Wednesday, June 22, 2016

PSLV Booster Soars into the Sky with a Fleet of 20 Satellites

Liftoff of PSLV-C34. Photo Credit: ISRO

India has successfully launched its flagship PSLV rocket carrying a record number of 20 satellites. The launch occurred as planned at 9:25 a.m. local time (3:55 GMT) from the Second Launch Pad at the Satish Dhawan Space Centre in Sriharikota. The mission, conducted by the Indian Space Research Organisation (ISRO) was designated PSLV-C34 and was initially scheduled for April 2016. It surpasses the previous India’s record of the most satellites put into space during one flight, set by PLSV on Apr. 28, 2008, when a PSLV rocket delivered 10 satellites into orbit.

Powered by its six strap-on boosters, the PSLV rocket began its short vertical ascent until it started heading southeast. However, as usual during the initial phase of the PSLV flight, the vehicle was accelerated by only its four ground-lit boosters, until 25 seconds on the mission clock. Then, the remaining duo of air-lit boosters was ignited to continue the rocket’s ascent.

The ground-lit boosters separated from the launch vehicle about one minute and 10 seconds after liftoff. Approximately 22 seconds later, the rocket lost its two air-lit boosters, what was followed by the separation of the first stage around one minute and 48 seconds into the flight. Afterwards, the rocket’s second stage assumed control over the mission, accelerating the vehicle for about two and a half minutes. During this phase of the mission, the rocket’s protective payload fairing was jettisoned, exhibiting the swarm of 20 satellites attached to the fourth stage.

The rocket’s third stage ignited its engine about four minutes and 22 seconds after launch. It boosted the launch vehicle for nearly four minutes until it was separated. Next, the fourth stage took control over the flight, leading the mission for slightly more than eight minutes, in order to deliver the payload into a 314-mile (505-kilometer) polar Sun-synchronous orbit (SSO), inclined 97.48 degrees.

At about 17 minutes and seven seconds into the flight, ISRO’s CartoSat-2C Earth-observing satellite was deployed. It was the mission’s main passenger, placed at the top of the payload stack. 

Weighing some 1,604 lbs (727.5 kg), CartoSat-2C is based on the IRS-2 bus and has two solar arrays that could generate up to 986 W of power and two lithium-ion batteries. It is expected to be operational for up to five years.

The spacecraft is equipped with a single panchromatic camera capable of providing scene-specific spot imageries. The data from the satellite will be useful for cartographic applications, urban and rural infrastructure development and management, as well as coastal land use and regulation. The imagery will also be helpful in utility management like road network monitoring, water distribution, the creation of land use maps, precision study, change detection to bring out geographical and manmade features, and various other Land Information System (LIS) and Geographical Information System (GIS) applications.

35 seconds after the deployment of CartoSat-2C, the rocket’s fourth stage released two other much smaller Indian satellites: SathyabamaSat and Swayam. 

Built by the Sathyabama University in Chennai, the SathyabamaSat is a two-unit CubeSat, weighing around 3.3 lbs (1.5 kg). The small satellite, equipped with an infrared spectrometer, will measure the densities of greenhouse gases. 

Swayam a one-unit CubeSat built by the College of Engineering in Pune. It has a mass of about 2.2 lbs (1 kg). The spacecraft is expected to provide a point-to-point messaging service for the HAM radio community.

After the deployment of all three spacecraft for India, an Indonesian Earth observation satellite, named LAPAN-A3, separated from the fourth stage at approximately 18 minutes and 22 seconds into the flight.

With a mass of 264 lbs (120 kg), the LAPAN-A3 spacecraft will be used for land, natural resources, and environment monitoring. It will be operated by the country’s National Institute of Aeronautics and Space (LAPAN).

Nearly at the same time when LAPAN-A3 detached from the fourth stage, the BIROS (Berlin Infrared Optical System) Earth-observing satellite was deployed. With a mass of 286 lbs (130 kg), it is the second heaviest payload of the PSLV-C34 mission. The spacecraft, operated by the German Aerospace Center (DLR), will be used to detect high-temperature events like forest fires. The satellite is expected to offer its services for about three years.

At exactly 19 minutes after liftoff, two other satellites were injected into orbit. The Maritime Monitoring and Messaging Micro-Satellite (M3MSat) is a communications spacecraft, weighing around 187 lbs. (85 kg). Operated by the Canadian Space Agency (CSA), it will collect and study the Automatic Identification System (AIS) signals from the low-Earth orbit (LEO). The second satellite released at T+19 minutes is the U.S. spacecraft called SkySat-C1. With a weight of about 242 lbs (110 kg), the satellite is an Earth-imaging spacecraft built by Space Systems Loral (SSL). It will be operated by Terra Bella (formerly known as Skybox Imaging), a Google subsidiary for about six years. The satellite is designed to provide a sub-meter resolution imagery and HD video.

20 seconds later, another Canadian satellite was inserted into orbit. The 56-lb (25.5 kg) GHGsat spacecraft, operated by GHGsat Inc. is designed for Earth observation purposes. It will measure atmospheric concentration of greenhouse gases.

At about 20 minutes and 20 seconds into the flight, the PSLV-C34 mission started releasing its last payload – a set of 12 three-unit CubeSats for the San Francisco-based Planet Labs. The constellation of Dove Satellites (also known as Flock-2P) will be used for Earth observation purposes. Each spacecraft weighs around 10.36 lbs (4.7 kg) and is designed to be operational for up to three years. Every Flock satellite is fitted with a telescope and a frame CCD camera to provide imagery utilized in environmental, humanitarian, and business applications. The last satellite of the constellation was deployed approximately 26 minutes and 30 seconds after launch.

The mission did not end when all the spacecraft were fully deployed into space. ISRO plans to re-ignite the rocket’s fourth stage engine, 50 minutes after the separation of the last satellite. The engine will burn for just about five seconds. Afterward, it will be shut down for 50 minutes and then re-ignited for another five seconds. These maneuvers are necessary for ISRO to check the ability of the fourth stage to place multiple satellites into different orbits using just a single rocket on future missions.

The four-stage PSLV booster is India’s most reliable launch vehicle. The rocket has been used to deliver more than 40 satellites into space for some 19 countries. PSLV is capable of lofting up to 3.25 metric tons to low-Earth orbit 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, which was used for Wednesday’s mission, is the upgraded variant of the rocket in its standard configuration. Its thrust is increased by the addition of more powerful, stretched strap-on boosters than on the standard version. The vehicle has a mass of 320 metric tons at liftoff and uses the larger strap-on motors (PSOM-XL) that provide the capability of hoisting heavier payloads into 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 was India’s fourth launch this year. The country’s next flight is currently scheduled to take place in July when a PSLV rocket will send ISRO’s Resourcesat-2A and ScatSat-1 satellites into orbit. However, the exact date of that launch has yet to be announced.

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