As ISRO gets ready to launch the much-talked about Chandrayaan 2 in April this year, it is already geared up to launch three satellites — GSAT 6, IRNSS 1-I and GSAT11 — in March. GSAT-6A and GSAT-29 communication satellites will be launched by GSLV Mk-ll and GSLV Mk-lll, respectively. The GSAT-11 communication satellite is planned to be launched through procured launch. With regard to earth observation satellites, it is planned to initiate necessary processes of development of Cartosat-3, Oceansat-3 and RISAT-1A (Radar Imaging) in addition to the GISAT-1, according to the annual report of the Department of Space, Government of India.
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ISRO’s future earth observation (EO) program will ensure the continuity of the application thematic series of satellites, namely, Resourcesat & RISAT (Land & Water), Cartosat (Cartography), Oceansat (Ocean & Atmosphere) and INSAT (Meteorology). It is also envisaged to realize geo-imaging satellites (GISAT) in geostationary orbit to enable near real-time imaging. The overall aim is to maintain the continuity of services and carryout enhancements in technological capabilities with respect to sensors and payloads in order to meet the operational applications. In this regard, several satellites have been planned to be launched in conversant with ISRO’s vision document.
Cartosat-3
Expected to be ready by third quarter of 2018. Cartosat-3 will join its eight siblings in the Cartosat-1 and Cartosat-2 series, which was specifically launched by ISRO for Earth’s resource management and monitoring. Cartosat-3 is an advanced agile satellite to obtain panchromatic and multispectral imagery with an operational life of 5 years. The payload has the capability of imaging with 0.25m GSD in panchromatic and 1m GSD in four-band multispectral modes with a swath of 16km. Many new technologies/elements are being developed like highly agile structural platform, payload platform, higher rate data handling and transmission systems, advanced onboard computer and new power electronics, dual gimbal antenna, etc.
Oceansat-3 & 3A
A continuity mission of Oceansat-2 with enhanced imaging capability. The satellites have three payloads each onboard a 13-Band ocean color monitor (OCM), a 2-band long wave (thermal) infrared sea surface temperature monitor and Ku-band pencil beam scatterometer. Improvements planned in the Oceansat-3 are simultaneous measurement of ocean color and SST, newer applications with increased number of bands and reduced bandwidth, wind vectors at 25km spatial resolution, improvements in signal to noise ratio, coverage from near pole to pole, etc. Oceansat 3 and 3A are planned to be launched in November 2018 and July 2019 respectively.
RISAT-1A & 1B
A repeat mission of RISAT-1 to facilitate cloud penetration and to carry out the other earth observation applications. The data from RISAT-1A will be used for applications in the areas of agriculture, forestry, soil moisture & hydrology, oceanography and disaster management. The satellite is planned to be launched into a sun synchronous orbit at an altitude of 536 km and will carry a SAR payload operating in C-band, which has the capability to penetrate clouds and take images during day/night. RISAT-1A & 1B are planned to be launched in the year December 2018 and March 2021 respectively.
INSAT-3DS
Is a stand-by mission planned to replace either of INSAT-3D in the orbital slot of 82-degree east longitude in the geostationary orbit or INSAT-3DR in the orbital slot of 74-degree east longitude in the geostationary orbit based on the need. Planned to be kept ready in stand-by mode by 2018, INSAT-3DS is a stand-by mission with improved geolocation accuracy and enhanced band to band registration. It has an atmospheric sounding system of 19 channels capable of providing vertical profiles of temperature, humidity and integrated ozone from surface to top of the atmosphere. INSAT-3DS also has an imager capable of imaging earth and its environment in six spectral channels and satellite aided search and rescue transponder similar to INSAT-3D/3DR.
HRSAT
Is a constellation of small satellites with sub-meter resolution in PAN and a daily revisit capability, and scheduled to be launched in February 2019. HRSAT has a great potential for commercial applications in large scale mapping, agriculture, urban planning, rural development, infrastructure development, Disaster management, etc. This is constellation of three high resolution satellites in a single orbital plane to be launched by a single PSLV into a 660 km polar sun synchronous orbit. The constellation will have daily revisit capability with about 45-degree tilts. The payloads will have imaging capability of around 1m ground sampling distance with 15 km swath in panchromatic mode, 2-4 m GSD in three band multi-spectralmode with 15 km swath, and 20 m GSD in IR band with a swath of 6 km.
GISAT-1
Will be realized for launch by June 2019. GISAT-1 is a geo-imaging satellite operating from geostationary orbit to provide high temporal resolution. It is expected to provide near real-time images of the large areas of the country, under cloud-free conditions, at frequent intervals. It will provide selected sector-wise image every 5 minutes and entire Indian landmass image every 30 minutes at 50 m spatial resolution. The potential applications include quick monitoring of disasters, natural hazards and calamities, episodic events and any short-term events. The spacecraft is planned to be positioned at 93.5-degree east longitude in the geostationary orbit of 36,000 km height, and will be capable provide a spatial resolution in the range of 50 m to 1.5 km, depending on the spectral band used. The satellite platform is a modified version of I-1K bus, with a power handling capability of around 2037 W during Equinox with a lift-off mass of 2,100 kg.
Resourcesat-3S & 3SA
This is a mission for stereographic mapping with improved resolution in panchromatic and multispectral bands and along track stereo images for generating improved digital elevation models (DEM) target of 5 m for the area of interest. The two satellites are capable of providing along track high-resolution panchromatic stereo and multi-spectral imagery. They carry two panchromatic camera with 1.25m resolution providing a swath of 60 km in PAN band, and a multispectral camera having bands in VNIR region with 2.5m resolution providing a swath of 60 km. Resourcesat-3S & 3SA are planned to be launched in the year May 2019 and January 2020, respectively.
Resourcesat-3 & 3A
Are medium resolution, wide swath satellites for advanced land and water resource management applications. The satellites will ensure continuity of data services required for the operational program in land and water resources management, and will carry advanced linear imaging scanning sensor-3 (ALISS-3) payload consisting of VNIR and SWIR bands. Besides providing medium resolution wide-swath imagery, it is equipped with on-board atmospheric correction band to improve the data products. The ground sampling distances will be 20 m for VNIR and SWIR bands with the central EOM providing 10m GSD. Hyper-spectral atmospheric correction bands will operate in VNIR bands and have ground sampling distances of 240m. Resourcesat-3 & 3A are planned to be launched in the year September 2019 and August 2020, respectively.
NISAR
The NASA-ISRO Synthetic Aperture Radar satellite is built jointly with NASA, a dual frequency (L & S band) radar imaging satellite, to provide data services for natural resources mapping and monitoring as well as studies related to deformation, ecosystem, dynamics of ice sheets, mountain glaciers, forest fires and oil slick. It carries an L Band in 1260 MHz and S Band in 3200 MHz SAR payloads, both operating in interferometric SAR with multiple polarization. The L band SAR would be augmented with S band component and both these SAR systems would make use of 12-meter diameter size common unfurlable reflector antenna. The payload uses innovative Sweep SAR technique for both L- and S-band in full polarimetric configuration to enable very wide swath measurements greater than 200 km and very high resolution (5-10 m) with repeat pass interferometric capability. The launch vehicle identified for NISAR is GSLV Mk-II and is planned to be launched in the year 2021.
