICT’s 1.5m optical ground station, and 0.3m mobile optical ground stations are under development. Future systems are envisioned involving communication between LEO micro/nano and GEO mid/large satellites.  The VSOTA terminal itself is substantially smaller than the previous SOTA at 0.7kg and consuming <10W. The desired maximum bitrate for this mission is 1 Mbps. [2]

Technologies

The High Precision Telescope (HPT) is a telescope equipped with two separate Liquid Crystal Tunable Filters (LCTFs) in overlapping wavelength ranges, which is based on an instrument of Rising 2. Each LCTF is combined with a CCD matrix detector, providing a pixel resolution of 5 m from an altitude of 700 km, used to measure the optical properties of solar radiation reflected from land and sea surfaces. The LCTF can be tuned to any desired wavelength by a computer command within its spectral range.

The Dual-band Optical Transient Camera (DOTCam) is a camera system developed by National Cheng Kung University (NCKU) of Taiwan to observe Transient Luminous Events (TLEs) in Earth’s upper atmosphere.

The Ocean Observation Camera (OOC) is a multi-band wide FOV camera system in the VIS range designed for ocean surface observation. The resolution is about 100 m with a swath width of about 65 km.

The Three-dimensional Telescope (TriTel) is an advanced dosimetric instrument developed by the Centre of Energy Research of the Hungarian Academy of Science, Budapest, Hungary.

The Space Radiation micro-Tracker (Timepix) is a detector developed at the Institute of Experimental and Applied Physics of the Czech Technical University (IEAP CTU) to characterize the mixed radiation field. This is especially focused on the entire charged particle spectrum from energetic electrons, protons, and up to relativistic cosmic-ray ions.

The micro-Magnetometer (µMAG) is a MEMS-based magnetic field detector developed by ÅAC Microtec, former Ångström Space Technology Centre (ÅSTC) of Uppsala University.

The Data Packet Decoder (DPD) is a store-and-forward device designed for global environmental monitoring based on technology developed for the Whale Ecology Observation Satellite (WEOS). [3]

Relatd Links

EO Portal: RISESAT

NASA: RISESAT

Article: Laser Data Downlink System of Micro-satellite RISESAT