The countdown for the Monday midnight launch of an Indian navigation satellite is progressing smoothly with the liquid fuel filling for the fourth stage engine getting completed, an official said Sunday.
"Yesterday (Saturday) evening, the filling of the liquid fuel in the fourth stage was completed and the fuel for the second stage will be filled during the countdown. In addition, pressurisation of the stages with gases will also be done," a senior official at the Indian Space Research Organisation (ISRO) told IANS Sunday.
The 64.5 hour countdown began at 7:11 a.m. Saturday.
The 44-metre-tall Polar Satellite Launch Vehicle-XL (PSLV-XL) weighing 320 tonnes at lift-off is a four-stage rocket powered by solid and liquid propellants alternatively.
The solid fuel hydroxyl-terminated-poly-butadiene comes readily cast while the liquid fuel -- unsymmetrical dimethyl-hydrazine-hydrate and 25 percent of nitrogen tetroxide for second stage and mono-methyl-hydrazine and mixed oxide nitrogen for fourth stage -- are filled during the countdown.
The PSLV will blast off into the dark skies from Sriharikota, around 80 km from here, Monday night around 11.41 p.m. carrying India's first navigational satellite the 1,425 kg IRNSS (Indian Regional Navigational Satellite System)-1A.
"We have had late evening and early morning launches. But this is the first time ISRO is launching a rocket around midnight," the ISRO official said.
The official said the launch time has been fixed taking into account the orbit and inclination at which the satellite will be injected into the space.
According to him, the weather at Sriharikota is fine and it may not pose any hindrance for the rocket launch.
He said ISRO chairman K. Radhakrishnan is expected to have a brief meeting with the media at the rocket port post-launch which will be around 12.45 a.m. Tuesday.
Around 20 minutes into the launch, the rocket PSLV-XL will eject the navigational satellite at an altitude of 501 km.
The satellite is intended to provide terrestrial, aerial and marine navigation services and help in disaster and fleet management.
The satellite with a life span of around 10 years is one of the seven satellites constituting the IRNSS space segment -- a regional navigational system developed by India designed to provide accurate position information service to users within the country and up to 1,500 km from the nation's boundary line, ISRO said.
The IRNSS will provide two types of services -- standard positioning service and restricted service. The former is provided to all users and the later is an encrypted service for authorised users.
ISRO had planned to launch IRNSS-1A last month. But it had to put it off after finding a problem in one of the electro-hydraulic control actuators in the second stage engine.
The rocket was fully assembled with the satellite when the problem was detected during checks.
The second stage had to be dismantled to replace the actuator which is an assembly of several components. It weighs around 20 kg.
Following the Monday launch of the navigational satellite, ISRO is planning to launch its communication satellite G-Sat 14 using a heavier rocket - Geosynchronous Satellite Launch Vehicle (GSLV) - powered by a domestic cryogenic engine some time in August this year.
Preparatory work for the G-Sat 14 launch is going ahead at the rocket launch pad in Sriharikota in Andhra Pradesh, around 80 km from here.
It will be followed by the mission to Mars later this year. The launch of one more remote sensing satellite is also being planned before the end of the year.
