An Indian polar satellite launch vehicle is preparing to go into orbit on Sunday with an Indian radar imaging satellite and two carpool payloads, including one built in the United States in partnership with scientific institutes in India, Singapore and Taiwan.
The nearly 146-foot-tall (44.4-meter) launch vehicle is set to lift off at 7:29 p.m. EST Sunday (0029 GMT Monday) with India’s EOS 4 Earth observation satellite.
The PSLV is stacked for liftoff from the Satish Dhawan Space Center on the east coast of India. Located on the island of Sriharikota north of Chennai, the spaceport is India’s main launch site. The launch from the Indian space base is scheduled for Monday at 5:59 a.m. local time, about half an hour before sunrise.
The launch will mark the first flight of a PSLV since last February, a slowdown in India’s launch cadence partly blamed on the impacts of the COVID-19 pandemic. India has launched 53 PSLV missions since 1993, flying up to six times in a single year after finding a niche in the international launch market to put small and medium-sized satellites into orbit.
But India has only launched three PSLV flights in the past two years. The pandemic has forced India’s space agency to suspend launch preparations, and many types of satellites once launched by the PSLV have switched to other rockets, primarily SpaceX’s Falcon 9 and emerging launch vehicles from companies like Rocket. Lab.
India’s PSLV is capable of delivering more than 3,850 pounds (1,750 kilograms) of payload to a 386-mile-high (622-kilometer) polar orbit, putting its lifting capacity above that of most smaller companies commercial launches, but well below that of SpaceX. Falcon 9.
The launch will also be the first orbital mission from India since the failure of the country’s more powerful GSLV Mk.2 rocket in August. A technical problem with the rocket’s third stage prevented it from reaching orbit with an Indian Earth observation satellite.
Sunday’s PSLV flight will launch the 3,770-pound (1,710-kilogram) EOS 4 radar satellite into polar orbit at an altitude of 328 miles (529 kilometers), according to a mission press kit released by the Indian Space Research Organization.
Two secondary payloads will be involved: the 39-pound (17.5-kilogram) INS 2TD Earth Imaging and Technology Demonstration Microsatellite and the 18-pound (8.1-kilogram) INSPIRESat 1 spacecraft.
India’s PSLV will fly in its most powerful configuration, called PSLV XL, with six strap-on solid rocket boosters. The core stage thrusters and engine, also burning pre-packaged solid propellants, will generate approximately 1.7 million pounds of thrust to send the rocket down over the Bay of Bengal.
The rocket’s liquid-fueled second stage, a solid-fueled third stage and a fourth stage will guide the three satellites into orbit, pointing the rocket southeast and then south to avoid flying over Sri Lanka.
The PSLV will deploy the EOS 4 spacecraft nearly 18 minutes after liftoff. About a minute later, the rocket will release its two rideshare payloads.
The EOS 4 satellite, formerly named RISAT 1A, will begin a 10-year mission monitoring the planet with a radar imager. The spacecraft will deploy its solar arrays and C-band radar antenna shortly after separation from the fourth stage of the PSLV.
According to ISRO, the EOS 4 satellite will collect images for use in agriculture, forestry, flood control, soil moisture and hydrology applications. Radar remote sensing satellites can see the Earth’s surface day or night and are not obscured by clouds like optical imaging missions.
The INS 2TD satellite carries a thermal camera for Earth observation, serving as a technological demonstrator for a future satellite that India is developing in cooperation with Bhutan.
INSPIRESat 1 is a joint project between the University of Colorado’s Laboratory of Atmospheric and Space Physics and the Indian Institute of Space Science and Technology, with additional contributions from institutions in Singapore and Taiwan.
It houses a scientific instrument to study the dynamics of the Earth’s ionosphere, a layer of the upper atmosphere where the influences of Earth weather and space weather come together, impacting satellite operations and radio communications.
Another instrument on INSPIRESat 1 is a NASA-funded X-ray spectrometer to observe solar flares.
The INSPIRESat 1 spacecraft was assembled and tested in Colorado and shipped to India to prepare for launch.
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