Featured image credit: CNSA
Lift Off Time
|November 23, 2020 20:30:12 UTC|
November 24, 2020 04:30:12 BJT
|Chang’e 5, a Lunar sample return mission|
|China Academy of Launch Technology (CALT)|
|China National Space Administration (CNSA)|
|Long March 5 (CZ-5)|
|LC-1, Wenchang Space Launch Center, Hainan Island, China|
|8,200 kg (18,100 lbs)|
Where did the spacecraft go?
|To the Moon (and back again)!|
Were they attempting to recover the first stage?
|No, but they did recover lunar samples in the 4th payload module! The landing happened in the Siziwang Banner area of Inner Mongolia.|
Where did the first stage land?
|It crashed into the South China sea, well away from any villages|
Did they attempt to recover the fairings?
Were those fairings new?
How was the weather?
This was the:
|– 6th flight of a Long March 5, ever|
– 353rd launch of any type of Long March, ever
– 35th orbital launch by China in 2020
– 7th launch from the Wenchang Space Center
Where to watch
Tim Dodd, the Everyday Astronaut, covered the launch!
How did it go?
China sent a sample return mission to the Moon! Chang’e 5 was sent to the Moon on the top of a Long March 5 rocket. This is the same rocket that will eventually send people into deep space. The sample return craft obtained its samples and successfully returned to Earth.
The captured samples are thought to be no more than 1.2 or 1.3 billion years old. This means that they are much younger than the rock samples obtained during the Apollo missions. They are expected to provide fresh insight on the internal make-up of the Moon. Also, they will allow scientists to more precisely timestamp various surfaces on the planets of the inner Solar System.
The CNSA has said that it will share the samples with its international partners and with the United Nations. Some of the samples will be put on display in one of China’s national museums.
On November 23, the Long March 5 took off from the Wenchang spacecraft launch site on Hainan Island and sent the payload initially into Low Earth Orbit. The upper stage shut down 12 minutes 32 seconds after lift off. After a coast phase, the stage then performed its Trans-Lunar Injection (TLI) burn. This started 27 minutes 45 seconds after take off and lasted for 6 minutes 55 seconds.
On November 28, the craft entered a 400 km (250 mi) lunar orbit with a 17-minute braking burn. Two days later, on November 30, the descent/ascent modules detached from the orbiter in advance of landing. The landing then occurred on December 1 at 15:11 UTC.
The descent stage successfully obtained more than 1.7 kg (61 oz) of lunar material, which it then transferred to the ascent module. On December 5, the ascent vehicle achieved lunar orbit rendezvous with the orbiter/reentry vehicle. The samples were transferred across to the return vehicle prior to departure.
The ascent module was deorbited on December 6 so as to avoid leaving space debris in Lunar orbit.
The orbiter with reentry vehicle took 4.5 days to return to Earth. The reentry module separated from the orbiter shortly before entry interface. The reentry profile was set so that the vehicle dipped into the atmosphere at a shallow angle. This led the spacecraft to skip back out of the atmosphere, slowing down at the same time. It performed this skip maneuver twice.
When the spacecraft returned to the atmosphere on the third occasion, it was traveling slowly enough not to burn up on reaching the thicker atmosphere. The reentry module then landed in Dorbod Banner, Inner Mongolia, in northern China.
The Chang’e 5 mission!
China has conducted its first lunar sample return plan. The aim was to complete a “soft landing” in the Mons Rümker area within the Oceanus Procellarum. (No, not Procol Harum, that’s a band – different thing).
The plan was to be operational for one lunar “day” (meaning two weeks). This was because Chang’e 5 did not have a radioisotope thermal generator (RTG) on board. So, it would not have survived a two week lunar “night”, since it would have run out of power. During this time, the goal was to obtain up to 2 kg of lunar “soil” or regolith. This could be from as deep as 2 meters (~7 feet) underground!
Having obtained the sample material, the return craft came back to Earth. Using the Earth’s atmosphere as an air brake, it slowed down from its immense speed. The craft dipped into the atmosphere more than once and skipped back out again. Finally it landed in largely empty grass plains in Inner Mongolia.
The mission was “rehearsed” previously with the Chang’e-5T1 test mission back in 2014. The goal of that mission was to test the return technology.
What’s the payload?
The payload consisted of 4 modules, so bear with us while we explain. The payload was as follows:
- Landing stage
- Ascent stage
- Return/re-entry module
Only the landing and ascent stages descended to the lunar surface. So, this mission featured Lunar Orbit Rendezvous. The landing took place 5 days after launch. The orbiter and return modules stayed in lunar orbit. After obtaining the sample, the ascent module docked with the return module in orbit. The orbiter and return modules then came back to Earth as described earlier. The return module detached itself from the orbiter before entering the atmosphere. This was 23 days after the launch.
The Long March 5 rocket!
The Long March 5 is China’s first heavy lift rocket designed to not rely on hypergolic propellants. That is, propellants that ignite spontaneously on mixing. Instead, the rocket runs on both RP-1 (refined kerosene) and liquid hydrogen for fuel, depending on the stage. In either case it uses liquid oxygen (LOx) as the oxidizer.
The Long March 5 (CZ-5 and CZ-5B) is intended to replace all of the existing CZ-2, CZ-3, and CZ-4 vehicles currently still in service. This will likely end the dubious practice of launching rockets over towns and villages. Which is nice!
The CZ-5B version can deliver around 25,000 kg to Low Earth orbit (LEO). The CZ-5 version with the second stage can deliver around 14,000 kg to Geostationary Transfer Orbit (GTO). Not bad!
The Long March 5 features 4 strap-on side boosters named CZ-5-300. Each booster uses 2 YF-100 engines.
The boosters use RP-1 for fuel and LOx for oxidizer. After their propellant is used, they detach and fall away while the first stage continues burning.
The first central stage is named CZ-5-500. It uses liquid hydrogen as fuel and also LOx as oxidizer. Its burn time is an impressive 490 seconds! That’s more than 8 minutes!
It is powered by two YF-77 engines. This engine has a specific impulse of 310 seconds at sea level, and an amazing 430 seconds in vacuum.
The Long March 5 is powerful enough that its CZ-5B variant doesn’t even need an upper stage! Isn’t that crazy to think about?
Second Stage (not the CZ-5B variant)
Similarly, the second stage is also powered by liquid hydrogen. It uses a pair of YF-75D engines. These have a specific impulse of 442 seconds, and can deliver a DV of 4 1/3 km/s. The burn time is an additional 700 seconds. That’s over 11 minutes!
Optional third stage
So we are back to hypergolics finally. The third stage (if used) uses UDMH / N2O4 for propellants. (We don’t know for sure, but it seems likely this mission did use the third stage.) UDMH is Unsymmetrical Di-Methyl Hydrazine, nasty stuff. N2O4 is Nitrogen Tetroxide. This stage can burn for over 1100 seconds, which is 18 minutes.
The Long March 5 is integrated vertically inside an enclosed launch tower. With between 5 and 7 hours before launch time, the lower section of the tower splits open. About 30 minutes later, the upper section follows suit, revealing the rocket on the pad.
Any other noteworthy information?
This was the first mission in more than 40 years to return Moon rock samples to the Earth. The last such mission being Luna 24, in 1976.
China has now become the third nation to ever return surface samples from the Moon. Previously only the USA and the Soviet Union have achieved this.
NASA achieved this with the 6 successful crewed Apollo lunar landing missions. Meanwhile the Soviet Union had their own Luna robotic missions. The first mission, Luna 16 returned about 100 grams in 1970. Luna 20 returned just 55 grams in 1972. Later, Luna 23 landed OK in 1974 but it could not obtain a sample. The last mission, Luna 24 was able to gather 170 grams from a depth of 2 meters in 1976.
China didn’t do this mission entirely on its own, interestingly. The European Space Agency (ESA) provided tracking support as shown below.
China has already soft-landed Chang’e spacecraft on the Moon, we should note. Chang’e is the Chinese goddess of the Moon. Initially, Chang’e 1 and 2 were lunar orbiters with no landers. This was considered “Phase 1” of China’s Moon mission program. Chang’e 3 and 4 had both orbiters and landers. This was “Phase 2”. Phase 3 is the sample return missions of both Chang’e 5 and 6.
The ultimate goal of the Chang’e missions is to lead to a crewed mission to the Moon in the 2030s.
If you want to know more about Chinese launches, check out the Chinese Space Program category.