Explore the Dark (Far) Side of the Moon - China's Space Mission
December 30, 2018Staff
We all know that there was a lot of speculation about the dark side of the moon regarding what information does it contain. Coming to our article today, we see that China is planning to launch its satellites orbit around the dark side of the moon so as to know what really lies beyond our vision. Dark side of the moon also often known as the "Far side of the moon" is really the dark side of the moon because all the satellite communications would black out once the satellite goes into that orbit. We will see in detail why it happens but don't worry we will keep it short. Before going to read, let's get familiarized with some technical aspects.
"There is no dark side"
The reason we can’t see the far side of the moon is that our
satellite rotates exactly once per orbit so as to keep that side hidden
from view (see video below).
Mission:
Chang'e 4 is the vehicle scheduled to launch in the late 2018 (but it's already late). This mission, if successful, gives deeper insights to the alien place of the moon. This lunar mission comes as a successor for the Chang'e 3 which landed on the moon in the year 2013 and deployed a robotic rover, Yutu, which malfunctioned on the second day itself but continued to record and transmit the data. The interesting part to continue this mission is that the robot has identified a new type of rock fueling the idea to relaunch another lunar rover.
Lagrange points:
China’s solution to this dilemma is to deploy a relay satellite that
will be able to see both the lander and the Earth at the same time.
Rather than being placed in orbit around the moon, the Chang'e 4
Communications Relay Satellite will be sent to one of the five
Earth-moon ‘Lagrange points’. These are positions where the
gravitational forces and orbital motions of the spacecraft, Earth and
moon interact to create a stable location. The one chosen in this case
is the Second Lagrange Point, ‘L2’, which is 67,000 km beyond the moon.
Earth-moon Lagrange points.
Seen from the exact L2 point, the moon would completely hide the
Earth. However, this can be solved by causing the relay satellite to
follow a “halo orbit” around the L2 point. This is like a small ring
around the Earth-moon-L2 line, of a diameter sufficient to keep the
Earth in view beyond the moon’s edge. This situation is one of “unstable
equilibrium”, but requires very little expenditure of fuel to sustain.
It may seem tricky to achieve, but several spacecraft have already made
successful visits to L2, including Chang'e 5-T1, a test mission for
another planned lunar mission, Chang'e 5 (which will land in 2017 and
return a sample to Earth).
Far side of the moon with Earth in the background.NASA
Big basin: The Chang'e 4 landing site has not been confirmed, but it is widely expected
to be inside the South Pole-Aitken basin. At 2500 km in diameter and 8
km deep, this is the largest impact basin on the moon. Unlike those on
the near side, it has for some reason not been flooded by lavas, so it
offers us a window deep into the Moon’s crust for study of the lunar
interior. There could even be fragments from the moon’s mantle scattered across
the surface here – the impact that created the basin could well have
reached the mantle and thrown up debris. Lunar geologists believe they
can deduce the mantle’s composition by examining the crust, and this
would be a good chance to test whether they are right.
Colour-coded topography of part of
the Moon, mostly the far side, seen from above the South Pole-Aitken
basin. Blue is lowest, red is highest.NASA
Other proposed missions to the far side of the moon – such as the crowd-funded Lunar Mission One, the Russian and European Space Agency jointly-planned Luna 27,
and maybe an independent ESA lander, too – are aiming at the fringes of
SPA basin at the moon’s south pole, from where the Earth stays in view
as it tracks around the horizon. These will have the benefit of
permanent sunlight, and a chance to find ice inside permanently-shadowed
craters. However, thanks to its relay satellite, Chang'e 4 looks set to
provide the first surface-based analyses from deep inside the lunar far
side.
Let's see what will work out with the China's mission!
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