China's Chang'e 5 successfully lands on Moon!
China has successfully put another probe on the Moon.
Its robotic Chang'e-5 mission touched down on December 1st 2020, with the aim of collecting
samples of rock and dust to bring back to Earth.
The venture has targeted Mons Rümker, a high volcanic complex in a nearside region known
as Oceanus Procellarum. The lander is expected to spend the next couple
of days examining its surroundings and gathering up surface materials.
It has a number of instruments to facilitate this, including a camera, spectrometer, radar,
a scoop and a drill. The intention is to package about 2kg of "soil",
or regolith, to send up to an orbiting vehicle that can then transport the samples to Earth.
It's 44 years since this was last achieved. That was the Soviet Luna 24 mission, which
picked up just under 200g.
“Follow me on this journey to learn more about this amazing mission program and to
understand how we accomplished this aim: we made it thanks the hard work made by Chinese
Engineers during the last twenty years.”
Chang'e 5 was launched on 23 November 2020 at 20:30 UTC and landed on the Moon on 1
December 2020, with an expected return to Earth around 16 December 2020. Chang'e 5 will be China's
first sample return mission, aiming to return at least 2 kilograms (4.4 pounds) of lunar
soil and rock samples to the Earth. Like its predecessors, the spacecraft is named
after the Chinese Moon goddess, Chang'e. This is one of the missions that we were waiting
for a long time. We really couldn't wait for this mission to
be launched. This will be the first lunar sample-return
mission since Luna 24 in 1976 and – if successful – would make China the third
country to return samples from the Moon after the United States and the Soviet Union. It launched
from the Wenchang Satellite launch centre in Hainan Island.
Missions like this are awesome missions: you can choose the place you want for landing,
dig a nice hole in the lunar soil and steal some rocks and stuff from its surface.
Then, you can finally launch a rocket that reaches an orbit around the moon, make it
hook to another spacecraft and then launch it on its way back to Earth.
And, if everything worked out well, you can return in the Earth's atmosphere, where the
heat shield does its work and returns home carrying the sample that, until a few days
ago, were belonging to the moon.
But let's go deeper into this mission: what's the Chinese plan?
This is the sixth Chang'e mission, but it is called Chang'e 5. Oh well, I know this
could be a little bit confusing, so let's see some of Chang'e missions history.
China is carrying out this mission program since 2007.
That was the first time for China to try to reach such a big accomplishment.
Chang'e 1 was thought and launched to orbit around the moon, helping engineers to improve
their skills, making experience before launching the second mission, Chang'e 2.
Chang'e 2 was launched in 2010, and after its success it was taken over the lunar orbit,
to make a fly in the deep space, in order to see if they could reach Mars with another
probe, and some years later, that's what they actually did: The mission — named Tianwen-1,
which means ‘questions to heaven’ — is the country’s first attempt to land on the
red planet.
And then it was the time for Chang'e 3 to map the moon.
It let us to find the first landing sites for the moon landing.
Chang'e 3 brought even a rover on the moon, in 2013. This was something which has not
happened for several years! When they finally found a good crater to land
on, Chang'e 4 was launched and it landed on the dark side of the moon, a place that has
never been explored before.
So, as you can see, the entire program was made of three steps:
1) orbit the moon 2) moon landing and exploration
3) bringing home moon samples
Chang'e 5 is the first one that will try to complete this 3rd part of the mission program.
But actually, it's the second one. Because Chang'e 5 had an older brother : Chang'e
5-T1. Chang'e 5-T1 was an experimental robotic lunar
mission that was launched on 23 October 2014 to conduct atmospheric re-entry tests on
the capsule design planned to be used in the Chang'e 5 mission. Its service module, called
DFH-3A, remained in orbit around the Earth before being relocated via Earth-Moon L2 to
lunar orbit by 13 January 2015, where it used its remaining 800 kg of fuel to test manoeuvres
key to future lunar missions.
So we can say that Chang'e 5-T1 was a test to make sure we could complete successfully
Chang'e 5 mission: if you had to launch a hippo, you have first
to be sure that you can bring the hippo back.
Chang'e 5-T1 also tested the re-entry phase of the mission.
The reentry phase is one of the most difficult aims to accomplish for the Chang'e program
because it isn't easy to create the right conditions in order to have a safe reentry
in the Earth's atmosphere. Also, the reentry method that will be adopted
for the Chang'e 5 capsule, will be similar to those technologies who will be employed
by the astronauts returning home from the Moon in the following years: dockings, Rendez-Vous,
manoeuvres, they will be exactly the same as the ones that will be used in the next
human missions. So this mission it is also a way to test what
we have to enhance our performances and skills in human exploration missions.
"Before finding out more about Chang'e 5 mission, be sure to like or dislike the video so that
we can continue to improve and make these videos better for you the viewer. Plus, be
sure to subscribe to the channel clicking the bell so that you don't miss ANY of our
weekly videos."
What's the Chang'e 5 spacecraft design?
The Chang’e 5 spacecraft consists of four modules – a Service Module, a Return Vehicle,
the Lander and the Ascent Vehicle. Overall, the spacecraft will have a launch mass around
eight metric tons requiring a larger launch vehicle than previous missions. It is expected
that Chang’e 5 and 6 will launch on the Long March 5 rocket that delivers the craft
to a direct trajectory to the Moon. The Chang’e 5 Service Module includes all
systems to support the assembled vehicle on the way to the Moon, remain in lunar orbit
for an extended period of time while surface operations are in progress, rendezvous with
the ascent vehicle in orbit and support the Return Vehicle during the transfer back to
Earth, setting up for re-entry. The Service Module is equipped with power-generating
solar arrays, communication systems for command uplink from Earth and telemetry downlink as
well as a propulsion system and attitude control thrusters. Likely based on propulsion technology
already used on Chang’e 3, the vehicle will use hypergolic propellants consumed by a throttlable
engine (likely the 7.5kN engine used on Chang’e 3). The propulsion system of the Service Module
would be used to conduct trajectory correction manoeuvres on the way to the Moon, the lunar
orbit insertion burns, orbital maintenance and the trans-Earth injection burn at the
end of the mission.
The Service Module directly interfaces with the Return Vehicle that is installed in a
cavity of the Service Module to reduce the overall length of the vehicle.
The return vehicle is equipped with a modified heat shield to be able to withstand the re-entry
into Earth’s atmosphere at speeds of 11 kilometres per second. Landing is accomplished
using parachutes that are deployed during atmospheric flight, starting with a drogue
followed by the main Chute. The Return Vehicle includes a thruster system to actively control
its orientation before re-entry and modify its re-entry path by adjusting aerodynamic
lift to target a reasonably sized landing zone. Onboard measurement systems and communication
beacons for the location of the landed vehicle are also part of the entry vehicle.
It is likely that the aim of the mission is to complete all sampling and drilling operations
within one lunar day to avoid risking hardware damage as a result of the harsh temperatures
of the lunar night. After sampling and transfers of up to 2 kilograms of lunar material to
the Ascent Vehicle is complete, all preparations for the return journey will be completed.
The Ascent Vehicle will then use its propulsion system to ascend into an orbit of 15 by 180
Kilometers and further raise its orbit and complete a fully autonomous docking with the
Service Module – Return Vehicle stack.
Re-entering at a speed up to 11 kilometres per second, the Return Vehicle would utilize
a Skip Re-Entry. But how does a Skipe Re-Entry work?
Well, imagine a pebble thrown into a small circular pond: it's pretty the same thing.
When the capsule reaches the atmosphere, the temperature on the capsule is so high that
the heat shield may literally fuse. So one has to re-enter the atmosphere decreasing
the amount of heating-exposure time, in order to avoid horrible things.
The basic concept is to "cut" the atmosphere at a certain angle so that the aircraft is
pushed out into space (as happens when a pebble jumps over the surface of a lake). Each time
the speed of the probe is reduced so that it can eventually descend into the atmosphere
at a low suborbital speed. Like air capture, skip reentry requires precise
guidance. An excessively low entry angle will lead to a shuttle speed that is too high,
with the possibility of permanently exiting into space if the vehicle exceeds the escape
speed. An entrance that is too steep, however, will produce more intense heating and the
thermal stress could exceed the limits for which the shuttle is designed, with the possibility
of destroying it. The skip reentry was first imagined in the
1930s when a leap suborbital trajectory was designed for the German bomber Silbervogel,
which never flew. The technique was used for the probes of the Zond Program in flights
around the Moon, which involved a jump before landing. Jumps Zond 6 and 7 were a success,
although the Zond 6 was largely destroyed in the impact to the ground for independent
reasons. Interesting fact: on its trip the Zond 7 craft
carried 4 turtles. By the way, if everything goes according to
the plan, Chang'e 5 will ditch into the ocean, and finally, it will be rescued, bringing
the rock samples in the laboratories to study them.
"This video ends here! Thanks for watching everyone! What do you think about Chang'e
5 mission? Do you think it will be useful to future Moon and Mars Missions? Let us know
in the comments below! See you next time on the channel!