Development and Testing of the Laser Transmitter and Pointing, Acquisition, and Tracking System for the CubeSat Laser Infrared CrosslinK (CLICK) B/C Mission

Abstract

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.

Link budget calculation in optical LEO satellite downlinks with on/off‐keying and large signal divergence: A simplified methodology

“…Table 1 lists transmitter-antenna properties of a selection of existing laser-terminal developments. [6][7][8][9][10]18,21,45…”

“…Employing such bulk detectors avoids the cumbersome task of preceding atmospheric correction by adaptive optics (AO) techniques, as would be required for single‐mode fiber coupling, to make use of preamplification in fiber amplifiers. Several missions have been flown or are planned to demonstrate operational OLEODLs, namely, by JAXA, NICT, NASA/JPL, ESA, and DLR 15–21 . OGS installations at the same time are operated by DLR, NICT, JAXA, NASA/JPL, ESA, CNES, NRL (Naval Research Lab), DSTG (Defense Science Technology Group), and more 22–28 …”

“…The hemispherical coarse pointing is still performed by the attitude of the satellite body. This method is most preferred when a small satellite can be rotated arbitrarily during the downlink phase, but does not provide enough precision for a narrow laser beam to be pointed precisely 19,21 Fine and coarse pointing performed by according beacon sensors and actuators of the laser terminal.…”

“…Several missions have been flown or are planned to demonstrate operational OLEODLs, namely, by JAXA, NICT, NASA/JPL, ESA, and DLR. [15][16][17][18][19][20][21] OGS installations at the same time are operated by DLR, NICT, JAXA, NASA/JPL, ESA, CNES, NRL (Naval Research Lab), DSTG (Defense Science Technology Group), and more. [22][23][24][25][26][27][28] The principle of optical data downlinks implies steering the data-modulated laser beam during downlink phase to dynamically point towards the OGS.…”

Transmitter and fine pointing system development and testing for the CubeSat Laser Infrared CrosslinK (CLICK) B/C mission

“…CLICK-B and CLICK-C will also conduct downlink experiments with PorTeL following a similar procedure. 6,7 Once the full CLICK mission demonstration has been completed, CLICK-B and CLICK-C will both be commanded into a high drag orientation in order to expedite their natural orbital decay.…”