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# The new equation for estimating alien life across the universe

How many other inhabited planets are there? It’s a question that fascinates scientists and lay people alike. A new equation may help weigh up the possibility

Many of us have glanced upwards at the stars and wondered whether there is other life out there somewhere. Few, however, have then tried to write down an equation to express the probability in numbers.

Sara Seager of the Massachusetts Institute of Technology has done just that. Her equation collects together all the factors that could determine how many planets with detectable signs of life may be discovered in the coming years.

The factors include the number of stars that will be observed, the fraction of those stars with habitable planets, and the fraction of those planets that can be observed. First presented at a conference earlier this year, the equation is written as N = N*FQFHZFOFLFS. It was published yesterday in the online Astrobiology magazine.

This is not the first time an astronomer has put such thoughts into numbers, as Seager acknowledges. Back in 1961, astronomer Frank Drake gave a lecture about the search for extraterrestrial intelligence. To set the agenda, he wrote down a list of the factors needed to estimate the number of intelligent civilisations in the galaxy.

The resulting string of factors is known as the Drake equation, and it has become a bit of a scientific superstar. It may even be the most famous equation after E=mc2.

Drake’s factors were:
1: The average number of stars to form per year in the galaxy.
2: The fraction of those stars that form planets.
3: The fraction of those planets that could support life.
4: The fraction of life-supporting planets that form life.
5: The fraction of those living planets that develop intelligent life forms.
6: The fraction of those intelligent life forms that develop technology.
7: The average lifetime of a communicating species; in other words how long a civilisation will use radio technology, leaking signals into space for us to hear.

Rather discouragingly, the only factor that is known is the first one. Astronomers have shown that the galaxy gives birth to about seven new stars per year. They are now working on an estimate of the second term, the fraction of stars that form planets. All the rest is still guesswork.

Seager’s new equation makes no assumption that extraterrestrials are intelligent and using radio technology. Instead, she simply works on the idea that life of any type may be present in sufficient abundance to alter the chemical composition of its planet’s atmosphere.

On Earth, for example, our atmosphere has been driven to a specific chemical composition by the combined metabolisms of all the living things. It is as distinctive as a fingerprint. So, by analysing the atmosphere of another planet, we may be able to detect the presence of life, even if it is only pondweed.

Nevertheless, Seager’s new equation suffers many of the same drawbacks as Drake’s original: we have no idea what value to assign to most of the factors.

Last year, I appeared at the International Festival of Authors in Toronto alongside Canadian poet Larissa Andrusyshyn. Realising the probabilistic nature of the Drake Equation, she had written her own tonugue-in-cheek equations to estimate such things as the number of men in her city who displayed boyfriend potential.

Similarly, I could write down an equation to estimate the probability of me finishing this article. Factors could include: the number of computers in the house that I could potentially use to write, the fraction of those computers equipped with a word processor, the fraction connected to the internet, the amount of time I had to spare, and of course, how motivated I felt (which on my cynical days could be a function of how much I was getting paid for the article).

In short, you can think up a “Drake equation” for anything.

While Seager’s and Drake’s equations are useful ways of organising one’s thoughts about the challenge of looking for life, the bottom line is that the factors are too loosely constrained for either to have any quantitative value.

The only way to know if there is truly life on other worlds is to design and build missions that will look for it. Thankfully, Seager is at the forefront of that effort too. Her planet-finding telescope, TESS, will be launched by Nasa around 2017 and could locate hundreds of Earth-sized planets.

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# 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.

# 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.

# 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.”