Chennai, July 8 : Is the Mars mission the silver jubilee commercial flight for India's rocket Polar Satellite Launch Vehicle (PSLV)? There are claims from officials that this is indeed so, but there are also reasons to dispute the claim.

Immediately after the launch of India's first navigation satellite, Indian Space Research Organisation (ISRO) officials said the space agency is gearing up for PSLV's silver jubilee mission, which will carry the Mars orbiter.

Strictly speaking, the Mars mission is not PSLV's 25th commercial mission, but 22nd.

ISRO, for inexplicable reasons, jumped one number while naming one of its earlier PSLV rockets.

After its PSLV-C12 (C stands for commercial) rocket that flew in April 2009, ISRO jumped one number and called its next rocket PSLV-C14, which launched Oceansat-2 and six other foreign satellites in September 2009.

Following that, several PSLV rockets flew and ISRO early this month launched its first navigation satellite Indian Regional Navigation Satellite System-1A (IRNSS-1A), badging its rocket as PSLV-C22.

As per plans, the PSLV-C23 rocket is slated to carry a foreign satellite later this year; preceding that is the Mars mission, with a rocket badged as PSLV-C25.

ISRO has, till date, flown 21 commercial and three developmental flights of PSLV rocket.

If one takes into account also the developmental flights, then ISRO is right to term its Mars mission rocket as its silver jubilee mission.

"The rockets are numbered based on the missions, and work will progress based on that number. Once in two years, the missions decided and gave numbers. Based on the mission's progress, the vehicle is scheduled," a senior ISRO official told IANS.

He said ISRO had earlier flown rockets numbered higher first, before those with lower numbers. (IANS)