We know a lot about the history of life on Earth, but how it began is still one of our greatest scientific mysteries. One hypothesis is that life actually originated on another planet, and many scientists today take the idea quite seriously. Though it sounds like the plot from recent scifi movie Prometheus, it's an old idea that even the celebrated nineteenth century physicist Lord Kelvin and Nobel winning geneticist Francis Crick have advocated. That's right — the evolution of life might have its beginnings on another planet.
Over 120 years ago, Kelvin shocked the British scientific community in a speech about what he called "panspermia," where he suggested that life might have come from planets smashing into each other and sending bits of life hurtling through space. He and a few colleagues had hit upon this notion after observing the massive 1880 eruption of a volcano on Krakatoa. To be more precise, they observed the aftermath of the volcano, which completely sterilized the island. No life was left at all. But then, within months, seedlings began to sprout and life took hold again.
Cal Tech geologist Joe Kirschvink has suggested that Mars is a likely origin for life in the solar system because it would have been habitable long before Earth was. 4 billion years ago, when Earth was still a roiling cauldron of methane and magma, Mars was a stable, cool planet covered in vast oceans. It would have been the perfect place for microbial life to take hold. But how did that life make it all the way from the seas of Mars to the seas of Earth? Most likely, meteorites crashing into Mars would send fragments of the planet's surface back into space — packed with millions of microbes. In fact, around the time that Mars might have been developing life, the solar system was undergoing what astronomers call the "late heavy bombardment," a time of countless intense meteorite strikes.
Purdue geologist Melosh, who has spent most of his career studying meteorite impacts, has actually done experiments where he and a team recreated what might have happened when meteorites slammed into Mars billions of years ago, sending ejecta out of the atmosphere and eventually all the way to Earth. This process is sometimes called "ballistic panspermia," or "lithopanspermia," because it depends on rocks being ejected into space. To recreate one part of this process in their experiments, Melosh and his team shot a bacteria-covered rock with an aluminum projectile moving at 5.4 km per second, and the shattered chunks flew over a kilometer. The bacteria survived the trauma of what Melosh and his team called "extremes of compressional shock, heating, and acceleration. A lot of the microbe species actually die, but a lot also survive in a dormant state. In space, their journey would take possibly millions of years. But it's as if atmospheres are almost designed for this transfer of life. The meteorite comes from Mars, full of microbes protected from radiation by the rock. It enters Earth's atmosphere, and as it comes in at high speed the outside melts because of friction and gets hot, but the inside is protected just like a spacecraft capsule. The microbes inside are protected. Then the aerodynamic forces in the lower atmosphere fracture the meteorite, exposing the interior."
A big question is why scientists are entertaining this idea at all? NASA planetary scientist Chris McKay offered a terrific, point-by-point explanation of why panspermia is, as he put it, "a valid scientific hypothesis" worth taking seriously:
1. The geological evidence for the earliest life on Earth is very early, soon after the end of the late bombardment. There is good evidence for life on Earth at 3.5 billion years ago, indirect evidence at 3.8 billion. The end of the late heavy bombardment is 3.8 billion years ago.
2. The genetic evidence indicates that the last universal common ancestor (LUCA) of life could have been roughly 3.5 billion years ago (but with large uncertainties) and that LUCA was a fairly sophisticated life form in terms of metabolic and genetic capabilities. 1 and 2 together give the impression that life appeared on Earth soon after the formation of suitable environments and it appears to have come in being remarkably developed - like Athena born fully formed from the head of Zeus.
3. Rocks from Mars have traveled to Earth and the internal temperatures experienced in these rocks during this trip would not have sterilized the interiors. Thus in principle life can be carried from Mars to Earth.
4. Mars did not suffer the large Moon-forming impact that would have been detrimental to the early development of life on Earth. 3 and 4 have lead to the suggestion that Mars would have been a better place for life to start in the early Solar System and it could have then been carried to Earth via meteorites.
5. Organic molecules are widespread in comets, asteroids, and the interstellar medium.
6. Comets could have supported subsurface liquid water environments soon after their formation due to internal heating by decay of radioactive aluminum.
7. As comets move past the Earth they shed dust which settles into Earth's atmosphere. 5, 6 and 7 have lead to the suggestion that life could have started in the interstellar medium or in small bodies such as comets and then been carried to the Earth by comet dust.
So, yes panspermia is a valid scientific hypotheses and warrants further investigation.
Mars One, a nonprofit organization based in the Netherlands, intends to establish a human settlement on Mars in 2023. Anyone on planet Earth can apply if they meet the basic requirements. But obviously, the job isn't for just anyone.
China's official news agency is reporting that the country's Chang'e 2 deep-space probe made an amazing flyby of the asteroid Toutatis this week, snapping a series of pictures as it passed by at a distance of just 2 miles.
Space Fellowship Giant Mars Crater Shows Evidence of Ancient Lake Space.com New photos of a huge crater on Mars suggest water may lurk in crevices under the planet's surface, hinting that life might have once lived there, and raising the...
An international team of astronomers led by Mikko Toumi from the University of Hertfordshire has discovered five new planets just 12 light years away. Additionally, the discovery implies that one or two of those planets could be conducive to life.
The last 12 months has seen the unveiling of a number of commercial space ventures whose audacious plans can’t be immediately dismissed given the technical and financial pedigree of their founders and backers. Almost exactly a year ago, Microsoft co-founder Paul Allen announced the formation of Stratolaunch Systems, an air-launch system that requires the development of the world’s largest airplane. Allen assembled a team that included Scaled Composites and, originally, SpaceX (since replaced by Orbital Sciences), with a board that included Burt Rutan and former NASA administrator Mike Griffin. In April, Planetary Resources announced plans for a series of robotic missions to prospect and, eventually, mine asteroids. That company has an impressive list of investors, including Google’s Larry Page and Eric Schmidt as well as Ross Perot Jr. and former Microsoft executive and two-time space tourist Charles Simonyi.
Yet, the goals of these startups—a giant air-launch system and missions to prospect and mine asteroids—pale in comparison to the goal of another new space startup: sending people to the surface of the Moon. That feat has been accomplished only six times, and by one nation, the United States, with the last such mission, Apollo 17, flying 40 years ago this month. At the time, it was a potent symbol of America’s capabilities, and one of the signature achievements of the 20th century. The scale of that accomplishment, in many respects, grows as the decades stretch on without anyone else repeating it.
Sharing your scoops to your social media accounts is a must to distribute your curated content. Not only will it drive traffic and leads through your content, but it will help show your expertise with your followers.
How to integrate my topics' content to my website?
Integrating your curated content to your website or blog will allow you to increase your website visitors’ engagement, boost SEO and acquire new visitors. By redirecting your social media traffic to your website, Scoop.it will also help you generate more qualified traffic and leads from your curation work.
Distributing your curated content through a newsletter is a great way to nurture and engage your email subscribers will developing your traffic and visibility.
Creating engaging newsletters with your curated content is really easy.