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Life From Space? (Panspermia; Lithopanspermia)

I'm inclined to wonder if the physics simply don't allow meaningful interstellar travel, or even perhaps meaningful communication between the time/distance that different ocurrances of life might have between them.
 
Star clumps harbour 'sweet spot' in search for alien life
By Jonathan Webb Science reporter, BBC News, Kissimmee, Florida

Ancient, tightly packed clumps of stars found at the fringe of the Milky Way are a good bet in the search for extra terrestrial intelligence (Seti), research suggests.
Because of their abundance of stars, these "globular clusters" were an early favourite in the Seti field.
But recent efforts to scour the sky for planets orbiting alien stars have had little success within star clusters.

Now, two astronomers say there is good reason to keep up the search.
Rosanne Di Stefano from the Harvard-Smithsonian Center for Astrophysics, US, and Alak Ray from the Tata Institute of Fundamental Research in India, have described what they call the "globular cluster opportunity".

At an average age of 10 billion years (much wrinklier than the Sun, at four billion), globular clusters don't have many young stars, rich in the metallic elements needed to build planets.
But Dr Di Stefano, speaking in Florida at the 227th meeting of the American Astronomical Society, pointed out that recent discoveries had placed exoplanets - especially small, rocky ones like Earth - around stars much less metal-rich than our Sun.

"When Seti first started in 50s and 60s, we didn't even know if there were exoplanets," she told reporters at the meeting.
"Now we can use the information that we've gleaned from other planet discoveries - and there are over 2,000 planets known today - to ask, is it likely that they'd be in globular clusters."

Dr Di Stefano also pointed to the remarkable example of PSR B1620-26 b, sometimes called "Methuselah". It is the only exoplanet so far detected orbiting a star - or in its case, two stars - within a globular cluster.
"I think most of us would say that the discovery of that one, bizarre planet indicates that there must be other planets in that cluster," she said.

Furthermore, Drs Di Stefano and Ray have identified a "sweet spot" in the dimensions of globular clusters.
Because most of their stars are old, cool red dwarfs, any habitable planets would have to huddle in very close orbits to sustain liquid water.

Staying wet, however, isn't the only challenge for a life-bearing planet in a crowded cluster. A ball of a million stars just 100 light years across is a raging turmoil of gravitational forces that can rip solar systems apart.
But there is a region within these clusters, Dr Di Stefano said, where the stars are not so tightly packed that huddled, small, rocky planets would be stripped from their stars - and yet they are still close enough together that an alien civilisation might manage the leap from one to another.
"In this large region... planetary systems can survive, and yet it's dense enough that it may facilitate interstellar travel."
In fact, she added, these planets - if they do exist - could last even longer than the current age of the Universe, leaving ample time for intelligence and interstellar ambition to flourish.

Other researchers at the conference agreed that these were interesting observations, even if the notion of ancient, star-hopping civilisations was - of course - a provocative speculation.
"It holds together," said Jessie Christiansen from the Nasa Exoplanet Science Institute at Caltech. "It's very speculative, but I like the idea that because globular clusters are old, they've had more time."
"Single-celled, simple life might develop quickly, but complex life - let alone intelligent life - seems to take a really long time," she added, citing Earth's natural history as an admittedly limited example.
"So you might need those tens of billions of years."

Alan Penny, an astronomer at the University of St Andrews in Scotland and co-ordinator of the UK Seti Research Network, told the BBC: "I think it does lift globular clusters up, in the wish list of targets to search."
But they remain very difficult targets, he added.
"They are still a very long way away. The nearest globular cluster is 400,000 light years away, whereas there are plenty of other, low-mass stars closer than that."

http://www.bbc.co.uk/news/science-environment-35248043
 
Aliens: The Big Think

The hunt for aliens is on! After a distinguished career in cosmology Professor Martin Rees, the astronomer royal, has taken up the search for extra-terrestrials. Looking for aliens is no longer science fiction - it is a question that's engaging some of the greatest minds in science.

As our knowledge of the universe has increased, we're getting closer to answers. Many scientists now think we live in galaxy with a billion Earth-like planets, many of which may be teeming with life. But what kind of life? Has anything evolved into beings we could communicate with? This film gets inside the minds of the scientists considering one of the most exciting and profound questions we can ask - are we alone in the universe?

Professor Rees thinks we may have our idea of what an alien is like all wrong. If he's right, it's not organic extra-terrestrials we should look for, it's machines.

http://www.bbc.co.uk/iplayer/episode/b0788q6m/aliens-the-big-think

First shown: 9pm 21 Apr 2016
Available for 28 days
 
Could these newly-discovered planets orbiting an ultracool dwarf host life?
Three Earth-sized planets are thought to have surface temperatures which would allow liquid water, making them potentially hospitable to life
Ian Sample Science editor
Monday 2 May 2016 16.00 BST

Three distant worlds that orbit a feeble star in the constellation of Aquarius are the most likely places discovered so far to find life beyond the solar system, astronomers say.
The Earth-sized planets are all thought to have regions where surface temperatures fall within the Goldilocks zone and are neither too hot nor too cold for water to run freely, making them at least potentially hospitable to life.

Belgian astronomers found the planets using the Transiting Planets and Planetesimals Small Telescope (Trappist) at the La Silla Observatory in Chile’s Atacama desert. The planets revealed themselves through the periodic dimming that occurred as they passed in front of their parent star, an ultracool dwarf that lies only 40 light years away.
Known formally as 2MASS J23062928-0502285, but helpfully dubbed Trappist-1, the star is not much larger than Jupiter and emits a fraction of the sun’s radiation. The star is too faint to see in the night sky with the naked eye, or even through a large amateur telescope.

Observations from the Trappist telescope taken from September to December last year, and follow-up measurements from larger instruments, revealed three small planets orbiting very close to the star, at 1%, 1.5% and about 3% of the distance that Earth lies from the sun. A year on the innermost planet passes in only 1.5 Earth days, and in 2.4 Earth days on the second. The orbit of the third planet is less certain, with a year passing in 4.5 to 73 Earth days, according to a report in the journal Nature.
“Because the star is so faint, all of these planets have temperatures that are similar to those on Earth. They could have liquid water on the surfaces, and on Earth life is critically dependent on water. We don’t know, but maybe there could be life there,” said Michaël Gillon who led the research at the University of Liege.

The planets are thought to be tidally-locked to their star, meaning one half is in permanent daytime, and the other in constant darkness. If the planets have atmospheres, the alien air would even out the temperature difference across the hemispheres. At the hottest spots, the temperature would reach about 100 Celsius on the innermost planet, 70 Celsius on the second, and perhaps 30Celsius on the outermost world.
“These are the first temperate Earth-sized planets found outside the solar system, and the first we can study in detail,” said Gillon. “That makes them extremely promising targets for us.” The composition of the planets is not yet known, but the sizes mean they must be solid. “They could be iron-rich like Mercury, or mostly silicate rocks, or extremely icy, like the moons of Jupiter,” said Gillon.

Plans have already been drawn up to study the planets in greater detail. With the Hubble space telescope, the astronomers hope to learn whether the worlds have their own atmospheres. But future instruments will be needed to find out much more about the planets. If they do have atmospheres, then analysing the molecular constituents for water, carbon dioxide and ozone could reveal evidence for life.

Those measurements will be possible from two forthcoming observatories, the European Extremely Large Telescope, which is under construction in the Atacama desert, and the James Webb Space Telescope, Nasa’s new infrared observatory, which is due to launch in 2018. Once they are in operation, astronomers can begin the search for biological activity on the planets. “That’s a giant step in the search for life in the universe,” said Julien de Wit, a co-author on the study at MIT.

https://www.theguardian.com/science...planets-orbiting-an-ultracool-dwarf-host-life

I find it interesting that Belgian astronomers should name their telescope and the star 'Trappist'. In Belgium, Trappist beers are very popular; they come in blonde and brune varieties, and in a range of strengths. I think my local Tesco does some Trappist beers - I'll get some tomorrow to celebrate this news! :D
 
Likely they did that on purpose, some people like making up fun acronyms. Even the Pentagon had their BaTMAN and RoBIN projects.
 
Fossilised stardust could hold secret to origins of life on Earth...and beyond
Sarah Knapton, Science Editor
11 May 2016 6:00pm

2.7 billion years ago a tiny speck of iron entered the Earth’s atmosphere and fell to the surface where it became trapped in sediment, and was eventually fossilised.
Now this minute particle of cosmic dust, the oldest ever found, could help scientists to explain how oxygen-breathing life came to exist on Earth.

Previously scientists thought there was little or no oxygen in Earth’s ancient atmosphere.
But the little grain of iron was found to have transformed into iron oxide, or magnetite, by the time it hit the ground, which means it must have passed through a thick layer of oxygen on its journey to the surface.

Smaller than the width of a human hair, it is one of several ‘micrometeorites’ discovered in Western Australia to show the transformation.
“This was an exciting result because it is the first time anyone has found a way to sample the chemistry of the ancient Earth’s upper atmosphere,” said Dr Andrew Tompkins, from the School of Earth, Atmosphere and Environment at Monash University in Melbourne, Australia.

“We found that most of the micrometeorites had once been particles of metallic iron – common in meteorites – that had been turned into iron oxide minerals in the upper atmosphere, indicating higher concentrations of oxygen than expected.”

The finding could shed light on the ‘Great Oxidation Event’ which occurred 2.4 billion years ago when there was a sudden jump in oxygen concentration in the lower atmosphere which led to the evolution of air-breathing plants and animals.
It could also help scientists who are hunting for life on other planets as evidence of an oxygen-rich upper layer could suggest that bacteria are living on the surface below.

etc...

http://www.telegraph.co.uk/science/...could-hold-secret-to-origins-of-life-on-eart/
 
Nasa to announce major discovery about ocean worlds and the search for alien life
Video: 1m 3s.
Helena Horton
13 April 2017 • 8:28am

Nasa is due to reveal information from its research into ocean worlds and alien life in a press conference today at 7pm UK time.
It will be live-streamed and will feature commentary from the world's experts on alien life.

Nasa has kept its cards close to its chest about what exactly will be revealed, but the organisation is prone to holding mysterious press conferences about major discoveries.

Nasa said: "These new discoveries will help inform future ocean world exploration - including NASA’s upcoming Europa Clipper mission planned for launch in the 2020s - and the broader search for life beyond Earth".
The discoveries came from the Cassini spacecraft and the Hubble Space Telescope.

etc...

http://www.telegraph.co.uk/news/201...jor-discovery-ocean-worlds-search-alien-life/
 
Tonight I've been watching
Seven Ages of Starlight

This is the epic story of the stars, and how discovering their tale has transformed our own understanding of the universe.

Once we thought the sun and stars were gods and giants. Now we know, in a way, our instincts were right. The stars do all have their own characters, histories and role in the cosmos. Not least, they played a vital part in creating us. There are old, bloated red giants, capable of gobbling up planets in their orbit, explosive deaths - supernovae - that forge the building blocks of life and black holes, the most mysterious stellar tombstones. And, of course, stars in their prime, like our own sun. Leading astronomers reveal how the grandest drama on tonight is the one playing above our heads.

First shown: 9pm 25 Oct 2012
Available until Wed 12:20am Why?
Last Chance
90 mins
http://www.bbc.co.uk/iplayer/episode/p00yb434/seven-ages-of-starlight

Now I've been following astronomy since boyhood, and in the 60 odd years since, I've come across most of these ideas and discoveries before, but I thought I'd recommend the programme as a good overview of the life story of stars - sometimes it gets hard to remember all the details, and see the big picture.

But I didn't think of posting it in this thread until the very end, when the story switched back to the start and looked in more detail at what was happening in the various nebulae in the Milky Way...

Enjoy - but hurry!
 
The hunt for aliens is on! After a distinguished career in cosmology Professor Martin Rees, the astronomer royal, has taken up the search for extra-terrestrials. Looking for aliens is no longer science fiction - it is a question that's engaging some of the greatest minds in science.

As our knowledge of the universe has increased, we're getting closer to answers. Many scientists now think we live in galaxy with a billion Earth-like planets, many of which may be teeming with life. But what kind of life? Has anything evolved into beings we could communicate with? This film gets inside the minds of the scientists considering one of the most exciting and profound questions we can ask - are we alone in the universe?

Professor Rees thinks we may have our idea of what an alien is like all wrong. If he's right, it's not organic extra-terrestrials we should look for, it's machines. :eek:

http://www.bbc.co.uk/iplayer/episode/b0788q6m/the-big-think-aliens

Prog from 2016: 60 mins.
 
The hunt for aliens is on! After a distinguished career in cosmology Professor Martin Rees, the astronomer royal, has taken up the search for extra-terrestrials. Looking for aliens is no longer science fiction - it is a question that's engaging some of the greatest minds in science.

Professor Rees thinks we may have our idea of what an alien is like all wrong. If he's right, it's not organic extra-terrestrials we should look for, it's machines. :eek:

http://www.bbc.co.uk/iplayer/episode/b0788q6m/the-big-think-aliens

Prog from 2016: 60 mins.

Great. We pick up a distress message that says 'We're running out of food' and spend a hundred years working out where it came from, how we could help, only to find it's some alien fridge on their wifi reminding the owners to get more milk and eggs.
 
Professor Rees thinks we may have our idea of what an alien is like all wrong. If he's right, it's not organic extra-terrestrials we should look for, it's machines. :eek:
It seems to be the most likely thing to happen.
 
Great. We pick up a distress message that says 'We're running out of food' and spend a hundred years working out where it came from, how we could help, only to find it's some alien fridge on their wifi reminding the owners to get more milk and eggs.
No. They'll be machines that need blood. Human blood.
Because they need the iron.
 
It seems to be the most likely thing to happen.
Well, we all mutter about alien life being here or not, but what is there is no 'faster than light travel'?

Then the only thing that is likely to make it here is a machine and that will be one of a very large number which set off.
 
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The only other life forms we may encounter out in space are bacteria and viruses that have been floating around the universe for billions of years. Hoyle's panspermia theory.
The only problem with that is that they may be almost indistinguishable from the bacteria or viruses that are already here on this planet - so we won't be able to work out their alien origin.
 
... Then [the] only thing that is likely to make it here is a machine and that will be one of a very large number which set off.

Our own short spacefaring experience has demonstrated machines are the most reasonable, cost-effective, and risk-reducing options for initial survey missions.
 
The only problem with that is that they may be almost indistinguishable from the bacteria or viruses that are already here on this planet - so we won't be able to work out their alien origin.
That's not really true. We should be able to date the last point of divergence quite accurately - within a few hundred million years, at least, and probably much better than that. If we find bacteria on Mars we could compare the various genomes and arrive at a date for the Last Common Ancestor, using the Molecular Clock methodology.
https://en.wikipedia.org/wiki/Molecular_clock
 
That's not really true. We should be able to date the last point of divergence quite accurately - within a few hundred million years, at least, and probably much better than that. If we find bacteria on Mars we could compare the various genomes and arrive at a date for the Last Common Ancestor, using the Molecular Clock methodology.
https://en.wikipedia.org/wiki/Molecular_clock
Well...they may be pouring out of space right now...
 
Well...they may be pouring out of space right now...
This would imply that all bacteria in the Solar System (at least) are genetically indistinguishable from those we find on Earth today, otherwise we'd be able to identify new arrivals. A hypothesis that could be tested with a few sample-and -return missions to comets and asteroids, and preferably to Mars as well. The Lunar samples showed nothing, except a possible streptococcus on Surveyor 3.
https://en.wikipedia.org/wiki/Reports_of_Streptococcus_mitis_on_the_Moon
(note that nothing was found in the Lunar soil).
 
New research seems to confirm microbes can survive for years in space - adding credence to the notion of panspermia.
We Just Got More Evidence Bacteria Could Survive The Journey Between Earth And Mars

What if microbes could drift through the vastness of space like pollen in the wind, planting the seeds of life on planets both far and wide? Is that how life started on our own planet? Is such a journey even possible?

New research from the astrobiology mission "Tanpopo", which means 'dandelion' in Japanese, suggests it very well could be.

Samples of a highly resistant bacterium genus called Deinococcus, which can be found high up in our atmosphere, has officially survived three years in the vacuum of space - withstanding microgravity, intense ultraviolet radiation and extreme temperatures whilst riding on the outside of the International Space Station.

The study adds a level of feasibility to the controversial panspermia theory, which posits that life did not originate on Earth, but arrived here from elsewhere in the Universe. ...

FULL STORY: https://www.sciencealert.com/bacter...ourney-between-earth-and-mars-iss-study-finds
 
Going out on a thin branch, my opinion is that viruses are alien that rode into earth on meteors.

They are just a few strands or RNA wrapped in a protein coat and not alive.

We really are being invaded by aliens.
 
Going out on a thin branch, my opinion is that viruses are alien that rode into earth on meteors.

They are just a few strands or RNA wrapped in a protein coat and not alive.

We really are being invaded by aliens.
How do you account for the fact that when you decode the RNA it uses the same language to make proteins as we do on earth?
 
So... from outer space!
I deliberately worded it to leave that possibility open. What Charliebrown appears to be saying is origin for viruses and a separate origin for life on Earth. I’m arguing because of the common language the same origin for both.
 
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