Moons of Confusion: Why Finding Extraterrestrial Life may be Harder than we Thought

Astronomers and planetary scientists thought they knew how to find evidence of life on planets beyond our Solar System. But, a new study indicates that the moons of extrasolar planets may produce “false positives” adding an inconvenient element of uncertainty to the search.

More than 1,800 exoplanets have been confirmed to exist so far, with the count rising rapidly. About 20 of these are deemed potentially habitable. This is because they are only somewhat more massive than Earth, and orbit their parent stars at distances that might allow liquid water to exist.

Astronomers soon hope to be able to determine the composition of the atmospheres of such promising alien worlds. They can do this by analyzing the spectrum of light absorbed by them. For Earth-like worlds circling small stars, this challenging feat can be accomplished using NASA’s James Webb Space Telescope, scheduled for launch in 2018.

They thought they knew how to look for the signature of life. There are certain gases which shouldn’t exist together in an atmosphere that is in chemical equilibrium. Earth’s atmosphere contains lots of oxygen and trace amounts of methane. Oxygen shouldn’t exist in a stable atmosphere. As anyone with rust spots on their car knows, it has a strong tendency to combine chemically with many other substances. Methane shouldn’t exist in the presence of oxygen. When mixed, the two gases quickly react to form carbon dioxide and water. Without some process to replace it, methane would be gone from our air in a decade.

On Earth, both oxygen and methane remain present together because the supply is constantly replenished by living things. Bacteria and plants harvest the energy of sunlight in the process of photosynthesis. As part of this process water molecules are broken into hydrogen and oxygen, releasing free oxygen as a waste product. About half of the methane in Earth’s atmosphere comes from bacteria. The rest is from human activities, including the growing of rice, the burning of biomass, and the flatulence produced by the vast herds of cows and other ruminants maintained by our species.

By itself, finding methane in a planet’s atmosphere isn’t surprising. Many purely chemical processes can make it, and it is abundant in the atmospheres of the gas giant planets Jupiter, Saturn, Uranus, and Neptune, and on Saturn’s large moon Titan. Although oxygen alone is sometimes touted as a possible biomarker; its presence, by itself, isn’t rock solid evidence of life either. There are purely chemical processes that might make it on an alien planet, and we don’t yet know how to rule them out. Finding these two gases together, though, seems as close as one could get to “smoking gun” evidence for the activities of life.

A monkey wrench was thrown into this whole argument by an international team of investigators led by Dr. Hanno Rein of the Department of Environmental and Physical Sciences at the University of Toronto in Canada. Their results were published in the May, 2014 edition of the Proceedings of the National Academy of Sciences USA.

Suppose, they posited, that oxygen is present in the atmosphere of a planet, and methane is present separately in the atmosphere of a moon orbiting the planet. The team used a mathematical model to predict the light spectrum that might be measured by a space telescope near Earth for plausible planet-moon pairs. They found that the resulting spectra closely mimicked that of a single object whose atmosphere contained both gasses.

Unless the planet orbits one of the very nearest stars, they showed it wasn’t possible to distinguish a planet-moon pair from a single object using technology that will be available anytime soon. The team termed their results “inconvenient, but unavoidable…It will be possible to obtain suggestive clues indicative of possible inhabitation, but ruling out alternative explanations of these clues will probably be impossible for the foreseeable future.”

References and further reading:

The Habitable Exoplanets Catalog, Planetary Habitability Laboratory, University of Puerto Rico at Arecibo

Kaltenegger L., Selsis F., Fridlund M. et al. (2010) Deciphering spectral fingerprints of habitable exoplanets. Astrobiology, 10(1) p. 89-102.

Major J. (2013) Earthlike exoplanets are all around us. Universe Today

Rein H., Fujii Y., and Spiegel D. S. (2014) Some inconvenient truths about biosignatures involving two chemical species on Earth-like exoplanets. Proceedings of the National Academy of Sciences, 111(19) p. 6871-6875.

Sagan C., Thompson W. R., Carlson R., Gurnett, D., Hord, C. (1993) A search for life on Earth from the Galileo spacecraft. Nature, 365 p. 715-721.

A New Mantra: Follow the Methane — May Advance Search for Extraterrestrial Life

The search for life is largely limited to the search for water. We look for exoplanets at the correct distances from their stars for water to flow freely on their surfaces, and even scan radiofrequencies in the “water hole” between the 1,420 MHz emission line of neutral hydrogen and the 1,666 MHz hydroxyl line.

When it comes to extraterrestrial life, our mantra has always been to “follow the water.” But now, it seems, astronomers are turning their eyes away from water and toward methane — the simplest organic molecule, also widely accepted to be a sign of potential life.

Astronomers at the University College London (UCL) and the University of New South Wales have created a powerful new methane-based tool to detect extraterrestrial life, more accurately than ever before.

In recent years, more consideration has been given to the possibility that life could develop in other mediums besides water. One of the most interesting possibilities is liquid methane, inspired by the icy moon Titan, where water is as solid as rock and liquid methane runs through the river valleys and into the polar lakes. Titan even has a methane cycle.

Astronomers can detect methane on distant exoplanets by looking at their so-called transmission spectrum. When a planet transits, the star’s light passes through a thin layer of the planet’s atmosphere, which absorbs certain wavelengths of the light. Once the starlight reaches Earth it will be imprinted with the chemical fingerprints of the atmosphere’s composition.

But there’s always been one problem. Astronomers have to match transmission spectra to spectra collected in the laboratory or determined on a supercomputer. And “current models of methane are incomplete, leading to a severe underestimation of methane levels on planets,” said co-author Jonathan Tennyson from UCL in a press release.

So Sergei Yurchenko, Tennyson and colleagues set out to develop a new spectrum for methane. They used supercomputers to calculate about 10 billion lines — 2,000 times bigger than any previous study. And they probed much higher temperatures. The new model may be used to detect the molecule at temperatures above that of Earth, up to 1,500 K.

“We are thrilled to have used this technology to significantly advance beyond previous models available for researchers studying potential life on astronomical objects, and we are eager to see what our new spectrum helps them discover,” said Yurchenko.

The tool has already successfully reproduced the way in which methane absorbs light in brown dwarfs, and helped correct our previous measurements of exoplanets. For example, Yurchenko and colleagues found that the hot Jupiter, HD 189733b, a well-studied exoplanet 63 light-years from Earth, might have 20 times more methane than previously thought.

The paper has been published in the Proceedings of the National Academy of Sciences and may be viewed here.

Lone Signal: First Continous Message Beacon to Find and Say Hello to an Extraterrestrial Civilization

Although scientists have been listening for years to search for indications of other sentient life in the Universe, just a few efforts have been made by humans to purposefully send out messages to the cosmos. Called METI (Messaging to Extraterrestrial Intelligence) or Active SETI (Search for Extraterrestrial Intelligence), these messages have so far been just one-time bursts of info – or “pulses in time” said Dr. Jacob Haqq-Misra.

Haqq-Misra is leading a team of scientists and entrepreneurs who are launching a new initiative called “Lone Signal” which will send the first continuous mass “hailing messages” out into space, starting later this month. They’ll be specifically targeting one star system, Gliese 526, which has been identified as a potentially habitable solar system.

And yes, the general public can participate.

“From the start we wanted to be an experiment where anyone on Earth could participate,” said Haqq-Misra during a press event on June 11, 2013, announcing the project.

“Our scientific goals are to discover sentient beings outside of our solar system,” said Lone Star co-founder Pierre Fabre, also speaking at the event. “But an important part of this project is to get people to look beyond themselves and their differences by thinking about what they would say to a different civilization. Lone Signal will allow people to do that.”

Lone Signal will be using the recommissioned radio dish at the Jamesburg Earth Station in Carmel, California, one of the dishes used to carry the Apollo Moon landings live to the world.


Timelapse of the Jamesburg Earth Station

Lone Signal will be sending two signals: one is a continuous wave (CW) signal, a hailing message that sends a slow binary broadcast to provide basic information about Earth and our Solar System using an encoding system created by astrophysicist and planetary scientist Michael W. Busch. The binary code is based on mathematical “first principles” which reflect established laws that, theoretically, are relatively constant throughout the universe; things like gravity and the structure of the hydrogen atom, etc.

“This hailing message is a language we think could be used to instigate communication,” said Haqq-Misra, “and is the most advanced binary coding currently in use.”

The second signal, embedded in the first signal, will be messages from the people of Earth.

Strength of various signals from Earth.  Graph courtesy of Dr. Haqq-Misra.
Strength of various signals from Earth. Graph courtesy of Dr. Haqq-Misra.

Since Gliese 526 is 17.6 light years from Earth, the messages will be beamed to the coordinates of where the star will be in 17.6 years from now. Even though no planets have been found yet in this system, the Lone Signal team said they are confident planets exist there since missions like Kepler and Corot have found that most stars host multiple planets.

The Lone Signal team is allowing anyone with access to the internet to send the equivalent of one free text message or Twitter message — a 144-character text-based message — into space. The team said they want to have messages sent from people all around the world to provide messages that are “representative of humanity.”

Anything additional, like more messages, images, etc., will cost money, but those funds will help support the project.

“In effect we are doing our own Kickstarter and doing the crowdfunding on our own,” said Lone Signal CEO Jamie King. “Long Signal would not be possible without crowd sourcing support, which will be used for maintaining the millions of dollars in equipment, powering the dish, running the web portal and other critical tech that makes the project possible.”

If you want to be part of the project and be a “beamer” you can currently sign up at the Lone Signal website –which currently doesn’t have much information. But on June 18th their public site will go live and ‘beamers will be able to submit messages as well as:

• Share Beams / Track Beams – Once signed in, users can see how far their beam has traveled from Earth as well as share it with the beaming community.

• Dedicate Beams – Parents, friends and loved ones can dedicate a beam to others.

• Explore – The Explore section gives beamers current data on the Lone Signal beam, who is sending messages, from where on Earth, overall stats, etc.

• Blog / Twitter – Via their blog and Twitter, the Lone Signal science team and other contributors will be posting opinion articles on associated topics of interest as well as sharing the latest science news and updates.

One you submit your “beam” you’ll be able to “echo” it on your Facebook and Twitter accounts.

After a user sends their initial free message, Lone Signal will be offering paid credit packages for purchase that allow users to transmit and share longer messages as well as images using credits in the following USD price structure:
• $0.99 buys 4 credits.
• $4.99 buys 40 credits.
• $19.99 buys 400 credits.
• $99.99 buys 4000 credits.

Following the initial free message, each subsequent text-based message costs 1 credit. Image-based messages cost 3 credits.

The team said that each message will be sent as an individual packet of information and won’t be bunched with other messages.

While some scientists have indicated that sending messages out into space might pose a hazard by attracting unwanted attention from potentially aggressive extraterrestrial civilizations, Haqq-Misra thinks the benefits outweigh the potential hazards. In fact, he and his team have written a paper about the concept.

“We want to inspire passion for the space sciences in people young and old, encourage citizens of Earth to think about their role in the Universe, and inspire the next generation of scientists and astronauts,” said Lone Signal chief marketing officer Ernesto Qualizza. “We’re really excited to find out what people will want to say, and the science of METI allows people to do this – to think about more than their own backyard.”

More info: Lone Signal

SETI: The Search Goes On

In this new video, SETI founder Frank Drake and astronomer Jill Tarter about why the search of the cosmos is important and needed. Visit SETI online to learn more about the search for signals of extraterrestrial life using radio telescopes on Earth and how you can help.

“Tidal Venuses” May Have Been Wrung Out To Dry

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Earth-sized exoplanets within a distant star’s habitable zone could still be very much uninhabitable, depending on potential tidal stresses — either past or present — that could have “squeezed out” all the water, leaving behind a bone-dry ball of rock.

New research by an international team of scientists suggests that even a moderately eccentric orbit within a star’s habitable zone could exert tidal stress on an Earth-sized planet, enough that the increased surface heating due to friction would boil off any liquid water via extreme greenhouse effect.

Such planets are dubbed “Tidal Venuses”, due to their resemblance to our own super-heated planetary neighbor. This evolutionary possibility could be a factor in determining the actual habitability of an exoplanet, regardless of how much solar heating (insolation) it receives from its star.

The research, led by Dr. Rory Barnes of the University of Washington in Seattle, states that even an exoplanet currently in a circular, stable orbit could have formed with a much more eccentric orbit, thus subjecting it to tidal forces. Any liquid water present after formation would then have been slowly but steadily evaporated and the necessary hydrogen atoms lost to space.

The risk of such a “desiccating greenhouse” effect would be much greater on exoplanets orbiting lower-luminosity stars, since any potential habitable zone would be closer in to the star and thus prone to stronger tidal forces.

And as far as such an effect working to create habitable zones further out in orbit than otherwise permissible by stellar radiation alone… well, that wouldn’t necessarily be the case.

Even if an exoplanetary version of, say, Europa, could be heated through tidal forces to maintain liquid water on or below its surface, a rocky world the size of Earth (or larger) would still likely end up being rather inhospitable.

“One couldn’t do it for an Earthlike planet — the tidal heating of the interior would likely make the surface covered by super-volcanoes,” Dr. Barnes told Universe Today.

So even though the right-sized exoplanets may be found in the so-called “Goldilocks zone” of their star, they may still not be “just right” for life as we know it.

The team’s full paper can be found here.

No Alien Visits or UFO Coverups, White House Says

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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

Calm Down: NASA Hasn’t Found any Aliens

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You may have heard in your wanderings through the blogosphere and in the internet today that NASA will be holding a press conference on December 2nd in which they will make an announcement regarding information the search for extraterrestrial life. And that this announcement involves astrobiology, the study of life outside what we know about here on Earth. While true, it is nothing to get worked up about.

Speculation abounds that this is, “the big one,” and that an announcement will be made that extraterrestrial life has been discovered. You can find this speculation at Kottke.org, io9, Gawker, and a lot of other places.

To be clear, there is almost no chance that the press release will be announcing little green men or little brown bacteria anywhere. Follow along for the long explanation below the fold.

Here’s what the press release is titled: “NASA Sets News Conference on Astrobiology Discovery: Science Journal Has Embargoed Details Until 2 p.m. EST On Dec. 2”. All this means is that Science Journal will be publishing some results related to astrobiology that are under embargo until that time. The embargo system is a basically a way of allowing journalists to see scientific results and get interviews and do research on an article before it’s published, but only if they promise to publish their information after the original publication does so. It makes sense, and it works most of the time to the benefit of almost everyone.

NASA regularly – like every day – announces upcoming press conferences and releases, and embargoed press releases float around to science writers like those of us here at Universe Today. This in itself is nothing out of the ordinary, and anyone with an email address can sign up to have these announcements delivered to their inbox or view them on NASA’s website. These emails are meant mainly to notify members of the press that there is something coming up worthy of being a phone-in listener of, the details of which require you to have press credentials.

The press release goes on to say,

“NASA will hold a news conference at 2 p.m. EST on Thursday, Dec. 2, to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life. Astrobiology is the study of the origin, evolution, distribution and future of life in the universe.
The news conference will be held at the NASA Headquarters auditorium at 300 E St. SW, in Washington. It will be broadcast live on NASA Television and streamed on the agency’s website at http://www.nasa.gov.
Participants are:
– Mary Voytek, director, Astrobiology Program, NASA Headquarters, Washington
– Felisa Wolfe-Simon, NASA astrobiology research fellow, U.S. Geological Survey, Menlo Park, Calif.
– Pamela Conrad, astrobiologist, NASA’s Goddard Space Flight Center, Greenbelt, Md.
– Steven Benner, distinguished fellow, Foundation for Applied Molecular Evolution, Gainesville, Fla.
– James Elser, professor, Arizona State University, Tempe”

And that’s about it. My first reaction to this was that they had potentially made the discovery of exotic, new organic molecules in an exoplanetary atmosphere, or that some chemical conducive to the existence of life as we know it was possibly found on some body in the Solar System. Announcements like this come out of NASA all of the time.

Just because some of the participants do work in fields that are related to oceanography or ecology or biology, does not mean that their services are required here to help make an announcement that life other than that on Earth has been discovered, as other speculative bloggers might think.

As Nancy wrote in a post earlier today, extraterrestrial life is very much of interest to Universe Today readers. Which is why she’ll be listening in on that news conference Thursday, and reporting what findings are released.

Extraterrestrial life is very much of interest to probably most of the population of our planet, too, and the fact that we have the tools necessary to potentially make this discovery within the next few hundred years (or sooner), is really, really exciting.

But just because it’s exciting doesn’t mean we have to jump all over a NASA press release that includes the words “extraterrestrial life” or “precursor to life on Mars” and make wild speculations. When that announcement is made (or if, depending on how you choose to solve the Drake Equation), you can be sure that it will be very closely guarded until being made public, and after that the President will likely have some things to say.

For some more level-headed analysis, Keith Cowing at Nasa Watch has some much more reasonable speculation that the announcement involves arsenic biochemistry. The Bad Astronomer, Phil Plait, also has a good debunking of the rampant speculation, and makes some good points about how NASA can create press releases in the future that have better-worded announcements.

So calm down – but don’t stop looking up! Keep being excited about all of the genuinely cool and exciting developments we’re currently making with regards to space.

Source: NASA press release

[email protected] Needs You!

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If your New Year’s resolutions include trying something new, expanding your horizons, or doing something to benefit humanity, this is for you: [email protected] needs more volunteers to help crunch data in the search for extraterrestrial intelligence (SETI). And the easy part is that your desktop computer does all the work.

SETI uses radio telescopes to listen for narrow band-width radio signals from space. Since these signals don’t occur naturally, a detection of such a signal would indicate technology from an extraterrestrial source.

The SETI project at the University of California-Berkley gets data from world’s largest radio telescope in Arecibo, Puerto Rico, which has recently been updated with seven new and more sensitive receivers. The improved frequency coverage for the telescope is now generating 500 times more data for the SETI project than before, and more volunteers are needed to handle the increase in data.

According to project scientist Eric Korpela, the new data amounts to 300 gigabytes per day, or 100 terabytes (100,000 gigabytes) per year, about the amount of data stored in the U.S. Library of Congress. “That’s why we need all the volunteers,” he said. “Everyone has a chance to be part of the largest public participation science project in history.”

The [email protected] premise is simple but brilliant: Instead of using a monstrously huge and expensive supercomputer to analyze all the data, it uses lots of small computers, all working simultaneously on different parts of the analysis. Participants download a special screensaver for their home computers, and when the computer is idle, the screensaver kicks in to grab data from UC Berkley, analyze the data and send back a report. [email protected] was launched in May of 1999.

The [email protected] software has now been upgraded to deal with all the new data generated by the updated Arecibo telescope. The telescope can now record radio signals from seven regions of the sky simultaneously instead of just one. It also has greater sensitivity and 40 times more frequency coverage.

So, if the phrase “to search out new life and new civilizations” inspires you, her’s your chance to be part of the largest community of dedicated users of any internet computing project. Currently [email protected] has 170,000 individuals donating time on 320,000 computers.

“Earthlings are just getting started looking at the frequencies in the sky; we’re looking only at the cosmically brightest sources, hoping we are scanning the right radio channels,” said project chief scientist Dan Werthimer. “The good news is, we’re entering an era when we will be able to scan billions of channels. Arecibo is now optimized for this kind of search, so if there are signals out there, we or our volunteers will find them.”

Check out [email protected] here.
Original News Source: UC Berkley Press Release