Midori 2

The main scientific task of Midori-2 was to study the global mechanisms of changes in the Earth's ecosphere. The spacecraft was supposed to collect information about the processes associated with water in the oceans, the circulation of carbon, ozone and energy in the earth's atmosphere. In addition, it was planned to use the results of observations in the fishing and agricultural sectors ^[1] .

Spacecraft Name

Midori-2 consists of two modules: the instrument module ( mission module and the bus module ). The overall dimensions of the two modules are 6 × 4 × 4 m. A solar battery with dimensions of 3 × 24 meters is mounted on the base module The overall dimensions of the satellite along the longitudinal axis are 11 m, and perpendicular - 29 m. Each of the modules is assembled on its own frame and has its own thermal control system. The modules are connected by a minimum number of interfaces, which reduced the number of pre-launch tests. 2 "was the hardest Japanese their companion Zemlm ^[1] .

Base Module

Functional subsystems are located on board the base module: power supply, orientation and orbit control, engines. In addition, communication systems (direct communication with the ground segment and interorbital), two data processing subsystems (service data and scientific data) are mounted on the functional module. The coordination of the systems and subsystems of the basic module is assigned to the on-board computer, it also controls communications and processes the data generated by the spacecraft systems. It is entrusted with the verification of the scientific instruments of the instrument module and the autonomous planning of operations on board the satellite. The interorbital communication subsystem provided communication with Midori-2 via a relay satellite during periods of lack of direct communication with ground-based communication points ^[1] .

The power supply system, in addition to the main function (providing on-board consumers with power), was responsible for monitoring the pyrotechnic elements that ensured the deployment of satellite elements after putting into orbit. To be able to work during periods of solar shading, the power supply system charged on-board buffer batteries and controlled their discharge ^[2] .

The orbit orientation and control system was responsible for the formation and maintenance of the satellite’s triaxial orientation. For this, gyrodines and a reactive control subsystem were used. The latter used rocket engines with a thrust of 20 N and 1 N ^[2] .

Instrument Module

AMSR

AMSR ( Eng. Advanced Microwave Scanning Radiometer ) - a microwave scanning radiometer , released by the company Eng. Matsushita Electric Industrial Co. Ltd. . The radiometer worked in eight frequency channels: from 6.9 GHz to 89 GHz. The instrument received data related to the formation and condensation of water vapor, sea surface temperature, surface wind speed, ice and snow cover, etc. The scanning width on the Earth's surface was about 1,600 kilometers. The spatial resolution was 5 km in the 89 GHz band and 60 km in the 6.9 GHz band. The scanning antenna of the radiometer was 2 m - at the time of launch it was the largest antenna of this type ^[1] . Scanning was carried out at a frequency of 40 revolutions per minute with a constant angle of incidence of about 55º. The moving mass of the scanner elements was about 200 kg. To compensate for disturbances, gyrodines were used ^[3] .

It is very important for the microwave radiometer to regularly calibrate the equipment. The creators of AMSR used an external calibration scheme. To calibrate the radiometer, two calibration targets were used. One target was a microwave mirror with which the AMSR measured the temperature of deep space - approximately 2.7 ° K ^[1] . The second target was a source of high-temperature radiation - approximately 340 ° K. For the first time, such a solution was used in the SSM / I tool on satellites launched under the DMSP ( Defense Defense Meteorological Satellite Program ). While passing through the scanning strip, the AMSR main mirror observes both calibration targets, which allows each of the eight working channels to be calibrated. In addition, in the framework of ground preparatory work, a large number of calibration tests were carried out ^[3] .

The predecessor of the radiometer operating on board the Midori-2 was the MSR radiometers flying on the MOS-1 and MOS-1B satellites. The development of AMSR was the radiometers AMSR-E and AMSR-2 ^[3] .

GLI

GLI ( Global Imager ) is an optical instrument for observing solar radiation reflected from the Earth's surface (land, oceans, cloud cover). The sensor worked in the visible and infrared ranges. Using GLI, surface temperature and distribution of vegetation and ice cover were estimated ^[1] . GLI was created as a continuation of work on the OCTS instrument operating in orbit on the ADEOS satellite ^[4] .

GLI was designed to study and monitor the carbon cycle in the ocean, mainly in relation to biological processes. Observations in a wide spectral band (from near UV to near IR) of solar radiation reflected by the Earth's surface included: various types of soils, the ocean and clouds; chlorophyll pigment, phycobilin and dissolved organic matter in the ocean; classification of phytoplankton by its pigment; measurement of sea surface temperature, cloud distribution, vegetation index, etc. ^[4] .

GLI was a 36-channel optical-mechanical spectrometer with spectral interference (dichroic) filters. The scanning mirror oscillated with a frequency of 16.7 Hz in the range of ± 20º from the nadir. The instrument had five focal planes: two for the VNIR channel, two for the SWIR channel, and one for the MWIR / TIR channel. Two focal planes of VNIR had arrays with 13 and 10 lines of detectors, respectively. Two focal planes of SWIR had arrays with 4 and 2 lines of detectors. The MWIR / TIR channel had one focal plane with an array of detectors for 7 ranges. The SWIR range of detectors was cooled to 220 K using a multi-stage Peltier element. The MWIR / TIR detectors were cooled to 80 K using a Stirling cycle cooler. The material of the VNIR detectors is Si, SWIR is InGaAs, the material is MWIR / TIR CMT ^[4] .

ILAS II

ILAS II ( Eng. Improved Limb Atmospheric Spectrometer II ) - a spectrometer for the study of the ozone layer in the polar regions. The spectrometer was supposed to analyze the atmospheric limb for clearance. The purpose of the spectrometer was to continuously monitor the atmosphere in the regions above the north and south poles for a long time to study the mechanisms of depletion of the ozone layer. These studies could help evaluate the effectiveness of measures taken by mankind, such as the regulated use of substances that deplete the ozone layer ^[1] .

ILAS II was a further development of the ILAS instrument, operating aboard the ADEOS spacecraft. The tool consists of the following elements ^[5] :

• a mirror suspended on a biaxial cardan;
• Cassegrain telescope with a diameter of 13 cm
• channel separator;
• three infrared spectrometers;
• visible light spectrometer;
• sun sensor;
• signal processing module.

The infrared spectrometer system consisted of three channels:

• 1st spectral band: 44 IR channels from 6.21 to 11.76 μm (850-1610 cm ⁻¹ ) with a resolution of 0.1296 μm;
• 2nd spectral band: 22 IR channels from 3.0 to 5.7 μm (1754-3330 cm ⁻¹ );
• 3rd spectral band: 22 IR channels from 12.78 to 12.85 μm (778.2-782.4 cm ⁻¹ ) with a resolution of 1024 cm ⁻¹

The spectrometers of the 1st and 2nd spectral bands were performed as the Czerni-Turner monochromator . Detectors of all spectral bands were made of PbTiO ₃ .

SeaWinds

The task of the scatterometer SeaWinds were daily high-precision observations of the direction and speed of the wind above the surface of the ocean. These observations should help to understand the influence of the atmosphere and the ocean on the planet's meteorological system. Such studies can lead to improved accuracy in weather forecasting, and in particular prediction of typhoon behavior. SeaWin was an improved version of the NSCAT scatterometer (NASA Scatterometer), previously installed on the Midori satellite. The method of operation of the SeaWind scatterometer was based on measuring the height and direction of ocean waves irradiated with a radar signal. The signal reflected from the surface was analyzed and wind data were generated on its basis. The first sensor model of this type was launched into orbit in July 1999 on the Earth observation satellite QuikSCAT (NASA) ^[1] .

POLDER

POLDER ( English Polarization and Directionality of the Earth's Reflectances ) is a wide-format imaging radiometer, which was supposed to provide systematic measurements of the spectral and polarization characteristics of solar radiation reflected by the Earth and the atmosphere. Its capabilities created new perspectives for studying the differences between radiation scattered by the atmosphere and radiation reflected by the earth's surface. The radiometer was manufactured by the French space agency CNES ^[1] . POLDER is completely identical to the instrument of the same name that worked on board the ADEOS satellite. Tool weight 32 kg, dimensions approximately 800 × 500 × 250 mm. The device consumed 42 watts.

POLDER was an imaging system in which a CCD matrix, wide field telecentric optics, and a rotating wheel that carried spectral and polarized filters were presented.

The spectral characteristics of the device are defined in the table:

TEDA

TEDA ( English Technical Engineering Data Acquisition Equipment ) - a set of elements for monitoring the effects of space radiation ^[1] .

Launch

Midori-2 was launched on December 14, 2002. To launch, Tanegashima's launch complex was used. For launching into orbit, the H-IIA launch vehicle in configuration 202 was used. This was the fourth launch of the launch vehicle and the second operational launch. To launch the payload, a 5S-type head fairing was used with a diameter of five meters ^{[k 1]} . This was the first launch of the H-IIA with such a fairing. In this launch, for the first time, the H-IIA launched a payload into the circumpolar, near-circular, mid-altitude solar-synchronous orbit. Another feature of the launch was the cyclogram of the second stage: unlike the previous three starts, the second stage produced only one engine start, and not four. Launching the Midori-2 into orbit was the main goal of the launch. In addition, along the way, three more spacecraft were launched into orbit: FedSat , WEOS and μ-LabSat . This launch was not regarded as a cluster one, since Midori-2 was the main goal and it was its launch that was a priority, which determined the procedure for separating spacecraft. Midori-2 was the first to separate, which significantly increased the chances of successful launch into orbit. Then, in order of decreasing priority, FedSat, WEOS and μ-LabSat were separated. Unlike a cluster launch, when launching a passing load, the launch services operator was not responsible for an unsuccessful launch. The launch of all spacecraft occurred without comment, in accordance with the planned sequence diagram ^[7] .

Operation

After separation of the launch vehicle from the adapter, a cyclogram of the activation of the on-board systems and the opening of the solar battery started. After the solar battery was opened, the satellite was oriented in space along three axes and the solar battery was rotated on the Sun. After that, the deployment of SeaWind systems and inter-orbital communications took place. The next step was the launch of the gyrodines of the orientation system - from that moment on, gyrodines are responsible for the orientation of the device. The launch of gyrodynes was an important element of the program, after which the launch of the spacecraft was recognized as successful and the four-month period of putting scientific equipment into working condition and calibrating the devices began ^[2] .

When analyzing incoming telemetry, it was revealed that the solar battery produces 9% more electricity than planned. This effect was accompanied by an excess of the internal electric voltage of the solar battery. An error occurred while testing the AMSR Scanning Radiometer. After reviewing the situation, NASDA stated that the causes of the error were identified and the device was operating normally ^[2] .

Crash

On October 25, 2003, JAXA issued a press release that spoke of an emergency on board the satellite. At 7:28 JST , Midori 2 did not contact. At 8:49 a.m., the control center managed to contact the malfunctioning satellite and it turned out that the device is in minimum power consumption mode. In this mode, all scientific equipment and most systems not connected with the direct operation of the satellite were turned off. The reason for switching to this mode was not known. At 8:55, interruptions in communication began and the transmission of telemetry ceased completely ^[8] .

• Herbert J. Kramer. Operational Anomaly with Midori-II (Advanced Earth Observing Satellite II, ADEOS-II ) . EOportal . Date of treatment June 9, 2018.

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