The Indian Space Research Organisation  is on the verge of a historic century as it gears up for its 100th indigenous mission today. The space agency's old warhorse, the Polar Satellite Launch Vehicle , will blast off into space with two foreign satellites from the spaceport of Sriharikota in Andhra Pradesh. Prime Minister Manmohan Singh is at the Satish Dhawan Space Centre in Sriharikota to witness the landmark event as the PSLV is scheduled to take off at 9:51 am. During the 51-hour countdown that began at 6:51 am on September 7, mandatory checks on the launch vehicle and spacecraft would be carried out and charging of batteries and pressurisation of propellant tanks on board the satellite would be performed, ISRO had said. As part of the mission, 720-kg SPOT-6 remote sensing satellite from France and a 15-kg Japanese spacecraft Proiteres would be placed in orbit by ISRO's PSLV C-21. The launch of the foreign satellites is also indicative of the rapid strides made by ISRO in furthering the nation's space programme - today's launch, a purely commercial one, has firmly placed the country in a select club of rocket-makers on which private utilities can bank upon to launch their operational satellites in a cost-effective and reliable manner.