Laser crosslinks can provide high data rate communications and precision time transfer and ranging, using low size, weight, and power (SWaP) terminals to enable constellations of small satellites. The CubeSat Laser Infrared CrosslinK (CLICK) mission will demonstrate terminals capable of conducting fullduplex, high data rate crosslinks and enabling high precision ranging on 3U CubeSats in low Earth orbit (LEO). An initial risk reduction mission, CLICK-A, will demonstrate a downlink of at least 10 Mbps to a 28 cm aperture optical ground station. CLICK-B and CLICK-C will follow to demonstrate laser crosslinks with data rates of at least 20 Mbps over separation distances ranging from 25 km to 580 km. The CLICK-B/C mission will also demonstrate precision ranging better than 50 cm. Key to achieving these capabilities are the performances of the transmitter and fine pointing, acquisition, and tracking (PAT) system. We present results from recent testing and characterization of the transmitter and PAT subsystems. The testing of the transmitter includes confirming the output power and modulation of the seed laser and semiconductor optical amplifier (SOA) and characterizing the output pulse shape. For the PAT system, testing focuses on characterizing the noise of the quadrant photodiode used for the closed-loop, fine PAT sequence. This testing was conducted using a dedicated hardware-in-the-loop testbed with an optical test setup. CLICK-A is expected to launch no earlier than May 2022 for deployment from the International Space Station (ISS) in June 2022, while CLICK-B/C is anticipated to launch in late 2022.

Rapid International Scientific Experiment Satellite (RISESAT) is a small Japanese experimental Earth-observing, science and technology demonstration satellite. One of the scientific instruments onboard is a miniature radiation monitor telescope RISEPix with two Timepix detectors, developed and built at the Institute of Experimental and Applied Physics, Czech Technical University in Prague. After its successful launch in January 2019, RISESAT joined two other still operational satellites with our Timepix-based radiation monitors, SATRAM onboard the ESA satellite Proba-V (launched in 2013) and the Czech VZLUSAT-1 cubesat (launched 2017). In this work, we present general technical and scientific details about the RIS-ESAT satellite mission and the RISEPix module, and a basic comparison of space weather monitoring from SATRAM and VZLUSAT-1 radiation monitors. K E Y W O R D elementary particles -instrumentation: detectors -ISM: cosmic rays -space vehicles: instruments 1

We discuss image segmentation algorithms and additional space considerations for BeaverCube-2, a project under development between the MIT Space Telecommunications, Astronomy, Radiation (STAR) Lab and the Northrop Grumman Corporation that aims to demonstrate the use of an Artificial Intelligence (AI) Computational Accelerator System-on-a-Chip (SoC) on a 3U CubeSat in Low-Earth Orbit (LEO). The processing power afforded by the SoC will allow the use of modern artificial intelligence techniques as part of an Earth observation mission to obtain and process visible and infrared imagery of coastal features.We focus on three algorithms used for cloud segmentation in satellite imagery. These are a luminosity-thresholding method, a random forest method, and an autoencoder-based deep learning method. Our luminosity thresholding method classifies each pixel based on its luminosity and achieved 84% accuracy using 2 MB of memory. Our random forest method contextualizes pixels within a 3 × 3 kernel and classifies them based on the luminosity of each pixel in the kernel -it achieved 90% accuracy, with a memory usage of 700 MB. Finally, our U-Net-based deep learning method achieved 92% accuracy with 1500 MB memory usage, demonstrating modest gains over the two simpler methods, with higher accuracy in snow scenes.

Constellations of CubeSats will benefit from high data rate communications links and precision time transfer and ranging. The CubeSat Laser Infrared CrosslinK (CLICK) mission intends to demonstrate low size, weight, and power (SWaP) laser communication terminals, capable of conducting full-duplex high data rate downlinks and crosslinks, as well as high precision ranging and time transfer. A joint project between the Massachusetts Institute of Technology (MIT), the University of Florida (UF), and NASA Ames Research Center, CLICK consists of two separate demonstration flights: the initial CLICK-A, which will demonstrate a space-to-ground downlink and serve as a risk-reduction mission, and CLICK-B/C, a crosslink demonstration mission.The CLICK payloads each consist of laser transceivers and pointing, acquisition, and tracking (PAT) systems, and will fly on 3U CubeSat buses from Blue Canyon Technologies to perform their optical downlink and crosslink experiments in low Earth orbit (LEO). We present an update on the status of both the CLICK-A and CLICK-B/C payloads. At the time of writing, the final assembly and testing of the CLICK-A payload has been completed and the payload has been delivered for integration with the spacecraft bus. The final testing included the validation of the transmitter and the PAT system, the performance of both of which was characterized under various environmental test conditions and shown to meet their requirements for operation on orbit. On CLICK-B/C, the payload electronics have been designed and are under test. The optical bench of the payload has been assembled, the characterization of which is ongoing.

No abstract

No abstract

The Rapid International Scientific Experiment Satellite (RISESAT) is a 50-kg-class Earth observation microsatellite that is currently being developed at the Space Robotics Laboratory (SRL) of Tohoku University, with a planned launch data in 2018. Intended to demonstrate a cost-effective and reliable microsatellite bus system, RISESAT features various scientific payload instruments from institutions and organizations around the world. Among the payloads are the Very Small Optical Transponder (VSOTA), a compact, dual-band (980 nm, 1550 nm), lightweight laser signal transmitter developed by the Japanese National Institute for Information and Communications Technology (NICT), and the High Precision Telescope (HPT), a multi-spectral, high-resolution Cassegrain telescope developed by Hokkaido University and intended for Earth and astronomical observations. Using these two payloads, RISESAT can demonstrate satellite-toground one-way laser communication. This experiment is intended to demonstrate optical communication capability within the scope of the available hardware resources on a microsatellite dedicated to numerous other scientific endeavors. Hence, VSOTA is lighter, less power intensive, and more simplified than other optical transmitter terminals. Internal gimbal mechanisms for fine pointing have also been eliminated, thus the tracking of the optical ground stations will be achieved using body pointing of the satellite. Recently, end-to-end electrical configuration and communication tests have been conducted for both the engineering model (EM) and the flight model (FM) of the VSOTA assembly. This paper provides an overview of VSOTA and its space-to-ground optical communication demonstration, and describes the current status of the RISESAT optical communication subsystem assembly and integration.

No abstract