In what will prove to be its most critical flight to date, China’s Chang Zheng 5 (or Long March 5, as it is known outside of China) rocket has conducted its third mission after two less-than-perfect previous flights.

Should Friday’s flight be confirmed as successful, it would pave the way for three critical launches in 2020: a lunar flight, a Mars mission, and a human spacecraft test flight.

The Chang Zheng 5 lifted off from the Wenchang Spacecraft Launch Site in Hainan, People’s Republic of China at 07:45 EST (12:45 UTC) on Friday, 27 December 2019 with the Shijian-20 test satellite bound for Geostationary Orbit.

Chang Zheng 5 rocket overview:

The Chang Zheng 5 is China’s heavy lift rocket – comparable in lift capacity to the Ariane 5, Delta IV Heavy, Falcon 9 and Proton-M rockets.

It has a single launch site at the Wenchang Spacecraft Launch Site in southern China.

The Chang Zheng 5 can take the following payload masses to the following destinations:

Destination Mass Low Earth Orbit (200 x 400 km orbit inclined 42°) 25,000 kg (55,115 lb) Geostationary Transfer Orbit (GTO) 14,000 kg (30,864 lb) Trans-Lunar Injection (TLI) 8,200 kg (18,077 lb)

Its first stage core is augmented by four strap-on liquid fueled boosters that together produce 10,631 kN (~2,390,000 lbf) of thrust at liftoff, increasing to a maximum of 12,054 kN (~2,710,000 lbf) thrust as the rocket ascends into vacuum.

Each of the four strap-on boosters contain two YF-100 engines and fire for 180 seconds.

The YF-100 engines burn RP-1 rocket-grade kerosene and liquid oxygen.

The core stage uses two upgraded YF-77 engines burning liquid hydrogen and liquid oxygen. Total stage burn time is 480 seconds (8 minutes).

The YF-77 engines were found to be faulty and not as reliable as hoped and were the direct cause of the Chang Zheng 5’s 2017 launch failure on its second mission.

The rocket’s second stage likewise burns liquid hydrogen and liquid oxygen for its two YF-75D engines – which produce a total of 176.52 kN (39,680 lbf) thrust for 700 seconds (11 minutes 40 seconds).

The rocket can fly with or without a third stage. To date, both flown missions – as well as today’s third flight – have all used a third stage.

The optional third stage uses two YF-50D engines burning nitrogen tetroxide and unsymmetrical dimethylhydrazine for up to 1,105 seconds (18 minutes 25 seconds) of powered flight.

The Chang Zheng 5’s first flight took place on 3 November 2016 after a 2 hour 43 minute delay caused by oxygen venting and engine chilldown issues.

The first two stages of flight accidentally inserted the third stage and payload into the incorrect orbit. The third stage was able to compensate and take the payload into the correct orbit for deployment and operation.

The first flight was deemed a success.

A second mission followed on 2 July 2017 and quickly encountered a serious issue with one of its YF-77 engines during first stage flight.

The issue resulted in a shallower flight profile than intended and the complete loss of the mission.

After the failure, the China Aerospace Science and Technology Corporation redesigned the first stage and the YF-77 engine.

Those changes have been heavily tested.

The Shijian-20 payload, Chang Zheng 5’s Return To Flight mission:

While arguably the most important aspect of this mission was to demonstrate the Chang Zheng 5’s ability to successfully Return To Flight, the mission carried a payload.

Riding atop the Chang Zheng 5’s third stage was the Shijian-20 test satellite.

LAUNCH! Long March 5 returns to flight.https://t.co/v1x0xQh0te pic.twitter.com/FXT98YbTyi — Chris B – NSF (@NASASpaceflight) December 27, 2019

In Mandarin, “Shijian” means “Practice”. To this end, Shijian-20 is a Chinese telecommunications satellite designed in part to test or practice new technology for follow-on missions.

The Shijian-20 satellite is the maiden flight of the DFH-5 ultra-high-performance satellite platform featuring a high-thrust ion propulsion system with up to 28 Kilowatts power.

The satellite will have 70 Gbps of high-throughput communications capability in the Ka-band.

In everyday use on Earth, the Ka-band frequency range is most commonly used for 5G mobile telecommunication networks.

The Shijian-20 satellite also carries an optical infrared laser communications terminal for downlink data rates of up to 4.8 Gbps.

Moreover, the satellite has an experimental quantum communications payload.

But the most important part of this mission, unusually, was not the payload but rather proving the rocket’s ability in flight.

After a hiccup on the first flight and the outright failure of the rocket on its second mission, this third flight carries weighted importance due to the Chang Zheng 5’s schedule for 2020.

Next year, China plans to use the rocket for three immensely important flights:

a 23 July launch of the Mars Global Remote Sensing Orbiter and associated Mars Rover, a September test flight of the nation’s new crew spacecraft, and a fourth quarter 2020 launch of the Chang’e 5 lunar sample return mission.

Beginning in 2021, the rocket will also be called upon to launch China’s multi-module space station.

For its 2020 schedule, the crew spacecraft test and lunar sample return missions can adjust their launch dates, but the Mars mission must meet a strict 20-ish day interplanetary launch window or stand down for 26 months until the window between Earth and Mars opens again.

Any issue with the Chang Zheng 5’s Return To Flight today would have called into question its ability to meet the 2020 Earth-Mars launch timeline and would be a blow to China’s rapid-pace spaceflight industry.

Wenchang launch site:

In what was the103rd and final orbital launch attempt of 2019, the China Aerospace Science and Technology Corporation will launch the Chang Zheng 5 rocket from LC-1 at the Wenchang Spacecraft Launch Site on the island province of Hainan.

The Wenchang Spacecraft Launch Site is part of the Xichang Satellite Launch Center and is not an independently administered launch site.

Located on the northeastern part of the island, the Wenchang Spacecraft Launch Site was chosen for its proximity to the equator – allowing for greater payload launch mass – as well as its location next to the open waters of the Pacific Ocean which allows for launches to take place over the sea instead of land.

Located at 19° 36′ 52.17″ N latitude, it is China’s southernmost launch site.

A former suborbital launch test location, Wenchang was converted for orbital launch operations beginning October 2007. Construction of the site was completed October 2014, and its first orbital launch took place 25 June 2016 with a Chang Zheng 7 rocket from LC-2.

Not counting today’s scheduled mission, Wenchang has hosted four launches: two Chang Zheng 5 and two Chang Zheng 7 rockets.