A satellite constellation is a group of artificial satellites working together as a system. Unlike a single satellite, a constellation can provide permanent global or near-global coverage , such that at any time everywhere on Earth at least one satellite is visible. Satellites are typically placed in sets of complementary orbital planes and connect to globally distributed ground stations . They may also use inter-satellite communication .
37-800: The Cartosat is a series of Indian optical Earth observation satellites built and operated by the Indian Space Research Organisation (ISRO). The Cartosat series is a part of the Indian Remote Sensing Program . They are used for Earth's resource management, defence services and monitoring. The Department of Space (DoS) had launched and managed the IRS series of remote sensing satellites for Earth's resource management and monitoring. These satellites were very successful in providing data in various scales ranging from 1:1 Million to 1:12,500 scale. Each of
74-399: A collection of circular orbits with the same altitude and, oftentimes, orbital inclination , distributed evenly in celestial longitude (and mean anomaly ). For a sufficiently high inclination and altitude the orbital shell covers the entire orbited body. In other cases the coverage extends up to a certain maximum latitude . Several existing satellite constellations typically use
111-694: A commercial arrangement between several firms and ISRO's commercial arm Antrix Corporation Limited , run under the auspices of the Indian Government's Department of Space . PSLV-C37 was launched from the First Launch Pad of Satish Dhawan Space Centre in Sriharikota at 09:28 IST on 15 February 2017. It was the 39th flight of the PSLV and the sixteenth in the XL configuration. It carried
148-463: A high quality resolution which is a major improvement from the previous payloads in the Cartosat series. Satellite series Satellite constellations should not be confused with: Satellites in medium Earth orbit (MEO) and low Earth orbit (LEO) are often deployed in satellite constellations, because the coverage area provided by a single satellite only covers a small area that moves as
185-401: A large number of constellations that may satisfy a particular mission. Usually constellations are designed so that the satellites have similar orbits, eccentricity and inclination so that any perturbations affect each satellite in approximately the same way. In this way, the geometry can be preserved without excessive station-keeping thereby reducing the fuel usage and hence increasing the life of
222-495: A mission life of six months. An ISRO official said: "The nano satellites are an experimental class of satellites introduced by ISRO because there are requests from academic institutions to use them for data collection. The universities do not have the knowledge to build satellites and tend to take a long time… We want them to focus on the instruments as we can provide the nano satellite bus." The 103 co-passenger satellites weighed approximately 664 kilograms (1,464 lb), bringing
259-618: A single mission, breaking the earlier record of launching 37 satellites by a Russian Dnepr rocket on 19 June 2014. This record was held until the launch of the Transporter-1 mission by SpaceX on 24 January 2021 which launched 143 satellites. Its primary payload was the Cartosat-2D Earth observation satellite , while the secondary payloads included a total of 103 nanosatellites , including two experiments from ISRO. The 101 international satellites were launched as part of
296-406: A single orbital shell. New large megaconstellations have been proposed that consist of multiple orbital shells. Total number of operational satellites: 634 as of 20 May 2023 Other Internet access systems are proposed or currently being developed: Some systems were proposed but never realized: Satellite constellation simulation tools: More information: PSLV-C37 PSLV-C37
333-464: A total of 104 satellites including the primary payload Cartosat-2D . The launcher started placing the satellites into polar Sun-synchronous orbits one after another after a flight of 16 minutes and 48 seconds. It first ejected the satellite Cartosat-2D at an altitude of approximately 510 kilometres (320 mi), with 97.46 degrees inclination, followed by the two ISRO nanosatellites INS-1A and INS-1B. It then took 11 minutes for PSLV C-37 to place
370-482: Is (t,p,m) where m is a multiple of the fractional offset between planes. Another popular constellation type is the near-polar Walker Star, which is used by Iridium . Here, the satellites are in near-polar circular orbits across approximately 180 degrees, travelling north on one side of the Earth, and south on the other. The active satellites in the full Iridium constellation form a Walker Star of 86.4°: 66/6/2, i.e.
407-936: The Global Positioning System (GPS), Galileo and GLONASS constellations for navigation and geodesy in MEO, the Iridium and Globalstar satellite telephony services and Orbcomm messaging service in LEO, the Disaster Monitoring Constellation and RapidEye for remote sensing in Sun-synchronous LEO, Russian Molniya and Tundra communications constellations in highly elliptic orbit , and satellite broadband constellations, under construction from Starlink and OneWeb in LEO, and operational from O3b in MEO. There are
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#1732791740175444-521: The IRS missions ensured data continuity while introducing improvements in the spatial, spectral and radiometric resolutions. Considering increased demand for large scale and topographic mapping data, the DoS launched the expanded Cartosat series of remote sensing satellites. The first satellite of the series, Cartosat-1, was launched in 2005. Cartosat-1 was launched by PSLV-C6 on 5 May 2005 from Satish Dhawan Space Centre 's SLP at Sriharikota . Images from
481-473: The rocket engine nozzle manufactured by Vijayawada , from Andhra Pradesh-based company Resins and Allied Productions (RAP). This is the 100th nozzle manufactured by RAP to be used in a PSLV. Several components of PSLV-C37 were manufactured by Larsen & Toubro at its advanced composite facility in Vadodara , Gujarat. The honeycomb deck panels used for mounting the heat shield and electronic packages on
518-513: The 710 kg satellite, the seventh of the Cartosat-2 series, along with 30 other nano satellites from India, Canada, Finland, France, Republic of Korea, UK and the USA. Cartosat-3 was launched on 27 November 2019 by PSLV -C47 rocket along with 13 other cubesats from USA. It has a panchromatic resolution of 0.25 metres making it the imaging satellite with highest resolution and Mx of 1 metre with
555-610: The Netherlands, Switzerland, and the United Arab Emirates, along with 96 from the United States – 88 Dove satellites and 8 LEMUR satellites. The three Indian satellites launched were Cartosat-2D, INS-1A, and INS-1B. Arrangements for the launch of the 104 satellites were made between ISRO's commercial arm Antrix Corporation Limited , under the auspices of the Indian Government's Department of Space , and
592-399: The direction of its movement to facilitate imaging of any area more frequently. Cartosat-2B was launched by PSLV-C15 on 12 July 2010 from Sriharikota . The satellite carries a panchromatic (PAN) camera capable of taking black-and-white pictures in the visible region of electromagnetic spectrum . The highly agile CARTOSAT-2B can be steered up to 26 degrees along as well as across
629-421: The direction of its movement to facilitate imaging of any area more frequently. Cartosat-2C has a lower resolution of 25 cm (10"). It uses 1.2 m optics with 60% of weight removal compared to Cartosat-2. Other features include the use of adaptive optics, acousto optical devices, in-orbit focusing using MEMs and large area-light weight mirrors. The satellite was to be launched on board PSLV C-34 during 2014, but
666-691: The international customers. The Cartosat-2D weighs 714 kilograms (1,574 lb), and its design life is five years. The two Indian nanosatellites, designated INS-1A and INS-1B, each carried two payloads from ISRO's Space Applications Centre and the Laboratory for Electro-Optics Systems . INS-1A carried a Surface Bidirectional Reflectance Distribution Function Radiometer (SBR) and a Single Event Upset Monitor (SEUM). INS-1B carried an Earth Exosphere Lyman-Alpha Analyzer (EELA) and Origami Camera as payloads. They weigh 8.4 kilograms (19 lb) and 9.7 kilograms (21 lb) respectively and have been designed with
703-400: The launch of PSLV-C37, Planet Labs increased its fleet of satellites to 143, which was the largest private satellite fleet in operation at the time. Eight Lemur-2 satellites belonging to Spire Global are to provide vessel tracking and weather measurement services. These satellites have a short lifetime of about two to three years requiring replacement at regular intervals. PSLV-C37 used
740-449: The lower altitude of MEO and LEO satellite constellations provide advantages over a geostationary satellite, with lower path losses (reducing power requirements and costs) and latency. The propagation delay for a round-trip internet protocol transmission via a geostationary satellite can be over 600 ms, but as low as 125 ms for a MEO satellite or 30 ms for a LEO system. Examples of satellite constellations include
777-418: The phasing repeats every two planes. Walker uses similar notation for stars and deltas, which can be confusing. These sets of circular orbits at constant altitude are sometimes referred to as orbital shells. In spaceflight , an orbital shell is a set of artificial satellites in circular orbits at a certain fixed altitude . In the design of satellite constellations, an orbital shell usually refers to
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#1732791740175814-548: The previous record of Russia, which in 2014 launched 37 satellites using Dnepr rocket. This record set by ISRO stood until 24 January 2021, when SpaceX launched the Transporter-1 mission on a Falcon 9 rocket carrying 143 satellites into orbit. Imagery from the primary satellite, Cartosat-2D , is used for various land information system and geographical information system applications in India. Data collected by
851-690: The remaining 101 "co-passenger" satellites into their intended orbits. Soon after separation from the launch vehicle, the two solar arrays on board the Cartosat-2D satellite were automatically deployed. Afterwards, ISRO's Telemetry, Tracking and Command Network at Bengaluru took control of the satellite. "In the coming days, the satellite will be brought to its final operational configuration following which it will begin to provide remote sensing services using its panchromatic (black and white) and multispectral (colour) cameras," an ISRO statement read. The mission lasted 29 minutes. Originally, PSLV-C37
888-460: The satellite are available from GeoEye for worldwide distribution. The satellite covers the entire globe in 1867 orbits on a 126-day cycle. It carries two state-of-the-art panchromatic (PAN) cameras that take black and white stereoscopic pictures of the earth in the visible region of the electromagnetic spectrum . The two cameras with 2.5 m spatial resolution, acquire two images simultaneously, one forward looking (FORE) at +26 degrees and one aft of
925-401: The satellite at −5 degrees for near instantaneous stereo data. The time difference between the acquisitions of the same scene by the two cameras is about 52 seconds. Cartosat-2 was launched by PSLV-C7 on 10 January 2007 from Satish Dhawan Space Centre 's FLP at Sriharikota . Cartosat-2 carries a state-of-the-art panchromatic (PAN) camera that take black and white pictures of the Earth in
962-456: The satellite travels at the high angular velocity needed to maintain its orbit . Many MEO or LEO satellites are needed to maintain continuous coverage over an area. This contrasts with geostationary satellites, where a single satellite, at a much higher altitude and moving at the same angular velocity as the rotation of the Earth's surface, provides permanent coverage over a large area. For some applications, in particular digital connectivity,
999-559: The satellites. Another consideration is that the phasing of each satellite in an orbital plane maintains sufficient separation to avoid collisions or interference at orbit plane intersections. Circular orbits are popular, because then the satellite is at a constant altitude requiring a constant strength signal to communicate. A class of circular orbit geometries that has become popular is the Walker Delta Pattern constellation. This has an associated notation to describe it which
1036-591: The students of Al-Farabi Kazakh National University , Nayif-1 satellite built by the Mohammed bin Rashid Space Centre , Dubai , and PEASSS satellite built by an all-European consortium of Partners, are technology demonstrator satellites whereas DIDO-2 built by SpacePharma from Switzerland is a micro-research satellite. BGUSAT (Ben Gurion University SATellite) built by Israel Aerospace Industries (IAI) in cooperation with Ben Gurion University
1073-504: The total payload mass to 1,378 kilograms (3,038 lb). The total launch mass of the rocket was 320,000 kilograms (710,000 lb). Among the 96 satellites belonging to US companies, 88 CubeSats were owned by Planet Labs , a private Earth imaging company based in San Francisco, California. Weighing roughly 5 kilograms (11 lb) each, the satellites separated from the rocket in different directions to avoid collision. With
1110-648: The two Indian nanosatellites—the INS-1A and INS-1B—will be used by ISRO's Space Applications Centre and the Laboratory for Electro-Optics Systems. The Dove satellites from the US are used to photograph the Earth for commercial, environmental, and humanitarian purposes. Eight LEMUR satellites, weighing 4.6 kilograms (10 lb) each, carried two different payloads, namely SENSE for vessel tracking purposes and STRATOS for atmospheric measurements. Al Farabi-1 satellite built by
1147-418: The upper stage of the PSLV, the antenna mount structure, and the 13 metres (14 yd) diameter bull gear were all manufactured by L&T. ISRO released a statement stating that it will recover half of the mission's cost from the foreign countries whose satellites it launched. With this launch, ISRO created a new world record for the largest number of satellites ever launched on a single rocket, surpassing
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1184-717: The visible region of the electromagnetic spectrum . The swath covered by this high resolution PAN camera is 9.6 km and their spatial resolution is less than 1 metre. The satellite can be steered up to 45 degrees along as well as across the track. Cartosat-2 is an advanced remote sensing satellite capable of providing scene-specific spot imagery. The data from the satellite is used for detailed mapping and other cartographic applications at cad-astral level, urban and rural infrastructure development and management, as well as applications in Land Information System (LIS) and Geographical Information System (GIS). Cartosat-2A
1221-469: Was delayed and finally launched on 22 June 2016. Its uses include weather mapping, cartography, and strategic applications. Cartosat-2D was launched by PSLV-C37 on 15 February 2017 from Satish Dhawan Space Centre. Cartosat-2E was launched by PSLV-C38 on 23 June 2017. The PSLV-C38 rocket launched the 712 kg satellite along with 30 other nano satellites. Cartosat-2F was launched successfully by PSLV-C40 on 12 January 2018. The PSLV-C40 rocket launched
1258-615: Was launched by PSLV-C9 on 28 April 2008 from Satish Dhawan Space Centre in Sriharikota along with nine other satellites. It is a dedicated satellite for the Indian Armed Forces which is in the process of establishing an Aerospace Command . The satellite carries a panchromatic (PAN) camera capable of taking black-and-white pictures in the visible region of electromagnetic spectrum . The highly agile Cartosat-2A can be steered up to 45 degrees along as well as across
1295-574: Was proposed by John Walker. His notation is: where: For example, the Galileo navigation system is a Walker Delta 56°: 24/3/1 constellation. This means there are 24 satellites in 3 planes inclined at 56 degrees, spanning the 360 degrees around the equator . The "1" defines the phasing between the planes, and how they are spaced. The Walker Delta is also known as the Ballard rosette, after A. H. Ballard's similar earlier work. Ballard's notation
1332-557: Was set to launch on 27 January 2017 with 83 satellites. With the addition of twenty more satellites to the payload, the schedule was changed to 15 February 2017. On October 6 2024, the upper stage of the rocket (PS4) Re-entered the atmosphere at about 15:48:25 UTC. The corresponding impact point is located in the North Atlantic Ocean , off the coast of Cuba . The rocket launched Cartosat-2D and 103 nanosatellites : two from India, one each from Kazakhstan, Israel,
1369-692: Was the 39th mission of the Indian Polar Satellite Launch Vehicle (PSLV) program and its 16th mission in the XL configuration undertaken by the Indian Space Research Organisation (ISRO). Launched on 15 February 2017 from the Satish Dhawan Space Centre at Sriharikota , Andhra Pradesh , the rocket successfully carried and deployed a record number of 104 satellites in Sun-synchronous orbits in
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