Sikisai

The Sikisay spacecraft was created as part of the GCOM project (the Global Change Observation Mission ). The goal of the project is to track global climate change for 10-15 years. For this analysis, the geophysical parameters of the ocean and atmosphere are collected and studied. As part of the project, on May 18, 2012, the Shizuku Ocean Monitoring Satellite ( GCOM-W ) was launched ^[1] . It was originally planned to launch three satellites GCOM-W and GCOM-C, and each subsequent one had to be launched one year before the end of the previous lifetime. Thus, it was planned to conduct continuous monitoring for 15 years ^[2] . Initially, GCOM-C1 was to be launched in 2013 - one year after the launch of GCOM-W1. In 2016 and in 2017, the launch of the second pair was planned, and in 2020 and 2021 - the third pair of satellites ^[1] .

Satellite tasks

The GCOM-C mission, which began on December 23, 2017, is the first of the planned three and is often referred to as GCOM-C1 (respectively, the second and third are designated as GCOM-C2 and GCOM-C3). The satellite "Sikisay" should track the dynamics of absorption of solar radiation by the Earth's atmosphere, oceans and land. For this, the amount of aerosols, the color of the oceans and the reflecting capacity of the continents (ice and vegetation cover) will be assessed. To fulfill the mission tasks on board the "Sikisay" is a device of the second generation SGLI. The expected lifetime of a satellite is 5 years ^[3] .

Design and manufacture of a satellite

Financing the development of the satellite "Sikisay" started in December 2009 with a planned launch in 2013. The design of the SGLI payload toolkit began in July 2009 - before the official start of financing the project ^[4] . In 2011, the tests of the satellite platform on the vibrating table were successfully completed. During the tests, the stability of the designed structure and satellite systems to vibration and acoustic loads during launch on the launch vehicle was evaluated ^[5] . But the full development of spacecraft equipment began in February 2013 after the critical protection of the project ^[6] .

At the end of 2014, the official mission emblem was approved. As the primary color, the traditional color “Tokiva” was chosen ( Japanese 常 磐 色 Tokiva Iro ) ^[7] . March 17, 2017, it was announced the completion of thermal vacuum tests of the satellite. During the tests, the stability of the spacecraft elements to changes in thermal conditions in vacuum conditions was checked. Tests simulated the dynamics of thermal loads that occur when a satellite moves in a near-earth orbit under varying light ^[8] . On May 26, tests of the spacecraft on a vibration stand and in an acoustic chamber were completed at the Tsukuba space center. The purpose of the test was to confirm the readiness for vibration and acoustic loads that occur when the apparatus is launched on a launch vehicle ^[9] .

Spacecraft Name

Initially, the project and the spacecraft were called GCOM-C, which is an acronym for English. Global Change Observation Mission . April 25, 2017 it was announced the beginning of the reception of proposals for the personal name of the spacecraft. When proposing a name, it was necessary to fulfill fairly simple conditions: the use of hiragana or catagan , easy pronunciation, no coincidence with the name of other satellites, no curses, the authors do not claim copyright. The winner received an invitation to launch the satellite ^[10] . On July 14, the results of the competition were announced, in which 6673 people took part. The name “sikisay” ( jap. し き さ い ) won - “color”, “coloring” ^{[11] [1]} .

Sikisai consists of two main modules: a more compact payload module is located in the bow, and a larger service module in the stern. On the service module, two two-section solar panels are fixed, totaling up to 4250 W. The nominal three-axis orientation ensures that SGLI tools are constantly directed towards the nadir . The orientation is supported by flywheels, and, if necessary, with the help of onboard LPRE . Fuel capacity 176 kg ^[6] .

The payload is represented by the only tool of the Second Generation GLobal Imager (SGLI). SGLI includes several instruments: a Visible and Near Infrared Radiometer (VNR) radiometer and an Infrared Scanner (IRS) infrared scanner. The VNR radiometer measures unpolarized radiation in the visible and near-infrared range in 11 channels (from 0.38 to 865.5 nm) and polarized radiation in two channels (673.5 and 868.5 nm). The IRS infrared scanner measures near infrared radiation in four channels (1.05, 1.38, 1.63 and 2.21 microns) and average infrared radiation (10.8 and 12.0 microns). For the transfer of scientific data using X-band (frequency 8105 MHz) with a speed of 138.76 Mbit / s ^[6] . The power consumption of a scientific instrument 480 W ^[12]

With a viewing width of 1000 km and a resolution of 250 m, SGLI provides a full scan of the Earth’s surface within two days. This allows us to estimate the amount of aerosols, the density of clouds and the state of vegetation, which is important for the construction of climate models ^[13] .

The launch of the satellite was made on December 23, 2017 by the H-IIA carrier rocket (type 202, No. F37). Sikisai was the main payload; the second payload was the technological demonstrator Tsubame . The launch took place at 10:26:22 UTC time (JST) (01:26:22 UTS) from the first launch facility of the Yoshinobu starting complex. The launch of the launch vehicle was successful and after 16 minutes 13 seconds after the launch at a height of 792 km, the Sikisai separated from the second stage adapter ^[1] . A feature of the launch was that two satellites were launched into orbit, which should operate on uneven orbits. And the first one, “Sikisai”, should work at a much higher orbit than the second one, “Tsubame”. On December 24, JAXA issued a press release announcing the successful completion of critical procedures: the deployment of solar cells, the launch of on-board equipment, and telemetry transmission ^[14] . Works on putting the satellite into full activity mode should continue for three months after launch ^[2] .

January 12, 2018 JAXA published the first photos transmitted from the satellite. They depicted the Kanto area (Japan) (taken at 10:30 JST on January 6, 2018), the mouth of the Ganges (taken at 11:40 JST on January 3, 2018) and the Sea of ​​Okhotsk , Sakhalin and the Japanese archipelago (taken in 10:20 JST January 6, 2018) ^[2] .

• E. Ryzhkov. “Coloring” for predicting the climate of the earth and the technological demonstrator “Swallow” // Cosmonautics news : magazine. - 2018. - February ( No. 2 (421) ). - pp . 35—37 .

• Global Change Observation Mission - Climate "SHIKISAI" (GCOM-C) (English) . Satellites and Spacecraft . Jaxa The appeal date is March 9, 2018.
• Global 候 変 動 観 測 測 衛星 「し き き さ さ い」 (GCOM-C) / Global Change Observation Mission - Climate SHIKISAI 」(GCOM-C) (Unc.) . Jaxa The appeal date is March 9, 2018. Archived April 26, 2014.
• 成 成 29 年度 ロ ケ ッ ッ ト 打上 げ 計画 書 書 気 候 動 оп оп оп оп оп 」」 」」 」」 」」 」」 」」 」 .) . Jaxa The appeal date is March 9, 2018. Archived March 10, 2018.
• 日本 の 地球 観 測 衛星 30 周年 未来 に つ YouTube YouTube on YouTube
• Herbert J. Kramer. GCOM (Global Change Observation Mission-Water) (Neopr.) . eoPortal.org. The date of circulation is March 11, 2018. Archived December 14, 2017.
• Herbert J. Kramer. GCOM-C1 (Global Change Observation Mission - Climate 1) Mission / Shikisai ( Neopr .) . eoPortal.org. The appeal date is March 11, 2018. Archived March 11, 2018.
• T. Igarashi. GLOBAL CHANGE OBSERVATION MISSION - CLIMATE (GCOM-C) (Unc.) . The appeal date is March 11, 2018. Archived March 10, 2018.
• GCOM-C1 Satellite (Unc.) . spaceflight101.com. The date of circulation is March 11, 2018. Archived December 31, 2017.
• SGLI Second-Generation Global Imager on GCOM-C (Japan) (English) . International Ocean-Color Coordinating Group. The appeal date is March 14, 2018. Archived March 10, 2018.
• Global Change Observation Mission-C (Unsolved) . JAXA EORC. The appeal date is March 18, 2018.