ISRO touches milestone in foreign payload launches

The Indian Space Research Organisation's (ISRO) rocket Polar Satellite Launch Vehicle (PSLV) touched the 25-satellite launch score when Algerian remote sensing satellite Alsat-2A (116 kg) and two nano satellites - NLS 6.1 AISSAT-1 weighing 6.5 kg built by University of Toronto, Canada and one-kg NLS 6.2 TISAT built by University of Applied Sciences, Switzerland - were placed in orbit successfully.

With Monday's successful launch, ISRO with its PSLV rocket once again proved its capability in multiple satellite launches and also in different orbits - polar sun synchronous, geosynchronous transfer orbit, and highly elliptical and low earth orbits.
ISRO has been carrying out multiple launches for several years and in 2008 set a world record by launching 10 satellites at one go.

The Indian space agency started carrying foreign luggage in its PSLV rockets in 1999  when it launched the 110 kg Kitsat-3 of South Korea and the 45 kg DLR-Tubsat of Germany.

Initially, the foreign payloads were taken as additional luggage piggy-backing on ISRO's own satellite mainly to utilise the available cargo space and in the process earn some revenue.

Subsequently ISRO designed its 'core alone' version of PSLV - a lighter rocket without the usual six strap on motors that gives additional thrust during the initial flight stages.
The heaviest foreign payload that ISRO has launched with its PSLV is the 350-kg Italian satellite Agile in 2007.

However, the big money for ISRO is in the launch of heavier communication satellites that weigh a minimum three tonnes.

As PSLV's maximum carrying capacity is around 1,750 kg, the Indian space agency has developed another rocket - Geosynchronous Satellite Launch Vehicle (GSLV) - for launching satellites that weigh more than two tonnes.

The fully Indian built GSLV rocket - the ones without the Russian made cryogenic engine - is still in the test phase. The GSLV rocket with Indian made cryogenic engine in April this year ended in the Bay Bengal owing to component failure.