China launches Fengyun 4B meteorological satellite

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China’s Fengyun 4B weather satellite takes off aboard a Long March 3B rocket. Credit: Xinhua

China launched the Fengyun 4B weather observatory June 2 aboard a Long March 3B rocket, deploying the second in a new generation of geostationary spacecraft tracking typhoons, monitoring Earth’s climate, and measuring the space environment.

The Fengyun 4B satellite will join Fengyun 4A, which launched in 2016, to form a “dual-satellite network” collecting real-time data on the atmosphere and clouds, ice and snow cover, sea surface temperature, aerosol and ozone, and vegetation, according to the China Meteorological Administration.

A Chinese Long March 3B rocket hauled the Fengyun 4B satellite into orbit from the Xichang space base in Sichuan province located in southwest China. The 184-foot-tall (56-meter) launch vehicle took off at 1617 GMT (12:17 p.m. EDT) June 2 powered by hydrazine-fueled engines on its core stage and four strap-on boosters.

After jettisoning it is four boosters and first stage, the Long March 3B next fired a second stage, then ignited a cryogenic hydrogen-fueled third stage to place the Fengyun 4B spacecraft into an elliptical, or oval-shaped, geostationary transfer orbit ranging in altitude between 122 miles (197 kilometers) and 22,249 miles (35,807 kilometers), according to U.S. military tracking data.

The rocket deployed the 11,700-pound (5.3-metric ton) Fengyun 4B spacecraft into an orbit inclined 28.5 degrees to the equator.

The satellite will use its own engine to maneuver into a circular geostationary orbit more than 22,000 miles over the equator, where its velocity will match the rate of Earth’s rotation, giving Fengyun 4B a constant view of the Asia-Pacific region.

Fengyun 4B is the second satellite in an upgraded series of Chinese Fengyun weather observatories. Fengyun 4A launched as a pathfinder satellite in 2016 but remains operational, while Fengyun 4B introduces several new upgrades.

Artist’s concept of the Fengyun 4B satellite. Credit: CMA

According to the China Meteorological Administration, Fengyun 4B adds new water vapor detection channels in its radiation imager, improved spectrum detection capabilities, and is capable if providing more accurate atmospheric radiation and temperature and humidity profiles.

CMA said Fengyun 4B also has a “newly equipped fast imager” with a resolution of about 820 feet, or 250 meters, to better monitor typhoons, rainstorms, and other extreme weather events. Fengyun 4B also has an improved data download system using Ka-band communications.

Like other satellites in China’s meteorological observatory fleet, Fengyun 4B data will be shared with international users, Chinese officials said.

“The measurement resolution and measurement sensitivity of the Fengyun 4B satellite are both doubled compared with the Fengyun 4A satellite, which can better serve meteorological forecasts,” said Dong Yaohai, the chief designer of the Fengyun 4 satellite series, in a statement released by the China Aerospace Science and Technology Corp.

Fengyun 4B will undergo a seven-month in-orbit test campaign before entering operational service, CMA said.

The new Fengyun 4 satellite series replaces China’s previous family of Fengyun 2 geostationary weather satellites.

Unlike the Fengyun 2 series, the new observatories are three-axis stabilized, meaning they control their orientations without having to maintain a spin rate. The Fengyun 4 satellites are also designed for lifetimes of seven years, compared to four years for the Fengyun 2 satellites, the last of which launched in 2018.

China also operates a fleet of weather satellites in lower altitude polar orbits to collect data for medium- and longer-term forecasts.

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