Spaceflight Insider

India ready to launch its fifth IRNSS navigation satellite

IRNSS-1E propellant filling operation in progress.

IRNSS-1E propellant filling operation in progress. (Click to enlarge.) Photo Credit: ISRO

The Indian Space Research Organisation (ISRO) is ready to launch its IRNSS-1E navigation satellite on Wednesday, Jan. 20, from the Second Launch Pad (SLP) at the Satish Dhawan Space Centre (SDSC), located in Sriharikota. The fifth spacecraft in the IRNSS series is scheduled to be launched by a Polar Satellite Launch Vehicle (PSLV) at 9:31 a.m. IST, 04:01 GMT, 11:01 p.m. EST (Jan. 19).

The mission, designated PSLV-C31 will be the 33rd flight of the PSLV vehicle. As was the case during the previous four launches of IRNSS satellites, this mission will use the ‘XL’ version of the rocket. It will be the 11th flight of the PSLV in its XL configuration.

Close-up view of PSLV-C31 integration.

Close-up view of PSLV-C31 integration. Photo Credit: ISRO

The Mission Readiness Review (MRR) committee and the Launch Authorisation Board (LAB) have already decided to have the required 48-hour launch countdown begin on Monday, Jan. 18.

“MRR meeting was held today. The countdown is expected to start at 9:30 a.m. (local time) on Monday,” Devi Prasad Karnik, ISRO spokesperson told Deccan Herald on Sunday.

The rocket has been moved from the vehicle assembly building to the SLP. It will begin its short vertical ascent after liftoff on Wednesday until the separation of its six strap-on boosters.

The rocket’s first stage should detach from the launch vehicle nearly two minutes into the flight. Payload fairing separation is expected to occur three minutes and 18 seconds after launch. The launch vehicle’s second stage should separate about one minute after that.

PSLV’s third stage will continue the mission for an additional six minutes or so – until its separation. The upper stage will then ignite, carrying the IRNSS-1E satellite for its deployment 19 minutes and 23 seconds after the rocket and its precious cargo had left the launch site far below.

Weighing 1.42 metric tons at launch, the IRNSS-1E spacecraft is 5.18 by 4.92 by 4.92 feet (1.58 by 1.5 by 1.5 meters). It will be delivered into a geosynchronous orbit (GEO) at 111.75 degrees East with an initial inclination of 28.1 degrees with respect to the equator. The IRNSS 1E satellite has a planned operational life of some 12 years.

The satellite features two deployable solar arrays generating 1660 W of power and one lithium-ion battery of 90 ampere-hour capacity. The satellite is equipped with two primary instruments: a navigation payload and CDMA ranging payload in addition to a laser retro-reflector. The payload generates navigation signals on the L5 and S-bands.

The IRNSS-1E satellite is based on the Indian I-1K (I-1000) bus developed by ISRO. This platform is designed to be compatible with lightweight geostationary satellites and is commonly used to send meteorological satellites aloft.

PSLV-CA_1 launch Indian Space Research Launch Organisation photo posted on SpaceFlight Insider

The launch of the IRNSS-1E satellite will mark the first flight of the year for the ISRO. Photo Credit: Indian Space Research Organization

If everything goes according to plan, IRNSS-1E will provide accurate position information service to users in India as well as the region extending up to 930 miles (1,500 km) from the nation’s borders. It will deliver Standard Positioning Service (SPS), responsible for navigation parameter generation and transmission, satellite control, ranging and integrity monitoring, as well as timekeeping services.

The Indian Regional Navigation Satellite System (IRNSS) is a satellite-based positioning system for critical national applications. Its main objective is to provide reliable position, navigation, and timing services over India and its neighborhood.

When all is said and done, the IRNSS system should consist of some seven satellites. All the spacecraft will provide their services in a fixed orbit above the Indian region. The constellation is expected to be completed in March of this year. IRNSS-1A, 1B, 1C, and 1D were launched by PSLV-C22, PSLV-C24, PSLV-C26, and PSLV-C27 in July 2013, April 2014, October 2014, and March 2015, respectively. IRNSS-1F will be launched in February and IRNSS-1G will be sent into orbit in March 2016.

The four-stage PSLV booster is India’s most reliable launch vehicle. It has been in service for more than twenty years and has been used to launch various satellites for some of the country’s most historic missions, such as the Chandrayaan-1, the Mars Orbiter Mission (MOM), Space Capsule Recovery Experiment, as well as the IRNSS system.

The rocket has been used to delivered more than 40 satellites to space for 19 countries. PSLV is capable of lofting up to 3.25 metric tons to LEO and about 1.42 metric tons to a geosynchronous transfer orbit (GTO).

The rocket uses an Earth-storable liquid-fueled rocket engine for its second stage, known as the Vikas engine; it was developed by the Liquid Propulsion Systems Centre. The third stage of the PSLV is powered by a solid rocket motor that provides the upper stage’s high thrust after the atmospheric phase of the mission. The fourth stage is composed of two Earth-storable liquid-fueled engines.

The 144 ft. (44 meters) tall XL version of the PSLV is the upgraded version of the rocket in its standard configuration. It is boosted by more powerful, stretched strap-on boosters. The vehicle has a mass of 320 metric tons at liftoff and uses larger strap-on motors (PSOM-XL) to achieve higher payload capability. PSOM-XL uses larger 1-meter diameter, 44 ft. (13.5 m) length motors; it carries 12 metric tons of solid propellants instead of the nine metric tons that were used on an earlier configuration of the PSLV.

The PSLV rocket in its XL configuration was launched for the first time on Oct. 22, 2008, when it sent India’s Chandrayaan-1 lunar probe toward the Moon.

Wednesday’s mission will be India’s first launch this year. The country’s next flight is currently scheduled to take place in February when a PSLV-XL rocket is scheduled to send the IRNSS-1F navigation satellite to orbit.

Video courtesy of Geospatial Media


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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