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ISRO’s Polar Satellite Launch
Vehicle, PSLV-C7, successfully launched today four satellites into high
polar orbit from Satish Dhawan Space Centre
(SDSC) Shar, Sriharikota. For the first time, a Dual Launch Adopter (DLA) was
used in PSLV to accommodate two primary satellites in tandem. The four
satellites put into the orbit are India’s CARTOSAT-2 and Space capsule Recovery
Experiment (SRE-1), Indonesia’s LAPAN-TUBSAT and Argentina’s PEHUENSAT-1.
After the final count
down, PSLV-C7 lifted off from the first launch pad at SDSC SHAR, at 9.23 am
with the ignition of the core first stage and four of the six strap-on motors.
The remaining two strap-on motors were ignited at 25 sec after lift-off.
The important flight
events included the separation of the ground-lit strap-on motors, separation of
air-lit strap-on motors and the first stage, ignition of the second stage,
separation of the heatshield at about 121 km altitude after the vehicle had
cleared the dense atmosphere, second stage separation, third stage ignition,
third stage separation, fourth stage ignition and fourth stage cut-off.
The 680 kg main
payload, CARTOSAT-2, mounted over DLA, was the first satellite to be injected
into orbit at 981.3 sec after lift-off at an altitude of 639 km. About 45 sec
later, DLA with the 6 kg PEHUENSAT-1 mounted on it, was separated. 120 sec
later, the 550 kg Space capsule Recovery Experiment (SRE-1) mounted inside DLA
was separated and finally, 190 sec later, the 56 kg LAPAN-TUBSAT, mounted on
the equipment bay of PSLV fourth stage was separated.
The four satellites
have been placed in a polar orbit at an altitude of 637 km with an inclination
of 97.9 degree with respect to the equator. The initial signals indicate their
normal health.
PSLV is the workhorse
launch vehicle of the Indian Space Research Organisation (ISRO) with nine
consecutively successful flights so far. Since its first successful launch in
1994, PSLV has launched seven Indian remote sensing satellites, an amateur
radio satellite, HAMSAT, and four small satellites for foreign customers into
550-800 km high polar SSOs. Besides, it has also launched India’s exclusive
meteorological satellite, Kalpana-1, into Geosynchronous Transfer Orbit (GTO).
PSLV will also be used to launch India’s first spacecraft mission to moon,
Chandrayaan-1, during 2008.
The 44 m tall PSLV has a lift-off mass of 295 tonne. It is a
four-stage launch vehicle with the first and the third stages as well as the
six strap-ons surrounding the first stage using HTPB based solid propellant.
PSLV’s first stage is one of the largest solid propellant boosters in the
world. Its second and fourth stages use liquid propellants. PSLV’s bulbous
payload fairing has a diameter of 3.2 metre. The vehicle has S-band telemetry
and C-band transponder systems for monitoring its health and flight status. It
also has sophisticated auxiliary systems like stage and payload fairing
separation systems.
PSLV was originally
designed to put 1,000 kg class of India’s remote sensing satellites into a 900
km polar SSO. The payload capability of PSLV has been successively enhanced and
in today’s flight, PSLV-C7, it launched four payloads, in all weighing 1292 kg in
addition to the DLA. Some of the modifications incorporated in PSLV-C7 compared
to the previous flight, PSLV-C6, are:
- Use
of Dual Launch Adopter
- Reduction
of propellant from 2.5 tonne to 2 tonne in the fourth liquid propellant
stage, PS4
- Altitude
based Day of Launch wind biased steering programme during Open Loop
Guidance
CARTOSAT-2,
the twelfth in the Indian Remote Sensing (IRS) satellite series, is an advanced
remote sensing satellite capable of providing scene-specific spot imagery. It
will join the other six IRS satellites which are in service -- IRS-1C, IRS-1D,
OCEANSAT-1, Technology Experimental Satellite (TES), RESOURCESAT-1 and
CARTOSAT-1. It carries a Panchromatic camera (PAN) to provide imageries with a
spatial resolution of better than one metre and a swath of 9.6 km. The
satellite can be steered up to 45 deg along as well as across the track. The
data from the satellite will be used for cartographic applications at cadastral
level, urban and rural infrastructure development and management, as well as
applications in Land Information System (LIS) and Geographical Information
System (GIS).
Soon
after its separation from the DLA, the two solar arrays of CARTOSAT-2 were
automatically deployed to generate the electrical power for the satellite. The
satellite health is being continuously monitored from the Spacecraft Control
Centre of ISTRAC at Bangalore with the help of its network of stations at
Bangalore, Lucknow, Mauritius, Bearslake in Russia, Biak in Indonesia, as well
as support from Svalbard ground station in Sweden for the initial phase of the
CARTOSAT-2 mission. Further operations on the satellite like orbit trimming,
checking out the various subsystems and, finally, switching on the cameras will
be carried out in the coming days.
With
ISRO Satellite Centre (ISAC), Bangalore, as the lead Centre, CARTOSAT-2 was
realised with major contributions from Space Applications Centre (SAC), Ahmedabad,
LPSC at Bangalore, and IISU, Thiruvananthapuram. ISTRAC is responsible for
initial and in-orbit operation of CARTOSAT-2. The National Remote Sensing
Agency (NRSA), Hyderabad receives and processes the data from CARTOSAT-2.
Space
capsule Recovery Experiment (SRE-1), developed by ISRO’s VSSC and ISAC, is
a 550 kg capsule, intended to demonstrate the technology of an orbiting platform
for performing experiments in microgravity conditions. After the completion
of the experiments, the capsule will de-orbited after a few days and recovered.
SRE-1 mission will provide valuable experience in such important fields like
navigation, guidance and control during the re-entry phase, hypersonic aero-thermodynamics
facilitating the development of reusable thermal protection system (TPS),
recovery through deceleration and floatation besides acquisition of basic
technology for reusable launch vehicles.
SRE-1
carries two experiments, an Isothermal Heating Furnace [IHF] and a Biomimetic
(Biomineralisation of Inorganic materials) experiment. IHF will be operated
to perform metallurgical experiments while Biomimetic experiment will be operated
to perform Biomimetic synthesis. SRE-1 comprises aero-thermo structure, spacecraft
platform, deceleration and floatation system besides the micro-gravity payloads.
It has a sphere-cone-flare configuration with a spherical nose of about 0.5
m radius, base diameter of 2 m and 1.6 m height. The capsule is made of mild
steel. The parachute, pyro devices, avionics packages of triggering unit and
sequencer, telemetry and tracking system and sensors for measurement of system
performance parameters are placed inside SRE capsule.
Two
days before de-orbiting, SRE-1 will be placed in a Repetitive Elliptical Orbit.
Subsequently, it will be reoriented and deboost rocket is fired to make it
reenter the earth’s atmosphere. Close loop guidance system is employed during
deboost and coasting phases leading to its recovery. On re-entry, after initial
aerodynamic braking, a parachute system will reduce the touch down velocity.
SRE-1 will splashdown in the Bay of Bengal, east of Sriharikota coast. A floatation
system will keep SRE afloat and enables its recovery.
SRE-1
is being tracked and monitored by ground stations at Bangalore, Lucknow, Mauritius,
Biak in Indonesia, Bearslake in Russia, Saskatoon in Canada and Svalbard in
Sweden/Transo in Norway.
LAPAN-TUBSAT
and PEHUENSAT-1 were launched under commercial agreements.
LAPAN-TUBSAT
is a cooperative venture between Indonesian Space Agency, LAPAN and Technical
University of Berlin. It is an earth observation satellite besides a technical
demonstrator in control systems. The 56 kg LAPAN-TUBSAT carries two Charge
Coupled Device (CCD) cameras with ground resolutions of 5 m and 200 m respectively.
It also carries an experiment for message store and forward system.
PEHUENSAT-1
is a 6 kg Argentinean nano-satellite meant to serve educational, technological
and scientific fields. PEHUENSAT-1, developed by University of Comahue of
Argentina, AMSAT (Amateur Satellite Association of Argentina) and Argentina
Association for Space Technology, is intended to provide an experiment platform
to perform amateur radio experiments between colleges and universities of
Argentina.
RM: AT : NC
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PSLV successfully Launches four satellites
