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35-565: The Sentinel-5 Precursor , Sentinel-4, and Sentinel-5 missions are complementary elements of a constellation intended to serve the needs of the Copernicus Atmosphere Monitoring Service (CAMS). Sentinel-4 will consist of two instruments integrated onboard a Meteosat Third Generation Sounder (MTG-S) satellite intended to primarily observe the composition of the Earth's troposphere . The data gathered will be made available to

70-522: A Local Time of Ascending Node of 13:30 hours. The first large contract for Sentinel-5P was signed in July 2009 for Tropomi instrument between the European Space Agency and Dutch Ministry of Economic Affairs which contributed €78 million. On 8 December 2011, ESA selected Astrium UK as a prime contractor for the satellite, signing contract worth €45.5 million. Construction of the satellite itself

105-541: A cooling block. Light is separated into different wavelengths using grating spectrometers and then measured with four different detectors corresponding to the respective spectral bands. The UV spectrometer has a spectral range of 270-320 nm, the visible light spectrometer has a range of 310-500 nm, the NIR spectrometer has a range of 675-775 nm, and the SWIR spectrometer has a range of 2305-2385 nm. The SWIR spectrometer

140-736: A design life of 7 years. The TROPOspheric Monitoring Instrument (Tropomi) provides the most detailed methane emissions monitoring available. Sentinel-5P is the first mission of the Copernicus Programme dedicated to monitoring air pollution . Its instrument, Tropomi, is an ultraviolet , visible , near and short-wavelength infrared spectrometer . The satellite is built on a hexagonal Astrobus L 250 satellite bus equipped with S- and X-band communication antennas, three foldable solar panels generating 1500 watts and hydrazine thrusters for station-keeping . The satellite operates in an 824 km (512 mi) Sun-synchronous orbit with

175-569: A geostationary orbit ” – a quote from the MTG publication produced and published by OHB System AG . The MTG-S satellites make up 2 of the 6 satellites in the MTG satellite fleet. The MTG-S satellites are mounted on common 3-axis stabilised platforms and are dedicated to sounding applications, including the integration of the S4 UVN an IRS instrument payloads. MTG-S1 is currently planned to be launched in 2024, and MTG-S2 in 2034. The UVN multispectral spectrometer

210-542: A joint venture between the Netherlands Space Office , Royal Netherlands Meteorological Institute , Netherlands Institute for Space Research , Netherlands Organisation for Applied Scientific Research and Airbus Defence and Space Netherlands . The instrument is split into four major blocks: the UV, VIS and NIR spectrometers and a calibration block, the SWIR spectrometer with its optics, the instrument control unit, and

245-568: A single instrument, the TROPOspheric Monitoring Instrument (Tropomi). Tropomi is a spectrometer sensing ultraviolet (UV), visible (VIS), near-infrared (NIR) and short-wave infrared (SWIR) wavelengths of light to monitor ozone , methane , formaldehyde , aerosol , carbon monoxide , NO 2 and SO 2 in the atmosphere. It extends the capabilities of the OMI from the Aura satellite and

280-400: A source other than that intended. This light will often set a working limit on the dynamic range of the system; it limits the signal-to-noise ratio or contrast ratio , by limiting how dark the system can be. Ocular straylight is stray light in the human eye . Optical measuring instruments that work with monochromatic light , such as spectrophotometers , define stray light as light in

315-478: A vast improvement in weather forecasting reliability for the medium and long term. Eumetsat will head up the operations of the programme and will also ensure provision of meteorological data and services to European as well as International users and improved imaging capability to the scientific community. “ The objective of the MTG system is to provide continuous high-resolution observation data and geophysical parameters of

350-459: Is 460 kg, it will consume 736.0W nominally and its detection assembly is cryo-cooled with 56K detector temperature. Sentinel-5 Precursor Sentinel-5 Precursor ( Sentinel-5P ) is an Earth observation satellite developed by ESA as part of the Copernicus Programme to close the gap in continuity of observations between Envisat and Sentinel-5. It was launched in October 2017, and has

385-610: Is a hyperspectral spectrometer operating with spectral bands within the solar reflectance spectrum. For the UVVIS part the range is between 305 nm to 500 nm with a resolution of 0.5 nm and for the NIR part the range is 750 nm to 775 nm with a resolution of 0.12 nm. These bands work in combination with low polarization sensitivity and high radiometric accuracy. The instrument design allows for an east–west scan revisit time of approximately 1 hour, covering most of Europe and Northern Africa. With around 570 spatial samples in

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420-508: Is achieved through the use of a high-resolution telescope and scan mirror assembly operating in the IR spectral range. Further design features of the instrument include the ability to execute observation scenarios on-board autonomously with pre-uploaded scenario information and autonomous calibration including black-body and deep-space views. Observation scenario planning will also allow continuous operation including sun-avoidance capability. The IRS Mass

455-591: Is responsible for the design, development, procurement, AIT and delivery of two Flight Models (FM) of the IRS instrument. The Instrument payload will be deployed to two MTG-S satellites, similarly to the S4-UVN instrument. The IRS is essentially a hyperspectral spectrometer designed to cover the entire Earth with the mission to provide sounding data in two bands, the Long Wave Infra Red (LWIR) 700 cm-1 – 1210 cm-1 and

490-674: Is the use of double monochromators . The ratio of transmitted stray light to signal is reduced to the product of the ratio for each monochromator, so combining two monochromators in series with 10 stray light each produces a system with a stray light ratio of 10 , allowing a much larger dynamic range for measurements. Methods have also been invented to measure and compensate for stray light in spectrophotometers. ASTM standard E387 describes methods of estimating stray light in spectrophotometers. The terms used are stray radiant power (SRP) and stray radiant power ratio (SRPR). There are also commercial sources of reference materials to help in testing

525-514: Is to observe the concentration of air quality parameters in the atmosphere above Europe and North Africa, including ozone , nitrogen dioxide , sulfur dioxide , glyoxal , and formaldehyde . The information gathered will be used to further inform decision-makers. For the detection and measurement of these atmospheric characteristics, two payload instruments have been designed: the Ultra-Violet and Near Infra-Red Multispectral Spectrometer (S4 UVN) and

560-452: The SCIAMACHY instrument from Envisat . Tropomi is taking measurements every second covering an area approximately 2,600 km (1,600 mi) wide and 7 km (4.3 mi) at a resolution of 7 x 7 km. The total mass of Tropomi is approximately 200 kg (440 lb) with a power consumption of 170 watts on average and a data output of 140 Gbit per orbit. Tropomi was built by

595-440: The coronavirus pandemic which greatly reduced industrial and other polluting activities. Tropomi pollution data also helped to confirm a correlation between a higher incidence of COVID-19 and chronic exposure to air pollutants. Stray light Stray light is light in an optical system which was not intended in the design. The light may be from the intended source, but follow paths other than intended, or it may be from

630-695: The Copernicus Programme with the aim of contributing to air quality applications with the Copernicus Atmosphere Services, as well as air quality monitoring efforts over Europe and Northern Africa. As with other aspects of the Copernicus Programme, the Sentinel-4 initiative is funded mostly through the European Union, with the technical design and development under responsibility of the European Space Agency (ESA). The main mission objective

665-503: The Earth spectral radiance and of the Sun irradiance is required to be better than 3% with a goal of 2%. All values apply on a one-sigma confidence level. As the instrument ages in the space environment there may be some detectable limitations on the accuracy by the end of the currently expected Sentinel-4 mission lifetime of 10 years. The S4's UVN is also the first space-borne spectrometer to use dielectric reflection grating. This type of grating

700-420: The Earth system derived from direct measurements from the radiation it emits and reflects using satellite-based sensors from a geostationary orbit. Thanks to advances in technology, MTG, compared to the current MSG system, will also provide a more powerful tool by contributing significant improvements to the existing service with an improved imagery mission and by introducing new sounding and lightning missions from

735-560: The Infra-Red Sounder (IRS). The two instruments will be embarked on two Eumetsat Meteosat Third Generation Sounder (MTG-S) satellites due to be launched in 2024 and 2034. Meteosat Third Generation is the third generation of meteorological satellites and is developed by Thales Alenia Space (TAS) under the responsibility of Eumetsat and ESA . It is the ‘next generation’ for numerical weather predication and nowcasting. The unprecedented high-resolution and profiling technology will yield

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770-488: The Mid Wave Infra Red (MWIR) 1600 – 2175 cm-1 with spectral sampling of 0.625 cm-1. Profiles of the circulation and distribution of Earth's atmospheric water vapour and temperatures will be acquired and analysed on a layer by layer basis. This will allow further insight into the complex composition of the Earth's atmosphere as well as its dynamic. The spectral sampling will measure velocity components as part of

805-749: The across-track direction and 1024 elements in the spectral direction, with an element pitch of 30 microns; it is operated cold (typically 140 K). The SWIR spectrometer optics are mounted on a cooled optical bench (approximately 200K) and the instrument is insulated by a multiple-layer insulation (MLI) blanket. The SWIR instrument was aligned, focussed and characterised at the Mullard Space Science laboratory thermal vacuum facility in Surrey, UK. Sentinel-5P Tropomi showed substantial reductions in nitrogen dioxide amounts over Chinese cities between late January and February 2020. These were linked to China's response to

840-534: The availability of two Charged-Coupled Devices (CCDs) on board the instrument, the UV and NIR spectral elements can be separately recorded. Each CCD observes both the spectral dimension and the north–south spatial dimension. The instrument Earth polarization sensitivity has to be less than 1% with respect to the GEO orbital conditions. The instrument is also equipped with 2 solar diffusers that will minimize spectral and spatial anomalies and which would otherwise interfere with

875-498: The data sampling to determine these profiles at varying altitudes above the Earth's surface and with a high rate of spatial sampling and temporal resolution. The IRS instrument will be able to scan the full circle of the Earth within 1 hour with spatial sampling dimensions of 4 km x 4 km from the Geostationary Earth Orbit (GEO) of the host Meteosat Third Generation Sounder (MTG-S) satellite. The high sampling rate

910-407: The detection and retrieval of the atmospheric trace gases. The instrument is also equipped with a 5W White Light Source (WLS) as part of its calibration assembly. In the UVVIS range between 315 nm and 500 nm, the maximum relative radiometric spectral accuracy error over a spectral window width of 3 nm is required to be smaller than 0.05%. The in-flight absolute radiometric accuracy of

945-477: The east–west spatial dimension a corresponding scan rate (spatial sample rate) of approximately 8 km every 6 seconds is possible (around 1.3 km/s). At sunrise in the East the instrument will only scan the illuminated part of the Earth, allowing a total scan time of less than 1 hour. The same applies to the west in the evening. During Autumn-Winter area of coverage is shifted by 5 degrees twice, which optimizes for

980-510: The illuminated areas and during Winter-Spring it is reversed. The instrument is deployed to the MTG satellite which will be in a Geostationary Earth Orbit (GEO) with longitude of around 0 degrees at an attitude in the region of 36000 km above the Equator. Deployment to the satellite is optimized and will allow Earth radiance as well as Sun irradiance and thermal fields of view, clear and unhindered by obstruction. By design, via other components of

1015-411: The main instrument via an intermediate pupil , and directs it via a telescope towards a slit which defines the along-track footprint of the instrument on the ground. Light from the slit is re- collimated , diffracted by the immersed-grating at high-order, and finally imaged onto a two-dimensional detector by a high aperture relay lens. The SWIR detector (furnished by Sofradir, France) has 256 elements in

1050-468: The satellite, other stray light from sun or Earth is kept to a minimum. Minimizing the stray light is very important with respect to the class of this instrument, involving the requirement for level 1B and 2 data product accuracies where the sensitivity to stray light is very high. The MTG-S satellite performs Yaw-flip maneuvers at the Equinoxes in order to optimize the instrument thermal environment. Through

1085-622: The stray light level in spectrophotometers. In optical astronomy , stray light from sky glow can limit the ability to detect faint objects. In this sense stray light is light from other sources that is focused to the same place as the faint object. Stray light is a major issue in the design of a coronagraph , used for observing the Sun's corona. There are many sources of stray light. For example: A number of optical design programs can model stray light in an optical system, for instance: Such models can be used to predict and minimize stray light in

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1120-458: The system at wavelengths (colors) other than the one intended. The stray light level is one of the most critical specifications of an instrument. For instance, intense, narrow absorption bands can easily appear to have a peak absorption less than the true absorption of the sample because the ability of the instrument to measure light transmission through the sample is limited by the stray light level. One method to reduce stray light in these systems

1155-530: Was completed in May 2014, followed by successful integration with its primary instrument. From design to launch Tropomi cost €220 million. The satellite was launched by Eurockot Launch Services onboard Rokot . The launch was originally planned for late 2014, but after multiple postponements, was launched on 13 October 2017 at 09:27 UTC from Plesetsk Cosmodrome Site 133 . Sentinel-5P successfully reached its final orbit 79 minutes after lift-off. Sentinel-5P carries

1190-580: Was designed and built by the Optical Payloads Group of Surrey Satellites (SSTL); it employs an immersed grating design in which light impinges upon an etched grating from within a high-index silicon substrate. The reduced wavelength within the refractive medium permits an efficient, space-saving design. The SWIR grating was provided by SRON (Netherlands), who also provided the Front-End Electronics (FEE). The SWIR spectrometer receives light from

1225-551: Was initially developed for the manipulation of laser pulses, but the Fraunhofer Institute of Applied Optics and Precision Engineering in Jena, Germany was able to convert the concept for use on Sentinel-4's spectrometer. The instrument is a Fourier Transform spectrometer. Its task will be to detect Earth's atmospheric gas structure and relay data to the ground for use in more accurate and reliable weather forecasting. OHB System AG

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