Monday, May 30, 2016

China’s Long March 4B Rocket Sends a Trio of Earth-observing Satellites Aloft

China’s Long March 4B launch vehicle took to the skies on Sunday, May 29 at 11:17 p.m. EDT (3:17 GMT on Monday, May 30), on a mission to orbit the country’s Ziyuan-3 No. 2 high-resolution remote sensing satellite and two commercial ÑuSat Earth-observing spacecraft for Argentina. Credit: Xinhua

China’s Long March 4B launch vehicle took to the skies on Sunday, May 29 at 11:17 p.m. EDT (3:17 GMT on Monday, May 30), on a mission to orbit the country’s Ziyuan-3 No. 2 high-resolution remote sensing satellite and two commercial ÑuSat Earth-observing spacecraft for Argentina. Lift off took place from the Launch Site 9 at the Taiyuan Satellite Launch Center located in China’s Shanxi Province.

After liftoff, the Long March 4 rocket began its vertical ascent powered by its YF-21B booster that consists of four YF-20B engines. These engines burned for nearly three minutes until the launch vehicle’s first stage separation.

The rocket’s second stage continued the flight for slightly more than two minutes. The separation of the second stage occurred about five minutes after liftoff. Afterwards, the third stage took control over the mission, burning for approximately six minutes until the satellites were deployed into orbit.

Ziyuan-3 No. 2, developed jointly by the China’s Academy of Space Technology (CAST) and the Beijing Institute of Spacecraft System Engineering, is the country’s third generation Earth-observing satellite for civilian purposes. It will be operated by the Ministry of Land and Resources for up to five years.

Weighing about 2.6 metric tons, the spacecraft features two deployable solar arrays and is fitted with three high-resolution panchromatic cameras and an infrared multispectral scanner. The cameras will cover a 32-mile (51-kilometer) wide swath on the ground, reaching a resolution of 6.9 to 8.2 feet (2.1 to 2.5 meters). The scanner has a spectral resolution of 19.7 feet (6 meters) and a 32-mile (51-kilometer) ground swath.

Residing in a sun-synchronous solar orbit (SSO) at an altitude of 314 miles (506 kilometers), inclined 97.4 degrees, the satellite will be employed to conduct surveys on land resources, help with natural disaster-reduction and prevention and lend assistance to farming, water conservation, urban planning and other sectors.

First Ziyuan satellite was launched in 1999 to initiate China’s Earth Observation Program. Besides civilian purposes, the first two generations of Ziyuan spacecraft were used also to conduct military reconnaissance.

Piggybacking on the mission, two small Argentinian satellites were also launched into space. Designated ÑuSat-1 and ÑuSat-2, these box-sized spacecraft are part of the Aleph-1 constellation of Earth-observing satellites for commercial customers. Nicknamed “Fresco” and “Batata”, these two craft, were developed by Satellogic S.A. and will be also operated by this company.

“We have confirmation from the groundstation in Bariloche: Fresco and Batata are healthy and sending strong signals. The launch is 100 percent success,” Emiliano Kargieman of Satellogic S.A. tweeted shortly after the spacecraft were successfully inserted into SSO at an altitude of 310 miles (500 kilometers), inclined 97.5 degrees.

Each satellite weighs about 81.5 lbs. (37 kg) and has dimensions of: 1.31 x 1.41 x 2.46 feet (40 x 43 x 75 centimeters). ÑuSat spacecraft are equipped with an imaging system capable of operating in visible and infrared light. This equipment enables generating still imagery and video of Earth at a ground resolution of up to 3.3 feet (one meter). The duo of satellites will also carry a U/V linear transponder to offer services for the HAM radio community.

The three-stage Long March 4B carrier rocket employed for this launch is China’s long-serving booster, designed to deliver satellites into low Earth (LEO) and sun synchronous orbits. The 150 ft. tall launch vehicle is in service for over 16 years and has conducted 27 missions, only one of them was unsuccessful.

With a mass of 249 tonnes, the Long March 4B booster is capable of delivering up to 4.2 tonnes to LEO, 2.8 tonnes to SSO and 1.5 tonnes to a geostationary transfer orbit (GTO). The rocket’s first stage is 91.5 ft. (28 meters) long and has 11 ft. (3 meters) in diameter. It is powered by four YF-20B engines. The second stage, 35 ft. (11 meters) long and 11 ft. (3 feet) in diameter, is equipped in one YF-22C main engine and four YF-23C vernier engines. The 49 ft. (15 meters) long third stage is 9.5 ft. (3 meters) in diameter and is powered by two YF-40 engines.

Sunday’s liftoff was the 228th mission for the Long March family of boosters. It was also the first launch of the Long March 4B this year and also the first liftoff from the Taiyuan Satellite Launch Center in 2016. So far, the country launched six space missions this year and all of them were successful.

China’s next flight is currently planned for June 27, 2016, when a new version of the Long March booster, the Long March 7, will conduct its maiden flight. It will also be the first launch conducted from the Wenchang Satellite Launch Center, located on the Hainan Island, in southern China. The country plans more than 20 space missions this year.

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