India’s PSLV set to launch record 20 satellites on Wednesday
The Indian Space Research Organisation (ISRO) is about to send a record number of 20 satellites in a single mission. The country’s flagship Polar Satellite Launch Vehicle (PSLV) will take to the skies on Wednesday, June 22, from the Second Launch Pad at the Satish Dhawan Space Centre in Sriharikota, to orbit a panoply of spacecraft for various customers around the world. Liftoff is scheduled to take place at 9:26 a.m. local time (03:56 GMT).
If successful, Wednesday’s launch will surpass India’s previous record of the most satellites sent into orbit during one flight, set by a PLSV-CA rocket on April 28, 2008. Back then, the PSLV-C9 mission sent ten spacecraft aloft.
The upcoming mission, designated PSLV-C34, was primarily targeted for launch in April 2016. After a series of delays, ISRO now eyes June 22 as the most probable launch day; however, that date may still change.
PSLV-C34, which will be the 36th mission of the PSLV booster, will send the 20 satellites into a 314-mile (505-kilometer) polar Sun-synchronous orbit (SSO), inclined 97.48 degrees. The flight will last about 26-and-a-half minutes, and the first spacecraft are expected to separate from the launch vehicle at 17 minutes and seven seconds after liftoff. The total weight of the mission’s payload is about 1.3 metric tons.
However, according to ISRO, the PSLV-C34 flight will not end when all the spacecraft are fully deployed into space. The mission controllers plan to re-ignite the rocket’s fourth stage engine, 50 minutes after the separation of the last satellite. The engine will burn for 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.
“After each satellite is injected into orbit, the vehicle will be re-oriented if required and the next satellite will be put into orbit with a varying velocity so that the distance between the satellites grows monotonically. We will do this to ensure that there is no collision of satellites. Then, after a huge gap of 3,000 seconds, the fourth stage will be re-ignited for five seconds. Then, it will be switched off for another 3,000 seconds. It will be re-ignited for another five seconds,” said K. Sivan, Director of ISRO’s Vikram Sarabhai Space Centre in Thiruvananthapuram.
The mission’s primary payload is ISRO’s CartoSat-2C Earth-observing satellite. With a weight of some 1,604 lbs (727.5 kg), the satellite will be placed at the top of the payload fairing and will be released first during the flight. The car-sized spacecraft 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.
CartoSat-2C 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.
The satellite’s camera has a resolution of 2.13 feet (0.65 meters). It will be able not only to provide high-resolution pictures of the Earth’s surface, but it will also be capable of recording videos of sensitive targets from space, compress it, and relay it back.
“It will be a follow-up mission in the CartoSat series and is expected to provide very high-resolution pictures and videos captured from space,” an ISRO official said in April 2016.
First in the series, CartoSat-2 was launched in 2007. It had the capability to monitor missile launches in India’s neighborhood. However, the satellite suffered some problems after launch and ISRO decided to send its improved version, designated CartoSat-2A, one year later. CartoSat-2B was launched in 2010.
Besides CartoSat-2C, PSLV-C34 will launch two other much smaller Indian satellites. 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. Next to the SathyabamaSat in the payload fairing, will be placed a one-unit CubeSat, named Swayam. It was built by the College of Engineering in Pune and 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. Both CubeSats are planned to be deployed approximately 17 minutes and 42 seconds after liftoff.
Riding at the bottom of the payload fairing will be a swarm 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 constellation will be released from the rocket’s fourth stage during the timespan of the last six minutes of the flight.
PSLV-C34 carries one more U.S. satellite 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.
The mission will see also two Canadian satellites being injected 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. The second Canadian payload is the Maritime Monitoring and Messaging Micro-Satellite (M3MSat) for the Canadian Space Agency (CSA). This communications spacecraft, weighing around 187 lbs (85 kg), will collect and study the Automatic Identification System (AIS) signals from the low-Earth orbit (LEO).
The second heaviest payload of the PSLV-C34 mission is the 286-lb (130 kg) BIROS (Berlin Infrared Optical System) Earth-observing satellite. 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.
Wednesday’s mission will also carry an Indonesian Earth observation satellite. 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).
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 will be 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 will be 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. The exact date of that launch has yet to be announced.
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