Sriharikota (Andhra Pradesh) Sep 2 : It is going to be a 30-year-old vehicle. And it is still going strong. Well, that is India's first rocket Polar Satellite Launch Vehicle (PSLV). It was on September 20, 1993, that the first developmental flight of PSLV took place carrying the 846kg IRS-1E satellite. Come September 20, 2023, India's first commercial rocket PSLV would achieve the milestone of three decades of nation's service. The service includes not only orbiting India's own satellites but also hundreds of foreign satellites and in the process earn foreign exchange for the country. India has till date launched 431 foreign satellites belonging to 36 countries since 1999 with its rockets and bulk of the numbers were by the PSLV rocket. The rocket has also been used to put into orbit 104 satellites in a single flight. That apart, the PSLV rocket has been used for three of India's interplanetary missions ' Chandrayaan-1, Mars Orbiter Mission and the Sun Mission. In its normal configuration, PSLV is a four stage/engine expendable rocket powered by solid and liquid fuels alternatively with six booster motors strapped on to the first stage to give higher thrust during the initial flight moments. ISRO has five types of PSLV rockets ' Standard, Core Alone, XL, DL and QL. The major difference between them is the use of strap-on boosters which in turn largely depends on the weight of the satellites to be orbited. (Venkatachari Jagannathan can be reached at v.jagannathan@ians.in) /IANS