Universal Studios

E.T. charmed Elliott (Henry Thomas) and millions of moviegoers in the 1982 movie "E.T.: The Extraterrestrial."

Thirty years ago, a different kind of alien hit the screen: a vulnerable, cuddly, candy-munching creature that captured hearts as well as box-office records. Is "E.T." still relevant for the 21st century? If you're looking for the extraterrestrial that humanity is most likely to run into first, E.T. definitely doesn't fit the mold. But if you're looking for the cultural icon that's most likely to motivate the search for honest-to-goodness extraterrestrials, E.T. just might be your A-list alien.

"If you look at the number of films that involve extraterrestrials these days, it's something like five or 10 a year," Seth Shostak, senior astronomer at the California-based SETI Institute, told me today. "And most of them are kinda nasty. What I liked about E.T. is that, after all, he was just a botanist who came to Earth and played with the kids.

"He was a good tonic against the xenophobia we have about aliens. He's no more realistic than those other aliens, but his appeal encouraged folks to think that searches such as SETI were maybe not a bad thing."

SETI — the search for extraterrestrial intelligence — is Shostak's specialty. In addition to conducting decades of research in the field, he's written books about aliens, advised moviemakers about them, and hosts a radio show that often touches upon the search for alien signals. If an unrealistically cute and cuddly alien gets more people interested in the quest, that's just fine by him.

"Look, none of these movie aliens are realistic," he said. "Certainly all of the good guys are relatively anthropomorphic. You could analyze it in terms of the science ... but to me, all of the alien films stimulate the idea that there could be something out there. I can see that only as a good."

So what would a realistic alien look like? Probably more like R2-D2 than E.T.: Intelligence that's encased in metallic hardware will travel much better than the kind of intelligence that's carried around in relatively fragile wetware. R2-D2 could be pretty cute at times, but it's more likely that the real-life robo-aliens would be indifferent to our fate. To some extent, Shostak agrees with physicist Stephen Hawking: Our relationship with alien visitors might be similar to the Native Americans' relationship to the Europeans in the 1500s. In short, not all sweetness and light.

"If any were to come, at least extrapolating from the history of visitations here on Earth, most likely they would be nasty," Shostak said. "It wasn't the nice guys who got on the ship to visit the Aztecs."

But then again, perhaps E.T. suggests a sunnier scenario. Why would the aliens visit? Probably not for resources, because any civilization capable of coming to Earth would already command prodigious reserves of power. Certainly not for mating. Even if E.T. was made of flesh and blood rather than metal, the genetic code (and reproductive system) would be different. Perhaps, like E.T., the aliens would come just to catalog the flora, the fauna, maybe even check out the rock and roll.

"That might make sense," Shostak said.

What do you think? Is anyone else out there, or are we alone? How have our perspectives on extraterrestrial life evolved over the past 30 years? Feel free to weigh in with your comments below.

More perspectives on E.T. and "E.T.":

• Aliens won't eat us, and we won't mate with them
• Expert doubts aliens would visit Earth to terrorize us
• Stephen Hawking: Aliens may pose risks to Earth
• Steven Spielberg considered creepy 'E.T. sequel
• Henry Thomas recalls leaving Spielberg in tears
• Cosmic Log archive on aliens

Correction for 10:20 a.m. Oct. 10: Shostak said there were five or 10 alien-themed movies per year, but I mistyped the quote to make it sound as if E.T. got far less screen time. Sorry about the miscue, which has been mended. 

Alan Boyle is NBCNews.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. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

A study that reviews a host of sci-fi scenarios for contact with extraterrestrials stirred up such a ruckus today that NASA had to step in and distance itself from the research. The controversy focuses on the idea that E.T. could well decide that we're a threat to interstellar order, and therefore we have to be stopped before we spread.

The report itself, published in the journal Acta Astronautica, covers ground that's familiar to dedicated fans of E.T. lore. For example, the premise of the 1951 sci-fi classic "The Day the Earth Stood Still" is that universalist-minded aliens see our civilization as so rooted in violence that it's better to snuff us out than let us ruin the neighborhood. (The 2008 remake, starring Keanu Reeves, recycled that idea with an environmental theme.)

Then there's the "Hitchhiker's Guide to the Galaxy" scenario, in which Earth is destroyed merely to make way for a new stretch of intergalactic infrastructure.

"At the heart of these scenarios is the possibility that intrinsic value may be more efficiently produced in our absence," the researchers write.

The most familiar sci-fi scenario is the one in which the aliens are as selfish and territorial as we are, and want to wipe us out or enslave us and take our stuff. Think "War of the Worlds" or "Independence Day." In such cases, the researchers note that there's the potential for big payoffs ... if we prevail.

"Humanity benefits not only from the major moral victory of having defeated a daunting rival but also from the opportunity to reverse-engineer ETI [extraterrestrial intelligence] technology," they write. Indeed, New York Times columnist Paul Krugman joked last weekend that a fake alien invasion might be just the thing to spark an economic turnaround.

The researchers touch on more benign scenarios as well — for example, the "Star Trek" scenario, in which helpful aliens welcome us into the United Federation of Planets because we're all basically good guys (as opposed to those evil Klingons, until they become good guys, too). And then there's something like the "E.T." scenario, in which the aliens mostly just want to stay out of our way.

The 33-page study reflects at length on the potential risks.

"The possibility of harmful contact with ETI suggests that we may use some caution for METI [sending messages to extaterrestrial intelligence]," the researchers write. "Given that we have already altered our environment in ways that may be viewed as unethical by universalist ETI, it may be prudent to avoid sending any message that shows evidence of our negative environmental impact. The chemical composition of Earth's atmosphere over recent time may be a poor choice for a message because it would show a rapid accumulation of carbon dioxide from human activity. Likewise, any message that indicates widespread loss of biodiversity or rapid rates of expansion may be dangerous if received by such universalist ETI."

In short, let's keep our environmental bad habits on the down low, so as not to get the sad-Keanu E.T.'s on our case.

The basis of the brouhaha
By themselves, these ideas are not all that, um, alien. For years, sci-fi author David Brin has advised keeping quiet about our existence, and celebrity physicist Stephen Hawking agrees. U.N. officials and scientific experts also say the messages we direct toward any aliens we come across would have to be carefully managed.

So what's the big deal? Well, one of the authors of the paper, Shawn Domagal-Goldman, happens to be a postdoctoral student working at NASA Headquarters — and that highly tenuous connection to the world's most influential space agency sparked a huge wave of scare headlines. It started with The Guardian's story, and rolled onto The Drudge Report's webpage with a headline reading "NASA REPORT: Aliens may destroy humanity to protect other civlizations..." Another variant was this one: "NASA: Aliens May Destroy Humanity Over Greenhouse Gases."

Eventually, NASA had to send out a Twitter update saying "Yes, @drudge and @guardiannews are mistaken about an 'alien' report. It's not NASA research. Ask the report's author...." The space agency followed up later with two more tweets, emphasizing that it was not involved in the study and saying that Fox News and CNN "have it wrong."

In each case, NASA linked to a lengthy clarification and apology from Domagal-Goldman, who made clear that the study was not a "NASA report," that no NASA funding was expended on it, and that he spent none of his working hours on writing the paper. He said his two co-authors, Seth Baum and Jacob Haqq-Misra of Pennsylvania State University, "put in the vast majority of work on it."

"It was just a fun paper written by a few friends, one of whom happens to have a NASA affiliation," Domagal-Goldman wrote.

He admitted that including the NASA affiliation turned out to be a "horrible mistake":

"I did so because that is my current academic affiliation. But when I did so I did not realize the full implications that has. I'm deeply sorry for that, but it was a mistake born out of carelessness and inexperience and nothing more. I will do what I can to rectify this, including distributing this post to the Guardian, Drudge and NASA Watch. Please help me spread this post to the other places you may see the article inaccurately attributed to NASA.

"One last thing: I stand by the analysis in the paper. Is such a scenario likely? I don't think so. But it's one of a myriad of possible (albeit unlikely) scenarios, and the point of the paper was to review them. But remember — and this is key — it's me standing for the paper ... not the full weight of the National Aeronautics and Space Administration. For anything I have done to mis-convey that to those covering the story, to the public, or to the fine employees of NASA, I apologize."

This isn't the first case where the NASA connection has become entangled in scientific speculation. In March, the space agency took great pains to distance itself from NASA researcher Richard Hoover's claims to have found evidence of outer-space organisms in meteorites.

In Domagal-Gordon's case, the substance was far less controversial. As I've tried to point out above, the views expressed in the paper aren't that far off from the typical science-blog fare. I'm willing to bet a goodly sum of quatloos that Domagal-Gordon will go on to have a fine career in science ... and also that this won't be NASA's last P.R. kerfuffle over E.T.

More about aliens:

• Hollywood remakes an alien
• What would you ask the aliens?
• Why we love to fear E.T.
• The alien files on Cosmic Log

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

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.

Univ. of St. Andrews photoillustration

On a world that spins around two dim suns, the vegetation may well look black to human eyes.

Researchers suggest that vegetation on an alien planet like Tatooine in "Star Wars" might well look black or gray to human eyes. But they probably wouldn’t seem devoid of color to the eyes of the aliens — assuming they have eyes, that is.

The conjecture comes from a paper presented by the University of St. Andrews' Jack O'Malley-James at the Royal Astronomical Society's National Astronomy Meeting in Wales. O'Malley-James is working on a Ph.D. project to assess the potential for photosynthetic life in multiple-star systems with different combinations of sunlike stars and red dwarfs.

On Earth, the leaves of plants generally look green because two types of chlorophyll absorb the reddish and bluish wavelengths in the visible-light spectrum. Those red and blue wavelengths drive the photosynthetic process by which plants convert the sun's energy into chemical energy. In contrast, the green wavelengths are reflected into the RGB optical sensors known as our eyes.

Scientists surmise that the birds and bugs may see plants quite differently, with greater sensitivity to different shades of green and the ability to sense ultraviolet wavelengths as well.

O'Malley-James suggests that in different corners of our galaxy, plants could evolve to take advantage of different combinations of wavelengths, depending on the light coming from their parent sun ... or suns. The possibilities become particularly intriguing for a planet in a multiple-star system — like Tatooine, Luke Skywalker's fictional home planet in the "Star Wars" movie saga.

J. O'Malley-James / Univ. of St. Andrews

On planets orbiting red-dwarf stars, the vegetation may have more photosynthetic pigments in order to make use of a fuller range of wavelengths, giving them a "black" appearance. Here are some earthly examples of dark plants and flowers.

"If a planet were found in a system with two or more stars, there would potentially be multiple sources of energy available to drive photosynthesis. The temperature of a star determines its color and, hence, the color of light used for photosynthesis. Depending on the colors of their starlight, plants would evolve very differently,"  he said in a news release.

Statistics show that more than 25 percent of sunlike stars and 50 percent of the red dwarfs in our galaxy are found in multiple-star systems. Armed with such statistics, O'Malley-James and his colleagues ran computer simulations to determine the optimal strategy for photosynthesis over a wide spectrum (heh, heh) of planetary alignments.

“Our simulations suggest that planets in multi-star systems may host exotic forms of the more familiar plants we see on Earth," O'Malley-James reported. "Plants with dim red dwarf suns for example, may appear black to our eyes, absorbing across the entire visible wavelength range in order to use as much of the available light as possible. They may also be able to use infrared or ultraviolet radiation to drive photosynthesis. For planets orbiting two stars like our own, harmful radiation from intense stellar flares could lead to plants that develop their own UV-blocking sunscreens, or photosynthesizing microorganisms that can move in response to a sudden flare."

But even if the plants reflected none of the visible-light wavelengths, extraterrestrial gardeners might well have their own special appreciation for an ultraviolet bloom, or leaves that are variegated in the thermal infrared.

I know it sounds like a flight of fancy, but this is just the kind of flight I enjoy the most. The subject reminds me of the scene from "Battlestar Galactica" where Brother Cavil complains about the "ridiculous gelatinous orbs" in his head. "I want to see gamma rays!" he shouts. "I want to hear X-rays!" Which new senses do you think the aliens might have ... and which do you wish you could have? Feel free to weigh in with your own conjectures in the comment section below.

More about alien perspectives:

• Want to call E.T.? Keep it simple, stupid Earthling
• Rare exoplanet has 'Star Wars' twin sunset
• How to find aliens: Follow the photosynthesis
• Alien plants get new twist in world of 'Avatar'
• Plants on other planets might not be green

O'Malley-James' supervisors on the Ph.D. project include Jane Greaves of the University of St. Andrews, John Raven of the University of Dundee and Charles Cockell of The Open University.

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 my book on Pluto and the search for planets, check out the website for "The Case for Pluto."