High resolution Cartosat-2C to be set into orbit in May.

While the seventh and last of the regional navigation spacecraft is due to be launched on April 28, space agency Indian Space Research Organisation (ISRO) has lined up a record-making feat towards the end of May. It will put in orbit 21 small and mostly foreign commercial satellites along with a larger Indian spacecraft.

The primary passenger on the PSLV-C33 launcher will be the Earth observing, high-resolution Cartosat-2C, weighing around 700 kg.

Offering a resolution of about 60 cm, Cartosat-2C is touted to be the best Indian eye yet in the sky. It will cater to the country’s military requirements. Its camera, among other functions, can spot objects that are 60 cm wide or long - roughly an arm’s length, from its orbit of around 600 km.

As far as multiple launches go, the PSLV has launched 10 spacecrafts including eight small foreign ones in April 2008. Then, too, the main passenger was Cartosat-2A, another defence enabler, giving pictures of 80 cm resolution of the ground below. Last December, a PSLV took up six small Singapore satellites into orbit in one go.

NASA holds the 2013 record for placing the highest number — 29 — of mostly small customer satellites in orbit on a Minotaur launcher.

Multiple launches need multiple interfaces between the rocket and the spacecraft, and coordination with operators of each spacecraft.

ISRO Chairman A.S.Kiran Kumar said such missions must be planned meticulously by timing the release of each customer satellite carefully without affecting the others.

The launch team must ensure that one spacecraft does not get into the path of the other. The needs of each customer and its spacecraft must be accounted for.

Such many-in-one flights add to ISRO’s capability to service more and more small satellites commercially, said an ISRO official familiar with the launch process. “It speaks for the versatility of the vehicle which could accept so many spacecrafts at once,” he said.

3 Indian varsities

According to secondary sources, the small satellites are of masses ranging from one kg to 130 kg. Three are from Indian universities – the 12-kg NIUSAT from the Noorul Islam University in Kanyakumari; the 2-kg SathyabamaSat; and the 1-kg Swayam from Pune’s College of Engineering.

According to the ISRO official, considering the global demand for launching small satellites, packing many of them into one PSLV optimises a globally scarce service. Otherwise, satellite operators would have to wait for the next PSLV or look for another launcher.