Filled Under: exoplanet

Eavedropping on ET: Two New Programs Launching to Listen for Aliens

The 305-meter telescope at Arecibo is just one of a collection that SETI will use to search nearby stars for electronic signals that could indicate intelligent life. If such a civilization was utilizing a similar dish to image exoplanets, SETI’s team should be able to detect it.
CREDIT: Arecibo Observatory

SETI is stepping up its search for alien lifeforms on far off worlds.

The Search for Extraterrestrial Intelligence (SETI) program recently announced two new methods to search for signals that could come from life on other planets. In the Panchromatic SETI project, multiple telescopes will scan a variety of wavelengths from 30 stars near the sun; the project will look for powerful signals beamed into space, potentially by intelligent extraterrestrials. SETI is also launching an interplanetary eavesdropping program that is expected to search for messages beamed between planets in a single system.

“If we are polluting space, perhaps other extraterrestrials are leaking signals,” Dan Werthimer, director of the Berkley SETI Research Center, told an audience during the Smithsonian Magazine’s “The Future is Here” Festival in May. “Maybe they’re sending something our way.” [10 Exoplanets That Could Host Alien Life]


‘Everything we’ve got’

Since humans made their first FM radio and television transmissions, signals from Earth have been spilling out into space, announcing the presence of intelligent life to any group that might be searching for it. According to Werthimer, signals from the 1950s television show “I Love Lucy” have reached thousands of stars, while the nearest suns have already enjoyed the “The Simpsons.”

If Earth has unintentionally leaked signs of its presence, other alien civilizations may have done the same thing. SETI’s new Panchromatic project will utilize a variety of telescopes covering a range of frequencies to scour the nearest stars.

“We’re going to throw everything we’ve got at it,” Werthimer added.

The panchromatic project will examine a sample of the 30 stars that lie within 5 parsecs (16 light-years) from the sun. The list includes 13 single stars, seven binary systems and one triple system. Most of the stars are smaller than the sun, but the project will also examine two white dwarfs and one moderately evolved F star. No confirmed exoplanets have been found around any of the stars.

By setting distance as the criteria, the SETI team hopes to alleviate any bias that might otherwise result from focusing on systems similar to that of Earth. The team selected stars for study based only on how far they lie from the sun.

According to SETI-Berkeley’s Andrew Siemion, chief scientist of the eavesdropping project, the search will also probe a diverse stellar population already well studied at many wavelengths.

“In the event of a non-detection, these attributes of the sample will allow us to place strong and broadly applicable limits on the presence of technology,” Siemion told via email.

Observations from the Low Frequency Array (LOFAR) telescope in Europe and the Green Bank Telescope (GBT) in West Virginia will begin over the summer and fall of 2014. Instrument development and commissioning is still in progress for the Infrared Spatial Interferometer (ISI) at Mount Wilson Observatory and the Nickel Telescope at Lick Observatory, both in California. But according to Siemion, the pair should be ready at about the same time. The Nickel Telescope will conduct the first-ever SETI observations done in the near-infrared.

The project has also proposed time on the William E. Gordon telescope at Arecibo Observatory in Puerto Rico, and hopes to piggyback on observations obtained at the Keck Telescope in Mauna Kea, Hawaii.

“Pending availability, we also intend to observe our initial panchromatic target list with other telescopes,” Siemion said.

The close distances of the stars selected for the Panchromatic project should make potential signals from intelligent civilizations easier to detect, Siemion said.

“Within a couple of parsecs, E.T. wouldn’t have to have technology much more advanced than ours in order for us to detect it,” Siemion said. [5 Bold Claims of Alien Life]

Signals from E.T.’s rovers

The second SETI project will make use of the observations of multi-planet systems gathered by NASA’s Kepler mission as it attempts to eavesdrop on signals broadcast from one planet to another.

The Kepler telescope detects planets as they pass in front of their stars, causing a dip in the stars’ brightness. If two planets lie in the same orbital plane, pointed toward Earth, they will occasionally line up. If an intelligent species originated on one planet in a system, then went on to explore or inhabit a second planet, signals sent from one planet to the other should be detectable when the two are lined up facing the Earth.

So far, the team has observed about 75 of these events in multi-planet systems using the Green Bank Telescope. The range of radio frequencies include those used on Earth to communicate with craft sent to other planets.

“Our detection algorithms are sensitive to communications like those used by NASA’s Deep Space Network to communicate with spacecraft, so if E.T. broadcasts something similar at sufficient power, we could hear it,” Siemion said.

Detecting such signals doesn’t necessarily mean researchers will be able to translate them. Scientists may not be able to determine if the communication is to an outpost or a rover. However, that won’t make the discovery any less exciting.

Though a signal between planets should be detectable, Siemion said that it is more likely that a broad signal would be intercepted. Although terrestrial television broadcasts in large beams, these would be too weak to detect under the current experiments. Instead, scientists would be looking for something like the U.S. Air Force’s “sky fence,” a high-frequency radar used in an attempt to track space junk in orbit.

Distance poses one of the biggest problems in eavesdropping on extraterrestrials. The required power for a transmitter to be detected increases with the square of the distance. A transmitter 150 light-years away would need to be 100 times as powerful as one 15 light-years away, if everything else remains the same.

Most of the Kepler planets and planetary candidates lie at significant distances from Earth, making it difficult for scientists to detect weaker signals like those emitted by spacecraft communication. However, if alien civilizations used something akin to Arecibo, Siemion said, scientists would stand a far better chance of detecting it.

“The flood of multiplanet systems discovered by Kepler and the high precision of the planetary ephemerides the Kepler team publishes has directly made this experiment possible,” Siemion said. Ephemerides are tables that provide the positions of astronomical bodies at a given time.

He expressed his excitement about NASA’s planned Transiting Exoplanet Survey Satellite (TESS) mission, set to launch in 2017.


“TESS will find lots of multiplanet systems as well, but they will be closer to Earth,” said Siemion.

Astronomers also look forward to using the Square Kilometer Array (SKA), which could be more than an order of magnitude more sensitive than current systems and thousands of times faster.

The explosion in discoveries of planets and planetary candidates over the past two decades has provided a strong encouragement for SETI’s search for intelligent life, Siemion said.

“If there is one message from exoplanet research in the last two decades, it is that, simply, planets are everywhere,” he said. “Moreover, rocky, lukewarm planets appear to be very common. We shouldn’t have to look very far, statistically speaking, to find planets where life could develop.”

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Alien ‘Star Engine’ Detectable in Exoplanet Data?

Alien ‘Star Engine’ Detectable in Exoplanet Data?

Alien ‘Star Engine’ Detectable in Exoplanet Data?
Jun 25, 2013 12:52 PM ET // by Ray Villard

In 1948, astronomer Fred Zwicky, the esteemed co-discoverer of dark matter, speculated that “fusion jets” could be used by a future civilization to navigate our sun and solar system planets through the galaxy. He suggested that pellets of fuel could be fired into the sun to produce explosions that would push the sun along like firecrackers exploding in a tin can. But where to go?

Zwicky thought that the entire solar system could reach Alpha Centauri in a few thousand years.

Forty years later, physicist Leonid Shkadov proposed that far advanced extraterrestrial civilizations might harness the energy output of their sun for interstellar migration. They would use a “stellar engine” — no need for fusion motors here. Simply construct an immense spherical mirror that reflects some of the star’s radiation back onto its surface.

13 Ways to Hunt Intelligent Aliens

This radiation pressure on the star creates an imbalance where a net force pushes the star in the opposite direction. This is simply Newtonian physics, though Sir Isaac would have never imagined such an application.

To work, such a stellar engine would have to be a megastructure, millions of miles across (shown above). The bad news is that a planet might have to be dismantled to make such a monstrosity. The good news is that such megastructures — if they exist — should be detectable with today’s telescope technology.

Duncan Forgan, of the University of Edinburgh, proposes that such a mega-mirror might obstruct part of the disk of a star during our observations that look for planets passing across the face of a star, an event call a transit.

He modeled hypothetical light curves produced by exoplanets transiting a star that possesses a Shkadov thruster. Depending on its position, the gigantic mirror would abruptly block off the planet’s shadow prematurely (shown below), because it is occulting a portion of the star. The silhouette of the immense mirror would mysteriously truncate the predicted symmetrical U-shaped dip in starlight that is measure with each transit as a planet follows along its racetrack orbit.

ANALYSIS: Asteroid Forensics May Point to Alien Space Miners

It would be difficult to explain the oddball light curve that would be cause by such a intervening structure. Forgan cautions that the presence of starspots can produce “dents” in the transit light curve, as the planet crosses a starspot and this could be misinterpreted as an artificial structure. However the starspot would rotate out of view on subsequent transits. Assuming the monster-mirror is fixed in space, it’s silhouette should remain stable.

alien structure?

NASA’s Kepler space observatory has spent the last five years amassing a huge vault of planetary transit data on 150,000 stars in the constellation Cygnus. And so this hypothesis is testable.

The problem is there are many unknowns heaped upon many other unknowns. What is the probability an alien civilization has the wherewithal and audacity to try building such a monstrosity, and that it is close enough to detect?

After much speculation Forgan cautiously estimates a lower limit of one star in one million stars having such a detectable megastructure. This would put the nearest such star thruster 1,000 light-years away at best.

The Kepler database is several orders of magnitude smaller in surveyed stars. With such low chances of success it would be hard to convince anyone to fund a space observatory to go looking for alien engineering. So it will all be left as a serendipitous SETT (Search for Extraterrestrial Technology) opportunity as exoplanet surveys continue.

ANALYSIS: Do Aliens Go Invisible by ‘Going Green’?

Why would a far advanced civilization go to the budget-busting expense of doing a megastructure project to steer its star around? It’s estimated that the sun has passed through 10 cold molecular hydrogen clouds laced with dust, along its galactic orbit. The consequences are that this would dim a star, and that it turn could cause some serious climate change on a planet. Long-lived aliens may want to steer around these galactic potholes.

Or the extraterrestrials might want to avoid a predicted close passage to a nearby star that might destabilize a comet cloud believe to surround planetary systems. (The approaching comet ISON is believed to be a distant visitor from this hypothesized Oort cloud around our solar system.)

There is an extraordinarily small but finite chance that evidence for such mega-engineering is buried in archival astronomy data. What’s more, the absence of such evidence might suggest there is an upper limit to how far a technological civilization can progress. Or, more sobering, it means there are narrow limits on the longevity of a technological society.

Image credit: NASA, R. Villard

Hubble spies a blue planet (not Earth)

Hubble spies a blue planet (not Earth)

Hubble Spies a Blue Planet (Not Earth)
Jul 11, 2013 08:00 AM ET // by Irene Klotz

As far as planets go, HD 189733b, a giant, sizzling Jupiter-like world that swoops around its parent star every 2.2 days, couldn’t be more different from Earth.
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But the planet, located 63 light-years away in the constellation Vulpecula (the Fox), has one feature that is familiar: it’s blue.

Astronomers weren’t specifically thinking about HD 189733b’s color per se when they requested observation time on the Hubble Space Telescope. They were following up previous studies showing the planet had clouds with an attempt to learn more about what is in its atmosphere.

As HD 189733b paraded around its star, astronomers used Hubble’s light-splitting spectrograph to home in on specific wavelengths of light reflecting off the planet’s surface.

HD 189733b is a so-called “transiting planet” meaning it passes in front of and then behind its host star, relative to the telescope’s line of sight. Taking data before, during and after eclipses often yields scientific treasures — and in this case an aesthetic one as well.

ANALYSIS: Quarter of Sun-Like Stars Host Earth-Size Worlds

When HD 189733b slipped behind the star, the light seen by Hubble dropped deeply into the blue part of the electromagnetic spectrum, while all other colors remained the same, a telltale sign of the planet’s color.

HD 189733b is far too hot for liquid water, but there are other molecules that could scatter blue light, mirroring what happens in Earth’s atmosphere. Scientists believe HD 189733b has clouds made of liquid glass.
Artist’s impression of a “hot Jupiter” planet known as HD 189733b orbiting its star, HD 189733. The location of the sun and other neighboring star systems are labeled.
NASA, ESA, and G. Bacon (AURA/STScI)

“Our best guess is that the color is due to a combination of reflection by silicate clouds and absorption by sodium atoms,” astronomer Frederic Pont, with the University of Exeter in the United Kingdom, wrote in an email to Discovery News.

“Other factors may be photochemical aerosols — i.e. smog — and absorption by other atoms or molecules than sodium,” though presently are no specific candidates,” he added.

ANALYSIS: ‘Earth-like’ Planets May Be Nothing Like Earth

Driving the planet’s extreme environment is its unenviable position 30 times closer to its parent star than Earth orbits the sun. At that distance, surface temperatures reach more than 1,800 degrees Fahrenheit.

To boot, the planet is likely gravitationally locked with one side permanently facing its star and the other in darkness. That dichotomy can generate wild winds that surpass 4,350 mph.

“I think of this planet in some ways as being about as alien a planet as you could possibly imagine,” astronomer Heather Knutson, with the California Institute of Technology (Caltech) in Pasadena, told Discovery News.

“If we could actually see it in person, I think we would find that there’s no good comparison we could make with anything that we’re familiar with. That’s what makes it interesting,” she added.

The research will be published in the Aug. 1 issue of Astrophysical Journal Letters.