What is the dark side of the moon – and I don’t mean the title of the famous Pink Floyd album? And why was the ill-fated Chandrayaan-2 module of the Indian Space Research Organization (ISRO) trying to get there? These are ever-present questions these days in many people’s minds, and I will try to offer some clear and easy to grasp answers. But before I go to the moon mystery represented by its dark side (also known as the far side) and moon resources, I want to clarify one important issue.
This is: why does the moon always look the same, year after year? Why don’t we see variations in the lunarscape at full moon?
The answer is simple: because we always see the same side of the Moon.
Why Does The Moon Keep The Same Side Towards Earth?
Our natural satellite is permanently locked in orbit around Earth. But it does not have only a simple rotation movement. It also has a revolutionary movement. This movement represents the spin around its orbit.
On Earth, the revolutionary movement is demonstrated by the day-night cycle. As each area approaches the sun, dawn comes, then full daylight. As it moves away from the sun, evening and night ensue. The moon does the same thing.
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But, that is not enough to explain why we never see the dark side of the moon. The effect responsible for this situation is called a tidal lock.
What Is the Tidal Lock?
According to Space Answers, tidal locking is “the situation when an object’s orbital period matches its rotational period”. Let me explain this to you. If we take the 0 positions of the moon as above New York City, it takes it 28 days to return to the same position. The moon also needs 28 days to complete a rotation around its axis.
For further clarifications, this video shows how tidal locking ensures that we never get to see the dark side of the moon.
Do We See Just One Half of the Moon?
Here’s another interesting fact about the moon. We see more than just half of its surface. More precisely, 59% of it is visible from Earth. This is due to a phenomenon called libration.
Libration is the wagging movement of the axis of the moon. Earth does the same thing, as well. As for the moon, it has various types of libration. The most important ones are:
- The libration in longitude:
The axis of the moon wobbles from east to west. The reason for this movement is the elliptical (oval) shape of the orbit of the moon around the Earth.
This movement stops at the moment when the moon is closest to the Earth (perigee) and farthest from it (apogee);
- The libration in latitude:
The axis of the moon wobbles from north to south. This movement occurs when the moon crosses the orbital planes of the Earth, that is, twice per month.
Now that you know why we only see the only one side of the moon, it’s time to move on to the moon mystery.
What Does the Dark Side of the Moon Look Like?
Thanks to NASA’s Lunar Reconnaissance Orbiter Camera we now have a clear image of the dark side of the moon and about moon mystery. It is quite pockmarked even more so than the visible side (with the outstanding Tycho Crater).
In total, the scientists have identified and named so far 118 geographical features of the dark side of the moon: craters, mountains, valleys, and sea-like basins.
The names of these lunarscape feature honor, various scientists and researchers, such as:
- Alexander von Humboldt, a Prussian explorer, geographer, and naturalist;
- Gottfried Wilhelm Leibniz, a German mathematician, and logician,
- Nicolas Carnot, a French scientist, the father of thermodynamics,
- Amedeo Avogadro, an Italian scientist who made great contributions to the molecular theory.
But what is hiding in the dark side of the moon? And what was Chandrayaan-2 moon mission hoping to discover there? This is a moon mystery that is worth exploring.
The Big Secret of the Dark Side of the Moon: Water
With the advance of technology, people wanted to know more about everything about the world around them. After most of the Earth was known to us, we looked up to the sky, and the most obvious object up there, apart from the sun, is the moon.
During the 1960s, the space age was in full swing. The United States of America, the Soviet Union, and China were all competing to send their spacecraft as close to the moon as possible – and even land on it.
And some of these space missions targeted the dark side of the moon. And the more scientists learned about it, the more they were interested in it. More precisely, in the possibility that its craters may contain a very precious substance, the very essence of life: water.
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Chandrayaan-2: What We Know About the Indian Moon Mission
According to NASA’s National Aeronautics and Space Administration, Chandrayaan-2 was an orbiter and a soft lander containing a lunar rover. It was built by the Indian Space Research Organization (ISRO) and launched on the 22nd of July 2019.
The mission had several scientific purposes:
- Study the topography of the moon
- Analyze the minerals present in the lunar soil
- Study the exosphere of the dark side of the moon
- Identify sources of water on the surface of the moon.
This mission came 11 years later after Chandrayaan-1 made the first detailed explorations for water on the surface of the moon using radars.
Chandrayaan-2 consists of:
- The orbiter with the shape of a box, with the orbital mass of approx. 2.400 kg. It contains several pieces of scientific equipment, including a terrain mapping camera, a neutral mass spectrometer, a solar X-ray monitor;
- The lander named Vikram, with a mass of over 1,400 kg (own mass plus the rover). It is also equipped with scientific devices, such as cameras, a seismometer and a laser retroreflector supplied by NASA;
- The rover named Pragyan, a vehicle with 6 wheels and a mass of 27 kg. The rover contains cameras, an X-ray spectrometer and other devices necessary for performing experiments on the lunar surface.
What Happened to Chandrayaan-2?
On the 20th of August, Chandrayaan-2 entered the orbit of the moon and everything seemed to be working according to schedule.
On the 7th of September, when the lander was supposed to make contact with the surface of the dark side of the moon, ISRO lost contact with it.
This happened when the lander was just 2 km above the surface of the moon.
According to the latest information published by the Associated Press, the Chandrayaan-2 mission team has located the lander on the surface of the moon.
They are currently trying to make contact with the rover, and, if possible, resume the mission.
In the aftermath of the apparent failure of the Chandrayaan-2 mission, the Prime Minister of India, Narendra Modi, came to visit the ISRO team. He gave an emotional speech and motivated the scientists, saying:
“We will look back at the journey and effort with great satisfaction. The learnings from today will make us stronger and better. […] The best is yet to come in our space program.”
What do you think about water on the moon? Will the scientist unfold the moon mystery? Will we find water on the dark side of the moon?