Science & Technology

‘DMC3 constellation has the capacity to capture any image on Earth’s surface’

Major applications also include surveying the resources on the planet and its environment, managing urban infrastructure and monitoring disasters

 
By Deepanwita Gita Niyogi
Published: Wednesday 15 July 2015

On July 10, 2015, the Indian Space Research Organisation (ISRO) successfully launched five British satellites from Sriharikota. This was the heaviest commercial launch undertaken by the Indian space agency. ISRO Director, publications and public relations unit, Deviprasad Karnik, shares with Down To Earth details about the launch and the agency’s future plans.

 

In what way was the latest launch the heaviest commercial mission undertaken by ISRO?

ISRO had launched 40 foreign satellites before the July 10, 2015 event. Till then, the maximum total mass that the Polar Satellite Launch Vehicle (PSLV) had launched for a foreign customer on a commercial basis was 714 kg (SPOT-7 satellite from France on June 30, 2014). The total mass of the five satellites launched on board PSLV-C28 was 1,440 kg. Hence, it was the heaviest commercial mission undertaken by ISRO.

What is special about the DMC3 series? What will be their purpose?

The three DMC3 mini satellites form a constellation of high-resolution optical Earth observation satellites. The constellation has the capacity to capture any image on the Earth’s surface. Major applications also include surveying the resources on Earth and its environment, managing urban infrastructure and monitoring disasters. 

Why was the PSLV ‘XL’ version used to launch the satellites? In what way is it different from the lighter “core alone” version of PSLV?

The payload capacity of the lighter “core alone” version of PSLV is about 1,050 kg (maximum) to the Polar Sun Synchronous Orbit (PSSO) whereas that of the “XL” version is about 1,700 kg. In the case of the latest launch, the total payload mass stood at 1,440 kg, and hence, the “XL” version was used.

What is the significance of the Polar Sun Synchronous Orbit in which the satellites were placed? How is it different from the other orbits?

Polar Sun Synchronous Orbits (PSSO) are used for optical Earth observation, to have sunlight for optical imaging. Communication satellites are launched into the Geosynchronous Transfer Orbit (GTO), and then taken to Geostationary orbit (36,000 km above the Earth), to have 24X7 visibility for uninterrupted use. Low earth orbit satellites are used for experimental purposes.

What is ISRO’s next project?

ISRO’s next project will be the launch of the communication satellite, GSAT-6, using the GSLV-D6 in the end of August. This will be followed by the launch of RLVTD, ASTROSAT, GSAT15 and reaming satellites (1E, 1F and 1G) of the IRNSS constellation by March 2016.

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