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Chemical Fingerprints: What The Planets Reveal About Alien Life Forms

In their search for extra-terrestrial life, scientists are zeroing in on so-called exoplanets. To narrow the field down even more, they use powerful telescopes to draw conclusions about the chemical makeup of those planets’ atmospheres.

Anybody out there? (Patrick Hoesly)
Anybody out there? (Patrick Hoesly)
Norbert Lossau

BERLIN - Twenty-two year ago sensors on the spacecraft Galileo picked up the existence of life on planet Earth. No big surprise. But what was salient about the experiment was that the space probe's analysis system reached an accurate conclusion.

When it comes to the discovery of life on planets outside the solar system – the so-called extra solar or exoplanets – researchers depend on the sort of information Galileo provided. So far, 770 exoplanets have been discovered, and some of them are similar to Earth in certain respects. Yet even if an exoplanet had an atmosphere and a life-friendly surface, there's still no guarantee that it hosts forms of life.

So how can the existence of life on these planets be established? Bio-astronomers begin with the premise that, as is true for Earth, the existence of life depends on the make-up of a planet's atmosphere. To analyze the chemical composition of the atmospheres of exoplanets, scientists use spectroscopic methods.

The principle underlying such methods is this: you choose a time when the exoplanet, as seen from Earth, is opposite its central star. If the planet has an atmosphere, some of that light will pass through it. Substances in the atmosphere will absorb certain wavelengths in a characteristic way. The result is that certain wavelength absorption lines can be seen through a suitable space telescope. These lines are the equivalent of chemical finger prints from which you can deduce whether the atmosphere of the planet contains oxygen, water, methane, or carbon dioxide.

From that information, in turn, various conclusions can be drawn. One indication of life, for example, is if a planet's atmosphere contains simultaneous concentrations of both oxygen and methane. That's because the interaction of the gases normally results in their mutual elimination – unless there are life forms to balance the concentration by regularly producing the gases anew.

Lisa Kaltenegger, 35, a scientist working at Germany's Max Planck Institute, has developed atmospheric models for exoplanets to be used as a basis for the interpretation of spectroscopic data gathered from space telescopes like the planned NASA James Webb space telescope. The space agency plans to launch James Webb in 2018.

Even if the presence of life on exoplanets can only be established indirectly, the news when it comes – "Extra Terrestrial Life Discovered!" – is going to be sensational.

For her scientific contribution, Kaltenegger was awarded the German research institute's 2012 Heinz Maier Leibnitz Prize which rewards work already accomplished and incentivizes further research with a 16,000-euro grant.

Read the original article in German

Photo - PatrickHoesly

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Geopolitics

Minsk Never More: Lessons For The West About Negotiating With Putin

The longer the war in Ukraine continues, the louder calls will grow for a ceasefire . Stockholm-based analysts explain how the West can reach a viable deal on this: primarily by avoiding strategic mistakes from last time following the annexation of Crimea.

"War is not over" protests in London

Hugo von Essen, Andreas Umland

-Analysis-

Each new day the Russian assault on Ukraine continues, the wider and deeper is the global impact. And so with each day, there is more and more talk of a ceasefire. But just how and under what conditions such an agreement might be reached are wide open questions.

What is already clear, however, is that a ceasefire between Russia and Ukraine must not repeat mistakes made since the open conflict between the two countries began more than eight years ago.

Stay up-to-date with the latest on the Russia-Ukraine war, with our exclusive international coverage.

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Contrary to widespread opinion, the so-called Minsk ceasefire agreements of 2014-2015 were not meant as a definitive solution. And as we now know, they would not offer a path to peace. Instead, the accord negotiated in the Belarusian capital would indeed become part of the problem, as it fueled the aggressive Russian strategies that led to the escalation in 2022.

In early September 2014, the Ukrainian army suffered a crushing defeat at Ilovaisk against unmarked regular Russian ground forces. Fearing further losses, Kyiv agreed to negotiations with Moscow.

The Minsk Protocol (“Minsk I”) – followed shortly thereafter by a clarifying memorandum – baldly served Russian interests. For example, it envisaged a “decentralization” – i.e. Balkanization – of Ukraine. An uneasy truce came about; but the conflict was in no way resolved.

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