Indian Space Research Organisation (ISRO) is all set for tonight’s launch of PSLV C28 cayying the heaviest ever commercial payload of five satellites, including three DMC3 earth observation satellites of UK-based Surrey Satellite Technologies.
In its daily update, ISRO said the countdown progress is normal and all the operations are in progress as scheduled. “Countdown operations are progressing normally. Preparations for Mobile Service Tower (MST) withdrawal and Propellant filling operation of second stage (PS2) are in progress,” said ISRO in its latest update on the mission.
Earlier, Mission Readiness Review (MRR) committee and Launch Authorisation Board (LAB) had cleared the starting of the 62 and half an hour countdown of PSLV-C28/DMC3 Mission on Tuesday and the countdown started at at 07:28hr IST on July 8, Wednesday for the scheduled launch on Friday, at 21.58 hours (IST).
During the countdown period, Mono Methyl Hydrazine (MMH) propellant filling operationof Fourth Stage (PS4) of PSLV-C28 has commenced at 10:10 hr (IST) and was completed making preparations for Mixed Oxides of Nitrogen (MON-3) oxidiser filling operation of fourth stage taken up. By Thursday the MON-3, oxidiser filling operation of Fourth Stage (PS4) was completed, informed ISRO.
Today, Friday, July 10, the Mobile Service Tower (MST) withdrawal upto parking end and N2O4 propellant filling operation of second stage (PS2) are completed by 07:00 hr (IST) this morning. Moving on, the UH-25 propellant filling operation of second stage (PS2) was completed by 09:40hr today.
“This is the heaviest payload for a commercial launch,” said Isro spokesman Deviprasad Karnik. Its last heavy mission was carried by PSLV C-23 carried a French satellite SPOT-7 that weighed 714 kg 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 that lifted off prestigious Mangalyaan (Mars Orbiter Mission) in 2013.
With the overall lift-off mass of the 5 satellites running into 1440-kg, the PSLV C28 mission becomes the heaviest commercial mission ever taken up by ISRO and its commercial arm Antrix.
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) and two auxiliary satellites — 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-PSLV C-28 Path
ISRO has built a special circular Launcher adaptor (L-adaptor) and a triangular deck called Multiple Satellite Adapter-Version 2 (MSA-V2) for launching the DMC3-1, DMC3-2 and DMC3-3 satellites for high spatial resolution and high temporal resolution optical Earth images.
The lift-off process has total 20 stages, with the First Stage Ignition followed by Strap-on 1.2 Ignition on ground 0.42 seconds after the lift off tonight. 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 mission life of DMC3 satellites will be 7 years..