extraterrestrial life – Page 2

Life: Not So Grim On The Galactic Rim?

M80 -- an old globular cluster in the Milky Way -- is full of metal-poor stars. Do they still have exoplanetary potential? (NASA) — M80 — an old globular cluster in the Milky Way — is full of metal-poor stars. Do they still have exoplanetary potential? (NASA)

The galaxy may be brimming with habitable small worlds and many older star systems could possess the conditions ripe for advanced alien civilizations to evolve. This prediction comes in the wake of new analysis of data from NASA’s Kepler space telescope and ground based observatories by a team of Danish and American astronomers.

Led by Lars Buchhave of the Niels Bohr Institute in Copenhagen, the team has revealed that stars containing low quantities of heavy elements — known as “metal poor” stars — are still capable of nurturing exoplanets with Earth-like qualities.

“I wanted to investigate whether planets only form around certain types of stars and whether there is a correlation between the size of the planets and the type of host star it is orbiting,” Buchhave said.

After analyzing the elemental composition of stars hosting 226 small exoplanets — some as small as the rocky planets in the Solar System — Buchhave’s team discovered that “unlike the gas giants, the occurrence of smaller planets is not strongly dependent on stars with a high content of heavy elements. Planets that are up to four times the size of Earth can form around very different stars — also stars that are poorer in heavy elements,” he concluded.

The Kepler mission, for example, is actively carrying out a search for exoplanets that pass in front of their host stars (events known as “transits”). With Kepler’s sensitive eye, it is capable of detecting exoplanets of similar size to Earth, or even as small as Mars.

Interestingly, as it surveys Sun-like stars, Kepler can detect tiny, rocky worlds that orbit within the “habitable zones” of their stars. It’s no huge leap of the imagination to think alien life may have evolved on some of these worlds.

But a problem facing astronomers hunting for bona fide “Earth-like” exoplanets is that many older stars have low quantities of heavier elements (such as the silicon and iron) that small rocky worlds need to become… well… rocky. But Buchhave’s discovery suggests that stars once considered infertile may in fact have a shot at birthing small exoplanets.

Jill Tarter, Chair of the SETI Institute, points out that this could be a boon for the search for intelligent extraterrestrials. “The idea that very old stars could also sport habitable planets is encouraging for our searches,” she said in a SETI press release on Wednesday.

Tarter also highlights the fact that life took a long time to evolve into an advanced technological state on Earth. Therefore, should there be small habitable rocky worlds orbiting ancient stars (as this research suggests), perhaps alien life far older and more technologically advanced than ourselves are out there.

Although this seems to make logical sense, it may not make biological sense. Metal-poor stars might have the ability to create small worlds, but just because there are likely many small worlds out there, it doesn’t mean life can be nurtured. But then again, regions of the Milky Way once considered to be devoid of exoplanets may now have a stab at providing a planetary habitat for extraterrestrial biology to gain a foothold. Whether or not these metal poor stars host the right ingredients for the building blocks of life probably won’t be known for some time.

In 2009, I wrote an article (see “Life Is Grim On The Galactic Rim“) that grabbed the attention of National Geographic writer Ken Croswell who quoted my Astroengine.com article in the December 2010 edition of the magazine. In the text, I discussed some research that investigated the strange lack of protoplanetary disks around a selection of metal-poor star clusters in the outermost regions of the galaxy. The lack of a protoplanetary disk means a lack of exoplanet-birthing potential and a grim outlook for life to evolve in regions of the galaxy distant from the galactic core.

The conclusion of this 2009 work appears to contradict these most recent findings and the suggestion that advanced alien civilizations may have evolved around metal-poor stars. Whether these stars are the exception rather than the rule, or whether their low metallicity influences the size or visibility of their protoplanetary disks would be an interesting factor to consider.

Although SETI searches have yet to turn up any signal from an advanced alien technology, Kepler is proving that stars — regardless of their metallicity — have the ability to host small rocky worlds. Should life have taken hold on these worlds, then perhaps, some day, we may intercept an interstellar phone call from one of them.

This topic and a myriad of others will be discussed on June 22-24 where the world’s leaders in the field of alien and exoplanet hunting will meet at the Hyatt Santa Clara hotel in California’s Silicon Valley for SETIcon.

UPDATE: After tweeting this article, @spacearcheology retweeted my link with the following comment:

More grim! This exacerbates the Fermi Paradox RT @astroengine Life May Not Be So Grim On The Galactic Rim, After All http://t.co/BLT6KOJy

— Space Archaeology (@spacearcheology) June 15, 2012

This is something I neglected to consider in the original post. If there are indeed many more small rocky worlds out there — particularly around metal-poor stars that are, by their nature, ancient — why the heck haven’t we detected any ancient extraterrestrial intelligences yet? This has just become the Fermi Paradox PLUS…

The Day Aliens Invaded… [UPDATE]

UPDATE (Mon. 9:50 a.m. PT): Shocker. NASA refutes Hoover’s claims. Apparently his paper failed peer review for publication in the International Journal of Astrobiology… in 2007! More here: “NASA Refutes Alien Discovery Claim — Discovery News”

Original post: On Saturday, a NASA astrobiologist announced his “irrefutable proof” that aliens — the size of bacteria — exist. Using a sophisticated electron microscope, Richard Hoover looked deep into meteorite samples to see complex fossilized microscopic structures that looked suspiciously like bacteria found here on Earth.

Some of the suspect alien microorganisms even resemble cyanobacteria, a basic microorganism that helped make early-Earth hospitable to life by producing oxygen. Cyanobacteria can live in space for extended periods of time; tests on the International Space Station have shown the single-celled specks are hardy little buggers, surviving in a kind of “suspended animation,” sleeping for months (even years) in vacuous, frozen, high-radiation conditions. When brought back to Earth, the critters come back to life.

Needless to say, when Hoover announced this discovery of “alien” microbes, I wasn’t the only one who was thinking panspermia, the hypothetical mechanism where life — in the form of a microbe like cyanobacteria — hops from one planet to the next encased inside meteoroids.

Is this really proof of aliens? Is it evidence for panspermia? Does this mean life on Earth may have been seeded by alien microbes stowing away inside chunks of space rock? Does mankind need to invent an anti(alien)bacterial handwash?! (I’ve watched The Andromeda Strain.)

As mentioned in my Discovery News article on the subject, I’m skeptical about Hoover’s claims. This isn’t because I think Hoover’s work is rubbish (I have yet to finish digesting his lengthy paper), it’s just the way he decided to publish his work. The online Journal of Cosmology isn’t exactly the best place to submit your paper if you want your research to be taken seriously. And why the hell he gave FOX News the “exclusive,” I have no idea.

Sure, Hoover has discovered some odd-looking, alien-looking, bacteria-sized shapes in meteorite samples (he’s even done some interesting chemical analysis on the micro-“fossils”), but he’s going to have to do a far better job at convincing the scientific community that they are extraterrestrials.

Personally, I think these dinky “fossils” are a little too well preserved. Perhaps a far simpler explanation can be found? *cough* Contamination. *cough*

I’d love to know what NASA’s official line is, they seem to be staying remarkably quiet considering one of their employees has just announced the discovery of ET…

Read more: “Has Evidence for Alien Life Been Found?“

Life on Mars? Only in The Sun.

In its haste to become the first newspaper to print the “NASA: Evidence of Life on Mars” headline, the UK’s Sun website caused a stir last week. Not only was this headline incorrect, it was a wee bit irresponsible.

For starters, no evidence for life has been found on the Red Planet. Second, NASA has not proclaimed such a discovery. In fact, The Sun riled the U.S. space agency so much, this headline prompted NASA spokesman Dwayne Brown to issue the following statement:

“This headline is extremely misleading. This makes it sound like we announced that we found life on Mars, and that is absolutely, positively false.”

So where did it all go so wrong?

This story stems from an astrobiology conference celebrating the 50th anniversary of the search for alien life. At this conference, findings by NASA’s Mars Exploration Rover Opportunity were reviewed. One of these findings was the tantalizing discovery of sulfates by the rover in 2004. Where there’s sulfates, water once existed. Where there’s water, life might have existed.

In an exciting twist to this discovery, scientists studying sulfate deposits on Earth (known as gypsum) were asked by scientists in the Mars Program to investigate terrestrial gypsum deposits more closely. Up until now, it was thought that gypsum contained no fossils, but on closer inspection it turns out that ancient gypsum deposits from the Mediterranean Sea (dated to about 6 million years old — when the sea was actually dry) are stuffed full of microscopic fossils of algae and phytoplanktons.

So, on Mars we have sulfates. On Earth we have sulfates (gypsum) full of fossils of aquatic microscopic life. If we know the terrestrial deposits of gypsum contain fossils of basic life forms, perhaps sulfate deposits on Mars would be a good place to start looking for basic ancient extraterrestrial life.

Of course, for the tabloid newspaper, these Martian sulfate deposits became “pond scum” and therefore “evidence” for life on Mars.

In actuality, the text of The Sun article wasn’t that misleading and actually did a good job of reporting the science (apart from the “pond scum” bit). Unfortunately, the title of the article let the rest of the article down, ultimately undermining the journalists’ work.

But, coming from the same publication that printed the silly “Pictures show life on Mars” article from 2008, the “Evidence for life on Mars” headline is pretty tame.

Now, time for the same news with a more appropriate headline by Irene Klotz on Discovery News: “Earth Fossil Find May Lead to Martian Discoveries”

Thanks to Astroengine.com reader Judy Mason for inspiring this post.

Life is Grim on the Galactic Rim

The White Star approaches the Shadow's homeworld of Z'ha'dum on the Galactic Rim. — The White Star approaches the Shadow’s homeworld of Z’ha’dum on the Galactic Rim.

It would appear that scientists have confirmed that the outer edge of the Milky Way is a bad location for life to even think about existing.

This research reminded me of the “Galactic Rim” in the 90’s sci-fi TV series Babylon 5. The Rim is the mysterious region of space right at the edge of our galaxy where only the hardiest of explorers dared to venture. As explained in the season 2 episode of B5, “In the Shadow of Z’ha’dum,” Captain Sheridan (Bruce Boxleitner) discovers that his wife (when exploring The Rim) went missing on a planet called Z’ha’dum. It turns out that an angry ancient alien race — called the Shadows — lived on this mysterious world and their discovery led to them being used in all kinds of plots during the latter four seasons of this awesome sci-fi show.

However, the existence of any kind of life (let alone life as complex as the evil Shadows) in the badlands of the Milky Way is looking very unlikely.

Located some 62,000 light years from the core of our galaxy (over twice the distance of the Earth from the galactic centre), two very young star clusters in the constellation of Cassiopeia have been studied. Chikako Yasui, Naoto Kobayashi and colleagues at the University of Tokyo, Japan, found these clusters in a vast cloud of gas and dust called Digel Cloud 2. The stars inside these clusters are only half a million years old, and the majority of them should possess proto-planetary disks (which is characteristic of local star-forming regions). However, it would appear that these stars contain very little oxygen, silicon or iron (i.e. they have very low metallicity) and only 1 in 5 of the 111 baby stars analysed in both clusters have disks.

If proto-planetary disks are rare, this means there will be a rarity of planets. This is an obvious bummer for life to form. After all, Life As We Know It™ is quite attached to evolving on Earth-like planets.

So why are these young stars lacking proto-planetary disks, when local star forming regions don’t seem to have this affliction? The authors of the paper, soon to be published in the Astrophysical Journal, suggest that these stars did have disks, but some mechanism is rapidly eroding them.

The most likely scenario is that low metalicity proto-planetary disks are more susceptible to photoevaporation. Simply put, these disks evaporate when exposed to EUV and X-ray radiation from their parent stars far more rapidly than disks that are metal-rich.

Therefore, if an alien race was able to form, they’d be very rare or they’d be very different from what we’d expect “life” to be like (i.e. they thrive in low metalicity star systems). Sounds like the mysterious Shadow homeworld of Z’ha’dum would be a very rare sight on The Rim of our Milky Way after all.

Publication: The Lifetime of Protoplanetary Disks in a Low-Metallicity Environment, Chikako Yasui et al., 2009. arXiv:0908.4026v3 [astro-ph.SR]
via New Scientist

Why Is SETI Not An Interstellar Switchboard?

Monolith by highdarktemplar on DeviantArt.

On reading an article in The Daily Galaxy today, I was interested by what the author had to say. In a nutshell, the article pointed out that it is a big mistake to believe we are the only intelligent life in the Milky Way.

Why is that?

The only reason given was that there are billions of stars, it is therefore foolish to think we are the only example of an advanced species. Unfortunately, there is no evidence to suggest that we aren’t the only intelligent life form in our galaxy. Just because there are hundreds of billions of stars possibly with billions of habitable planets does not constitute evidence that we’re not alone. That’s what science is all about, formulating a theory and then gathering the evidence. Simply saying, “There’s lots of stars, therefore there must be an intelligent species out there,” doesn’t cut it.

Dr Frank Drake toiled with this idea to eventually arrive at the famous Drake Equation, a concept I have never felt at ease with:

At first glance, we could say that the Drake equation really is nonsense (after all, how can any equation predict more than one intelligent civilization in our galaxy, when we only have experience of one: us), and that we are the only kids on the Milky Way block. — from If There’s an Alien Race Living on our Doorstep, Why Can’t We Hear Them?

How can you arrive at the conclusion that we are not the only intelligent life in the galaxy simply because there are a lot of stars?

Familiarity

It is true that the Milky Way contains billions of stars, of which a high percentage probably have exoplanets not dissimilar to Earth orbiting them. There’s every chance that a smaller percentage of those Earth-like terrestrial exoplanets have some kind of basic life form slivering around (or indeed swimming, flying, walking or ‘talking’). Also, there’s the chance that some of these exoplanets have nurtured something that we’d consider to be ‘intelligent.’

Now this is where things start to get a bit tricky.

There are massive international efforts under way to find any kind of extraterrestrial life. We’re toasting soil samples on Mars in the hope of finding the biological signature, and we’re using full-blown antennae scouring the skies for any organized signal from an intelligent alien species. However, whether we are looking for microbial life in the Solar System or something a little more sophisticated beyond, our search for extraterrestrial life is based on only one model: Earth.

It’s all very well saying that we should be looking for other possible forms of life, but if we have no experience of it, how do we know what to look for?

It’s a similar question to, “What is beyond a black hole’s event horizon?” We have no idea, because we cannot experience it, the physics of our Universe simply do not apply beyond an event horizon.

There are a lot of ideas, theories and conjecture but at the end of the day, we have to assume ET will have some trait we are familiar with.

When looking for intelligent extraterrestrials we make the assumption that these civilizations have progressed in a similar way to us, eventually transmitting radio signals (perhaps even laser beacons) to communicate on their home world, between planets with their own kind, or even reaching out into the cosmos, signalling their presence to other life forms capable of receiving interstellar signals.

We’ve been leaking radio signals into space for the last century and we are constantly communicating with our planetary probes. There’s every chance that if there’s an intelligent alien (with a radio receiver) within 100 light years, we may have already been detected. We are also being a bit more proactive these days, using programs such as Messaging Extraterrestrial Intelligence (METI) to make our presence known. (But what should we be saying?)

SETI, METI, SETA… SETT?

Unfortunately, apart from one isolated case, the Search for Extraterrestrial Intelligence (SETI) has drawn up blanks, we don’t think we’ve heard anything in the cosmos that’s originated from an alien.

On this single null result, we could jump to the conclusion that there is no other form of ‘intelligent’ life in our galaxy. Say if the ‘Rare Earth‘ theory is correct, and we are indeed the only form of intelligent life in our galaxy? But there are other explanations. What if ET is signalling via another method? What if there is some interstellar mechanism that is hindering (or even blocking) the transmission of electromagnetic communications? All these questions are valid as there is no scientific evidence to support otherwise. It’s very quiet out there, a fact that is bugging scientists quite a bit, and this problem been dubbed the Fermi Paradox.

The Milky Way is very old, in fact, the oldest star in our galaxy has been burning for 13.2 billion years (compare that with the age of the Universe at 13.74 billion years); you’d logically think that something resembling an intelligent civilization would have popped into existence in that time. If they did, surely we’d have detected them by now, wouldn’t we?

Actually, this spawns yet another debate: Have ancient interstellar alien civilizations come and gone? Was there a frenzy of intelligent life popping up all over the galaxy in the billions of years that our Sun was a proto-star surrounded by a proto-planetary disk? If old alien intelligence has since become extinct, our few thousand years as an evolving civilization is a mere spark in universal time scales. Could it be that we’ll have to wait until we can actually visit interstellar destinations first-hand to do the SETI equivalent of an archaeological dig, looking for alien artefacts? Perhaps SETI should be changed to the Search for Extraterrestrial Artefacts (SETA), where we’d have to look for evidence of alien civilizations past.

Dyson Microcosm by justravelin on DeviantArt

There’s another factor to consider. What if an advanced extraterrestrial civilization simply isn’t transmitting? If this is the case, perhaps we should consider a Search for Extraterrestrial Technology (SETT). In this case we could look for alien megastructures, searching for the stuff of science fiction. These structures could include examples of Dyson Spheres, huge alien-made hollow spheres containing a star; a means to harvest all the stellar energy for a vastly advanced civilization.

These are all options, and we shouldn’t close any possibility, no matter how extreme they may be.

Conclusion

There’s a reason why we haven’t received a signal via SETI, but we have no idea about what it could be. We really could be alone in the Milky Way. But then again, there’s a huge number of reasons why we might not be receiving a message from an intelligent species.

SETI may not be an interstellar switchboard, but the reasons for this are far from obvious. The theory that we are alone is just as valid as the theory that we are actually a part of a vast interstellar ecosystem. Until we have scientific evidence, we can’t say either way.

Could Extraterrestrial Genes Be Like Ours?

DNA and amino acids. Not just a terrestrial thing? (©CG4TV)

This is probably one of the biggest questions that hang over science fiction story lines: Will extraterrestrials have any resemblance to Life As We Know It™? To be honest, to toy with the thought of anything other than carbon-based life is pure conjecture, just because there might be some other form of life (such as silicon-based creatures), doesn’t mean there is (doesn’t mean there isn’t, either). So, here we are with the only form of life we know and understand, carbon-based life that was somehow spawned via a crazy mix of amino acids and some astronomical or terrestrial event that sparked the formation of prokaryotes (a.k.a. the simplest single-celled speck of life) some 4 billion years ago.

So we have an understanding of what formed life on Earth, perhaps if we look for the traces of evidence that evolved into Life As We Know It™ we can gauge whether extraterrestrial life has-formed/is-forming/will-form elsewhere in the observable Universe. From simulations of Earth evolution, scientists have predicted that 10 types of amino acids should form with the planet. These 10 amino acids are found inside the proteins of all living things on Earth. The same 10 amino acids have been found inside meteorites. Therefore, we already have a connection with the amino acids we find here on Earth and amino acids found in chunks of rock from elsewhere in the Solar System.

Now, a group of Canadian researchers have found that the same 10 amino acids are readily available elsewhere in the cosmos. Does this mean the components for life are common, not only on Earth, in the Solar System, but also in the Milky Way (and beyond)? It looks like it…
Continue reading “Could Extraterrestrial Genes Be Like Ours?”