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In a recently conducted poll, 19 percent of the respondents said they thought Washington, D.C., would be the most likely landing zone for a UFO. But if that ever happened, who's the best person to lead the welcoming party? About 65 percent said they'd rather have Barack Obama than Mitt Romney handle the situation.

A new poll suggests that 77 percent of Americans think there's evidence that aliens have already visited Earth. The same poll suggests most Americans think President Barack Obama would do a better job than presumptive GOP challenger Mitt Romney if we had to fight off an alien invasion. And if we have to rely on a superhero to save us, they'd rather go with the Hulk than Batman.

That somewhat silly survey was conducted to tout a "Chasing UFOs" TV series on the National Geographic Channel, but the results raise a serious question: If an alien civilization does get in touch with us, who's in charge of figuring out what to do?

"Nobody's in charge," says Seth Shostak, who is senior astronomer at the California-based SETI Institute as well as the chairman of the International Academy of Astronautics' SETI Permanent Study Group. Shostak and I talked about SETI — the search for extraterrestrial intelligence — as well as its serious and silly implications tonight on "Virtually Speaking Science." The hourlong talk show is archived as a podcast on the Web and on iTunes.

As the poll done for National Geographic suggests, a good number of people suspect the aliens have already arrived, presumably on UFOs or through interdimensional travel. Most scientists scoff at that idea. "Why would they appear only to cranks and weirdos?" British physicist Stephen Hawking asked earlier this month. But Shostak thinks it's only a matter of time before extraterrestrial civilizations actually do make themselves known, by sending signals across the light-years. Almost a decade ago, he predicted that we'd detect those signals by the year 2025, and today he told me he's sticking by that prediction.

During our pre-show interview, Shostak laid out his rationale for the 2025 date and discussed how an alien-contact scenario is likely to go down. Check out this edited transcript of the Q&A.

Cosmic Log: Do you still feel that 2025 is a good time frame for alien contact? And maybe more importantly, how do we know we're getting closer to the date?

SETI Institute

Seth Shostak is senior astronomer at the SETI Institute.

Shostak: People ask, 'Are you getting close?' And we no more know whether we're getting close than Chris Columbus knew he was getting close to the Americas — we might some palm fronds a day or two out, but other than that, we don't know. In some sense, it'll come as a complete surprise if we get a signal. We know that from false alarms. They never occur when you expect them, because you never expect them.

But in terms of the prediction, that's based on the following: We're looking for needles in a haystack. If you ask, when are you going to find a needle, you need to know three things: How big is the haystack? How fast are you going through the hay? And how many needles are in there? We know two out of three. The haystack's the galaxy, and we know how fast we're going through it. We don't know the number of needles. So I took estimates of the number from the Drake Equation, and figured that it's two dozen years out. What's happened in the meantime is that the funding crisis has slowed things down a bit.

Q: Do you think you need to revise the 2025 date?

A: I think 2025, 2030 is about right, given that we can continue to do the experiment.

Q: Is it a steady process, or is there an increasing rate of hay examination?

A: This is all predicated on an increasing rate. That's the march of technology, which is mostly digital electronics. Computers keep getting faster and faster at any given price point, and that's good news for us. We can look at a larger chunk of the radio dial at once. We can go through the stars faster. Or we can look at bigger hunks of sky at once. It's mostly computing power that is responsible for the increasing speed of SETI. We're not sitting around with earphones the way Jodie Foster was.

Q: Could it be that the patterns of communication by extraterrestrial civilizations take a form completely different from what we assume?

A: We kind of know what areas SETI is weak in. It's been slow, in the sense that you've got a couple of hundred billion star systems in the galaxy, and if you can look at only a couple a day, that's really slow going. That might take forever. Can we look at more stars in a given time, with adequate sensitivity?

The second thing is, it may be that you really have to look for a long time at any given star system. Of course, we don't do that. We look at any given star system, at any given frequency, for at most a few minutes. Some other search programs look for one and a half seconds at any given star system. If the aliens are broadcasting in our direction once a week, or once a day, or once an hour, we're not going to see it. We know that's a problem.

Another issue is that the aliens may not know we're here because they haven't picked up 'I Love Lucy' yet. They don't know Homo sapiens is here, they just know that Earth is a planet with biology. They may not be motivated to target us relentlessly with reality television. They may broadcast now and then, with a little ping just to see if anybody's here. You really need an experiment that can pick up an intermittent, maybe one-off signal that's designed to ping the planet. Everybody knows that. That's a technology issue, but it's an issue that's getting better.

Q: Has anybody come up with a concept for an all-sky, all-the-time receiver?

A: Yeah, well, all-sky, all the time, all frequencies — that's what you'd looove to have. On paper, you can design an instrument that can look at the entire sky. All frequencies, that's another problem, but you can certainly cover more frequencies than we do. It's all a question of whether you can afford to build such an instrument. The answer is, no, not now. It takes an enormous amount of computing power to do that. However, one thing you can say about the future is that there will be more computing power. This is not impossible. This is not like building rockets to go at 99 percent of the speed of light. That might work on paper, too, but in practice, that's a long way off. But this is something where you can say, with the computing power of a few decades hence, it becomes a practical thing.

Q: Assuming that alien signals are detected by 2025, is humanity ready for that?

A: Well, I don't know how much planning has been done. We've revised some protocols, but those are just the immediate steps you take if you pick up a signal. They deal with practical matters, like checking the signals out and alerting everybody. But I don't know that there's any large-scale effort to prepare humanity, any more than there was any preparation by the Indians in the Caribbean in case a Spanish ship showed up. I don't think that's a problem, to be honest. In poll after poll, the public has said they believe the aliens are out there. They see them on television every night, and at the movies every third weekend. A third of 'em think the aliens are already here, but they don't see a problem with that, either. Nobody's staying home. Everybody's still going to work.

I think that psychologically, everybody could handle it. It's just going to be a big news item. Whatever it would be, people would find it interesting. But they'd be savvy enough to realize there's no immediate threat. The aliens would be 500 light-years away, and we pick up their signal.  There's no reason to think that people would go just completely non-linear.

The long-term consequences are less predictable. People would ask, should we broadcast back? Should we send a rocket in that direction? What should we do?

Q: Who would be in charge if there was an alien signal? Assuming that scientists confirm that there's an anomalous signal pattern, hinting at extraterrestrial intelligence, what's the procedure?

A: I don't think that there's anybody designated to be in charge. There was a flap a few years ago, involving an official at the U.N., but that was all a red herring. She quickly admitted that she's not in charge. Nobody's in charge.

Look, the real people who will be in charge will be the media, because they'll be reporting it. In some sense, whoever finds the signal is probably in charge. If it's us, then somebody at the SETI Institute will be called. Or suppose it's the Berkeley group. Well, they're in charge. Or maybe it's a group that comes across the signal by accident. There's no hierarchy. Anyway, you know how the media work — they're not going to follow the rules.

There's no danger in any of this, except for one thing: That's the idea that you're sitting around, and suddenly there's a signal, and you call a press conference. That's not the way it will happen. We get signals all the time, and someday one of those signals will pass all the tests, and it slowly emerges as a real signal. But it takes something on the order of five days before you're convinced. During all that time, the media knows about this, because there is no secrecy. But there's no press conference yet, because the scientists aren't yet sure themselves. This time lag means there will be all sorts of stories before the official word is out. It isn't because of leakage, it's because anytime anybody finds something interesting, they may mention it. They'll put it on their blog. Who knows what they'll do?

It'll be very, very messy. And the corollary to this is that you can probably expect a lot of false alarms. There'll be something interesting, and a lot of people will write about it, and three days later it turns out to be nothing.

Q: Some people worry that our own radio signals are advertising our presence in what could be a rough neighborhood, but I take it that's not a concern of yours.

A: There are people who get their knickers in a knot about this deliberate broadcast stuff. National Geographic is supposed to be collecting tweets to broadcast as an answer to the "Wow Signal." I personally don't get heartburn about broadcasting. The fact is that NBC is broadcasting all the time, right? You can say, well, that's a weak signal. Sure it is. But if you're really worried about broadcasting into space, don't just shut down the publicity stunts. You better shut down the radars at the Seattle-Tacoma airport, too. They're broadcasting into space all the time.

Tune in "Virtually Speaking Science" on BlogTalkRadio or in Second Life — and bring lots of questions. Seth Shostak and I were at the StellaNova Small Auditorium, courtesy of the Meta Institute for Computational Astrophysics, at 9 p.m. ET (6 p.m. PT/SLT) tonight. If you missed the live event, don't worry: It's archived by "Virtually Speaking" on BlogTalkRadio as well as iTunes.

More nuggets from the National Geographic UFO poll: 

• The "Aliens Among Us" survey polled a random nationwide sample of 1,114 Americans between May 21 and May 29. The poll was conducted by Kelton Research, which used email invitations and online surveys. Quotas were set to ensure reliable and accurate representation of the total U.S. population ages 18 and older. Margin of error is +/- 2.9 percent.
• More than one-third of those surveyed (36 percent) believe UFOs exist. Eleven percent are confident they've spotted a UFO, and 20 percent know someone who claims to have seen one.
• Nearly two-thirds (65 percent) said Obama would be better-suited than Romney to handle an alien invasion. Seventy-nine percent believe the government has kept information about UFOs a secret from the public. Nineteen percent think Washington, D.C., is the most likely landing zone for a UFO, while 28 percent think a UFO would touch down in Roswell, N.M.
• Seventy-seven percent think there are signs that suggest aliens have visited Earth. Most of these people said that the evidence came in the form of photographs (60 percent) and videos (57 percent) of UFOs.
• If aliens landed, 22 percent said they would try to befriend the visitors. Fifteen percent said they would run away, 13 percent said they would lock their doors, and 2 percent said they would try to inflict bodily harm.
• Seventy-one percent think that aliens are more likely to exist than are superheroes, vampires and zombies. But if aliens attacked Earth, 21 percent said they would most likely call on the Hulk to deal with the havoc, compared with Batman (12 percent) or Spider-Man (8 percent). Fifty-five percent believe there really are officials like the "Men in Black" who claim to be agents and threaten those who come forward with UFO sightings. 

Previous episodes of "Virtually Speaking Science":

• Paul Doherty on solar eclipses and the transit of Venus
• Veronica Ann Zabala-Aliberto on spaceflight and Yuri's Night
• JPL's Dave Beaty on the search for life on Mars
• Shawn Lawrence Otto on science and politics
• Ig Nobel impresario Marc Abrahams on silly science
• Rocket scientist Robert Zubrin on Mars exploration
• Propulsion expert Marc Millis on interstellar spaceflight
• Sean Carroll on the puzzling frontiers of physics
• Rand Simberg on the private-enterprise vision for spaceflight
• Martin Hoffert on the future of energy policy
• George Djorgovski on science in virtual worlds
• Alan Stern on suborbital research and NASA's mission to Pluto
• Col. 'Coyote' Smith on the outlook for space solar power
• Tim Pickens on rocket ventures and the Google Lunar X Prize

Seth Shostak has a talk show, too! Hear it at "Big Picture Science."

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

If we ever come across traces of an advanced alien civilization like the one featured in "Prometheus," the new semi-prequel to the "Alien" movie series, our first course of action should not be to send them a shipload of human meat. Instead, send in the robots.

At least that's the prescription from Seth Shostak, senior astronomer at the California-based SETI Institute. "Would you indeed load up a starship with alien fodder and send it out?" he asked me. "Of course you wouldn't, because we don't know how to do that."

Sure, the crew of the starship Prometheus starts out in the year 2089, when we can assume that fusion power has solved our energy woes. But there's no chance that we'd be able to mount an interstellar trip by then, unless Spock and his pals from the planet Vulcan beam down and show us how. Even assuming that an ion-powered starship like the Prometheus could somehow get to other stars in a realistic (and relativistic) time frame, Shostak said he wouldn't send the humans on the first expedition to LV-223, the scene of the action in "Prometheus." 

"I think what you'd probably do is load up a spacecraft with sensors of all types, radio receivers, cameras, spectrometers, anything you can take up, essentially make it a Mars Viking mission, and just have it radio back what it finds," he said. "That's a heck of a lot less dangerous, and beyond that, it's a lot easier, because you don't have to put all this life support stuff and these cantankerous hominids on the rocket."

Even better, you could have that spaceship peopled by androids like David (played by Michael Fassbender in the movie), who basically steals the show in "Prometheus" anyway. That way, you avoid the ickiness of having monsters incubate inside human wetware, as they did in the original "Alien."

"If you can design an android that can do all the things that they do in these films, why is it that they haven't gone one step further and just replaced us with the androids?" Shostak asked. "Machinery can evolve much more quickly than biology. It's funny that they all get stunted at just the level where they're mostly helpful and occasionally malevolent."

Of course, without all that human cantankerousness and ickiness, you don't have much of a space horror movie. And be assured, there's plenty of both in "Prometheus." There's also a little real-life science in the movie, thanks in part to Kevin Hand, deputy chief scientist for solar system exploration at NASA's Jet Propulsion Laboratory. Hand served as a consultant on the film, and one of the first things he learned is that you should never let scientific qualms get in the way of a good movie.

"Being a scientist working with filmmakers, you have to keep in mind that the story comes first," Hand told me. "The science is a way to motivate certain elements and provide aspects of the plot. As long as you go in with that understanding, as a scientist, you can let your guard down a bit and not be constrained — which is different from our normal day-to-day scientific metabolism."

With that in mind, here are five themes in the movie that include a twist of scientific realism:

Habitability: Early into his involvement, Hand gave film director Ridley Scott and his team a tutorial on the different environments in our own solar system, ranging from steaming-hot Venus to cold, dry Mars and ice-covered Europa and Enceladus. The setting for the movie, LV-223, is a moon that orbits a giant planet in its parent star's habitable zone. That's similar to the fictional moon in the movie "Avatar," which orbits a Jupiter-like world named Polyphemus. It might also be similar to the theoretical moons circling 55 Cancri f, a planet detected about 41 light-years from Earth.

Hand noted that LV-223 is habitable in the Earthlike sense, meaning that it has an atmosphere and could conceivably support life at the surface. But he thinks that most livable environments are less like Earth and more like Europa, a Jovian moon that is thought to have a miles-deep ocean of water hidden beneath its forbidding surface ice. "Much of the habitable real estate in the universe might be within these ocean worlds that are covered with ice," Hand said. By his reckoning, Earth would be the peculiar planet.

Panspermia: I hope I'm not giving anything away when I say that "Prometheus" touches on the theme of panspermia — the idea that the building blocks of life, if not life itself, can be transferred from one planet to another. It's a great sci-fi theme, but it's not necessarily science fiction. Some theorists have proposed that life could have gotten its start on Mars, which was warmer and wetter billions of years ago, and then hitchhiked its way to Earth on the debris thrown up from a meteor blast. Or life could have come to Earth from farther out in the cosmos, borne by an impacting comet.

Hand pointed out that NASA's Kepler mission has detected thousands of potential planets in just one little patch of sky. That leaves plenty of opportunities for finding life out there, and plenty of opportunities for life to make its way here.

"Here we are on Earth, a planet in a solar system around a star that is 4.6 billion years old, which seems like an incredibly long period of time to us," Hand said. "But the universe is 13.7 billion years old. So there was a lot of time before the solar system even came about, 8 billion years or so of the history of the universe, during which many forms of life, many advanced civilizations, could have come and gone. They could still be there now, or they could have died off billions of years ago."

Propulsion: The Prometheus starship uses an ion propulsion system that gives a nod to the real-life ion drives used by probes such as the Dawn spacecraft, which is currently in orbit around the asteroid Vesta, Hand said. "The spacecraft that they're using is a much more advanced version of that kind of propulsion, but it's got a link to our current mode of exploring the solar system," he said.

It's unlikely that ion propulsion will be able to provide the power and maneuverability that Prometheus has anytime soon, and certainly not by 2089. But ion drives could offer a good option for interplanetary or interstellar flight. Their hallmark is slow but steady acceleration, starting out with as much force as it takes to hold up a piece of paper. Unlike chemical rocket engines, ion propulsion drives keep going, and going, and going, building up a figurative head of steam. Some experts suggest that nuclear or solar electric ion propulsion will provide the oomph for eventual missions to Mars.

Mapping: In the film trailer, there's a scene where the away team tosses out a few flying robotic spheres that scan the underground caverns with lasers and send back mapping data. Hand said he couldn't take total credit for that idea, but the robo-balls are based on the same principle that Stone Aerospace is using to design real-life submersible robots capable of observing and mapping subglacial lakes in Antarctica or, perhaps eventually, on Europa. "I mentioned some of that work to the artistic team," Hand recalled. There's just one big difference: The real-world robot, known as the Deep Phreatic Thermal Explorer, or DEPTHX, will be "going through underwater environments on Earth as opposed to exploring alien spaceships," Hand said.

Terraforming: At one point in the movie, Prometheus' away team finds out that they can take off their helmets and breathe the air inside an underground cavern. Hand was asked to come up with a plausible explanation for that plot point, and he proposed that an alien civilization could easily come up with a nuclear-powered device that electrolyzes water to produce oxygen. Heck, even we puny humans are thinking of ways to use rock-eating microbes to make Mars more livable. It won't happen overnight ... but maybe it could happen by 2089, if we play our cards right.

"Prometheus" focuses on an expedition to go after to the aliens, but what if the aliens were of a mind to come after us? Should we lie low, as famed physicist Stephen Hawking has suggested? Unfortunately, it's too late for that, Shostak said.

"For any society that could come here to do nasty things to us ... it's very easy to show that they could pick up all the stuff we've been sending out since the Second World War. In fact, they could pick up the lights of New York City," he said. "In a sense, we've already told the aliens we're here. The idea that it might be dangerous if we found some planet over there, so don't send them anything ... it's too late. That's not to say it might or might not be dangerous. We have no idea. But it's too late. It's silly to worry about it, because it would require that you lay low not just for the weekend, but forever. Forever! That would so cramp the sorts of things that our descendants could do, that I don't think that policy would have legs."

And if the aliens really do come after us? If they have the capability to project their firepower over a distance of light-years, forget what you saw in the movie "Battleship." We're toast.

More about the search for alien civilizations:

• Expert doubts alien visitors would terrorize us
• Queen of SETI retires from research
• City lights could point to E.T.
• What if E.T. thinks we're evil?
• What would you ask E.T.?
• Cosmic Log archive on aliens

More Hollywood reality checks:

• Reality check on 'Hunger Games' tech
• Invisibility and other 'Harry Potter' technologies
• 'John Carter' and the real-life Martian quest
• Virtual actor takes over in 'Tron: Legacy'
• Apollo 18 in fiction and fact
• 'Avatar' and the future of 3-D moviemaking
• Reality check for 'Star Trek' tech

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Alan Boyle / msnbc.com

SETI astronomer Jill Tarter looks out from the radio dish named after her at the Allen Telescope Array in northern California. The array's 42 linked dishes search for signals from extraterrestrial civilizations.

The real-life astronomer who inspired the central character in "Contact," the book and movie about the search for extraterrestrial intelligence, is retiring from her research post at the age of 68. But that doesn't mean Jill Tarter is giving up on the SETI quest. Instead, she's focusing on the search for funding for the non-profit SETI Institute.

For most of the institute's 28-year history, Tarter has been serving as director of the Center for SETI Research as well as holding the Bernard M. Oliver Chair for SETI. "I've worn two hats," she explained. Now she's passing along the center's top research hat to physicist Gerry Harp, a colleague at the institute — and wearing the Oliver Chair hat full-time as a fundraiser.

"We have got to get this endeavor stably funded," she told me.

Tarter knows as well as anyone on Earth how much of a challenge that will be. In the 1980s and 1990s, she participated in NASA-funded efforts to search for alien radio signals — efforts that drew intense fire from some members of Congress. The fire became so intense that NASA as well as the National Science Foundation were barred from funding SETI research in 1993. To keep hope alive, Tarter spearheaded a program to continue the search with private donations.

Breakthrough ... then, a bummer
A breakthrough came in 2007 with the dedication of the 42-antenna Allen Telescope Array in Northern California, a facility funded with $25 million in seed money from software billionaire Paul Allen and matching funds from other contributors. The SETI Institute partnered with the University of California at Berkeley to operate the array, and it looked as if the search for alien signals was finally on stable footing.

That didn't last long, however.

Berkeley had to drop out of the partnership due to money troubles. Last year, the institute mothballed the array and put out a plea for $200,000 in contributions to restart operations. "That certainly put an exclamation point on the funding crisis," Tarter said. The money was raised in a month and a half — thanks in part to a big financial and moral vote of support from actress-director Jodie Foster, who played the Tarter character (named Ellie Arroway) in the movie version of "Contact."

Now the telescope array is back in business with a new partner, SRI International, which maintains the facility in return for getting half of the array's observing time to track satellites and orbital debris for the U.S. Air Force. But Tarter wants to get the institute's SETI effort out of its scrimp-and-scrape mode. "Lots of startups do that, but they don't last very long if they don't get secure funding," she said.

One of Tarter's top objectives is to build up an endowment for SETI research. "I find it very interesting that at any one time, even in this economy, there are endowment campaigns of $100 million. We could be one of them," she said.

Stable funding would reassure the researchers who work with the institute that they'll be able to pursue their projects over the long term, Tarter said. "We have to make this a real destination for folks who want to do visionary things. ... They're in some sense hanging on a cliff, because there's no guaranteed scientific payoff, although there are lots of interesting instrumentation payoffs along the way," she said.

New twists for SETI
Lots of interesting twists are in store for the SETI quest. For example, researchers are working their way through a list of hundreds of candidate planets identified by NASA's Kepler mission. Tarter said about 10 percent of the Kepler field has been surveyed so far, at a rate of 30 targets a day.

"We don't yet have Earth 2.0, but we almost can taste it," she said. "That will change the whole approach. Does anybody live there? That's going to concretize so many things which are now a bit abstract."

The institute is already using a survey setup that checks three star systems at once for telltale patterns in radio emissions that could hint at an artificial source. The setup, known as SonATA, uses the triple-check to confirm the nature of any interesting effect that's detected. If the same effect is detected from three separate directions, that's a tip-off that the telescopes are picking up on earthly radio interference rather than E.T.'s phone call. 

"The next thing we're going to take on is real-time imaging of a wide field of view," Tarter said. "There are lots of challenges there, and lots of opportunities for SETI detections that haven't been there in the past."

Those are the sorts of challenges that Gerry Harp will be taking on as the new director of the Center for SETI Research. Meanwhile, Tarter will be focusing on the long-term future of the search for extraterrestrial intelligence.

"If we can get the research to the next level, there is something so fundamental that we can learn from the detection of a signal, even if it's just a cosmic dial tone," Tarter said. The message would be that technological civilizations can actually survive long enough to reach out to other corners of the cosmos.

"If they can do it, then dammit, we can do it," Tarter said.

More about the SETI quest:

• Gallery: 50 years of looking for E.T.
• Interactive: What are the odds of finding E.T.?
• Scientists need your eyes to look for E.T.
• Cosmic Log archive on SETI

The SETI Institute is celebrating Tarter's 35 years of SETI research at SETIcon II, set for June 22-24 at the Santa Clara Hyatt in California's Silicon Valley. SETIcon is a public convention that draws together more than 60 scientists, artists and entertainers to focus on the present and future search for life in the universe. Tarter will be honored at a gala event on June 23. Speakers will include fellow SETI astronomer Frank Drake; former astronaut Mae Jemison, a leader of the 100 Year Starship effort; and "Star Trek" actor Robert Picardo. Tickets are available via the SETIcon website.

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.

Planetary Habitability Lab / UPR

This "periodic table" of exoplanets, including confirmed planets as well as candidates from NASA's Kepler mission, places exoplanets into 18 categories based on mass and temperature. The numbers keep track of how many worlds are in which categories. Click on the image to see a larger, more readable version.

Researchers have set up an online "periodic table" for extrasolar planets ranging from Hot Mercurians to Cold Jovians, with Earthlike worlds right in the middle. 

The Habitable Exoplanets Catalog, drawn up by the University of Puerto Rico's Planetary Habitability Laboratory, is aimed at pigeonholing the hundreds of worlds that are being identified by NASA's Kepler space telescope and other planet-hunting projects. Eventually, the tally of exoplanets is expected to mount into the thousands, and that's where researchers hope the proposed catalog will come in handy.

"One important outcome of these rankings is the ability to compare exoplanets from best to worst candidates for life," Abel Mendez, the laboratory's director and principal investigator for the project, said today in a news release.

Also today, Kepler's scientists said they've confirmed the existence of their first exoplanet solidly within the habitable zone of its solar system, where water could exist in liquid form at a pleasant 72 degrees Fahrenheit (22 degrees Celsius). That certainly sounds livable, but Mendez told me that the planet, known as Kepler-22b, doesn't quite fit into the sweet spot for habitability because it's closer in size to Neptune than to Earth.

"I confirmed its radius, and Kepler-22b is a low-end Warm Neptunian, very close to a Superterran," Mendez said in a Twitter back-and-forth from NASA's Ames Research Center in California, where he was presenting his research at the Kepler Science Conference.

Neptunians are likely to have a gaseous rather than a rocky composition, which might make it tough for life as we know it on Kepler-22b. However, the situation might be more hospitable on a moon orbiting the planet, just as it is in the movie "Avatar" for the inhabitants of Pandora, a fictional moon orbiting the gas giant Prometheus.

How the catalog was created
The Habitable Exoplanets Catalog sets up a matrix of 18 pigeonholes based on temperature and mass: Planets in the Hot Zone would be too close to their parent suns for water to exist in liquid form. Water would exist only as ice in the Cold Zone, but could take liquid form in the Warm Zone. The catalog sets up six categories of planetary mass: Mercurians (think Mercury), Subterrans (Mars-size), Terrans (Earth-size), Superterrans (up to 10 times as massive as Earth), Neptunians (Neptune-size) and Jovians (Jupiter-size).

To figure out which planets fit which categories, the catalog draws upon a variety of resources, including the Kepler database of candidates, the Extrasolar Planets Encyclopaedia, the Exoplanet Data Explorer, the Earth Similarity Index, the Habitable Zones Distance metric and the Global Primary Habitability index.

The initial classification of more than 1,600 confirmed planets and yet-to-be-confirmed candidates puts only 16 potential worlds in the habitable categories — that is, Warm Subterrans, Warm Terrans and Warm Superterrans. But that list will grow: The Kepler team announced today that its tally of candidates has risen to 2,326, based on the first 16 months of the space telescope's mission. Forty-eight of those candidates are said to lie in their stars' habitable zones.

"The tremendous growth in the number of Earth-size candidates tells us that we're honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable," Natalie Batalha, Kepler's deputy science team lead at San Jose State University, said in a NASA news release. "The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods."

Mendez and his colleagues are working on software to keep the Habitable Exoplanets Catalog updated. "The computers are doing the job," he told me. "I am trying to automate everything, but it takes time."

Right now, the world in the database that's judged most similar to Earth is a candidate known as KOI 736.01, which is 1,750 light-years away and is estimated to have a surface temperature of 55 degrees F (286 Kelvin). But the top prospect for surface habitability is KOI 255.01, a Warm Superterran that's 1,169 light-years away with a surface temperature of 86 degrees F (303 K). Some researchers believe super-Earths can be even more conducive to life than Earth.

Gliese 581d, a world that orbits a red dwarf just 20 light-years from Earth, shows up among the Sweet 16 on both lists.

The search revs up
So what's next? "I hope this database will help increase interest in building a big space-based telescope to observe exoplanets directly and look for possible signatures of life," Jim Kasting, a planetary scientist from Penn State, said in the Planetary Habitability Laboratory's news release.

A habitability index could help scientists set the priorities for future observations, but they don't necessarily need to wait until a new super-space telescope is launched. During the Kepler conference, the California-based SETI Institute announced that it was once again searching planetary systems for radio signals that could serve as evidence of extraterrestrial intelligence. Some of Kepler's planetary candidates are among its first targets.

"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," Jill Tarter, director of the institute's Center for SETI Research, said in a news release. "That's the type of world that might be home to a civilization capable of building radio transmitters."

Tarter and her colleagues makes use of the Allen Telescope Array, a network of radio antennas in northern California that had to be put into hibernation due to money troubles. The SETI Institute was able to restart work at the array thanks to contributions made by the public through the SETIStars.org website, as well as funding from the U.S. Air Force to assess the array's utility for space situational awareness (that is, monitoring the skies for hazardous asteroids and space debris).

Tarter said the highest priority would be given to Kepler planets that are located within their stars' habitable zones. But the search for extraterrestrial intelligence won't stop there.

"In SETI, as with all research, preconceived notions such as habitable zones could be barriers to discovery," she said. "So, with sufficient future funding from our donores, it's our intention to examile all of the planetary systems found by Kepler."

More about the planet quest:

• Which alien worlds are most livable?
• City lights could point to E.T.'s home
• Super-Earth on the 'edge of habitability'
• Interactive: How scientists search for planets
• Astronomers find 18 alien planets, and they're huge

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

David A. Aguilar / CfA

If an alien civilization builds brightly lit cities like those shown in this artist's conception, future generations of telescopes might allow us to detect them.

Astronomers suggest that artificial illumination creates a signature that could point to the existence of civilizations on other worlds — and they say we should get started on a survey of the edges of our own solar system, just in case.

The suggestion comes from Harvard's Abraham Loeb and Princeton's Edwin Turner, in a research paper submitted to the journal Astrobiology. A version of the paper appears on the arXiv.org preprint server and sparked a write-up today on Technology Review's Physics arXiv Blog.

Loeb, who chairs Harvard's astronomy department and is affiliated with the Harvard-Smithsonian Center for Astrophysics, acknowledged that detecting aliens by looking for the glow of their cities would be a long shot. But he pointed out that the cost of the exercise would be low.

"We say that we can piggyback on existing surveys that people are doing anyway. There's no need to use extra resources. ... My philosophy is simple: If we can do it, why not do it and check? Why put blinders on ourselves?" Loeb told me today.

Here's how the idea could work: An object's brightness varies with distance, but the relationship between those two factors will depend on whether the brightness is due to reflected sunlight or due to illumination from the object itself. For a self-illuminated object, the brightness varies by a factor of 1 over the distance squared, but "if you have an object that reflects light from another source ... the flux dies out like 1 over the distance to the fourth power," Loeb said.

Monitoring the changes in the brightness of an object on the edge of our solar system, in a broad disk of icy material known as the Kuiper Belt, could provide a "very simple test" to determine whether extraterrestrials have turned on the lights, Loeb said.

"We conclude that existing telescopes and surveys could detect the artificial light from a reasonably brightly illuminated region, roughly the size of a terrestrial city," on a Kuiper Belt object, Loeb and Turner write.

NASA

The lights of Cairo, Alexandria and the Nile shine through the night on Oct. 28, 2010, as seen from the International Space Station. Astronomers say such illumination could serve as a tip-off in the search for civilizations on other worlds.

How likely is it that E.T. would be found on the edges of our own solar system? Not that likely, but Loeb and Turner speculate that it could happen. "Artificially lit KBOs [Kuiper Belt objects] might have originated from civilizations near other stars," they write. "In particular, some small bodies may have traveled to the Kuiper Belt through interstellar space after being ejected dynamically from other planetary systems."

In addition to the E.T. search, Loeb said the Kuiper Belt survey would also be useful for studying how Kuiper Belt objects reflect light at different points in their orbits. "Even if the answer is, 'No, there is nothing peculiar,' we can still learn something from doing that," he told me. "And if there's something out there worth finding, that could change our perception of our place in the universe."

The technique could conceivably be extended to other stars once next-generation telescopes such as the James Webb Space Telescope and the Giant Magellan Telescope come online, over the next decade or so. There's been a lot of debate over whether the traditional search for radio signals from alien civilizations might be fruitless if E.T. moved beyond analog radio transmissions — and the search for artificial illumination could be worth checking out as a new frontier.

Someone could even try looking for the spectral signature of artificial light. (Do aliens use incandescent bulbs, compact fluorescent or LEDs?) But that particular kind of search would not be easy.

"For this signature to be detectable, the night side needs to have an artificial brightness comparable to the natural illumination of the day side," Loeb and Turner write. And when you consider that Earth's day side is about 600,000 times brighter than the night side, that means E.T. would have to cope with one heck of an electric bill.

What do you think about the search for E.T.'s city lights? Feel free to add your comment below.

More about the search for extraterrestrial intelligence:

• Donations revive the SETI quest
• Gallery: Four decades of SETI
• Alien-hunters add super-Earths to their list
• A new idea in the search for E.T.'s footprints
• More from Cosmic Log about aliens ... and about SETI

Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding me to your Google+ circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds. 

SETI Institute

Radio antennas stand sentinel at the Allen Telescope Array, north of San Francisco.

The SETI Institute's search for extraterrestrial intelligence is back on track, thanks to more than $200,000 in donations from thousands of fans.

"We're not completely out of the woods yet, but everybody's smiling here," the institute's chief executive officer, Tom Pierson, told me today.

In April, the institute had to put its big ear for hearing E.T.'s radio call, the 42-antenna Allen Telescope Array in Northern California, into "hibernation" due to budget woes. The biggest hit was the loss of funding by the University of California at Berkeley, the institute's partner for operating the antenna array.

The SETI Institute has been around for decades: It stepped in to help keep the search for alien radio signals active after NASA cut off funding for the quest in 1993. It's not the only organization doing SETI, but it's the leader in the field. The Allen Telescope Array, or ATA, was launched with $50 million in contributions from software billionaire Paul Allen and others — and if the array ever takes in 350 linked antennas, as it's designed to do, it would rank among the world's premier radio-telescope facilities.

But in light of the financial challenges, that's a huge "if" right now. In fact, until last week it wasn't certain if or when the ATA would come back online.

After the antenna array was mothballed, the institute and its fans in Silicon Valley set up a Web-based campaign for donations, known as SETIstars. The campaign kicked off in June, and about 45 days later, on Aug. 3, contributions hit the $200,000 mark. That was how much money the SETI Institute said would be needed to bring the antenna array back into operation. (Since then more than $4,000 in additional contributions have come in.)

Among the contributors are Jodie Foster, the actress who played a SETI researcher in the movie "Contact"; science-fiction writer Larry Niven, creator of the "Ringworld" series of novels; and Apollo 8 astronaut Bill Anders, who flew around the moon in 1968. "It is absolutely irresponsible of the human race not to be searching for evidence of extraterrestrial intelligence," Anders wrote in a note accompanying his contribution.

Pierson said the institute's managers and scientists were drawing up a plan that would restart science operations in September.

"We think we're going to come out of hibernation and be solid for the next five months or so, and during those five months we're going to take care of calendar year 2013 and put that under our belt," he said.

Pierson acknowledged that the ATA's long-term success would "require a mix of funding," including continued contributions as well as renewed cash flow from other applications for the radio array. The institute is hoping that the U.S. Air Force will use the array to  track orbital objects that otherwise might pose a threat to the International Space Station and other satellites. During the daytime, the ATA could be used for the Air Force's "debris deconfliction," and during the night it could search for alien signals, Pierson said.

The institute is also looking for ways to reduce the array's operating costs from the current level of $1.5 million per year, plus another $1 million for science operations, Pierson said. "We need to transition to a new modality without UC-Berkeley," he said.

Eventually, astronomers at the SETI Institute hope to use the ATA to listen for signals from the most promising planetary systems identified by NASA's Kepler planet-hunting mission. Jill Tarter, the institute's director of SETI research, said in April that the fund-raising target for the Kepler follow-up project would be $5 million.

The institute has already set up a website called setiQuest, where citizen scientists can help sift through the data expected from the ATA, and SETIstars will remain open to receive donations, Pierson said. He had two messages for the SETI supporters: "No. 1 is how grateful we are," he told me. "More than 2,000 people jumped in and help. Also, stand by for future campaigns from SETIstars. We hope to build opportunities that will really excite the public."

More about the search for alien signals:

• New E.T. hunt tunes in on Earthlike planets
• Calculate the odds of finding E.T.
• Are we alone in the universe? Well, maybe
• Gallery: 50 years of searching for E.T.
• Search for extraterrestrials on msnbc.com

Connect with the Cosmic Log community by "liking" the log's Facebook page or following @b0yle on Twitter. You can also add me to your Google+ circle, and check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

SETI Institute

The Allen Telescope Array, a field of radio dishes in northern California looking for E.T. has been put in hibernation mode due to budget woes.

Financial woes have delivered a serious blow to the search for E.T. One of its best tools, the Allen Telescope Array in northern California, has been put on hold until new funding is located.

"It is a huge irony," Jill Tarter, director of SETI research at the SETI Institute in Mountain View, Calif., told me today. "Now we actually know where to point the telescopes to look at planets, but we don't have the telescopes to point right now, so a very ironic situation."

For decades, astronomers have pointed their telescopes at stars they thought were likely to have planets around them. This February, the first results from the NASA's Kepler Mission revealed 1,235 potential worlds in orbit around distant stars.

ATA financial woes

Since October 2007, the array of 42 radio telescopes located about 300 miles north of San Francisco has been searching for radio signals from stars that could indicate the presence of technologically advanced extraterrestrials.

The array is the instrument most dedicated to the E.T. search. The first phase was built with a $25 million gift from the foundation of Microsoft co-founder Paul Allen and another $25 million in private donations. Plans call for an eventual build out to 350 antennas, though the recession has slowed progress. (Msnbc.com is a joint venture of Microsoft and NBC Universal.)

In a letter to donors, Tom Pierson, the CEO of the SETI Institute, explained that the array was put in "hibernation" due to budget woes and is being maintained in a safe state by a skeleton staff.

The array is a partnership between the SETI Institute and the Radio Astronomy Laboratory at the University of California at Berkeley. The institute is responsible for construction; the university for operations.

Franck Marchis, an astronomer affiliated with both institutions, broke the news about the hibernation in a blog post April 22. The ATA was put to sleep on April 15.

The Hat Creek Observatory, where the array is located, took a financial hit when the Radio Astronomy Laboratory lost funding from the National Science Foundation and the state of California that was used for its operations.

Running the ATA costs about $1.5 million a year and the SETI science campaign at ATA costs an additional $1 million annually, according to Pierson's letter.

New funding opportunities
One hope for new funding of long-term operations at the array is a potential partnership with the United States Air Force Space Command to use the array to help track space debris, a growing threat to satellites and manned spacecraft such as the International Space Station.

"This effort is ongoing and showing much promise, but near term funding has been delayed due to the same, highly publicized large scale federal budget problems we all read about in the news," Pierson writes in his letter.

NASA funding for SETI projects ceased in 1993, though the space agency continues to support tangentially-related research, including the Kepler mission to search for planets orbiting other stars. The SETI Institute hopes to raise $5 million to use the ATA to search the most promising Kepler targets.

"We hope that the public will get inspired to help us explore those Kepler worlds," said Tarter, who added the institute is also relying on citizen scientists to help develop computer code and algorithms for the setiquest and Galaxy Zoo programs.

The is all part of a push, she noted, to get people really thinking about what it means to be on the lookout for extraterrestrial intelligence and "to think about how we are so intimately related to the cosmos, to think about us in a bigger perspective so that perhaps we can do something about minimizing the differences we struggle with and make the point that we really are all Earthlings."

More stories on SETI and the ATA:

• E.T. calling? Here's what to do
• Hey, E.T.! The line is open
• SETI: 50 years of searching for E.T.
• New channels in the search for E.T.

What would happen if we found out that we are not alone in the universe? Or, on the flip side, what would happen if we decided that we really were alone? Experts provided updated answers to those age-old questions, from a scientific as well as a religious angle, during a Sunday session at the American Association for the Advancement of Science's annual meeting. But one of the most intriguing questions had more of a personal spin: What would you ask E.T. if you had the chance?

First, here's some background:

Questions surrounding the possibility of life beyond Earth might get more serious sometime in the next quarter-century or so. Wesley Traub, chief scientist for NASA's Exoplanet Exploration Program, predicted that by 2030, five Earth-scale planets would be identified among the 100 closest star systems as worthy of being studied for signs of life. He based that prediction on the most recent lineup of candidates from NASA's planet-hunting Kepler probe.

"About a third of all planets are planets that could have life on them," he said — that is, Earth-size worlds or super-Earths.

Looking for alien life
What would scientists look for when it comes to life detection? Traub speculated that future spacecraft could analyze the atmospheres of alien worlds for signs of high oxygen levels and water vapor. Spectral analysis of the light reflected by those planets might even turn up the chemical signature of chlorophyll or other chemicals indicative of life. But it'd be almost impossible to tell whether the alien organisms are one-celled creatures, six-legged dinosaurs or intelligent species. If they're smart enough to communicate with us, the only way we'd know is through well-known means such as radio signals or laser bursts (or maybe orchestrated blasts from a stellar beacon).

Seth Shostak, senior astronomer at the SETI Institute, has said that evidence of alien life — either through such direct contact or through long-distance chemical analysis — could become available in a time frame ranging from 2025 to 2035. And he bet his listeners at Sunday's talk that he'd buy them a cup of coffee if E.T. wasn't found in their lifetime. (Will that bet ever pay off? Think about it: You can't take your Starbucks with you.)

So what would society do if life is detected? At Sunday's talk, science historian Owen Gingerich said the first scientific claims for E.T.'s existence would likely be hotly contested, just as the Mars meteorite microfossils have been for the past 15 years. Even if the findings are confirmed, it would take years for the implications to sink in.

Most of the leaders of the world's religions say extraterrestrial life wouldn't shake their faith. But 16th-century theologian Giordano Bruno was burned at the stake after saying so, and even today some believers say E.T.'s existence would make a "mockery" of Christianity. Like it or not, religious institutions and other pillars of society would have to accept (or deny) a paradigm shift at least as big as the shifts sparked by astronomy and biology. 

Misanthropic principle
What if life is not detected? It's pretty hard to prove a negative, but suppose future probes analyze the atmospheres of scores of Earth-size planets ... and find nothing worthy of note. Suppose the search for extraterrestrial intelligence continues for a century ... and no messages are received. Howard Smith, a senior astrophysicist at the Harvard-Smithsonian Center for Astrophysics, said the evidence already suggests that intelligent life is extremely rare in the universe, and we're the only sentient beings within a 1,250-light-year radius. (Smith chose that figure because it's about as far as humans could possibly travel during a 100-generation round trip at the speed of light.)

"We are probably alone and will have to solve our own problems," he said at Sunday's talk.

Smith calls this the "misanthropic principle." That term plays off the widely cited anthropic principle — the idea that Earth appears to be so suited for life as we know it not necessarily because God made it that way, but simply because we wouldn't be around to see it if it wasn't.

The way Smith sees it, the misanthropic principle is a good thing. The view that we alone are responsible for our zone of the cosmos should make us feel "blessed," and more careful about not spoiling the good thing we've got here.

"The misanthropic principle is joyous," Smith said. "We should rejoice in our good fortune."

Is it depressing or liberating to think that we're truly the best the universe has to offer, at least in this celestial neck of the woods? Feel free to add your comments below.

Oh, and about the question we started out with: What would you ask E.T. if you had the chance? This came up during the question-and-answer session, and one of the suggestions was along the lines of "Dear E.T.: Do you have a religion?" (That led science writer David Despain to quip in a Twitter comment: "Hello, I'm a Jatravartid. Let me share with you the message of the Great Green Arkleseizure's white handkerchief.")

Personally speaking, I'd rather ask: "How did you do it? How did you survive long enough to get to this point of contact?" If E.T. responds by raising its ray gun, I'd probably have the answer I wasn't hoping to get.

But what would you ask? 

More about the search for aliens:

• How would alien life change your life? 
• What to do if we find alien life
• Calculate the odds of finding E.T.
• Hawking: Aliens may pose risks to Earth
• Still more about the search from msnbc.com

Join the Cosmic Log community by clicking the "like" button on our Facebook page or by following msnbc.com science editor Alan Boyle as b0yle on Twitter. To learn more about Alan Boyle's book on Pluto and the search for planets, check out the website for "The Case for Pluto." 

NASA

In 1977 NASA's Voyager 1 and 2 spacecraft launched into space carrying phonographs called the Golden Records containing pictures and sounds meant to show extraterrestrials a glimpse of life on Earth. The records were engraved with pictures explaining how to play them. Click on the picture for an explanation of the code.

When E.T. sends us Earthlings a message, what should we say in response? Three alien hunters suggest in the journal Space Policy that we should develop an international protocol for sending effective, intelligible communications. A website could be set up for people around the world to leave messages, following the protocol, so that we can then figure out what messages are best-suited for cross-cultural communication.

"An effective message to extraterrestrials should at least be understandable by humans," Dimitra Atri of the University of Kansas, Julia DeMarines of the International Space University, and Jacob Haqq-Misra of Penn State University write in their paper.

The concept of creating and testing such a protocol fits with the thinking of other space experts, according to Douglas Vakoch, director of interstellar message composition at the California-based SETI Institute.

Cornell

This graphic was transmitted in coded form in 1974, using the Arecibo radio telescope. Click on the picture for an explanation of the code.

The proposal from the three researchers "is on target in really wanting to encourage an open, transparent process for engaging the world community in thinking about how we would want to represent ourselves, and how we would create a message that stands a chance of being understood," Vakoch told me today.

Talking to E.T.
Unless E.T. comes to Earth in a spaceship and gets out for a meet-and-greet, the chances of a face-to-face encounter anytime soon are close to nil. Instead, cross-civilization communication will have to span vast distances, using technology such as radio waves and pulses of light.

Astronomers on the lookout for these types of communications have already established protocols for making sure a communication received isn't just a natural noise or interference from a satellite. They've also established first-order steps to decipher the message, such as determining the basic units of the information sent.

This same community of researchers has also spent the past 50 years chewing on the question of what to say to E.T. The trick, noted Vakoch, is finding something that is universal.

"Some have focused on pictures, with the idea that vision has been very helpful here on Earth and so too might be helpful on another world," Vakoch said. "You might expect intelligent creatures on another world to be visual creatures as well."

But what may be a meaningful picture to a person from a Western culture may be gibberish to the indigenous Maori people in New Zealand, for example.

"Similarly, a Westerner may look at some ceremonial carving from the Maori and say, 'You know, that's a beautiful geometrical shape,' but a Westerner may miss the fact that there's a human body being depicted in that message," Vakoch said.

Another idea is to use basic math and science. After all, if alien beings are able to communicate with us, they must have the engineering and technical know-how required to send messages across interstellar distances.

"I think the key to creating a message that has a reasonable chance of being understood is to send as many distinct messages as you can, with the hope that at least one of them might be understood," Vakoch said. "Anyone who claims they have one message that will undoubtedly be understood is overly optimistic."

Sharing ideas
The Space Policy paper calls for setting up a website where users around the world can submit messages that fit the protocol. This will allow the discovery of "the types of messages better suited for cross-cultural communication," the authors write.

The SETI Institute's Earth Speaks project is built along these lines, notes Vakoch. The website solicits suggestions for the most important things that people want E.T. to know about life on Earth at the beginning of the 21st century.

Vakoch said the idea proposed in the Space Policy paper is complementary and attracts another audience to mull the questions surrounding what to say to E.T. "We need more people involved in space policy to be thinking about these issues," he said.

More on the alien quest:

• E.T. calling? Here's what to do
• How should we 'talk' to aliens?
• What to do if we find alien life 
• Are we missing E.T.'s call?
• Calculate the odds of finding E.T.
• Stephen Hawking worries about the aliens
• Too risky to phone E.T.? Too late — NASA's tried
• Six frontiers for extraterrestrial life

Tip o' the Log to Lisa Grossman at Wired.com.

John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).

Rumors and speculation are swirling on the Internet about the subject of a news conference to be carried live at 2 p.m. ET Thursday on NASA TV "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," NASA explains in its advisory. And that's about as much as the space agency is saying about the discovery right now. However, the advisory includes a list of the speakers for the briefing. That's what led to the online guessing game.

Among those speakers is Felisa Wolfe-Simon, a researcher at the U.S. Geological Survey who says she's concentrating on "arsenic biogeochemistry, cyanobacteria, novel uses for as yet undescribed metalloenzymes and of course, arsenic-based life!"

Other speakers include NASA astrobiologist Pamela Conrad, who specializes in planetary habitability assessment; Steven Benner of the Foundation for Applied Molecular Evolution, who studies the chemical foundations of biology; and Arizona State University's James Elser, who focuses on life in extreme environments. 

Blogger Jason Kottke put all those pieces together and speculated that Thursday's announcement would be about the discovery of life on Saturn's moon Titan. But that suggestion was shot down as false in a Twitter post from The Atlantic Monthly's senior editor and science blogger Alexis Madrigal.

Will the secret survive until Thursday? Back in August, NASA let information slip out an hour before the embargo lifted on a report in the journal Science about the discovery of two giant planets in constantly changing orbits. In that instance, NASA made its news release and other information about the discovery publicly available. Going even further back, to 1996, there's the famous case of the Mars meteorite study that leaked out in advance of publication in Science.

What do you think has been found? Feel free to weigh in with your comment, but please respect any information known to be under embargo.

John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).