Wednesday, January 20, 2016

India’s PSLV Rocket Blasts off with IRNSS-1E Navigation Satellite

PSLV-C31 mission launch. Credit: ISRO

An Indian Polar Satellite Launch Vehicle (PSLV) has successfully blasted off 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.

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.

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 atop the rocket’s fourth stage. Together with its payload, the launch vehicle was cleared Sunday, Jan. 17, for the 48-hour countdown operations. The Mission Readiness Review (MRR) committee and the Launch Authorisation Board (LAB) confirmed that all systems are ready for the mission.

During the countdown, the rocket was fueled and configured for the mission. Four stages of the launch vehicle underwent extensive checkouts and ground stations were prepared for the flight and orbital operations.

After the liftoff, the PSLV rocket began its short vertical ascent before pitching and rolling in a south-east direction. The rocket’s six strap-on boosters, crucial for the first phase of the mission, 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 to release payload fairing approximately three minutes and 18 seconds after launch. Then, nearly one minute later, the second stage was detached from the launch vehicle. Third stage was ignited shortly afterwards, and carried on flying for 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 flying to reach 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 is 5.18 by 4.92 by 4.92 feet (1.58 by 1.5 by 1.5 meters) and weighs 1.42 metric tons at launch. It 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. 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 to send meteorological satellites aloft.

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.

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 and these two satellites would be made 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 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, 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) 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 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.

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