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India’s PSLV rocket blasts off with IRNSS-1E navigation satellite

PSLV-C31 rocket launch of IRNSS-1E satellite

The Indian Space Research Organisation (ISRO) has launched the IRNSS-1E navigational satellite atop the PSLV-C31 booster. The rocket took to the skies on Jan. 20, 2016, at the Satish Dhawan Space Centre Sriharikota. (Click to enlarge.) Photo Credit: ISRO

An Indian Polar Satellite Launch Vehicle (PSLV) was successfully launched on Wednesday, Jan. 20, carrying the fifth spacecraft for the country’s indigenous Indian Regional Navigation Satellite System (IRNSS). Liftoff took place as planned at 9:31 a.m. IST, 04:01 GMT, 11:01 p.m. EST (Jan. 19), from the Second Launch Pad (SLP) at the Satish Dhawan Space Centre (SDSC), located in Sriharikota, India.

The launch was conducted by the Indian Space Research Organisation (ISRO), started the nation’s first space flight of the year. The mission, designated PSLV-C31, is the 33rd flight of the PSLV vehicle.

Integration of an 'XL' strap-on motor with the Core Stage of PSLV-C31 in progress.

Integration of an ‘XL’ strap-on motor with the Core Stage of PSLV-C31 in progress. Photo Credit: ISRO

The mission campaign started last year with the integration of the launch vehicle. A series of tests was performed when the PSLV rocket was fully assembled.

After final checks of the vehicle, the IRNSS-1E satellite was mated to the top of the rocket’s fourth stage. Together with its payload, the launch vehicle was cleared for flight on Sunday, Jan. 17, to begin the prerequisite 48-hour countdown operations.

The Mission Readiness Review (MRR) committee and the Launch Authorisation Board (LAB) confirmed that all systems were ready to begin the mission.

During the countdown, the rocket was fueled and configured for the flight. All four stages of the launch vehicle underwent extensive checkouts prior to this launch, with ground stations being prepared for the flight as well as orbital operations.

After liftoff, the PSLV rocket began its short vertical ascent before pitching and rolling onto a southeasterly direction. The rocket’s six strap-on boosters, crucial for the first phase of the flight, were jettisoned about one minute and 32 seconds into the flight and the rocket’s first stage separated just 19 seconds later.

PSLV’s second stage continued the flight until the payload fairing split open approximately three minutes and 18 seconds after launch – revealing the IRNSS-1E satellite to space. Then, nearly one minute later, the second stage was detached from the remaining segments of the launch vehicle. The third stage was ignited shortly afterwards and carried on flying for the next six minutes until its separation.

The rocket’s fourth stage was tasked with the orbital injection of the satellite. It carried out this task perfectly, deploying the spacecraft about 19 minutes and 20 seconds after the launch. The satellite deployed its solar arrays and is currently traveling toward its targeted geosynchronous orbit (GEO) at 111.75 degrees East with an initial inclination of 28.1 degrees with respect to the equator.

The IRNSS-1E spacecraft measures 5.18 by 4.92 by 4.92 feet (1.58 by 1.5 by 1.5 meters) and weighed 1.42 metric tons at launch. It features two deployable solar arrays capable of 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. A highly accurate Rubidium atomic clock is also part of the navigation payload of this satellite.

The IRNSS-1E satellite is based on the Indian I-1K (I-1000) bus developed by ISRO and is expected to be operational for 12 years. The I-1K platform is designed to be compatible with lightweight geostationary satellites and is commonly used for meteorological satellites.

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

The IRNSS-1E spacecraft being integrated with the PSLV-C31 launch vehicle ISRO image posted on SpaceFlight Insider

The IRNSS-1E spacecraft being integrated with the PSLV-C31 launch vehicle. Image Credit: ISRO

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. Once complete, the constellation should provide their services in a fixed orbit above the Indian region. The IRNSS fleet is expected to be complete by 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 is scheduled to be launched in February, with IRNSS-1G set to be launched this March.

According to ISRO Satellite Centre (ISAC) Director M Annadurai, the next two IRNSS satellites 1F and 1G are in the very advanced stages of integration at the Bangalore satellite center. These two satellites should be functional by the end of March this year.

“The system will provide two types of services – standard positioning services to all users and restricted services to authorized users,” Annadurai said.

While four satellites are sufficient to start operations of the IRNSS system, the remaining three would make it more accurate and efficient.

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 Chandrayaan-1, the Mars Orbiter Mission (MOM), the Space Capsule Recovery Experiment, as well as the IRNSS system.

The rocket has been used to delivered more than 40 satellites to space for some 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, that was used in Wednesday’s mission, 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) that provide the capability of hoisting heavier payloads to orbit. PSOM-XL uses the larger, 1-meter diameter, 44 ft. (13.5 m) length motors. This version of the rocket 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 is India’s first launch this year. The country’s next flight is currently scheduled to take place in February when a PSLV-XL rocket will send the IRNSS-1F navigation satellite to orbit.

PSLV-C31 rocket launch of IRNSS-1E satellite

The PSLV-C31 rocket launching the IRNSS-1E satellite. Photo Credit: ISRO


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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