China launches Tianzhou 4 cargo ship heading for space station

EDITOR’S NOTE: Updated after docking.

Four booster engines and two core stage engines fire to propel a Long March 7 rocket off its launch pad at the Wenchang launch base Monday. Credit: CCTV

China launched the Tianzhou 4 cargo freighter for the country’s space station Monday, beginning a resupply mission to stage hardware, propellant, and provisions at the complex before arrival of the next long-duration crew in June.

Chinese state television broadcasted the launch, which occurred at 1:56:37 p.m. EDT (1756:37 GMT) Monday, roughly the moment Earth’s rotation brought the Wenchang launch base on Hainan Island under the orbital plane of China’s space station.

The unpiloted cargo ship docked with China’s space station at 8:54 p.m. EDT (0054 GMT), about seven hours after liftoff. The three astronauts training to launch on China’s Shenzhou 14 mission, set for launch next month, will unpack the cargo from the Tianzhou 4 spacecraft after they arrive at the station.

A 174-foot-tall (53-meter) Long March 7 rocket carried the Tianzhou 4 cargo ship aloft. Liftoff occurred at 1:56 a.m. Beijing time.

The Long March 7 rocket was powered by six kerosene-fueled engines during the climb off the launch pad at Wenchang. The engines generated 1.6 million pounds of thrust, and the Long March 7 steered southeast over the South China Sea to line up with the Chinese space station’s orbit inclined 41.5 degrees to the equator.

The Long March 7 is a two-stage rocket augmented with four strap-on boosters. The rocket consumed 45,000 gallons, or 170 cubic meters, of kerosene fuel in combination with cryogenic liquid oxygen during the 10-minute ascent into orbit.

The rocket shed its four boosters and core stage about three minutes into the mission. Four YF-115 engines on the second stage fired to continue the push into orbit. The rocket deployed the supply freighter into orbit about 10 minutes after liftoff.

After separating from the Long March 7, the Tianzhou 4 cargo ship extended solar panels and began automated thruster firings to link up with the Chinese space station some 240 miles (385 kilometers) above Earth.

Deng Hongqin, director of the launch center, said the Tianzhou 4 cargo ship “accurately entered the preset orbit.”

“The solar panels have been extended, and the cargo ship is in good condition. I now declare the launch mission a complete success,” Deng said.

The cargo ship carries food, hardware, and propellant, and other provisions for the space station and the next crew to live and work on the research complex for six months. The Tianzhou logistics vehicle is analogous to SpaceX’s Dragon cargo ship, Northrop Grumman’s Cygnus freighter, and Russia’s Progress supply craft that support the International Space Station.

The China Aerospace Science and Technology Corp., or CASC, said the Tianzhou 4 mission carried about 6 metric tons (13,200 pounds) of cargo. The supplies include food, spare parts, experiment hardware, and other items for the next space station crew.

While docked to the Tiangong station, Tianzhou cargo ships can provide propulsion to change the orbit of the complex. Chinese officials said the Tianzhou 4 mission also carries propellant to be pumped into the propulsion system tanks on the Tianhe core module.

The mission is the fourth flight of China’s Tianzhou cargo ship design, and the third Tianzhou mission in support of the Chinese space station, following an initial test flight in 2017. The Tianzhou 3 supply ship, which launched last September, remains docked to the Tianhe core module at the Chinese station, following an automated maneuver last month to relocate from the core module’s rear port to the forward port on Tianhe.

The official patch for the Tianzhou 4 mission, with an illustration of the configuration of China’s space station after and Tianzhou 4 docking. Credit: CMSE

The older Tianzhou 2 cargo ship departed the Tianhe module in March and burned up on re-entry into Earth’s atmosphere, as designed, disposing of trash and other unnecessary equipment loaded into the spacecraft by the station’s previous crew.

The three astronauts of the Shenzhou 13 crew left the station and landed in China’s Inner Mongolia region on April 15, completing a 182-day mission in orbit, the longest Chinese human spaceflight to date.

After the launch of the three Shenzhou 14 crew in June, China plans to launch two new lab modules to expand the Chinese space station in July and October.

The Tianhe module has starboard and port attachment points for the new lab modules, along with forward, rear, and nadir — or Earth-facing — docking ports for crew and cargo ships.

The Tianhe core module launched in April 2021 to begin assembly of the Chinese space station. The in-orbit construction of the station requires 11 launches, according to China’s space agency. The Tianzhou 4 mission is the sixth launch in that series of space station assembly and outfitting missions.

The 11 launches will be followed by a series of resupply and astronaut flights to maintain operations and perform scientific research on the station.

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