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Comets and Interstellar Objects Can Take Earth Life Out in the Milky Way



For over a century, supporters of Panspermia have argued that life is distributed throughout our galaxy by comets, asteroids, cosmic dust, and planetoids. But in recent years, scientists have argued that this type of propagation can transcend stellar systems and be intergalactic in scale. Some even offer intriguing new mechanisms for how this distribution could be made.

For example, it is commonly claimed that the effects of a meteorite and an asteroid are responsible for the rhythm of a material that will transport germs to other planets. However, in a recent study, two Harvard astronomers are exploring the challenges that this would present and suggest another means –

; pastures on Earth, of objects that collect germs from our atmosphere and then plunge into deep space.

The study entitled "Exporting Earth Life beyond the Earth's Gravity Slings Solar System", which is being reviewed for publication by International Journal of Astrobiology . The study was authored by Amir Siraj (Underground Astronomy at Harvard) and Abraham Lob – Frank B. Bair, Jr., Professor of Science and Chair of the Department of Astronomy at Harvard University.

The theory of Lithopanspermia states that life can be shared between planets within a planetary system. Credit: NASA

To break down, there are several versions of the theory of anpermia p p. There is lithopanspermia, the idea that rocks thrown out of impacts are responsible for spreading germs from planet to planet. Then there is the larger variant, in which stellar asteroids and comets are responsible for the distribution of life between stellar systems and perhaps even galaxies. Sirai summarized it for the Universe Today via email:

"Traditional theories of panspermia have shown that planetary impacts can accelerate debris from the planet's gravitational field and potentially even from the host star's gravitational field. Among other issues, this debris is often quite small in size, providing little protection against harmful radiation to all potentially closed germs while traveling debris into space. ”

In addition, the traditional approach to panspermia requires the process of both incorporating germs into rocks, but also providing enough energy to expel them from Earth and the Sola3r system. This is not an easy task, given that an object must travel at a speed of 11.2 km / s (7 mph) just to escape from Earth's gravity and 42.1 km / s (26 miles) / sec) to escape from the solar system.

In contrast, Siraz and Loeb examined whether long-period comets or interstellar objects (such as Oumuamua and C / 2019 Q4 Borisov) could extend life. This would consist of those objects entering the Earth's atmosphere, scooping germs – which were detected 77 km (48 miles) above the surface – and receiving a gravity sling that could send them from the solar system.

Artist's impression of the first interstellar asteroid / comet, "Oumuamua". This unique object was discovered on October 19, 2017 by the Pan-STARRS 1 telescope in Hawaii. Credit: ESO / M. Kornmesser

Compared to objects that affect the surface, Sirai explained, this mechanism offers a number of advantages:

"One advantage of a comet or long-range interstellar object that extracts germs from high in the earth the atmosphere is that they can be quite significant (hundreds of meters to several kilometers) and guaranteed to be ejected from the solar system, passing so close to Earth. This allows germs to enter corners of the site and gain significant protection against harmful radiation so that they remain alive until they encounter another planetary system. "

To evaluate this possibility, Siraj and Lob estimated the resistance that the Earth's atmosphere would have on an interstellar object, as well as the gravitational effect of a sling. This allowed them to limit the size and energy of objects that can carry germs from the Earth's atmosphere to other planets and planetary systems.

"Then we used the observed velocities of comets and interstellar objects to calibrate the number of times we would do expect such a process to occur during the time that life existed on Earth," added Siraj. From this, they discovered that over the life of the Earth (4.54 billion years), approximately 1 to 10 comets with a long period and 1 to 50 interstellar objects would export microbial life from the Earth's atmosphere.

The artist's impression of the interstellar object, `Oumuamua, experiences incredible quenching as it leaves our solar system. Credit: ESA / Hubble / NASA / ESO, M. Kornmesser

They further estimated that if the life of germs existed in our atmosphere over 100 km (miles), then the number of export events would increase dramatically to about 10 ^ 5 (that's 100,000!) Throughout life on Earth. This work builds on previous research that shows that interstellar objects can be quite common in our solar system. As Siraj explains:

"The exciting aspect of this document is that it provides a concrete process for the ejection of large rocks from the solar system laden with terrestrial germs. The dynamic processes of these rocks, which are then trapped in other planetary systems, were written earlier, so this book closes the outline in a sense to one specific process by which life could be transferred from Earth to another planet . "

When the next interstellar object passes through our system, we should naturally ask ourselves, 'Does this one bear the seed of life in another stellar system?' on the Earth, billions of years ago. If interstellar objects are the means by which microbial life is propagated, then sending an interception mission and studying it more carefully should be a major scientific priority in the coming years!

Further reading: arXiv


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