Major disasters and emergency events are covered with Pleiades imagery for Civil Protection needs. The new capabilities offered by PLEIADES-HR agility allowed to imagine new methods of image calibration and performance assessment. The spacecraft solar panels (GaAs cells of 5 m2) provides a power of 1.5 kW EOL of 33.6 V at summer solstice (mean power of 850 W). The Fregat upper stage used a new purpose-built payload dispenser developed for Arianespace's Soyuz missions. Even if a ground sequence test can be considered accurate enough or very representative, the instrument behavior may change after the launch and throughout its lifetime on orbit: on-ground calibration has to be considered as the first characterization before launch. One of them is the steady-mode, that provides a full set of couples (i.e., radiance mean, radiance standard deviation). The overall unit realizes the functions of detection and conversion of video signals in numerical data. The linear part can be computed by different calibration techniques. The camera design employs a pushbroom imaging concept. Similar to the present very high resolution missions of Ikonos, Quickbird, Worldview, or GeoEye, stereo data can be acquired during one Fiwre la: Pleiades panchromatic image of Melbourne, Australia n December 16, 201 1, the Plei- ades-l A was launched successfully in orbit via a Russian Soyuz ST rocket out of French Guiana. Figure 1: Artist's rendition of the deployed Pleiades spacecraft (image credit: CNES), Since 1997 CNES is studying the use of smaller satellites (a medium spacecraft size of about 1000 kg instead of 3 tons as for the SPOT-5 S/C), resulting in the “3S” platform concept (Small Satellite System) standing for “Suite de Systeme SPOT” or for “SPOT Successor System.” The focus is on cost reduction, technological innovation, user services, and performance upgrades for a new generation of optical imaging satellites, referred to as Pleiades. SSOT is a high resolution optical Earth observation satellite which was designed, built, integrated and tested by EADS Astrium SAS of France. - The very high resolution Pleiades satellite, captured the refloating on 17 September of the Costa Concordia (Figure 17), wrecked off the Island of Giglio, Italy. This engineering knowledge is used to define useful physical models dedicated to image quality: • The geometric model is used to compute the location on the Earth of any pixel. 10) 11), Figure 2: Overview of organizations in ORFEO agreement (image credit: CNES). Thanks to the huge satellite agility obtained with control momentum … With a roll ”pointing” capability of 30º with respect to the track, world access can be achieved in 5 days with one satellite, and in 4 days with the system's 2 satellites. Mechanical Architecture The main design drivers for the satellite architecture are the agility and the image location accuracy. To reduce the in-flight operations, the so-called AMETHIST method has been processed for the first time to be able to compute the parameters of the radiometric model in case of non-linear behavior. With the availability of ASAP-S on Soyuz, the ASAP launch capability on Ariane vehicles has been retired. DORIS is the CNES tracking system, based on measurements between the satellite and dedicated ground stations at two frequencies (400 MHz and 2 GHz). On the other hand, the term “location accuracy” addresses the knowledge (after the data take) of the image position accuracy. As these landmarks give the true location of the line of sight, a block adjustment of several images is performed to determine the alignment bias that minimize the location error. • The radiometric model is used to convert raw digital counts to TOA (Top-of-Atmosphere) radiance and to normalize the inter-detector sensitivities. In addition to images of well-characterized landscapes that have been used for years and continuously improved thanks to previous satellites commissioning, the Pleiades project has been taken many images of the Moon since the launch. Looking for alternate methods that need less usage of ground references is therefore an issue of importance. Each Pleiades satellite is capable of targeting images along any ground direction within 47° of vertical viewing position, with very low maneuvers durations between two consecutive images. The structure is completed by four vertical struts at each angle of the satellite and by four lateral panels made of alloy honeycomb, which concur to the lateral stiffness. The importance of a collaborative work between the different thematic working groups has been privileged in order to maximize the efficiency for the key thematic studies (i.e Green and Blue Corridors) and to gather the data acquisition over multi-thematic sites. About 70 geographical sites related to almost 130 thematic studies have been selected in the framework of PUTC. One MVP is able to process up to 10 CCD outputs, at a maximum pixel rate of 10 Mpixel/s. Spot Image is the official and exclusive worldwide distributor of Pléiades products and services under a delegated public service agreement. The Pleiades satellite system … Figure 9: Photo of the ASAP-S dispenser structure (image credit: Arianespace), Legend to Figure 9: The ASAP-S structure is based on a massive rigid low plate made of alloy, which provides the interface with the launcher and supports the propulsion system. 3) CNES hosts the dual control center (civil and military). . A dedicated antenna pointing algorithm is developed to orient the antenna during satellite maneuvers so that the ground station always stays in the antenna lobe. Intermediate products (level-2) are: Mosaicked imagery, DTM (Digital Terrain Model) extracted from stereo pairs. . 38), Figure 20: Pleiades-1B acquired this pansharpened, high-resolution image of Istanbul (Turkey) on Dec. 5, 2012 (image credit: Astrium Services), • December 02.2012: CNES is reporting that operations on the Pleiades-1B are nominal; the solar panels are deployed, the attitude is stabilized, the thermal and power balance is reached. In this way, the complete ground station visibility is used to downlink imagery. The spacecraft features both a high imaging resolution (0.7 meter panchromatic and 2.8 meters multispectral associated to a 20 km swath at nadir) and high agility. The parameters taken into account for the selection of the thematic studies were: • Projects ready for operational applications (e.g. • April 2014: Owing to their agility and capacity to capture a large collection of images, Pléiades-1A and Pléiades-1B become key elements within crisis management and military operations. The radiometric activities dealt with the following main topics: - MTF assessment and refocusing operations, - Onboard compression bit rate optimization, • In early June 2012, all the calibrations were performed; the precise measurement of the performances are still ongoing satisfactorily: the end of the Image Quality Commissioning Phase is scheduled for the end of June 2012. A high agility requires a very compact design, with a few stiff appendages. Three days after the launch, the Pleiades satellite MTF was computed thanks to images of stars in the Pleiades constellation, as a sign of destiny. B2= 620-700 (red), The mission involved four burns of the Soyuz' Fregat upper stage, which enabled the six satellites to be released for operations at altitudes ranging from 700 km to 610 km. The receiving stations have been developed by Zodiac. Each filter is composed of a high-pass filter and a low-pass filter. The IMU (Instrument Management Unit) gathers the instrument interfaces: instrument thermal control hardware, mechanisms command, detection unit power conversion. • In August 2012, Pleiades-1A has already acquired more than 10,000 images, the system is very robust and the availability of the satellite is excellent. Astrium Geo-Information Services takes over the spacecraft operations of the civil channel with an exclusive license once each Pleiades satellite has been commissioned. It contains a large amount of bright nebulous material and several hundred stars, of which six or seven can be seen by the unaided eye and have figured prominently in the myths and literature of many cultures. Hence, the mass of the new generation Pleiades spacecraft is only 1/3 that of its predecessor SPOT-5 with a mass of 3000 kg. Minimize chromatic aberrations, Integrated focal plane and video electronics. 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). In this mode, the agility capabilities of the satellite are used to acquire the maximum of scenes on a given surface, in one day. Pleiades-HR is a two-spacecraft constellation of CNES (Space Agency of France), representing a long-term engagement with the introduction of advanced technologies in Earth observation capabilities. 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. This agility coupled with particularly dynamic image acquisition programing make the Pleiades system very responsive to specific user requirements. The transfer of charge along the CCD is made synchronous with the velocity of the scan image. Figure 32: Illustration of various acquisitions modes with HiRI due to the agility of the spacecraft (image credit: Spot Image) 59). It was launched in December, 2011 from French Guiana. Its comprehensive portfolio means Airbus is able to provide the right satellite and system for every customer – whether they need a weather-independent data source, a small constellation for high-frequency revisits, very high-resolution imagery or even all of the above (and more) in a single system. Regional image receiving stations have been installed (Japan, China and Canada). The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. Pleiades satellite swath width is 20 km. The Pléiades tasking plan are refreshed and uploaded three times per day, allowing for last minute requests and the ability to utilize up-to-the-minute weather forecasts.[7]. 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