Spaceflight Insider

India to launch five British satellites on Friday

PSLV-C28 Strap-Ons are being assembled with Core Stage at the Satish Dhawan Space Centre

PSLV-C28 Strap-Ons are being assembled with Core Stage at the Satish Dhawan Space Centre. Photo Credit: ISRO

The Indian Space Research Organisation (ISRO ) is gearing up for the Friday launch of its long-serving Polar Satellite Launch Vehicle (PSLV), slated to deliver five UK satellites into orbit. Lift-off is currently scheduled to take place at 21:58 local time (12:28 p.m. EDT; 16:28 GMT) from the country’s Satish Dhawan Space Centre, located in Sriharikota.

The mission, designated PSLV-C28, will carry three identical DMC3 optical Earth-observation satellites built by Surrey Satellite Technology Limited (SSTL ) to orbit. In addition, the rocket will also haul two technology demonstrators: CBNT-1, an Earth observation microsatellite, also developed by SSTL; and De-OrbitSail, a nanosatellite built by Surrey Space Centre.

The total lift-off mass of the five satellites is about 1.44 tonnes, which makes PSLV-C28 the heaviest commercial mission to be sent aloft so far for the ISRO.

“This is the heaviest payload for a commercial launch. A successful PSLV-C28 start would give a big boost to ISRO’s commercial launch capabilities,” said ISRO spokesman Deviprasad Karnik.

India’s heaviest commercial mission to date was launched on June 30, 2014, when PSLV C-23 carried the French satellite SPOT-7 weighing 1,574 lbs. (714 kg).

Polar Satellite Launch Vehicle at the Satish Dawawn launch pad India Times photo posted on SpaceFlight Insider

A Polar Satellite Launch Vehicle at the launch site. Photo Credit: India Times (Archive Photo)

The 144 ft. (44 m) tall PSLV is an expendable launch system developed and operated by ISRO. It was produced to allow India to launch its Indian Remote Sensing satellites into Sun-synchronous orbits. PSLV can also launch small size satellites into geostationary transfer orbit. The rocket has four stages using solid and liquid propulsion systems, alternately.

Friday’s launch will be the ninth flight of the PSLV in ‘XL’ configuration. ‘XL’ is the updated version of the PSLV in its standard configuration boosted by more powerful stretched strap-on boosters. Weighing 320 tonnes at lift-off, the vehicle uses larger strap-on motors to achieve higher payload capability.

The third generation of the Disaster Monitoring Constellation (DMC3) will consist of three identical satellites, each with a height of about 9.8 ft. (3 m) and weighing 985 lbs. (447 kg). They will be launched into a 647 km Sun-Synchronous Orbit (SSO) and, thanks to the high spatial resolution and a separation of 120 degrees between them, these satellites can image any target on the Earth’s surface every day. They will mainly be used for surveying the resources on Earth and its environment, managing urban infrastructure and for disaster monitoring purposes. The constellation is expected to be operational for up to 7 years.

In addition to commercial activity, the DMC works actively within the International Charter ‘Space and Major Disasters’ to provide free satellite imagery for humanitarian use in the event of major international disasters such as tsunamis, hurricanes, fires, and flooding.

The first generation DMC was launched in 2002-2003 to create the first constellation designed to deliver daily repeat high-resolution imaging. The second generation DMC was put into orbit in 2009 and is currently in perfect health. It is expected to continue operations until at least 2018.

CBNT-1 (left) and three DMC3 Satellites (right) in the cleanroom at the Satish Dhawan Space Centre

CBNT-1 (left) and three DMC3 Satellites (right) in the cleanroom at the Satish Dhawan Space Centre. Photo Credit: ISRO

The DMC has monitored the effects and aftermath of the Indian Ocean Tsunami (December 2004), Hurricane Katrina (August 2005), and many other floods, fires, and disasters.

SSTL built the DMC satellites using its SSTL-300S1 platform equipped with advanced avionics and optical systems that make it possible to produce several different types of images such as mapping terrain, strip imaging, and mosaic imaging for wide areas.

The CBNT-1 microsatellite, weighing 200 lbs. (91 kg), is designed to test some technical Earth observation capabilities as well as new processing and rapid-build techniques. No further information on the spacecraft was released prior to launch.

The smallest of the five PSLV-C28 passengers is the De-orbitSail nano satellite, weighing just 15 lbs. (7 kg). Built by Surrey Space Centre at the University of Surrey, the satellite is designed for the demonstration of a large, thin membrane sail and drag deorbiting. A full mission success will be declared if orbital data shows the expected rapid decay of the satellite, leading up to its destructive re-entry.

All five of the satellites are planned to be separated from the PSLV rocket about 18 minutes after liftoff, according to the current launch timeline.

ISRO is on track to launch the satellites on Friday and has already started a 62 and a half hour countdown. The fourth stage of the rocket was filled with a Mono Methyl Hydrazine (MMH) propellant and a Mixed Oxides of Nitrogen (MON-3) oxidizer on Wednesday, July 8.

According to ISRO, accommodating the three DMC3 satellites within the existing payload fairing of PSLV was the biggest challenge.

“To mount these satellites onto the launcher, a circular Launcher adapter called an L-adaptor and a triangular deck called Multiple Satellite Adapter-Version 2 (V2) were newly designed and realized by ISRO for this specific purpose,” ISRO said in a press release.

The satellites will be launched Friday as part of the arrangement entered into between DMC International Imaging (DMCii), a wholly-owned subsidiary of SSTL and Antrix Corporation Limited (Antrix), the commercial arm of ISRO, a Government of India Company under Department of Space.

The July 10 lift-off will be the 30th for the PSLV rocket. So far, 27 have been successfully launched, all reaching their planned orbits. All launches took place from the Satish Dhawan Space Centre. Previously, the PSLV delivered the IRNSS-1D navigational satellite into orbit on Mar. 28, 2015.



Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.

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