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What does China want to do on the Moon’s far side?

What will China’s Chang’e-4 mission learn about the far side of the Moon? Here are a few things the mission is designed to do.

Learn about the Moon’s history

No space mission has ever explored the far side from the surface. As such, it’s the first chance to explore a mysterious region of Earth’s natural satellite.

The “face” that’s never seen from Earth has some key differences to the more familiar “near side”. The far side has a thicker, older crust that is pocked with more craters. There are also very few of the “maria” (dark basaltic “seas” created by lava flows) that are evident on the near side.

Chang’e-4 has reportedly landed at a site known as Von Kármán crater, a 180km depression located in the far side’s southern hemisphere. But Von Kármán lies within a much bigger hole punched in the Moon – the South Pole-Aitken basin.

It’s the oldest, largest and deepest such basin on the Moon and formed when an asteroid – perhaps 500km across, or more – collided with it billions of years ago.

This event was so powerful that it is thought to have ploughed through the Moon’s outer crust layer and through into the zone known as the mantle.

One of the mission’s objectives is to study any exposed material from the mantle present at the landing site. This would provide insights into the internal structure and history of the Moon.

The South Pole-Aitken basin was formed by a giant impact billions of years ago

Indeed, data from orbiting spacecraft show that the composition of the basin is different from the surrounding lunar highlands. But exposed mantle material on the surface is just one possibility among several to explain this observation.

The rover will use its panoramic camera to identify interesting locations and its Visible and Near-Infrared Imaging Spectrometer (VNIS) to study minerals in the floor of the crater (as well as of ejecta – rocks thrown out by nearby space impacts).

Additionally, the Lunar Penetrating Radar (LPR) instrument will be able to look into the shallow subsurface of the Moon, down to a depth of about 100m. It could probe the thickness of the lunar regolith – the broken up rocks and dust that make up the surface – and shed light on the structure of the upper lunar crust.

After the huge impact that created the South Pole-Aitken basin, a large amount of melted rock would have filled the depression. The science team wants to use Chang’e-4 to identify and study variations in its composition.

Filling an astronomy gap

The far side of the Moon has long been regarded as an ideal spot for conducting a particular kind of radio astronomy – in the low-frequency band – because it’s shielded from the radio noise of Earth.

There’s a frequency band (below about 10MHz) where radio astronomy observations can’t be conducted from Earth, because of manmade radio interference and other, natural factors.

Chang’e-4’s lander is carrying an instrument called the Low Frequency Spectrometer (LFS) which can make low frequency radio observations. It will be used in concert with a similar experiment on the Queqiao orbiting satellite.

Radio telescopes on the Moon would be able to observe at frequencies not accessible to arrays on Earth

The objectives include making a map of the radio sky at low frequencies and studying the behaviour of the Sun.

Speaking in 2016, Liu Tongjie, from the Chinese space agency (CNSA), said: “Since the far side of the Moon is shielded from electromagnetic interference from the Earth, it’s an ideal place to research the space environment and solar bursts, and the probe can ‘listen’ to the deeper reaches of the cosmos.”

Thus, the mission will fill a gap in astronomical observation, allowing scientists to study cosmic phenomena in a way that has never been possible from our planet.

Radiation on the Moon

Understanding the radiation environment will be vital for future human exploration

Several space agencies want to land humans on the Moon in the not-too-distant future, and might send astronauts there for longer than we’ve ever stayed before. So understanding the potential risks from radiation are vital.

Earth’s thick atmosphere and strong magnetic field provide adequate shielding against galactic cosmic rays and energetic charged particles travelling from the Sun.

But astronauts on the Moon will be outside this protective bubble and exposed to particles travelling through open space at near the speed of light – with potentially damaging consequences for their health.

The Lunar Lander Neutrons and Dosimetry (LND) experiment, supplied by researchers in Germany, will aim to fill in some gaps in our understanding about the lunar radiation environment.

It will provide dosimetry (measure the ionising radiation dose that could be absorbed by the human body) with a view to future exploration, and contribute to understanding of particles originating from the Sun.

Source www.bbc.co.uk

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Space

Voyager 2 has discovered something amazing: Denser space outside the solar system

In November 2018, after a 41-year voyage, Voyager 2 crossed the boundary beyond which the Sun’s influence ends, and entered interstellar space. But the mission of the little probe is not yet complete – it continues to make amazing discoveries

Perhaps the probes have found some kind of traffic jam at the edge of the solar system. The Voyager flight continues and we will soon find out what it was.

Voyager 2 discovered something amazing: as the distance from the Sun increases, the density of space increases.

Voyager 1, which entered interstellar space in 2012, transmitted similar indicators to Earth. New data have shown that the increase in density may be a feature of the interstellar medium.

The solar system has several boundaries, one of which, called the heliopause, is determined by the solar wind, or rather by its significant weakening. The space inside the heliopause is the heliosphere, and the space outside is the interstellar medium. But the heliosphere is not round. It looks more like an oval, in which the solar system is at the leading edge, and a kind of tail stretches behind it.

Both Voyagers crossed the heliopause at the leading edge, but within 67 degrees heliographic latitude and 43 degrees longitude apart.

Interstellar space is usually considered a vacuum, but this is not entirely true. The density of matter is extremely small, but it still exists. In the solar system, the solar wind has an average density of protons and electrons from 3 to 10 particles per cubic centimeter, but it is lower the further from the Sun.

The average concentration of electrons in the interstellar space of the Milky Way is estimated to be about 0.037 particles per cubic centimeter. And the plasma density in the outer heliosphere reaches approximately 0.002 electrons per cubic centimeter. When the Voyager probes crossed the heliopause, their instruments recorded the electron density of the plasma through plasma oscillations.

Voyager 1 crossed the heliopause on August 25, 2012 at a distance of 121.6 astronomical units from the Earth (121.6 times the distance from Earth to the Sun – about 18.1 billion km). When he first measured plasma oscillations after crossing the heliopause on October 23, 2013 at a distance of 122.6 astronomical units (18.3 billion km), he found a plasma density of 0.055 electrons per cubic centimeter.

After flying another 20 astronomical units (2.9 billion kilometers), Voyager 1 reported an increase in the density of interstellar space to 0.13 electrons per cubic centimeter.

Voyager 2 crossed the heliopause on November 5, 2018 at a distance of 119 astronomical units (17.8 billion kilometers. On January 30, 2019, it measured plasma oscillations at a distance of 119.7 astronomical units (17.9 billion kilometers), finding that the density plasma is 0.039 electrons per cubic centimeter.

In June 2019, Voyager 2’s Instruments showed a sharp increase in density to about 0.12 electrons per cubic centimeter at a distance of 124.2 astronomical units (18.5 billion kilometers).

What caused the increase in the density of space? One theory is that the lines of force of the interstellar magnetic field become stronger with distance from the heliopause. This can cause electromagnetic ion cyclotron instability. Voyager 2 did detect an increase in the magnetic field after crossing the heliopause.

Another theory is that the material carried away by the interstellar wind should slow down in the heliopause, forming a kind of plug, as evidenced by the weak ultraviolet glow detected by the New Horizons probe in 2018, caused by the accumulation of neutral hydrogen in the heliopause.

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Space

NASA has banned fighting and littering on the moon

New details of the agreement signed by representatives of a number of countries on the development of the moon and the extraction of minerals within the framework of the Artemis program have appeared. Reported by the National Aeronautics and Space Administration (NASA).

So, astronauts involved in the mission are prohibited from littering and fighting on the territory of a natural satellite of the Earth.

So, we present to you the new rules for being on the Moon:

Everyone comes in peace;

Confidentiality is prohibited, all launched objects must be identified and registered;

All travel participants agree to help each other in case of emergencies;

All received data is transferred to the rest of the participants, and space systems must be universal;

Historic sites must be preserved and all rubbish must be disposed of;

Rovers and spacecraft should not interfere with other participants.

“”It is important not only to go to the moon with our astronauts, but also that we bring our values ​​with us,” said Mike Gold, acting head of NASA’s international and inter-agency relations.

According to him, violators of the above rules will be asked to “just leave” the territory of the moon.

The effect of these principles so far applies to eight signatory countries of the agreement: the USA, Australia, Canada, Italy, Japan, Luxembourg, the United Arab Emirates and the United Kingdom. Countries other than China can join if they wish.

 It should be noted that at the moment NASA is prohibited from signing any bilateral agreements with the PRC leadership.

The first NASA mission to the moon, known as “Artemis 1”, is scheduled for 2021 without astronauts, and “Artemis 2” will fly with a crew in 2023.

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Space

Methane snow found on the tops of Pluto’s equatorial mountains

Scientists believe that it arose as a result of the accumulation of large amounts of methane at an altitude of several kilometers above the surface of the planet.

In the images of the Cthulhu region – a dark region in the equatorial regions of Pluto – planetary scientists have found large reserves of methane snow that covers the peaks of local mountains and hills. It formed quite differently from how snow forms on Earth, astronomers write in the scientific journal Nature Communications.

“The white caps on the tops of Pluto’s mountains did not arise from the cooling of air currents that rise along the slopes into the upper atmosphere, as it happens on Earth, but from the accumulation of large amounts of methane at an altitude of several kilometers above Pluto’s surface. This gas condensed on the mountain tops, “the scientists write.

We owe almost everything we know about Pluto to the New Horizons interplanetary station. It was launched in January 2006, and in mid-July 2015 the station reached the Pluto system. New Horizons flew just 13 thousand km from the dwarf planet, taking many photographs of its surface. 

New Horizons data indicated an interesting feature of Pluto – in its depths, a giant subglacial ocean of liquid water can be hidden. It can be a kind of engine of those geological processes, traces of which can be seen on the surface of a dwarf planet. Because of this discovery of New Horizons, many discussions began among planetary scientists. Scientists are trying to understand how such a structure could have arisen, as well as to find out the appearance of Pluto in the distant past.

Members of the New Horizons science team and their colleagues from France, led by planetary scientist from NASA’s Ames Research Center (USA) Tanguy Bertrand, have discovered another unusual feature of Pluto. They studied the relief of one of the regions of the dwarf planet – the Cthulhu region. This is what astronomers call a large dark region at Pluto’s equator, which is whale-like in shape and is covered in many craters, mountains and hills.

Snow in Pluto’s mountains

By analyzing images of these structures taken by the LORRI camera installed on board New Horizons, astronomers have noticed many blank spots on the slopes of the highest mountain peaks. Having studied their composition, scientists have found that they consist mainly of methane.

Initially, planetary scientists assumed that these are deposits of methane ice. However, Bertrand and his colleagues found that the slopes and even the tops of Pluto’s equatorial mountains are actually covered not only with ice, but also with exotic methane snow that forms right on their surface.

Planetary scientists came to this conclusion by calculating how methane behaves in Pluto’s atmosphere. In doing so, they took into account how the molecules of its gases interact with the sun’s rays and other heat sources. It turned out that at the equator of Pluto, at an altitude of 2-3 km from its surface, due to the special nature of the movement of winds, unique conditions have formed, due to which snow is formed from methane vapor.

Unlike Earth, where such deposits are formed as a result of the rise of warm air into the upper atmosphere, on Pluto this process goes in the opposite direction – as a result of contact of the cold surface of the peaks and slopes of mountains with warm air masses from the relatively high layers of the dwarf planet’s atmosphere.

Previously, as noted by Bertrand and his colleagues, scientists did not suspect that this was possible. The fact is that they did not take into account that due to the deposition of even a small amount of methane snow and ice, the reflectivity of the peaks and slopes of mountains in the Cthulhu region increases. As a result, their surface temperature drops sharply, and snow forms even faster.

Scientists suggest that another mysterious feature of Pluto’s relief could have arisen in a similar way – the so-called Tartarus Ridges, located east of the Sputnik plain. A distinctive feature of this mountainous region is strange peaks that are shaped like skyscrapers or blades. Bertrand and his colleagues suggest that these peaks are also methane ice deposits that grow “from top to bottom.”

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