I think it’s fair to say that, given your ‘druthers, you’d want an instrument that could map exoplanets in the kind of detail you get with Google Earth, with enough resolution to actually see the Great Wall of the Klingons, in case they’ve built one. Could we construct such a telescope … ever? Here’s what […]
Read more "The Ultimate Telescope"Sailing Past Neptune’s Moon Triton [Voyager 2 – August 25, 1989]
Read moreIn terms of the search for extraterrestrial intelligence (SETI), it may no longer be a matter of answering the “are we alone” question, some scientists say. Rather, just how crowded is the universe?
And if ET is out there, it may be possible to reach out with direct “radio waving” to potentially habitable exoplanets. This form of cosmic cryptography, called “Active SETI,” involves no longer merely listening for a signal but purposefully broadcasting to, and perhaps establishing contact with, other starfolk.
“It’s a subject of discussion, I’ll put it that way,” said Seth Shostak, senior astronomer at the SETI Institute in Mountain View, Calif. There have been many workshops and symposia over the years to discuss Active SETI, he said, and because it has a highly emotional component, “it’s like a third rail in a way,” he said.
Shostak told Space.com that he feels the topic is not something to worry too much about.
“But there may not be that perception in the broader public … that we have discussed this to death. They haven’t seen these discussions nor participated in them,” he said.
But exoplanet detections are making news around the world, Shostak said. “That’s putting the whole question of life in space in front of the public in a way that perhaps wasn’t true 20 years ago.”
Still, trying to figure out what’s the best thing to do, in terms of Active SETI, is a work in progress, Shostak said. “What is the best way to communicate? What do you do…just ping them with a carrier wave and you encode Wikipedia? If you are going to do it, what’s the best way to communicate?”
“[Hawking]’s right about our immaturity as a species,” Impey told Space.com, “but I think the argument is moot since intelligent civilizations are likely to be so sparsely distributed that communication in either direction is difficult or unlikely.”
Active SETI, Impey said, “makes us feel a little more proactive, but I think it’s a long shot worse than buying a lottery ticket.”
For Impey, the “promising approach” is not conventional SETI or broadcasting, but detection of civilizations by their energy or technology imprints, “and that avoids all the issues of intention and communication and the anthropocentric tangle people get into with that.”
“I am for passive SETI programs, and in fact would advocate for renewed government funding after a 20-year lapse,” Dick told Space.com. “That’s because the existence of extraterrestrial intelligence is one of the great unsolved mysteries of science.”
Dick said that the current NASA astrobiology hunt is centered on microbes, but surely there should be an effort to go beyond micro-organisms and search for complex life with whatever means are available.
“On the other hand, I would not propose government funding for messaging extraterrestrial intelligence. I think we need to find ET first, and then have a period where a team consisting of scientists, social scientists and humanities people consider what the message should be,” Dick said.
“Having said that, it would be very difficult to regulate individual or institutional projects that wish to attempt messaging extraterrestrial intelligence, and I would not advocate attempting to regulate,” Dick said. In his opinion, there is an equal chance that ET will be good or bad.
“We do not yet know enough about the evolution of altruism on Earth, much less among other possible intelligent life forms, to say ETs will all be good,” Dick said. “That is a hope rather than a fact.”
But haven’t we already revealed ourselves with TV signals, military radar and other outputs into the cosmos? Even music is wafting across the universe, purposely directed toward a specific star.
That is true, Dick said, but it’s not the same as sending a directed beam to a habitable exoplanet target.
“Still, the idea of planet Earth cowering and afraid to engage the universe is not a planet I would want to live on. SETI attempts are part of our rising cosmic consciousness, and as such cannot be stifled,” Dick said. “That this is the subject of such controversy…it’s an indication of how seriously the subject of intelligent life in the universe is now taken!”
“But Active SETI is not science,” said Michaud. “It is an attempt to provoke a response from an alien society whose capabilities and intentions are not known to us.”
Those most eager to send high-powered messages want their efforts to have consequences, Michaud said, not just for themselves, but for the entire human species. “There is no scientific or historical evidence telling us that the consequences of contact will be those they prefer."
Michaud says that an alien society able to detect our signals almost certainly would be more technologically advanced than our own, and might be capable enough and patient enough to send probes across light-years of space. Scientists and engineers have shown that robotic spacecraft able to reach nearby stars would be feasible for a civilization only slightly in advance of our own.
Michaud takes issue with the old claim that we already have been detected or that detection is inevitable. Experts have shown that the normal signals emitted by Earth are too weak to be heard at interstellar distances without colossal antennas, he said.
"Sending deliberate, unusually powerful signals is a decision that belongs properly with all Humankind,” Michaud said. “We should have an open debate about whether or not to call attention to ourselves by making our civilization more detectable than it already is.”
Read moreSince 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.
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 Committee to Nuke Elysium 