Indian Space Research Organisation (ISRO) is all set for its heaviest ever commercial mission on Friday, July 10. 2015 catering the Surrey Satellite Technology Limited of the UK carrying its three heavy DMC satellites and one micro satellite and another nano satellite.
The Indian Space Agency is taking up the porject as per the agreement entered by its commercial arm Antrix with the British SSTL weighing 447-kg each and a total payload of 1,440-kg, the heaviest so far for a commercial launch by ISRO.
“This is the heaviest payload for a commercial launch. A successful PSLV-C28 launch would give a big boost to Isro’s commercial launch capabilities,” said Isro spokesman Deviprasad Karnik. Its last heavy mission was undertaken lat year when PSLV C-23 carried 714-kg payload with French satellite SPOT-7 on June 30, 2014.
The PSLV C-28 will lift off on July 10 from Satish Dhawan Space Centre, Sriharikota (SDSC-SHAR) the spaceport of India from where all major launches including Chandrayaan-I and Mangalyaan (Mars Orbiter Mission) were launched successfully.
With the overall lift-off mass of the 5 satellites running into 1440-kg, this mission becomes the heaviest commercial mission ever undertaken by Antrix and ISRO.
The Polar Satellite Launch Vehicle (PSLV), in its 13th flight (PSLV-C28), will put the three DMC satellites into a 647 km Sun-Synchronous Orbit (SSO) using the high-end version of PSLV in ‘XL’ configuration. The other two auxiliary satellites are CBNT-1, a technology demo earth observation micro satellite built by SSTL, and De-OrbitSail, a demo nano satellite built by Surrey Space Centre.
ISRO has built a circular Launcher adaptor (L-adaptor) and a triangular deck called Multiple Satellite Adapter-Version 2 (MSA-V2) exclusively for the purpose. Further, the DMC3-1, DMC3-2 and DMC3-3 are designed to take simultaneous high spatial resolution and high temporal resolution opticalEarth images, said ISRO in a statement.
The lift-off process has 20 stages in all with the First Stage Ignition followed by Strap-on 1.2 Ignition on ground 0.42 seconds after lift off. The Strap-on 3.4 Ignition will be given at 0.62 seconds after lift off.
The Strap-on 5.6 Airlift Ignition will be at 25 seconds after lift off at 2.68 kilometres altitude and at a velocity of 570.51 metres per second. The first stage separation will be at 1 minute 50.38 seconds after the lift off at 68.82 km with a velocity of 2147.52 metres per second.
The second stage will follow then separating the payload in its first stage and then in the second and third stages within 4 minutes from launch. The third stage separation will at 8 minutes and the fourth stage will follow within seconds.
The DMC3-1 will separate from the launch vehicle 17 minutes 56.58 seconds, the DMC3-2 in less than 0.20 seconds thereafter and third one DMC3-3 will follow suit in another 0.22 seconds. All the three DMC3 satellites will separate at 653.09 km altitude with a velocity of 7532.16 metres per second.
The nano satellite De-Orbitsal will separate at 18 minutes 36.08 seconds after lift off and the fifth and last will the CNBT-1 separation at 19 minutes 16.08 seconds at an altitude of 654.75 km with a velocity of 7532.42 metres per second.
The DMC3 satellites will be launched into a single Low-Earth Orbit plane at a phase-wise distance of 120° between them, so they can take any image on the Earth’s surface every day. The mission life of DMC3 satellites will be 7 years and they are powered by Lithium Ion 480 Whr, Solar panel-230 W Peak BOL with an imaging resolution of 1m Panchromatic, 4m Multi-Spectral (Blue, Green, Red, NIR).