It will be the 100th space mission for the Indian Space Research Organisation (ISRO) tomorrow (September 9, 2012) as it launches another vehicle from  its workhorse series — PSLV-C21. The 49-year-old organisation has come a long way with  62 satellites and 37 launches in its repertoire. ISRO’s first mission — the Aryabhatta satellite launched using a Russian rocket — dates back to1975.

PSLV C-21{credit}ISRO{/credit}

As countdown begins for PSLV-C21, preparations are also underway to host VIPs such as Prime Minister Manmohan Singh — in charge of space and atomic energy — at Sriharikota, the launch venue. However, considering that it’s ISRO’s 100th mission, the event has not received as much publicity as one would expect of a landmark occasion like this. The ISRO press release announcing the countdown for the launch had no mention of its historic significance. ISRO might be playing it down, making room for some cautious and deferred celebrations until after a successful launch. Rightly so.

Coming back to ISRO’s century launch, it will carry two satellites — the French SPOT-6 and Japanese PROITERES. PSLV C-21 will be lifted off Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota as most of India turns on their television sets on Sunday — around 9:51 a.m. The two satellites are  expected to be propelled into an orbit of 655 km altitude at an inclination of 98.23 degrees. In the 13 years since PSLV has been undertaking business launches,  this one will also be its biggest ever commercial lift. The French satellite weighs 720 kg and the Japanese 15 kg.

Just how does ISRO count its missions considering that it launches foreign satellites and also its own satellites on foreign rockets?  An ISRO official solves the number crunching thus:  each ISRO rocket flight is considered one mission; an ISRO satellite launched by a foreign rocket is marked as one mission and; an Indian rocket (such as PSLV) launching a number of satellites built and owned by ISRO is marked as several missions — 2 if there are two satellites, 3 if there are 3 satellites.

So PSLV C-21 will be one mission — the one that strikes the ton for ISRO.

Post updated on September 9, 2012:

PSLV C-21 lifts off.{credit}ISRO{/credit}

ISRO’s 100th space mission PSLV C-21 was successfully launched from the Satish Dhawan Space Centre in Sriharikota in Andhra Pradesh at 9:53 a.m. Prime Minister Manmohan Singh, who witnessed the launch, described the mission as a ‘spectacular success’. Soon after launch, the vehicle put the two foreign satellites into orbit.

As is the norm, ISRO chief K Radhakrishnan had offered prayers at the Lord Venkateswara Temple in Tirupati yesterday for the success of the historic mission.