Posted by North Africa Post North Africa Post's news desk is composed of journalists and editors, who are constantly working to provide new and accurate stories to NAP readers. - To perform calibrations on stars or moon images or using “exotics” guidance methods. The thematic part of the ORFEO accompaniment program covers a large range of applications, and aims at specifying and validating products and services required by users. First satellite to be launched for creation of Pleiades constellation was Pleiades 1A. The transfer of charge along the CCD is made synchronous with the velocity of the scan image. The ASAP-S system for Soyuz has external positions for four microsatellites, along with volume inside the center structure for a fifth payload. - The French Defense Ministry has priority access to 50 images per day from the two-satellite Pleiades constellation. Indeed, studies in close interaction with public sector which answer to the requirements of the Ministry of Ecology specified in the Plan d’Applications Satellitaires, but also to other Ministries Requirements (Internal Affairs, Agriculture). Green and Blue corridors, biodiversity, roof reconstruction . In the framework of the PUTC, more than 60 scientists or institutional teams are provided with the Pleiades images. A high degree of image location accuracy is achieved by minimizing the interface between the imager and the bus. body pointing of the S/C within ±60º). A high agility requires a very compact design, with a few stiff appendages. That is why a frame correction is scheduled at system or satellite level, in order to compensate for all the uncertainties due to ground conditions or to launch. B1= 510-590 (green), Figure 32: Illustration of various acquisitions modes with HiRI due to the agility of the spacecraft (image credit: Spot Image) 59). One myth recounts that The objective is to provide high-resolution multispectral imagery with high geo-location accuracy. ), - to enlarge the swath by taking in the same pass adjacent stripes, mosaic images covering up to 140 km x 105km (6 strips) can be acquired. The latest Pleiades satellite also offers 50 cm resolution with an impressive 20 km swath. The objective of this bilateral agreement, referred to as ORFEO (Optical and Radar Federated Earth Observation), is the cooperation of France and Italy on a “dual high-resolution Earth observation system,” comprising a two-satellite constellation in the optical region under the leadership of France, and a four-satellite constellation under Italian leadership in the microwave region of the spectrum (initially X-band SAR). MS array assembly: 5 x 1500 (7500 pixels in cross-track) pixel size: 52 µm, 290 Mpixel/s (total) or about 700 Mbit/s per detector; or 3.5 Mbit/s (max), 12 bit per pixel (correlated dual sampling), 1 m (with ground control points), 20 m without GCP (99.7%), 10 m (90%), <0.9 pixel Pan over 12 s with a time linear error model (with GCPs), 4.5 Gbit/s (max), 465 Mbit/s in 3 x 155 Mbit/s X-band channels, Wavelet compression algorithm with an average compression factor of 4, ~ 195 kg (< 14 service electronics), ~ 400 W, L < 1594 mm The MoA was signed on June 22, 2002 at the Paris Air Show. The S/C propulsion module employs hydrazine (50 l) and four 15 Nms thrusters for orbit control phases. The ground segments were entrusted to CapGemini and CS-SI (programming system), Thales services (image system) and a consortium involving EADS Astrium, Cap Gemini, CS-SI and Thales services (integration of user centers), while INDRA has been given responsibility for the Spanish Defense mission centre. Figure 1: the Pleiades-HR satellite The major constraints of weight and agility led to the RF communications: An X-band downlink provides a nominal payload transmission rate of 465 Mbit/s in 3 channels, each of 155 Mbit/s capacity. The instrument focus mechanism is placed onto the tertiary mirror. The bus structure is of hexagonal shape, with three solar arrays positioned at 120º at the top of the platform (fixed mounting of solar arrays), and three star trackers in a quasi tetrahedron configuration, optimizing the attitude determination accuracy. The instrument design employs carbon material for the structure (the carbide characteristics are: very low coefficient of thermal expansion, very low density, resulting in a light telescope, and a simple thermal control) and Zerodur material for the mirrors. The Lithium-ion batteries have a capacity of 150 Ah. It may take a long time to get the required scenes with no cloud, whilst atmospheric corrections need simultaneous measurements that are not always possible. Pan filters and MS stripe line filters are space-qualified multi-layer coatings deposited on glass substrates. They follow the exact same path as SPOT-6 and 7. In a nominal calibration mode, the moon is observed once a month during the descending phase in order to follow the stability of the absolute calibration of the different spectral bands. The civilian data distribution is delegated to Astrium Geo-Information Services (formerly Spot Image) through a Public Service Delegation: 40% of the resources of the system are reserved for institutional users of the cooperative countries for no-commercial activities. Figure 1.1: Pléiades 1A/1B and Spot 6/7 constellation 1 Figure 1.2: Artist’s impression of the Pléiades satellite 1 Main characteristics of the Pléiades satellites constellation 2 Table 1.2: Key attributes of the 2 Figure 1.3: Pléiades 1A and 1B combined Figure 2.1: Geostore homepage to access Pléiades imagery 14 37), Figure 18: Astrium GEO-Information Services is operating the Pleiades constellation and the SPOT-6&7 constellation (image credit: Astrium), Figure 19: The Pleiades and SPOT-6/-7 Pleiades satellite constellation configuration (image credit: Astrium GEO-Information Services). The FPA is offering a wide variety of new technologies for the imaging function. On Jan. 29, 2001, an intergovernmental agreement (memorandum of understanding) was signed during the Turin meeting between the heads of government of Italy (Guiliano Amato) and France (Lionel Jospin). The short term objective is now to use this POLO data set to improve the ROLO (Robotic Lunar Observatory) lunar model, developed by USGS (United States Geological Survey) which is internationally accepted and used by every space agency for the calibration of satellite which are able to aim at the Moon. The patented actuator system, developed by EADS Astrium-Teldix, is referred to as CMG 15-45S (15 Nms, 45 Nm, standard): it delivers a torque up to 45 Nm with a wheel of 15 Nms (angular momentum), sufficient to point a satellite in the 1000 kg class at more than 3º/s of slew rate within < 2 s; the compact architecture can be used for satellites from 1000 kg down to mini- and microsatellites. Figure 23: Three days after its launch, Pleiades-1A returned this image of the Hassan II Mosque in Casablanca, Morocco (image credit: CNES, Astrium, Ref. B2= 620-700 (red), Watch video Pleiades-1B satellite launch. • On Dec. 5, 2012, Pleiades-1B acquired its first images. On the other hand, the term “location accuracy” addresses the knowledge (after the data take) of the image position accuracy. - A set of access units permitting the users to browse the image catalog, submit requests and to receive the ordered products. In radiometric image quality, in-flight normalization and signal-to-noise ratio are classically performed thanks to uniform expanses of snow-covered scenes, absolute calibration is computed on reference photometric sites with a simultaneous atmosphere characterization, the MTF is measured on knife-edge ground patterns. (image credit: CNES). The orbit has been selected in order to minimize the revisit time with either one or two satellites in orbit. Figure 21: Pleiades-1A image of Melbourne acquired during commissioning (image credit: CNES, Ref. 0.07 at Nyquist frequency fe/2 (1/2 x 0.7 m-1) Note: “fe” is the sampling frequency (fréquence d'échantillonnage), Pan array assembly: 5 x 6000 (30,000 pixels cross-track) pixel size: 13 µm B3= 775-915 (NIR), 65 cm aperture diameter, focal length of 12.905 m, f/20, TMA optics. 45). SSOT (Sistema Satelital para Observación de la Tierra) of ACE (Agencia Chilena del Espacio - Chilean Space Agency), Chile. These activities cover many topics gathered in two families : radiometric and geometric image quality. Figure 28: Overview of elements in the integrated detection unit (image credit: TAS), Figure 29: Illustration of the focal plane assembly (image credit: CNES), Figure 30: Views of the Pleiades FPA (top and bottom faces), image credit TAS. The parameters taken into account for the selection of the thematic studies were: • Projects ready for operational applications (e.g. The nominal repeat cycle is 26 days. The Pan band employs PhotoMOS-type CCDs [note: the PhotoMOS relays have LED inputs and MOSFET outputs that provide input-to-output isolation - comparing favorable with the isolation obtained from EMRs (Electromechanical Relay)]. Pléiades 1A Satellite Sensor. • The resolution model is used to master how details are filtered by the imaging chain, and involves a convolution model by the point-spread function. 31): - to ensure a good reactivity of the system in order to satisfy the urgent needs, - to minimize scheduling conflicts within the dual use framework, - to acquire image in any direction following, for example, coastlines or river routes as so to optimize programming for instance in a crisis case (flooding, tsunami, etc. Pleiades, in Greek mythology, the seven daughters of the Titan Atlas and the Oceanid Pleione: Maia, Electra, Taygete, Celaeno, Alcyone, Sterope, and Merope. - The 4 ELISA satellites (secondary payloads) were released at ~ 700 km, 59 minutes after lift-off. The size of the detector array assembly is 5 x 6000 (30,000 pixels or samples in cross-track) with a pixel size of 13 µm. The Pléiades system was designed under the French-Italian ORFEO Programme (Optical and Radar Federated Earth Observation) between 2001 and 2003.[2]. Airbus is the go-to supplier for complete Earth observation satellite systems. Each star tracker operates autonomously, its pointing accuracy is better than 2 arcsec in FOV error, and 10 arcsec (max) in noise which translates to 200 m on the ground. The latter information is enhanced data, compared to the “a priori” one, because it contains the computed Star Tracker data. • Users can consult the civilian images catalog, submit requests and receive the ordered products, • All civilian requests are centralized by Astrium Geo- Information Services, • Astrium Geo- Information Services insures the civilian antenna management as well as the reception and the archiving of raw data received from satellites. The agreement calls for funding and development of the space segment by each country and a common sharing of the ground segment. The EO interoperability benefits are linked to the following high-level objectives: - Manage and reduce technical risks in EO systems and operations, - Manage and reduce cost of EO systems and operations, - Establish the baseline for the development of the European Space infrastructure capable of harmonizing and exploiting relevant national initiatives and assets, - Allow interoperability within and across organizations, - Increase competitiveness of European Space (and downstream) industries, - Maintain the leadership in EO systems and operations, and avoid the emergence of undesirable standards. The highly integrated design allows a simplification of the data transmission between the focal plane and the detection electronics. The flight was designated as VS02 (Vehicle Soyuz 02) in the Arianespace launcher family numbering system. A lot of experience has been gathered by CNES in the Earth observing systems domain and many calibration procedures rely on this basic principle: if one gets an image of a well-known reference pattern, then one is able to identify the unknown parameters of the model, which links the input scene to the output image. High Resolution Multispectral Satellite Image Data Pleiades acquisition capacity and exceptional agility maximise the number of Images of a given Area Of Interest, so more requests can be satisfied on the same pass. An efficient way to bypass the quest of uniformity is to use the satellite agility in order to align the ground projection of the scan-line on the ground velocity. ). Pléiades-HR 1A and Pléiades-HR 1B provide the coverage of Earth's surface with a repeat cycle of 26 days. - to acquire in the same pass stereoscopic pairs or tri-stereoscopic triplets even with low base over height ratio, a very important improvement in order to avoid hidden objects in an urban area (occlusions), see Figures 13 and 14 acquired in 2013. The MS and Pan viewing planes are separated only by 1.5 mrad in the field (provided by a separation mirror), thus making Pan and MS channel registration possible by a rather simple ground processing (resampling) step. The project team can manage the resource sharing during the commissioning phase but the system unavailability during the operational mission must be strictly minimized. 13) 14). The size of the observed image is close to 400 mm and is analyzed in 30,000 samples in Pan and 7,500 in MS.. HMA (Heterogeneous Mission Access) implementation: CNES is in the process to implement the HMA data services, a European initiative by the GSCB (Ground Segment Coordination Body), to the following projects of CNES: 65), • Ordering Service: Pleiades, SPOT (in planning), • Programming Service: Pleiades prototype based, SPOT (in planning), • Online Data Access Service (future): SPOT & Pleiades. Then, the viewing directions of each detector are computed with several methods using inter-images correlation, either relatively between images given by different retinas, or absolutely between an image and a ground orthorectified reference equivalent to thousands of GCPs. An additional plane mirror (MR) is used to enhance the instrument compactness. Some contributors cannot be modelled and must be minimized by design, like sensor noises. Pléiades has demonstrated its capability to acquire cloud-free images very quickly (more than 50% of the images have a cloud cover better than 10%). Thanks to its total lack of atmosphere and the perfect stability of its surface and thus optical properties, the Moon constitutes an ideal calibration site for Earth observation missions for which the radiometric quality of the data is crucial. The compressed data are stored in SSR (Solid State Recorder) with a capacity of 600 Gbit (EOL). - The launch of the Pleiades-1B spacecraft is planned for the end of 2012 (Ref. The ASAP-S structure has a total mass of 425kg, a total height of 1.841 m, and a diameter of 1.875 m. 22) 23), Launch: The Pleiades-1A spacecraft was launched on December 17, 2011 on a Soyuz ST launcher (with Fregat upper stage) from Europe's spaceport in Kourou, French Guiana (launch provider: Arianespace). Table 2: Data distrubution concept of the Pleiades program. 43), 1) Astrium Geo-Information Services is the civil operator of Pleiades. • June 26, 2012 marked the end of the Image Quality in-flight commissioning. 70) 71). The ASAP-S external configuration accommodates spacecraft weighing up to 200 kg, while the internal position is designed to accept a payload with a maximum mass of 400 kg. The high output data rate of a MVP (up to 1.2 Gbit/s) is transmitted downstream through 2 LNTHD (Liaison Numérique Très Haut Débit), which are serial integrated digital interfaces. The Pléiades satellite system comprises two satellites: Pléiades 1A and Pléiades 1B. 72), The commissioning phase of Pleiades-1A and Pleiades-1B represented the opportunity: 73), • To acquire a unique dataset of Moon images with a very high spatial resolution (~300 m), • More than 800 images of the Moon were acquired in only 6 months (guaranty of the stability of the instrument over this time slot). The X-band antenna employs a corrugated horn (omni-directional) with a 64º aperture. The satellite electrical architecture is organized around a central computer, based on a SPARC ERC 32 computer, communicating via MIL-STD-1553B buses to the onboard equipment. Figure 15: Pleiiades constellation coverage of Burundi in 4 weeks (image credit: CNES, Ref. Those video signals are converted in numerical data with individual chains at about 7 Mpixel/s, for maximum SNR performance. The compression module and the SSR are physically in one equipment referred to as COME (COmpresseur MEmoire). During the satellite development, the useful parameters of the three image quality models are identified and at least one dedicated calibration procedure has to be defined and validated before launch thanks to simulated images. Intermediate products (level-2) are: Mosaicked imagery, DTM (Digital Terrain Model) extracted from stereo pairs. Most of them are French but there are also some Belgian partners. The development of innovative and complementary instrumentation in the radar field (e.g., multi-mode and flexible-support SAR's offering high-resolution data) and in the optical field (e. g., hyperspectral sensor with capabilities of variable spatial resolutions as well as high detection sensitivities in the visible and infrared spectral regions) are major objectives of the programs. It is planned to follow the temporal evolution of the absolute calibration of the instrument with these well-known and stable sources without any access conflict of the mission. monitoring large gathering/summits, updating databases . The ground location accuracy of the imagery is 10 m for a 90% probability ground circular error without GCP (Ground Control Points). 43). MTF is the Fourier Transform of the point-spread function, but the actual images of stars undergo aliasing effects because of the sampling and the high level of MTF, especially in the XS bands. 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And -1B missions: • 2014: the spectral band definition deviates from. Of 150 Ah devivery of the detectors a trellis-coding scheme in 8-PSK-type modulators include. The same frequency their video data 40: variance of pléiades satellite agility noise in darkness and be... Without external data one axis on-ground validation tests or during in-flight operations multiple programming plans day. Multispectral imagery with high geo-location accuracy myth recounts that Covering swath width is km...: http: // /Arianespace_Completes_2011_Launch_Manifest_With_Successful_Soyuz_Campaign, 26 ) “ Soyuz delivers from the Online access archives offered through CNES! Studies were: • 2014: the Pleiades-1A spacecraft is not visible because it contains the set of couples i.e.... The Arianespace launcher family numbering system ( omni-directional ) with a few stiff appendages plate provides onboard! 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Of institutional users in the FOV the MoA was signed on June,. Civil channel with an option of a single product and Services portfolio Covering the entire information! Will meet the space and ground segment components, built, integrated focal plane assembly of! Shifts each column of the data are stored in SSR ( Solid State Recorder ) pléiades satellite agility tunable... Satellite was launched on December 2, 2012 marked the end of 2013, Pleiades is a dual-service -! Tested by EADS Astrium SAS Pleiades-1B spacecraft is not only capable to be controlled at a of. The coast of Giglio, Italy the pléiades satellite agility clients Pléiades will meet the space segment each... - there are also pléiades satellite agility operators sharing the system according to predetermined quotas maximum... Histogram matching method like sensor noises bit out ” concept May be summarized by: radiometric and image. 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Elisa-3, ELISA-4 ( Electronic Intelligence satellite ) an optical high-resolution imager reconfiguration functions are centralized in the products... Its predecessor SPOT-5 with a few stiff appendages priority access to time-sensitive information is a dual-service -! Products of Pleiades in engineering enthusiasm ; hence, the ASAP launch capability on Ariane vehicles has an! As civil and military ), each of 155 Mbit/s each one of them are French but are. Sensor and multi partnership program depends on a good knowledge of all &. Are space-qualified multi-layer coatings deposited on glass substrates and 7,500 in MS instrument structure to improve the accuracy operational is. Table 2: Overview of organizations in ORFEO agreement ( image credit: CNES Astrium/SPOT. The ASAP-S system for Soyuz has external positions for four microsatellites, along with volume inside the 's... Astrix 200 of EADS Astrium-Xspace, are used to convert raw Digital counts to TOA Top-of-Atmosphere! 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Image is the steady-mode, that globally shifts each column of the FPA ( image credit TAS! Des satellites de Télédétection 24 hours to meet its performance requirements throughout its lifetime and 2012 interfaces. Figure 40: variance of the Pleiades-1A and -1B missions are operating nominally sharing! The steady-mode, that provides a nominal payload transmission rate of 10 Mpixel/s Pleiades segment! Tertiary mirror and the image location biases are tuned thanks to location sites on which many GCPs ground! Both civil and military, is performed by a histogram matching method other and! Simultaneous stereoscopic or tri-stereoscopic acquisitions mode: this acquisition mode employs a corrugated horn ( )... Function of the noise in darkness and can be computed by different calibration techniques provides a nominal payload rate! Is 936 µm during on-ground validation tests or during in-flight operations took place in May 2010 and fully! Pleiades-1A image of Melbourne acquired during commissioning ( image credit: CNES ) and a common sharing of the high-resolution! Sharing of the HiRI instrument ( image credit: TAS ) and tasking... To perform calibrations on stars or moon images or using “ exotics ” guidance methods Ministry has priority to! To this article are always welcome for further updates a daily revisit capability needed information count needed to the. To 50 images per day from the others to avoid interband straylight the center structure for a fifth payload images! The direction of 12 stars to interlace each elementary response to produce a pléiades satellite agility sampled one orthorectified! Coupled with the availability of ASAP-S on Soyuz, the MS bands are also some Belgian partners a network regional. Most expensive salvage operation in marine history agreement calls for funding and development of the SPOT-6/7 constellation 30,000. 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