Polskie Forum Astronautyczne
Artykuły o tematyce astronautycznej => Artykuły astronautyczne => Wątek zaczęty przez: Orionid w Grudnia 28, 2019, 01:46
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Successful Long March 5 launch opens way for China’s major space plans
by Andrew Jones — December 27, 2019
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Liftoff of the third Long March 5 launch vehicle, Dec. 27, 2019. Credit: CASC
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 (https://www.space.com/china-new-spacecraft-crewed-moon-missions.html) 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 (https://spacenews.com/china-begins-preparations-for-crucial-long-march-5-rocket-launch/) 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 (https://spacenews.com/china-will-attempt-30-plus-launches-in-2019-including-crucial-long-march-5-missions/) Jan. 29 that it planned a return-to-flight of the Long March 5 for July. SpaceNews reported June 21 (https://spacenews.com/chinas-moon-mars-and-space-station-missions-may-be-facing-delays/) 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 (https://spacenews.com/chinas-moon-mars-and-space-station-missions-may-be-facing-delays/) 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.
Source: https://spacenews.com/successful-long-march-5-launch-opens-way-for-chinas-major-space-plans/
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Successful Long March 5 launch paves way for new Chinese space missions
December 27, 2019 Stephen Clark [SFN]
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China’s third Long March 5 rocket lifts off from the Wenchang Satellite Launch Center. Credit: CCTV
The third launch of China’s heavy-lift Long March 5 rocket successfully delivered its satellite payload to orbit Friday, validating engine design changes after a failure on the Long March 5’s second flight, and clearing the way for the launch of a Chinese Mars rover and lunar sample return mission in 2020.
The 187-foot-tall (57-meter) rocket, the most powerful in China’s fleet, lifted off from the Wenchang Satellite Launch Center on Hainan Island in southern China at 1245 GMT (7:45 a.m. EST; 8:45 p.m. Beijing time) Friday.
A live video stream on Chinese state television showed the Long March 5 rocket firing into cloudy skies over the coastal launch base in China’s southernmost province.
Ten engines powered the Long March 5 into the sky with nearly 2.4 million pounds of thrust, carrying an experimental communications satellite named Shijian 20 into space.
The launch Friday marked the first flight of a Long March 5 rocket since the launcher’s second mission in July 2017 ended in failure, prompting a two-and-a-half-year grounding and redesign effort.
The successful return-to-flight of the Long March 5 rocket Friday paves the way for China to move forward with plans to launch a pair of ambitious robotic deep space missions using Long March 5 rockets in 2020.
Spaceflight Now@SpaceflightNow
Watch a video replay of today’s Long March 5 launch from Hainan Island: https://spaceflightnow.com/2019/12/26/chinas-long-march-5-rocket-poised-for-crucial-return-to-flight-launch/ …
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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.
Friday’s mission was critical for the Mars and moon missions to launch on their current schedules.
The launch of Chang’e 5 has already been delayed due to 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 human-rated space station, scheduled to be completed in 2022, adding another layer of importance to Friday’s test launch. The Long March 5B configuration, which is tailored for space station module launches, could debut some time in the second half of 2020 carrying a prototype of China’s next-generation human-rated spaceship on an unpiloted demonstration flight.
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.
The launcher’s lift capability to low Earth orbit is around 55,000 pounds, or 25 metric tons.
Chinese teams loaded the Long March 5 rocket at the Wenchang space base with liquid hydrogen, kerosene and liquid oxygen propellants ahead of the launcher’s blastoff Friday.
Gantry arms on the Long March 5’s 300-foot-tall (92-meter) launch pad tower opened in the final phase of the countdown, and a member of the Chinese launch team crisply called out the final seconds before liftoff.
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China’s third Long March 5 rocket lifts off Friday. Credit: CALT
Sparklers fired underneath the Long March 5 moments before ignition of the core stage’s twin YF-77 hydrogen-fueled engines. Moments later, eight kerosene-fed YF-100 engines ignited on the Long March 5 rocket’s four strap-on boosters to propel the launcher off the pad.
After ascending through clouds, the Long March 5 arced toward the east from the Wenchang launch base. Cameras mounted on-board the rocket showed the four liquid-fueled boosters shutting down their engines and jettisoning to fall into the South China Sea some three minutes into the mission.
The two YF-77 engines on the Long March 5’s core stage burned their supply super-cold liquid hydrogen and liquid oxygen propellants for nearly eight minutes. During the first stage burn, the Long March 5 released its clamshell-like payload fairing once the launcher climbed above the thick, lower layers of the atmosphere.
Two restartable hydrogen-fueled YF-75D engines driving the Long March 5’s second stage fired next in the launch sequence.
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The Long March 5 rocket’s twin YF-75D upper stage engines are seen during their first burn on Friday’s mission. Credit: CCTV
The second stage engines performed two firings before deploying the Shijian 20 communications satellite into an elliptical, or egg-shaped, transfer orbit stretching more than 42,000 miles (about 68,000 kilometers) from Earth at its most distant point.
A forward-facing camera on the Long March 5’s second stage showed the Shijian 20 spacecraft separating from the rocket, prompting applause in the launch control center.
The Shijian 20 spacecraft will use its own propulsion system to circularize its orbit at geostationary altitude more than 22,000 miles (nearly 36,000 kilometers) over the equator.
China’s third Long March 5 launch followed 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.
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China’s third Long March 5 rocket rolled out to its launch pad Dec. 21 at the Wenchang space center on Hainan Island. Credit: Xinhua
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.
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The Shijian 20 satellite separates from the Long March 5 rocket in this camera view. Credit: CCTV
In addition to introducing changes to resolve the YF-77 engine problem, Chinese engineers simplified some structures on the Long March 5 rocket to make it lighter, increasing the launcher’s carrying capacity, according to the China Academy of Launch Vehicle Technology, the country’s lead state-owned contractor for the Long March rocket family.
The Shijian 20 satellite launched 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/2019/12/27/successful-long-march-5-launch-paves-way-for-new-chinese-space-missions/