Background
In its seventeenth flight (PSLV-C15), ISRO’s Polar Satellite Launch
Vehicle will launch five satellites – the 694 kg Indian remote sensing
satellite CARTOSAT-2B, which is its main payload, and the 116 kg
ALSAT-2A of Algeria, 6.5 kg NLS-6.1 AISSAT-1 of Canada, NLS-6.2 TISAT
of Switzerland and STUDSAT, a picosatellite weighing less than 1 kg built
by a consortium of seven Engineering colleges in Bangalore and
Hyderabad – into a 630 km polar Sun Synchronous Orbit (SSO).
PSLV-C15 will be launched from the first Launch Pad at Satish Dhawan
Space Centre (SDSC) SHAR, Sriharikota, in the Nellore district of Andhra
Pradesh.
About PSLV:
PSLV was initially designed by ISRO to place 1,000 kg class Indian
Remote Sensing (IRS) satellites into 900 km polar Sun Synchronous
Orbits. Since its first successful flight in October 1994, the capability of
PSLV was successively enhanced from 850 kg to 1,750 kg. In its
previous flight (sixteenth) on September 23, 2009, PSLV launched India’s
960 kg remote sensing satellite Oceansat-2 and six nanosatellites from
abroad into a 728 km polar Sun Synchronous Orbit.
The improvement in the capability of PSLV over successive flights has
been achieved through several means. They include increased propellant
loading in the stage motors and the strap-ons, employing composite
material for the satellite mounting structure and changing the sequence
of firing of the strap-on motors.
In its standard configuration, the 44.4 metre tall 295 ton PSLV has four
stages using solid and liquid propulsion systems alternately. The first
stage, carrying 138 ton of propellant, is one of the largest solid propellant
boosters in the world. Six solid propellant strap-on motors, each carrying
nine tonne of solid propellant, are strapped on to the core stage. The
second stage carries 41 ton of liquid propellant. The third stage uses
7.6 tonne of solid propellant and the fourth has a twin-engine
configuration with 2.5 ton of liquid propellant.
The 3.2 metre diameter bulbous payload fairing of PSLV protects the
satellites carried onboard and it is discarded after the vehicle has cleared
the dense atmosphere. PSLV employs a large number of auxiliary
systems for stage separation, payload fairing separation and so on. It has
sophisticated systems to control the vehicle and guide it through the
predetermined trajectory. The vehicle performance is monitored through
telemetry and tracking.
With fifteen consecutively successful flights so far, PSLV has repeatedly
proved itself as a reliable workhorse. It has demonstrated multiple
satellite launch capability having launched 22 satellites for international
customers besides 17 Indian satellites of which twelve were remote
sensing satellites, a recoverable capsule (SRE-1), two small satellites for
HAM radio communications and experimental communications, one
meteorological (weather watching) satellite (KALPANA-1) and the
spacecraft for India’s first mission to Moon, Chandrayaan-1. PSLV has
launched satellites into a variety of orbits, including polar Sun
Synchronous, Low Earth, Highly Elliptical and Geosynchronous Transfer
Orbits.
Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, designed
and developed PSLV. The ISRO Inertial Systems Unit (IISU) at
Thiruvananthapuram developed the inertial systems for the vehicle. The
Liquid Propulsion Systems Centre (LPSC), also at Thiruvananthapuram,
developed the liquid propulsion stages for the second and fourth stages
of PSLV as well as reaction control systems. SDSC SHAR processed the
solid motors and carried out launch operations. ISRO Telemetry,
Tracking and Command Network (ISTRAC) provides telemetry, tracking
and command support during PSLV’s flight.
PSLV-C15:
PSLV-C15 employs the ‘Core Alone’ version of PSLV, which is almost the
same as its standard configuration except for the absence of the six
strap-ons (which surround the first stage of PSLV in the standard
configuration and enhance its payload capability). PSLV-C15 is the sixth
flight of the ‘core alone’ version of PSLV. One important modification in
PSLV-C15 compared to the previous flight is the use of a Dual Launch
Adopter (DLA) to carry two large satellites.
CARTOSAT-2B
The 694 kg CARTOSAT-2B is a state-of-the art remote sensing satellite
and the seventeenth remote sensing satellite of India. Data from the
satellite will find applications in cartography at cadastral level, urban
and rural infrastructure development and management, as well as Land
Information System (LIS) and Geographical Information System (GIS).
The satellite will be placed in a 630 km high polar Sun Synchronous
Orbit.
CARTOSAT-2B carries a state-of-the-art Panchromatic camera (PAN) that
takes black-and-white pictures in the visible region of the
electromagnetic spectrum. The imagery will have a spatial resolution of
0.8 metre. The camera covers a swath (geographical strip of land) which
is 9.6 km wide. The highly agile CARTOSAT-2B is steerable up to
± 26 degrees along as well as across the direction of its movement to
facilitate imaging of any area more frequently. The satellite also carries a
Solid State Recorder with a capacity of 64 Giga Bits to store the images
taken by its camera. These images can later be transmitted when the
satellite comes within the visibility of a ground station.
Soon after its injection into orbit and separation from PSLV-C15 fourth
stage, the two solar panels of CARTOSAT-2B will be automatically
deployed. The satellite’s health will be continuously monitored from the
Spacecraft Control Centre at Bangalore with the help of ISTRAC network
of ground stations at Bangalore, Lucknow, Mauritius, Biak in Indonesia,
Svalbard in Norway and Troll in Antarctica.
With ISRO Satellite Centre (ISAC), Bangalore, as the lead Centre,
CARTOSAT-2B was realised with major contributions from Space
Applications Centre (SAC), Ahmedabad, Liquid Propulsion Systems
Centre (LPSC) at Bangalore, ISRO Inertial Systems Unit (IISU),
Thiruvananthapuram and Laboratory for Electro Optic Sensors (LEOS),
Bangalore. ISTRAC is responsible for initial and in-orbit operation of
CARTOSAT-2B. The National Remote Sensing Centre (NRSC) receives,
processes and distributes the data from IRS satellites to various users.
The imagery from IRS satellites are disseminated worldwide on a
commercial basis through Antrix Corporation of DOS.
Salient Features:
Orbit : Circular Polar Sun Synchronous
Orbit height : 630 km
Orbit inclination : 97.91 deg
Orbit period : 97.44 min
Number of Orbits per day : 14
Local Time of Equator Crossing: 9.30 AM
Revisit : 4-5 days
Lift-off Mass : 694 kg
Attitude and Orbit Control : 3-axis stabilised using high torque
Reaction Wheels, Magnetic
Torquers and Hydrazine
Thrusters
Electrical Power : 930 W
Two 18 Ah Ni-Cd batteries
Payload : PAN Camera
PAN Specifications:
Swath : 9.6 km
Spatial Resolution : 0.8 metre
Spectral Band : 0.50-0.75 micron
Applications:
The multiple spot scene imagery sent by CARTOSAT-2B's PAN will be
useful for village level/cadastral level resource assessment and mapping,
detailed urban and infrastructure planning and development,
transportation system planning, preparation of large-scale cartographic
maps, preparation of micro watershed development plans and monitoring
of developmental works at village/cadastral level.
Besides, CARTOSAT-2B's imagery can be used for the preparation of
detailed forest type maps, tree volume estimation, village/cadastral level
crop inventory, town/village settlement mapping and planning for
comprehensive development, canal alignment, rural connectivity
assessment, planning new rural roads and monitoring their construction,
coastal landform/land use and coral/mangrove mapping and monitoring
of mining activities.
Indian Remote Sensing Satellite System:
India has established the National Natural Resources Management
System (NNRMS) for which the Department of Space (DOS) is the nodal
agency. NNRMS is an integrated resource management system aimed at
optimal utilisation of the country’s natural resources by a proper and
systematic inventory of resource availability using remote sensing data in
conjunction with conventional techniques. The major elements of NNRMS
encompass conceptualisation and implementation of space segments
with the necessary ground-based data reception, processing and
interpretation systems and integrating the satellite-based remotely
sensed data with conventional data for resource management
applications.
The Indian Remote Sensing (IRS) satellites form an important element of
the NNRMS for providing continuous remote sensing data services for the
management of natural resources of the country. A series of IRS
satellites have been launched by India starting with IRS-1A in March
1988. Nine remote sensing satellites of India are in service at
present – IRS-P4 (OCEANSAT-1), TES, RESOURCESAT-1, CARTOSAT-1,
CARTOSAT-2, CARTOSAT-2A, IMS-1, RISAT-2 and OCEANSAT-2 –
making IRS system the largest civilian remote sensing satellite
constellation in the world. CARTOSAT-2B is the latest satellite under the
IRS programme.
The follow-on satellites in the IRS series include RESOURCESAT-2
carrying an improved LISS-4 as well as LISS-3 and AWiFS cameras and
Radar Imaging Satellite (RISAT-1) incorporating a C-band Synthetic
Aperture Radar (SAR) that has imaging capability even under cloudy
conditions, both during day and night.
The data from IRS is being utilised for several applications. They include
landuse/cover mapping for agro-climatic zones planning, wasteland
mapping, forest cover mapping, wetland mapping, Crop Acreage and
Production Estimation, Coastal Zone Regulation mapping, Identification
of Potential Fishing Zones, Integrated Mission for Sustainable
Development, National (Natural) Resources Information System, etc. In
addition, different application studies of local/regional level are also
being carried out by many organisations. With high-resolution imageries
of CARTOSAT-2B, cadastral level applications will receive further
impetus.
Auxiliary Payloads of PSLV-C15:
Besides its main payload CARTOSAT-2B weighing 694 kg, PSLV-C15 will
also carry four small satellites as auxiliary payloads. Of these, the
116 kg ALSAT-2A of Algeria is a small remote sensing satellite, whereas
two Nanosats – NLS-6.1 AISSAT-1 weighing 6.5 kg and built by Space
Flight Laboratory of the University of Toronto, Canada and NLS-6.2
TISAT-1 weighing one kg and built by University of Applied Sciences of
Switzerland – are for testing various satellite technologies. The fourth
auxiliary payload – STUDSAT – is a Picosatellite weighing less than one
kg and built jointly by students from a consortium of seven engineering
colleges in Bangalore and Hyderabad.
The consortium of Project STUDSAT is represented by Nitte Meenakshi
Institute of Technology. The other institutions are: BMS Institute of
Technology (BMSIT), Bangalore, Chaitanya Bharathi Institute of
Technology (CBIT), Hyderabad, Institute of Aeronautical Engineering
(IARE), Hyderabad, M S Ramaiah Institute of Technology (MSRIT),
Bangalore, RV College of Engineering (RVCE), Bangalore and Vignan
Institute of Technology & Science (VITS), Hyderabad. STUDSAT is the
first picosatellite developed in the country.
Weighing about 650 gm, STUDSAT has the primary objective of
promoting space technology in educational institutions and encourage
research and development in miniaturised satellites, establishing a
communication link between the satellite and the ground station,
capturing the images of earth with a resolution of 90 meters and
transmitting the payload and telemetry data to the earth stations.
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