Watch live: China’s Long March 5 rocket return-to-flight

[Dante80]

Watch live: China’s Long March 5 rocket poised for crucial return-to-flight launch

December 26, 2019 Stephen Clark - SFN

China’s Long March 5 rocket — the country’s most powerful launcher — is set for its third flight Friday on a critical validation mission after a core stage engine failure doomed a launch in 2017 and forced a two-and-a-half-year investigation and redesign effort.

A successful return-to-flight by the Long March 5 Friday would allow China to move forward with plans to launch a pair of ambitious robotic deep space missions using Long March 5 rockets in 2020.

China’s first Mars rover is scheduled for launch on a Long March 5 in mid-2020, and the Chinese Chang’e 5 lunar sample return mission will also require the Long March 5’s lift capability to depart Earth and head for the moon.

The launch of Chang’e 5 was delayed during the grounding of the Long March 5 after the 2017 failure. China’s Mars mission must launch during a several-week-long period in mid-2020, or else wait until 2022, when Earth and Mars are in the proper positions again to make a direct interplanetary journey possible.

A future variant of the Long March 5 rocket will also launch modules of China’s planned space station, scheduled to be completed in 2022, adding another layer of importance to Friday’s test launch.

The Long March 5 is the heaviest rocket in China’s fleet, and one of the most powerful launcher’s in the world. The Long March 5 can deliver up to 14 metric tons — nearly 31,000 pounds — to geostationary transfer orbit, a popular target orbit for large communications satellites.

Ground crews at the Wenchang Satellite Launch Center, located on Hainan Island in southern China, transferred the 187-foot-tall (57-meter) rocket to its launch pad Dec. 21 for final countdown preparations. The two-hour rollout from the Long March 5’s vertical assembly building — where teams stacked the rocket’s components — occurred on top of a mobile launch table.

Once at the launch complex on Hainan Island’s eastern coast, the Long March 5 was enclosed inside folding gantry structures inside a 300-foot-tall (92-meter) launch pad tower to give technicians access to the vehicle for final testing and inspections.

The launch from the Wenchang launch base — China’s newest spaceport — is planned Friday. Chinese officials have not disclosed the target launch time, but airspace warning notices released to pilots suggest the Long March 5 could lift off as soon as 1246 GMT (7:46 a.m. EST; 8:46 p.m. Beijing time) Friday.

Chinese state television stations have broadcast previous Long March 5 launches, but authorities have not indicated any plans for an official live video feed of Friday’s mission.
When it takes off, ten liquid-fueled engines will power the Long March 5 rocket off the launch pad with nearly 2.4 million pounds of thrust.

The Long March 5’s flight path will take the rocket east from Hainan Island over the South China Sea, where it will drop its four-strap on boosters — each powered by two kerosene-fueled YF-100 engines — around three minutes after liftoff. Unlike launches from China’s inland spaceports, missions originating from Wenchang follow trajectories over the sea, allowing rockets to jettison stages over water rather than over land.

The third Long March 5 rocket inside the vertical assembly building at the Wenchang Satellite Launch Center. Credit: CASC​

Two YF-77 engines on the Long March 5’s core stage will burn super-cold liquid hydrogen and liquid oxygen propellants for nearly eight minutes. During the first stage burn, the Long March 5 will jettison its clamshell-like payload fairing once the launcher climbs above the thick, lower layers of the atmosphere.

Two restartable hydrogen-fueled YF-75D engines drive the Long March 5’s second stage. The second stage engines are expected to perform two firings before deploying the Shijian 20 communications satellite into an elliptical, or egg-shaped, transfer orbit stretching more than 22,000 miles (nearly 36,000 kilometers) from Earth at its most distant point.

The Shijian 20 spacecraft will use its own propulsion system to circularize its orbit at geostationary altitude more than 22,000 miles over the equator.
China’s third Long March 5 launch is expected to follow the same profile that engineers planned for the second Long March 5 flight in July 2017.

But a first stage engine failure on that mission prevented the rocket from reaching orbit, destroying the Shijian 18 communications satellite. China declared the first Long March 5 launch in November 2016 a success, despite a rocket problem that forced the Long March 5’s Yuanzheng upper stage to burn longer to place the Shijian 17 technology demonstration satellite into its planned orbit.

Investigators traced the cause of the July 2017 launch failure to a turbopump on one of the Long March 5’s two YF-77 first stage engines.

The YF-77 engine failure occurred in a “complex thermal environment” around six minutes after liftoff, leading to an instantaneous loss of thrust, according to Chinese investigators. Engineers redesigned the engine turbine exhaust structure for future Long March 5 missions, forcing officials to scrap engine parts already in stock.

The changes led to a gap of more than two years between the second and third Long March 5 flights. In the interim between launches, engineers conducted test-firings of the modified YF-77 engine to verify the design changes, according to the State Administration for Science, Technology and Industry for National Defense, or SASTIND, the Chinese government agency that oversees the country’s space activities.

The YF-77 engines were developed specifically for the Long March 5, the largest rocket in China’s fleet.
The Shijian 20 satellite poised for launch Friday will replace the Shijian 18 satellite lost on the Long March 5 failure in 2017.

Based on the new DFH-5 satellite design developed by the China Academy of Space Technology — a state-owned satellite manufacture — the Shijian 20 spacecraft will test new technologies to support higher-throughput data links with users on the ground.

Shijian 18 was also intended to test new higher-power ion thrusters. Shijian 20 may carry similar propulsion technology.

Source :. https://spaceflightnow.com/2019/12/...t-poised-for-crucial-return-to-flight-launch/

 

[Dante80]

Excited for this, and glad there is a livestream too. Btw, the payload is very important too, a 7,6t monster of a Com-sat

Shijian-20 will be the maiden flight of the DFH-5 ultra-high-performance satellite platform, featuring a high-thrust ion propulsion system. It will provide payload power up to 28 Kilowatts. The satellite hosts a Ka-band of 70 Gbps high-throughput communications payload and an optical infrared laser communications terminal for downlinks with data rates of up to 4.8 Gbit/s. An experimental quantum communications payload, similar to the one on QSS (Mozi), is also reported to be on board.

 

[Beast]

Excited for this, and glad there is a livestream too. Btw, the payload is very important too, a 7,6t monster of a Com-sat

Shows that CNSA is confident of their rocket.

The launch is successful. Congratulation!!!

https://spacenews.com/successful-long-march-5-launch-opens-way-for-chinas-major-space-plans/

China is clear to proceed with plans for a Mars rover mission, lunar sample return and space station module test flight in 2020 following a successful return-to-flight of the Long March 5 rocket.
HELSINKI — China is clear to embark on ambitious exploration and space station missions following a successful return-to-flight Friday of the Long March 5.

Liftoff from the Wenchang Satellite Launch Center, south China, occurred at 7:45 a.m. Eastern. The Shijian-20 communications satellite successfully separated from the upper stage and entered geostationary transfer orbit 40 minutes later.

The China Aerospace Science and Technology Corporation (CASC), the state-owned main contractor for the country’s space programs, declared mission success within an hour of launch.

The near 8-metric-ton Shijian-20 is based on the new large DFH-5 communications satellite bus. It will test Q/V band and laser communications.

The nominal launch means China can proceed testing a derivative launcher needed to construct its planned space station and attempt to launch its first independent interplanetary mission — to Mars — in summer 2020. The Chang’e-5 lunar sample return mission is expected to follow late 2020.

Chinese state media have been regularly promoting the country’s major missions planned for 2020, many of which depend on the Long March 5. Another failure would have been a cause of embarrassment for the leadership and likely brought heavy scrutiny upon CASC.

The launch comes over 900 days after the failure of the second Long March 5 mission, in July 2017. The cause of that failure was a faulty oxidizer turbopump which has since been redesigned at least twice.

Long March 5
The Long March 5 is a new generation launch vehicle with close to twice the payload capacity of the most powerful older Chinese rocket, making it crucial to China’s major plans over the next decade. These include missions to Mars, the lunar polar regions, and a solar polar orbit telescope project.

The 57-meter high, 867,000-kilogram launcher has an optional third stage, employed in today’s mission. The first stage uses liquid hydrogen and liquid oxygen propellant in contrast to the toxic hypergolic mix used by older Long March launchers.

The Long March 5 is capable of delivering 14 metric tons to geostationary transfer orbit and 8.2 tons to trans lunar injection. The derivative Long March 5B will be able to deliver 25 tons to low Earth orbit and is designed to launch modules for the Chinese Space Station.

Space station schedule, engine redesign
The Long March 5B could now launch as soon as the first half of 2020 and will be carrying a boilerplate test version of a new generation crewed spacecraft for deep space. If this test flight goes well, China will begin preparations for launching its first space station module. The 20-metric-ton ‘Tianhe’ core module was previously slated for launch in 2018 before the 2017 Long March 5 failure.

Preparations for the launch began in October with delivery of the rocket components to Wenchang. While most Chinese launchers are delivered by rail, the five-meter-diameter Long March 5 needs to be transported via specially designed cargo ships.

CASC stated Jan. 29 that it planned a return-to-flight of the Long March 5 for July. SpaceNews reported June 21 that the launch was not going to meet this schedule.

A Chinese language article by China Youth Daily published July 26 article stated that a ‘substantial’ redesign of the YF-77 turbopump had recently taken place. This included the addition of guide vanes and use of nickel superalloys instead of stainless steel.

Apparent swift progress was made, resulting in the third Long March 5 being delivered to Wenchang late October.