Posted on by Ray Sanders

SETI to Resume Search for Extraterrestrial Intelligence; Will Target Kepler Data

The Allen Telescope Array. Image Credit: SETI Institute

After being shut down for over six months due to financial problems, The Allen Telescope Array (ATA) is once again searching other planetary systems for radio signals, looking for evidence of extraterrestrial intelligence.

Some of the first targets in SETI’s renewed search will be a selection of recently discovered exoplanet candidates by NASA’s Kepler mission.

“This is a superb opportunity for SETI observations,” said Dr. Jill Tarter, the Director of the Center for SETI Research at the SETI Institute. “For the first time, we can point our telescopes at stars, and know that those stars actually host planetary systems – including at least one that begins to approximate an Earth analog in the habitable zone around its host star. That’s the type of world that might be home to a civilization capable of building radio transmitters.”

What other studies will SETI be performing with the array, and how were they able to restart the Allen Telescope Array?

This past April, SETI was forced to place the ATA into hibernation mode, due to budget cuts of SETI’s former partner, U.C Berkeley. Since Berkeley operated Hat Creek Observatory where the ATA is located, their withdrawal from the program left SETI without a way to operate the ATA.

SETI has since acquired new funding to operate the ATA and can now resume observations where they left off – examining planetary candidates detected by the Kepler mission. The planetary candidates SETI will examine first will be those that are thought to be in their star’s habitable zone (the range of orbital distance from a planet’s host star which may allow for surface water). Many astrobiologists theorize that liquid water is essential for life to exist on a planet.

“In SETI, as with all research, preconceived notions such as habitable zones could be barriers to discovery.” Tarter added. “So, with sufficient future funding from our donors, it’s our intention to examine all of the planetary systems found by Kepler.”

SETI will spend the next two years observing the planetary systems detected by Kepler in the naturally-quiet 1 to 10 GHz terrestrial microwave window. Part of what makes this comprehensive study possible is that the ATA can provide ready access to tens of millions of channels at any one time.

Resuming ATA operations was made possible due to tremendous public support via SETI’s www.SETIStars.org web site. In addition to the funds raised by the public, the United States Air Force has also provided funding to SETI in order to assess the ATA’s capabilities for space situational awareness.

Tarter notes, “Kepler’s success has created an amazing opportunity to focus SETI research. While discovery of new exoplanets via Kepler is backed with government monies, the search for evidence that some of these worlds might be home to intelligence falls to SETI alone. And our SETI exploration depends entirely on private donations, for which we are deeply grateful to our donors.”

“The year-in and year-out fundraising challenge we tackle in order to conduct SETI research is an absolute human and organizational struggle,” said Tom Pierson, CEO of the SETI Institute, “yet it is well worth the hard work to help Jill’s team address what is one of humanity’s most profound research questions.”

Dr. Tarter will be presenting during the first Kepler Science Conference (at NASA Ames Research Center) from December 5 to 9, 2011. You can view the agenda for the meeting, along with the abstract for her talk on Earth analogs at: http://kepler.nasa.gov/Science/ForScientists/keplerconference/sessions/.

If you’d like to learn more about SETI, or would like to make a donation to help fund their efforts, visit: https://setistars.org/donations/new

Read more about SETI’s partnership with the United States Air Force at: http://www.seti.org/afspc

Source: SETI Institute press release

Posted on by Tammy Plotner

Alien Artifacts May Be Here… Just Hard To Find!

This image highlights the special cargo onboard NASA's Voyager spacecraft: the Golden Record. Each of the two Voyager spacecraft launched in 1977 carry a 12-inch gold-plated phonograph record with images and sounds from Earth. An artist's rendering of the Voyager spacecraft is shown at bottom right, with a yellow circle denoting the location of the Golden Record. The cover of the Golden Record, shown on upper right, carries directions explaining how to play the record, a diagram showing the location of our sun and the two lowest states of the hydrogen atom as a fundamental clock reference. The larger image to the left is a magnified picture of the record inside. Credit: NASA

[/caption]

Greeting cards in space… We’ve certainly sent our share of them, haven’t we? So if humankind is foresighted enough to leave messages of our whereabouts – and our personalities – in space, then why haven’t other alien civilizations done the same? That’s a question a pair of postdoctoral researchers at Penn State are asking. By using mathematical equations, they’re showing us we simply haven’t looked in enough places… and would we recognize an alien artifact even if it were staring us in the face?

“The vastness of space, combined with our limited searches to date, implies that any remote unpiloted exploratory probes of extraterrestrial origin would likely remain unnoticed,” report Jacob Haqq-Misra, Rock Ethics Institute, and Ravi Kumar Kopparapu, Earth and Environmental Systems Institute, in a paper accepted by Acta Astronautica and posted online on ArXiv.

So far, we simply haven’t found any evidence of alien artifacts in our solar system – or anywhere else for that matter. According to the Penn State article, the Fermi paradox, originally formulated by Enrico Fermi, asks, if intelligent life is common, why have no technological civilizations been observed. Well, shucks… Maybe they’re shy – and maybe they’ve self-annihilated. There are hundreds of reasons “why” we haven’t found anything, but the most pertinent answer is we simply aren’t looking for the right thing in the right place at the right time. For example, have a look at just a few of the things we humans have sent into vastness of space to act as our ambassadors…

Duke Family Portrait: Apollo 16 Journal - Courtesy of Markus Mehring - Credit: NASA AS16-117-18841
Pioneer 10 and 11's famed Plaque features a design engraved into a gold-anodized aluminum plate, 152 by 229 millimeters (6 by 9 inches), attached to the spacecrafts' antenna support struts to help shield it from erosion by interstellar dust. Image Credit: NASA
Three LEGO figurines representing the Roman god Jupiter, his wife Juno and Galileo Galilei are shown here aboard the Juno spacecraft. Image credit: NASA/JPL-Caltech/KSC NASA's Jupiter-bound Juno spacecraft will carry the 1.5-inch likeness of Galileo Galilei, the Roman god Jupiter and his wife Juno to Jupiter when the spacecraft launches this Friday, Aug. 5. The inclusion of the three mini-statues, or figurines, is part of a joint outreach and educational program developed as part of the partnership between NASA and the LEGO Group to inspire children to explore science, technology, engineering and mathematics. Credit: NASA

And this is only just the tip of the human iceberg. How many of us have sent our name on missions to Mars, Pluto and more? There are footprints, plaques, flags, golf balls and an endless parade of human artifacts scattered far and wide. We might think they’re in plain sight, but would an alien culture see that? Would we comprehend what an alien culture might consider to be a greeting or sign or their presence? As far as we know, there could be unpiloted probes from alien civilizations out there right now, checking us out… But unless it were something the size of a proverbial school bus dropping itself on a house in Essex, our own arrogance would probably keep us from noticing it. And then again… it just might be hidden.

“Extraterrestrial artifacts may exist in the Solar System without our knowledge simply because we have not yet searched sufficiently,” said Haqq-Misra and Kopparapu. “Few if any of the attempts would be capable of detecting a 1 to 10 meter (3 to 33 foot) probe.”

Haqq-Misra and Kopparapu use a probabilistic method to determine the feasibility of aliens leaving us clues to their existence. Their work points to the Solar System as a fixed volume and then calculates the percentages of that volume that would need to be thoroughly searched to detect an alien probe or artifact. These searches would have to involve technology able to detect small, foreign objects and then apply it to a smaller portion of the volume to look for results. It’s a study which hasn’t been undertaken so far. We simply cannot say we’ve looked everywhere…

“The surface of the Earth is one of the few places in the Solar System that has been almost completely examined at a spatial resolution of less than 3 feet,” said Haqq-Misra and Kopparapu.

Sure. There are still a lot of nooks and crannies on Earth that haven’t been thoroughly explored – and our oceans are a good example. However, when it comes to searching elsewhere, it’s been a hit-or-miss proposition. While mapping the surface of the Moon, the Lunar Reconnaissance Orbiter is looking at the surface at a resolution of about 20 inches. It may take a few years, but perhaps something isn’t buried under the regolith. As for Mars, chances are slight – but new things seem to be discovered on Mars each day, don’t they? How about the LaGrange points, or the asteroid belt? Things could be hiding there, too.

“Searches to date of the Solar System are sufficiently incomplete that we cannot rule out the possibility that non terrestrial artifacts are present and may even be observing us,” said Haqq-Misra and Kopparapu. They add that “the completeness of our search for non terrestrial objects will inevitably increase as we continue to explore the Moon, Mars and other nearby regions of space.”

After all, what did we expect? E.T. to interrupt a prime time television program to announce their presence? A take-over of the Internet? Maybe each time a meteor makes it to Earth it’s a little calling card that life-possible organisms exists outside our own little sphere…

And maybe somebody needs to drop a bus on us.

Original Story Source: Penn State News Release.

Posted on by Nancy Atkinson

No Alien Visits or UFO Coverups, White House Says

Movie poster from 'Independence Day.' Credit: 20th Century Fox

[/caption]

The White House has responded to two petitions asking the US government to formally acknowledge that aliens have visited Earth and to disclose to any intentional withholding of government interactions with extraterrestrial beings. “The U.S. government has no evidence that any life exists outside our planet, or that an extraterrestrial presence has contacted or engaged any member of the human race,” said Phil Larson from the White House Office of Science & Technology Policy, on the WhiteHouse.gov website. “In addition, there is no credible information to suggest that any evidence is being hidden from the public’s eye.”

5,387 people had signed the petition for immediately disclosing the government’s knowledge of and communications with extraterrestrial beings, and 12,078 signed the request for a formal acknowledgement from the White House that extraterrestrials have been engaging the human race.

“Hundreds of military and government agency witnesses have come forward with testimony confirming this extraterrestrial presence,” the second petition states. “Opinion polls now indicate more than 50% of the American people believe there is an extraterrestrial presence and more than 80% believe the government is not telling the truth about this phenomenon. The people have a right to know. The people can handle the truth.”

These petitions come from an Obama Administration initiative called ‘We the People’ which has White House staffers respond and consider taking action on any issue that receives at least 25,000 online signatures. Regarding these two petitions, the White House promised to respond if the petitions got 17,000 or more signatures by Oct. 22.

Larson stressed that the facts show that there is no credible evidence of extraterrestrial presence here on Earth. He pointed out that even though many scientists have come to the conclusion that the odds of life somewhere else in the Universe are fairly high, the chance that any of them are making contact with humans are extremely small, given the distances involved.

But that doesn’t mean we aren’t searching, there is just no evidence yet. Larson mentioned SETI (correctly noting that this at first was a NASA effort, but is now funded privately) keeping an “ear” out for signals from any intelligent extraterrestrials, with none found so far. He also added that the Kepler spacecraft is searching for Earth-like planets in the habitable zones around other stars, and that the Curiosity rover will launch to Mars this month to “assess what the Martian environment was like in the past to see if it could have harbored life.”

Regarding any evidence for alien life, all anyone has now is “statistics and speculation,” said Larson. “The fact is we have no credible evidence of extraterrestrial presence here on Earth.”

Whether or not this will appease or satisfy any conspiracy theorists or UFO believers is yet to be seen, but it is gratifying to see the White House respond in such a no-nonsense manner.

UPDATE: The Paradigm Research Group, one of the organizations sponsoring the petitions, has issued a statement saying, “As expected it was written by a low level staffer from the Office of Science and Technology Policy – research assistant Phil Larson. The response was unacceptable.”

See the petitions and the response at the WhiteHouse.gov website.

Hat Tip: NASA Watch

Posted on by Jason Rhian

Book Review: A Dictionary of the Space Age

A Dictionary of the Space Age covers most aspects of space flight but is somewhat lacking in detail. Image Credit: John Hopkins University & Alan Walters/awaltersphoto.com

[/caption]
Writing a dictionary is not the same as writing a novel. While it might seem difficult to mess up a dictionary, even one with terminology that is as complicated as that used within the space industry – getting it right can be challenging. For those that follow space flight having such a dictionary can be invaluable. While A Dictionary of the Space Age does meet the basic requirements easily it fails somewhat in terms of its comprehensiveness.

When normal folks, even space enthusiasts watch launches and other space-related events (EVAs, dockings, landings and such) there are so many acronyms and jargon thrown about – that it is extremely hard to follow. With A Dictionary of the Space Age on hand, one can simply thumb through and find out exactly what is being said, making it both easier to follow along and making the endeavor being witnessed far more inclusive. That is as long if you are only looking for the most general of terms. The book is far from complete – but given the complex nature of the topic – this might not have been possible.

Crewed, unmanned, military space efforts and satellites – all have key terms addressed within the pages of this book.

The book is published by The Johns Hopkins University Press and was compiled and written by aerospace expert Paul Dickson. One can purchase the book on the secondary market (Amazon.com) for around $12 (new for around $25). The dictionary also has a Kindle edition which is available for $37.76. Dickson’s previous works on space flight is Sputnik: The Shock of the Century.

Weighing in at 288 pages, the book briefly covers the primary terms used within the space community. In short, if you are interested in learning more about space flight – or wish to do so – this is a good book for you.

Posted on by Nancy Atkinson

Now Available: 30 Free Lectures by Noted Astronomers

We just received a note from Andrew Franknoi and the Astronomical Society of the Pacific that they are making available, free of charge, 30 audio and video podcasts from talks given by distinguished astronomers on the latest ideas and discoveries in the field. Speakers include:

* Frank Drake, who began the experimental search for intelligent life among the stars,
* Mike Brown, who discovered most of the dwarf planets beyond Pluto (and whose humorous talk is entitled “How I Killed Pluto and Why it Had it Coming”),
* Natalie Batalha, project scientists on the Kepler Mission to find Earths around other stars,
* Alex Filippenko (national professor of the year) on finding black holes.

Recent topics added to the offerings include: multiple universes, Saturn’s moon Titan (with an atmosphere, rivers, and lakes), our explosive Sun, and whether we should expect doomsday in 2012.

The talks are part of the Silicon Valley Astronomy Lectures, jointly sponsored by NASA’s Ames Research Center, the Astronomical Society of the Pacific, the SETI Institute, and Foothill College.
They are available via the web and ITunes. For a complete list and to begin listening, go to:
http://www.astrosociety.org/education/podcast/

Posted on by Steve Nerlich

Astronomy Without A Telescope – The Unlikeliness Of Being

The Search for ExtraTerrestrial Intelligence could be a waste of time according to a recent statistical analysis of the likelihood of life arising spontaneously on habitable-zone exoplanets out there in the wider universe (and let's face it - when have predictive statistics ever got it wrong?) Credit: SETI Institute.

[/caption]

History has proved time and again that mathematical modelling is no substitute for a telescope (or other data collection device). Nonetheless, some theoreticians have recently put forward a statistical analysis which suggests that life is probably very rare in the universe – despite the apparent prevalence of habitable-zone exoplanets, being found by the Kepler mission and other exoplanet search techniques.

You would be right to be skeptical, given the Bayesian analysis undertaken is based on our singular experience of abiogenesis – being the origin of life from non-life, here on Earth. Indeed, the seemingly rapid abiogenesis that occurred on Earth soon after its formation is suggested to be the clinching proof that abiogenesis on habitable-zone exoplanets must be rare. Hmm…

Bayes theorem provides a basis for estimating the likelihood that a prior assumption or hypothesis (e.g. that abiogenesis is common on habitable-zone exoplanets) is correct, using whatever evidence is available. Its usage is nicely demonstrated in solving the Monty Hall problem.

Go here for the detail, but in a nutshell:
There are three doors, one with a car behind it and the other two have goats. You announce which door you will pick – knowing that it carries a 1/3 probability of hiding the car. Then Monty Hall, who knows where the car is, opens another door to reveal a goat. So, now you know that door always had a zero probability of hiding the car. So, the likelihood of the remaining door hiding the car carries the remaining 2/3 probability of the system, since there was always an absolute 1/1 probability that the car was behind one of the three doors. So, it makes more sense for you to open that remaining door, instead of the first one you picked.

In this story, Monty Hall opening the door with a goat represents new data. It doesn’t allow you to definitively determine where the car is, but it does allow you to recalculate the likelihood that your prior hypothesis (that the car is behind the first door you picked) is correct.

Applying Bayesian analysis to the problem of abiogenesis on habitable-zone exoplanets is a bit of a stretch. Speigel and Turner argue that the evidence we have available to us – that life began quite soon after the Earth became habitable – contributes nothing to estimating the likelihood that life arises routinely on habitable-zone exoplanets.

They remind us that we need to acknowledge the anthropic nature of the observation we are making. We are here after 3.5 billion years of evolution – which has given us the capacity to gather together the evidence that life began here 3.5 billion years ago, shortly after the Earth first became habitable. But that is only because this is how things unfolded here on Earth. In the absence of more data, the apparent rapidity of abiogenesis here on Earth could just be a fluke.

Stromatolites - which were a fairly early form of life on Earth. Earth became inhabited by such early life shortly after it became habitable. This might seem suggestive that life is somewhat inevitable when the conditions are right. But a statistician is never going to buy such an argument when it's based on a single example.

This is a fair point, but a largely philosophical one. It informs the subsequent six pages of Spiegel and Turner’s Bayesian analysis, but it is not a conclusion of that analysis.

The authors seek to remind us that interviewing one person and finding that she or he likes baked beans does not allow us to conclude that all people like baked beans. Yes agree, but that’s just statistics – it’s not really Bayesian statistics.

If we are ever able to closely study an exoplanet that has been in a habitable state for 3.5 billion years and discover that either it has life, or that it does not – that will be equivalent to Monty Hall opening another door.

But for now, we might just be a fluke… or we might not be. What we need is more data.

Further reading: Spiegel and Turner. Life might be rare despite its early emergence on Earth: a Bayesian analysis of the probability of abiogenesis.

Posted on by Nancy Atkinson

Fundraising for Aliens

Allen Telescope Array. Credit: SETI

[/caption]

SETI, the Search for Extraterrestrial Intelligence suffered a big blow in April of this year when the primary alien search engine –the Allen Telescope Array (ATA) in northern California — was put into “hibernation” due to lack of funds. But now you can help get the ATA back online through a crowdsourcing effort called SETIstars. Similar to fundraising efforts like KickStarter, SETIstars is working to raise enough money to bring the telescope array online again and provide operating costs for at least one year. The goal is to raise $200,000.

As of this writing, nearly $30,000 has been raised already.

While the ATA is not the only radio telescope that can be used for SETI searches, it was the observatory that was primarily used for that task. The funding crisis occured when state and the National Science Foundation contributions were significantly cut.

SETIstars is an initiative by the SETI Institute to rally support from the community to help fund the SETI Institute’s operations and that of the Allen Telescope Array. SETIstars has clearly defined fundraising goals, and will recognize supporters and contributors to the SETI Institute — both financial and non-financial.

“We are starting with a simple site with a clear mandate: raise funds from the community to help bring the ATA back on line,” says the SETIstars website. “But this is just the beginning…Bringing the ATA back online is a critical first step. However, sustaining operations is also of vital importance. SETIstars will be a rallying point for future community engagement and fundraising efforts.”

Here’s your chance to allow SETI scientists to start listening for signals from space again, especially in the region in space where Kepler has found a boatload of exoplanets. Your donations are tax free (in the US) since SETI is a nonprofit institution. International donors should contact their government for information on tax deductions for charitable gifts to U.S. based charities.

So, go donate. Do it.

Posted on by Nancy Atkinson

Budget Woes Put SETI’s Allen Telescope Array into “Hibernation”

Allen Telescope Array. Credit: ATA

[/caption]

SETI, the Search for Extraterrestrial Intelligence has suffered a big blow. The primary alien search engine –the Allen Telescope Array (ATA) in northern California — has been shut down due to budget woes. In a letter last week, the CEO of the SETI Institute, Tom Pierson told donors that in the ATA has been put into “hibernation,” — a safe mode of sorts, where “the equipment is unavailable for normal observations and is being maintained in a safe state by a significantly reduced staff.”

The ATA has been in hibernation since April 15, with the equipment put in a safe configuration so that it stays ready to be turned back on should the SETI Institute find new sources of funding.

While the ATA is not the only radio telescope that can be used for SETI searches, it was the observatory that was primarily used for that task, and now SETI researchers will have to borrow time on telescopes where “competition for observing time can be fierce or piggyback their searches on other ongoing observations,” according to John Matson, writing for Scientific American.

The ATA was operating with 42 antennas, and was scheduled to expand gradually to 350 six-meter radio antennas to listen for possible radio emissions from any faraway civilizations that might exist elsewhere in the galaxy. But after the first $50 million phase was completed in 2007, additions to the array were delayed due to lack of funding.

NASA had funded some of the early SETI projects, but Congress canceled any NASA contributions in 1993. The nonprofit SETI Institute, founded in 1984, relies mainly on private donations to support its research. Microsoft co-founder Paul Allen, had contributed $25 million to the first phase, with donations and grants funding the rest.

According to astronomer Franck Marchis, who works for the SETI Institute and the University of California, Berkeley – which is responsible for operating the ATA, “the financial state of the observatory degraded significantly over the past 2 years with the loss of various sources of funding (NSF, California state) at UC Berkeley” forcing UC Berkeley to withdraw from the SETI project. And, as Marchis wrote on his blog, “because the project is mainly funded through private donors, the economic recession had a huge impact and delayed significantly the expansion of the array impacting the overall project.”

In his letter, Pierson said that NSF funding has been reduced to approximately one-tenth of what it formerly gave to SETI. “This is compounded by growing State of California budget shortfalls that have severely reduced the amount of state funds available to the Radio Astronomy Lab.”

ATA operations cost about $1.5 million per year, Pierson said, and the SETI science campaign at ATA costs another $1 million annually.

Pierson said that the SETI Institute has been working for more than two years to find additional funding, such as providing assistance to the US Air Force in tracking orbital debris. The SETI Institute is also currently working on a fundraising campaign to raise $5 million so that the ATA can be used to focus on the potentially habitable planets found by the Kepler telescope.

For anyone who is interested in donating SETI, and in particular the ATA and their search of signals from the Kepler database of planets, see this website.

Sources: Scientific American, Cosmic Diary, SETI Institute

Posted on by Ken Kremer

“Astrobiology” Parody Video of Ke$ha’s “We R Who We R”

Wanna get turned on by … “Astrobiology” ?? Are we alone in the universe?

Well check out just this newly-released music video parody of Ke$ha’s hit song “We R Who We R” – “Astrobiology.”

Suspend your disbelief. It’s different. It’s cool. And it’s very clever.

And .. It’s even better the second time around when you listen to the lyrics more closely … combined with the shocking video .. Featuring beautiful maidens and alien dolls galore. Continue reading ““Astrobiology” Parody Video of Ke$ha’s “We R Who We R””

Posted on by Nancy Atkinson

Buzz About Gliese 581g: Doubts of Its Existence; Aliens Signals Detected

Goldilocks Zone
Artists impression of Gliese 581g. Credit: Lynette Cook/NSF

[/caption]

Ever since the announcement of the discovery of exoplanet Gliese 581g, there has been a buzz in the news, on websites, Twitter – pretty much everywhere, about the first potentially habitable extrasolar planet. But the past couple of days there has been a different sort of buzz about this distant world. Two stories have surfaced and they both can’t be true. The first one is fairly off the deep end: an astrophysicist from Australia claims that while doing a SETI search two years ago, he picked up a “suspicious signal” from the vicinity of the Gliese 581 system, and a couple of websites have connected some dots between that signal and a potentially habitable Gliese 581g.

The second one is more sobering. At an International Astronomical Union meeting this week, other astronomers have raised doubts whether Gliese 581g actually exists.

Unless you’ve been under a rock the past two weeks, you likely know that this newest and most promising of potential habitable extra solar planets was described by the scientists who discovered it as a rocky world about 3 times the mass of Earth, and it orbits within the red dwarf star’s habitable zone, the place that is just right for water to remain as a liquid on a planetary surface. And it is fairly close to us, too, at about 20 light years away, located in the constellation Libra.

Also announced was the discovery of planet ‘f’, a 7-Earth mass planet with a 433-day orbit around Gliese 581.

Astronomer Steven Vogt announced the discoveries by his team, which used the HIRES instrument on the Keck I telescope in Hawaii. They also used 119 measurements from the HARPS instrument on the La Silla telescope at the European Southern Observatory in Chile.

On Monday, Steinn Siggurdson broke the news on his Dynamics of Cats blog that an astronomer who works on HARPS data at the Geneva Observatory, said at the IAU meeting this week that his team could not confirm the existence of Gliese 581 g.

In an article on the Astrobiology Magazine website today (Tuesday) the astronomer, Francesco Pepe, said that not only can they not confirm the existence of planet ‘g’, but also the ‘f’ planet.

In 2009, the Geneva team announced the discovery of planet ‘e’ in the Gliese 581 solar system. At approximately 1.9 Earth masses, this ‘e’ planet is the lowest mass extrasolar planet found at that time, and has a 3.15-day orbital period around the star.

Pepe said they have studied this planet-rich system frequently, gathering a total of 180 data points in 6.5 years (with about 60 of those data points since 2009) and they can only see evidence of the 4 previously announced planets b, c, d, and e.

There is a signal which could possibly be f, but the signal amplitude of this potential fifth planet is very low and basically at the level of the measurement noise, said Pepe.

The planets in the Gliese 581 system were discovered using spectroscopic radial velocity measurements. Planets ‘tug’ on the star they orbit, causing it to shift in position (stars and planets actually orbit a common center of mass). By measuring the star’s movement in the sky, astronomers can figure out what sort of planets are orbiting it. Multi-planet systems create a complicated signal, and astronomers must tease out the spectral lines to figure out what represents a planet, and what is just “noise” – shifts in the star light not caused by an orbiting planet. Astronomers have developed various ways to reduce such noise in their telescopic observations, but it still creates a level of uncertainty in detecting extrasolar planets.

The Geneva team plugged the HARPS data on Gliese 581 into computer models, and the models show “the probability that such a signal is just produced ‘by chance’ out of the noise is not negligible, of the order of several percents,” Pepe said. “Under these conditions we cannot confirm the presence of the announced planet Gliese 581 g.”

While this doesn’t definitively mean Gliese 581g doesn’t exist, it certainly casts doubt on it. More teams will be looking at the Gliese 581 star to try and determine what is really out there. This story is not over yet.

As for the alien signal, this news has met some pretty harsh criticism — even from Dr. Frank Drake, a leader in SETI community. Astronomer Ragbir Bhathal, a scientist at the University of Western Sydney, said he detected an unusual pulse of light nearly two years ago from the same region at Gliese 581, and with the news of the potential habitable world there, his claims came up again. In an article in Space.com Drake said is suspicious because Bhathal would not share his data with anyone.

You can read an article published in 2009 in the Australian about Bhathal’s claimed discovery.