Gaia is Now Finding Planets. Could it Find Another Earth?

Artist's impression of the ESA's Gaia Observatory. Credit: ESA

The ESA launched Gaia in 2013 with one overarching goal: to map more than one billion stars in the Milky Way. Its vast collection of data is frequently used in published research. Gaia is an ambitious mission, though it seldom makes headlines on its own.

But that could change.

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Could We Find Aliens Terraforming Other Worlds?

Artist's conception of a terraformed Mars. Credit: Ittiz/Wikimedia Commons

The first early humans to use fire had no inkling of what it would lead to.

Fire was one of our first technologies, and humans have been making changes to their environments since the advent of controlled fire hundreds of thousands of years ago. Fast forward to current times, and our modern technological and global civilization is changing the Earth’s entire biosphere. From carbon emissions that acidify the oceans and weaken the shells of marine life to microplastics that find their way into organisms’ bloodstreams, our technology is intersecting, or combining, with the biosphere.

This has spawned a useful word: biotechnosphere.

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Is Anyone Planning for Diplomacy with an Extraterrestrial Civilization?

Artist impression of an alien civilization. Image credit: CfA

Imagine we detect an interstellar object entering our Solar System. At first, astronomers think it’s just another natural interloper like Oumuamua or comet Borisov. We’re warming up to the idea of visitors from other parts of the galaxy, though they’ve been inanimate so far.

But then, what if it becomes clear that something’s different about this visitor? What if it moves unnaturally or somehow behaves purposefully? What if it takes up a stable orbit somewhere? What if, as we gather more evidence, it becomes clear that it’s a probe of some sort sent to us intentionally? What if it communicates with us?

Suddenly, as if thrust into a science fiction plot, humanity is in a totally different situation. What do we do?

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Do Technological Civilizations Depend on Atmospheric Oxygen?

Humans gathered around an evening campfire. Credit: Jarek Tuszy?ski / CC-BY-SA-3.0 & GDFL

Nearly two million years ago a species of upright apes known as homo erectus began to utilize fire. It was a gradual process, from opportunistic users of natural fires to masters able to craft flames from flint and tender. We are their descendants. We are creatures of forge and kiln, hearth and home. Fire has become so central to us that instead of homo sapiens, we could call ourselves homo ignus, the fire-wielding ape. Fire is central to the rise of our civilization. It cooks our food, keeps us warm, and illuminates our night. This raises an interesting question. Could we have built a civilization without fire?

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Astronomers are Searching for a Galaxy-Wide Transmitter Beacon at the Center of the Milky Way

Artist's impression of a Dyson Sphere, an proposed alien megastructure that is the target of SETI surveys. Credit: Breakthrough Listen / Danielle Futselaar

It has been over sixty years since the first Search for Extraterrestrial Intelligence (SETI) survey occurred. This was Project Ozma, a survey led by Dr. Frank Drake (who devised the Drake Equation) that used the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, to listen for radio transmissions from Epsilon Eridani and Tau Ceti. While the search revealed nothing of interest, it paved the way for decades of research, theory, and attempts to find evidence of technological activity (aka. “technosignatures”).

The search continues today, with researchers using next-generation instruments and analytical methods to find the “needle in the cosmic haystack.” This is the purpose behind Breakthrough Listen Investigation for Periodic Spectral Signals (BLIPSS), a collaborative SETI project led by Cornell graduate student Akshay Suresh to look for technosignatures at the center of the Milky Way. In a recent paper, Suresh and his team shared their initial findings, which were made possible thanks to data obtained by the Greenbank Observatory and a proprietary algorithm they developed.

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NASA Uses Powerful Transmitters to Talk to Deep Space Spacecraft. Will Other Civilizations Receive Those Signals?

Artist rendition of Voyager 1 entering interstellar space. (Credit: NASA/JPL-Caltech)

In a recent study submitted to the Publications of the Astronomical Society of the Pacific, a pair of researchers from the University of California, Los Angeles (UCLA) and the University of California, Berkeley (UC Berkeley) examine the likelihood of extraterrestrial intelligent civilizations intercepting outward transmissions from NASA’s Deep Space Network (DSN) that are aimed at five deep space spacecraft: Voyager 1, Voyager 2, Pioneer 10, Pioneer 11, and New Horizons. Members of the public are free to track such transmissions at DSN Now, which displays real-time data of outgoing and incoming transmissions to all spacecraft at various times.

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A Lack of Alien Signals Actually Tells Us a Lot

Credit: iStock

In a  recent study published in The Astronomical Journal, a researcher from the École Polytechnique Fédérale de Lausanne (EPFL) discusses the potential reasons why we haven’t received technoemission, also called technosignatures, from an extraterrestrial intelligence during the 60 years that SETI has been searching, along with recommending additional methods as to how we can continue to search for such emissions.

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Do Advanced Civilizations use Black Holes as Giant Quantum Computers?

Artist view of an active supermassive black hole. Credit: ESO/L. Calçada

If life is common in our Universe, and we have every reason to suspect it is, why do we not see evidence of it everywhere? This is the essence of the Fermi Paradox, a question that has plagued astronomers and cosmologists almost since the birth of modern astronomy. It is also the reasoning behind the Hart-TIpler Conjecture, one of the many (many!) proposed resolutions, which asserts that if advanced life had emerged in our galaxy sometime in the past, we would see signs of their activity everywhere we looked. Possible indications include self-replicating probes, megastructures, and other Type III-like activity.

On the other hand, several proposed resolutions challenge the notion that advanced life would operate on such massive scales. Others suggest that advanced extraterrestrial civilizations would be engaged in activities and locales that would make them less noticeable. In a recent study, a German-Georgian team of researchers proposed that advanced extraterrestrial civilizations (ETCs) could use black holes as quantum computers. This makes sense from a computing standpoint and offers an explanation for the apparent lack of activity we see when we look at the cosmos.

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Does Failing to Detect Aliens Mean We’ll Never Be Contacted?

Image of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Parkes radio telescope taken in 1969. (Credit: CSIRO; licensed under the Creative Commons Attribution 3.0 Unported license.)

In a recent paper submitted to The Astronomical Journal in November 2022, a scientist at the Swiss Federal Institute of Technology Lausanne quantifies how the Earth has not heard a radio signal from an extraterrestrial technological civilization over the course of approximately the last 60 years, which is when the Search for Extraterrestrial Intelligence (SETI) began listening for such signals. They also quantify the potential likelihood pertaining to when we might hear a signal, along with recommending potential strategies that could aid in the ongoing search for detecting a signal from an extraterrestrial technological civilization.

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