The search for extraterrestrial life will focus on our closest galactic neighbor


Scientists are starting to search for life in our galactic backyard.

Alpha Centauri, two stars just over four light years apart (about 25,000 billion kilometers) are the closest solar stars to our solar system, is at the center of a new effort to find planets that could reveal signs of life. The project focuses on building a small space telescope – nicknamed TOLIMAN after the star’s medieval name – that will enter Earth orbit in about two years and could start detecting planets by around 2025.

Although Alpha Centauri is next in astronomical terms, no planet has been detected around its binary star system. If found, their atmospheres could be scanned for “biosignatures” created by extraterrestrial life – a relatively new astronomical technique that could allow scientists to telescope to determine whether there is extraterrestrial life, especially microbial, on it. distant planets.

More than 4,000 alien planets have now been confirmed, but they have been largely discovered thanks to lucky alignments, said project leader Peter Tuthill, professor of astrophysics at the University of Sydney.

“There is a dark little secret that astronomers have been keeping,” he said. “In fact, we are not very good at finding planets. “

Most “exoplanets,” as they are called, were discovered by automated systems like the Kepler Space Telescope, which constantly monitors planets crossing in front of hundreds of thousands of stars.

But finding planets around a particular star system – like Alpha Centauri – is much more difficult.

To improve their chances, the new space telescope will have a specially etched mirror to create what is known as a “diffractive pupil” effect – scattering incoming starlight from a tiny dot in a much flower-shaped pattern. larger which can better reveal one of the very slight “oscillations” caused by gravity of orbiting planets.

The Alpha Centauri system has two stars similar to the sun, orbiting each other about 20 times the distance between the sun and Earth, Tuthill said.

Each has its own area known as the Goldilocks – where rocky planets are at the right temperature to have liquid water on their surface, which is considered necessary for the evolution of life as we know it.

In 2016, two planets were discovered around what could be a third star in the system: the red dwarf Proxima Centauri, discovered with a telescope in 1915 and slightly closer to us than the other two.

But they’re not thought to be suitable for life because Proxima gives off dramatic flares that can be 100 times more powerful than flares from the sun, Tuthill said.

This means Alpha Centauri’s solar stars may be our best bet for locating signs of alien life.

“If we found a landmass planet in the habitable areas over there, that would be a holy grail – a true analogue of Earth,” he said. “It would potentially be an environment that could have all of the same conditions that we experience here on Earth.”

The TOLIMAN project is supported by Breakthrough Initiatives, a California-based space exploration fund.

The group proposed to explore Alpha Centauri with Breakthrough Starshot, a project made up of thousands of tiny space probes that can be propelled at very high speed by lasers on Earth.

In theory, the “nanocraft” Breakthrough Starshot could reach Alpha Centauri in about 20 years – an epic 25 trillion mile journey that would take tens of thousands of years with the fastest spacecraft in existence today.

“Alpha Centauri is very close, so if people ever want to have visionary dreams about interstellar flight, then Alpha Centauri has to be our first bus stop on the way to the galaxy,” Tuthill said.

If the TOLIMAN telescope finds planets, the next step will be to study them with other telescopes to determine the makeup of their atmospheres – and perhaps even find chemical “biosignatures” produced by life.

The latest astronomical techniques to study the atmospheres of exoplanets only work well with very large planets orbiting near their stars, and studying the atmospheres of Earth-sized planets is currently beyond their reach, said astrophysicist Chris Watson from Queen’s University Belfast in Northern Ireland.

But chemicals are being discovered on smaller, more “difficult” planets as scientists find new ways to analyze their data and new instruments – such as the James Webb Space Telescope – become available, he said. he declares.

Watson, who is not involved in the TOLIMAN project, is part of a team that recently detected hydroxyl radicals – a component of water – in the atmosphere of a planet orbiting a star at about 400 light years from Earth.

Detecting chemicals and perhaps biosignatures on Earth-like planets around the stars of Alpha Centauri will be difficult, but “observing the closest and brightest planetary system will be our most likely route to success. “, did he declare. “The signals will be very weak, so we will need every photon of light to make it work.”

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