
Chennai, Apr 11: The 32-hour countdown for the launch of 1,425 kg navigation satellite IRNSS-1I
by the indigenous rocket PSLV-C41 commenced at 2004 hrs in the spaceport of
Sriharikota on Tuesday night and has been progressing smoothly.
ISRO sources on Wednesday said, in its 43rd
flight, the 44.4 m tall PSLV-C41, with a lift off mass of 321 tonnes, would
soar into the skies from the First Launch Pad at 0404 hrs early tomorrow
morning.
During the countdown propellant filling
operations would be carried out in the four stage vehicle.
About 19 minutes after lift off, the 1,425 kg
satellite, would be injected into the sub-Geosynchronous Transfer Orbit
(Sub-GTO) at a perigee of 284 km and an apogee of 20,650 km, with an
inclination of 19.2 deg to the equator.
After carrying out Orbit raising manouevres
using the onboard propulsion systems, the satellite would be placed in the
Geosynchronous Orbit at a height of 36,000 km with an inclination of 29 deg.
ISRO would be using the 'XL' version of PSLV for
the mission.
This would be be 20th flight of PSLV-XL version
and the 32nd PSLV mission from the First Launch Pad.
The Satellite, with a life span of ten years,
would transmit signals for the determination of position, navigation and time.
It would be the ninth satellite in the Indian
Regional Navigation Satellite System (IRNSS) segment.
It would also serve as a replacement for
IRNSS-1A after its failure of its rubidium atomic clocks, which would provide
accurate positional data.
Its predecessors, IRNSS-1A, 1B, 1C, 1D, 1E, 1F
and 1G were launched by PSLV-C22, PSLV-C24, PSLV-C26, PSLV-C27, PSLV-C31,
PSLV-C32 and PSLV-C33 in July 2013, April 2014, October 2014, March 2015,
January 2016, March 2016 and April 2016 respectively.
The configuration of IRNSS-1I is similar to
IRNSS-1A, 1B, 1C, 1D, 1E, 1F and 1G.
Like its other IRNSS predecessors, IRNSS-1I also
carries two types of payloads--navigation payload and ranging payload.
The navigation payload of IRNSS-1I transmits
signals for the determination of position, velocity and time.
This payload was operating in L5-band and
S-band. Rubidium atomic clocks are part of the navigation payload of the
satellite. The ranging payload of IRNSS-1I consists of a C-band transponder,
which facilitates accurate determination of the range of the satellite.
It also carries Corner Cube Retro Reflectors for
Laser Ranging.
It may be recalled the previous
PSLV-C39/IRNSS-1H mission failed as the satellite did not get separated from
the heat shield. UNI