Scientists: "Aliens might not have radio"

QMI AGENCY

Toronto SUN

A new theory has stargazers thinking maybe we haven't found signs of extra-terrestrial life yet because we're going about it the wrong way. Right now, a scientific project known as the Search for Extraterrestrial Intelligence (SETI) is leading the way in the search for life beyond Earth.

Their method is to scan outer space for radio transmissions, new or old. They've been doing it for 50 years, and so far, it hasn't really worked out.Physicists interviewed in the Economist say that's not necessarily because there are no aliens. But maybe aliens just don't use radio technology, they propose,

Paul Davies, a physicist at Arizona State University, pointed out thatradio-communications are likely to be a short-lived technology, even on Earth, where people are increasingly using fibre optics to communicate.Instead, Dick Carrigan, a retired particle physicist, suggested looking for other signs, like evidence of tampering with the energy output or pollution.The basic idea is to think outside the box and not focus on modern Earth technologies, which could easily become obsolete.Instead of looking for the earliest signs of industrialization, then, perhaps the thing to do is to let the imagination run riot and ask what technology might do to a solar system if it had tens or hundreds of thousands of years to work its magic,” reads the Economist article, Signs of Life.

SETI at 50: 10 key moments in the search for extraterrestrial life

By Tom Chivers, The Telegraph
Published: 7:30AM BST 29 Sep 2009

In 2015, Voyager 1 will become the first man-made object to leave the solar system Photo: NASA

SETI was founded in response to a September 1959 Nature journal article, “Searching for Interstellar Communication”, which suggested that a systematic search for alien life was worthwhile.

Since then, it has spent 50 years listening to the stars with radio telescopes, and at times trying to send messages of its own to other planets.

Here are 10 of the most significant events in mankind’s search for other life.

Little Green Men: Pulsars
In 1967, astronomers in the UK spotted a radio signal from another star. Nothing too remarkable in that, as all stars emit radio waves.

What was unexpected, though, was that this one turned itself on and off with perfect regularity: one 0.04 second pulse every 1.3373 seconds.

The metronomic beat sparked speculation that it might be a signal from an alien life form, and the signal was given the name LGM-1, standing for Little Green Men.

In fact, the astronomers had discovered a new type of star – a pulsar. A form of neutron star (an incredibly dense dead star: one just 12 miles across would weigh more than our Sun), they rotate at a huge velocity, giving off powerful beams of radiation as they spin.

Martian bacteria?
In 1984, a rock was found in the Allan Hills, Antarctica. It is believed to have been formed on Mars around 4.5 billion years ago, before being blasted into space by meteorite impacts around 15 million years ago.

It then wandered through space for millions of years, before crashing into our planet about 11,000 years before the birth of Christ.

An interesting enough history, but the meteorite – known as ALH84001 – really made the headlines in 1996. Structures that resembled tiny fossilised bacteria were found, as were organic molecules, sparking theories of ancient life on Mars. The excitement grew so great that US President Bill Clinton made a televised announcement about the find.

Arguments over whether these really are evidence of Martian life, or whether the sample has become contaminated during its time on Earth, are still raging today.

Earth-like planets
‘Terrestrial’, or rocky, planets, are considered the most likely place for life to be found. There are four in our own solar system – Mercury, Venus, Earth and Mars.

But in the last few years, the first possible examples of Earth-like planets outside our system have been found. In 2007 European scientists said they had found two – the third and fourth planets around the red dwarf Gliese 581 – which might be habitable.

Water on Mars
This month the news broke that the Mars Reconnaissance Orbiter has spotted evidence of ice in five locations on Mars. It is the latest in a series of discoveries of water on the planet, indicating that the planet may have had a more humid climate at some stage in the last few thousand years.

Water is required for all known forms of life, so the existence of water on other planets increases the likelihood that life exists elsewhere.

Drake equation
The first serious attempt to quantify the likelihood of humanity coming into contact with alien life, the Drake equation reads: N=f^p n^e f^l fⁱ f^c L.

It states that if we know the rate of star formation, the percentage of stars that have habitable planets, and the percentage of those planets that are likely at any given time to support life that signals its existence to the universe, we could estimate how many civilisations in our galaxy we might communicate with.

Unfortunately, none of those factors are known, so we are still guessing.

The Aricebo Message
Not part of the search for life per se, but rather helping anyone else who may be looking for us. In November 1974, a message was beamed from the Aricebo radio telescope towards the M13 star cluster, about 25,000 light years away. The message, created by Drake equation author Frank Drake and physicist Carl Sagan, included an image of a human and information about the makeup of DNA.

Sadly, M13 will have moved by the time it arrives.

A later broadcast - beaming the music of the Beatles at the Pole Star, 431 light years away - was, in all apparent seriousness, condemned as inviting an interstellar attack from warlike aliens.

Voyager
Three years later, in 1977, the two Voyager space probes were launched. As well as their scientific equipment, they contain gold discs containing information about Earth, including Mozart’s music and greetings in 54 human languages. It is currently around 10 billion miles from Earth; its radio signals take 15 hours to reach us, even at the speed of light.

In May 2005, NASA scientists said that Voyager 1 had reached the heliosheath, the boundary that marks the edge of the solar system. It is expected to pass through into interstellar space in 2015, becoming the first man-made object ever to leave the Sun’s orbit.

Kepler telescope
In March, the Kepler Mission was launched with the express goal of finding Earth-like planets around other stars.

It is designed to find small planets by watching stars closely to see if they suddenly get dimmer, indicating that something has passed in front of them. For an Earth-sized planet, that would mean the star becoming dimmer by just 0.01 per cent.

The Wow! signal and Radio source SHGb02+14a
In 1977, an astronomer with SETI spotted an unusual radio signal while working on a radio telescope at Ohio State University. He was so excited by it that he wrote “Wow!” in the margin of the printout.

However, it was never spotted again. After he had calmed down, the discoverer Dr Jerry R Ehman said he believed it was “an Earth-sourced signal that simply got reflected off a piece of space debris.”

Another candidate for evidence of alien life was SHGb02+14a, a signal spotted three times in March 2003. It was at a frequency expected to be used by extraterrestrials – the frequency at which hydrogen absorbs and emits photons.

However, again there were reasons to be sceptical, not least that it came from a direction in which there are no stars for 1000 light years. While impossible to rule out extraterrestrial origin, it may have been a distorted signal from a pulsar, or just random noise.

SETI@home
In the 21st century the search for extraterrestrial life continues in hundreds of thousands of bedrooms and offices around the world.

Launched in 1999, SETI@home is the name given to a virtual supercomputer made of huge numbers of internet-linked home computers. Anybody can download the software and allow SETI to use their spare processing power to scour data from radio telescopes for evidence of alien intelligence.

In terms of power it is the fourth most powerful computer on the planet. It was this network of home computers that spotted SHGb02+14a, and one NASA scientist has predicted that it will find an alien signal by 2025.

Are You Out There, ET? Searches for Habitable Planets Are About to Get a Boost

UP, UP AND AWAY: The Kepler satellite, scheduled to take flight March 6, is lifted for attachment to its launch rocket at Cape Canaveral Air Force Station in Florida. Kepler will look for Earth-like planets that may be hospitable to life.
NASA

Next week brings a milestone in the search for extraterrestrial life with the scheduled launch Friday of NASA's Kepler satellite. The mission, named for 16th- and 17th-century German astronomer Johannes Kepler, will study a group of stars for three-plus years in search of subtle, periodic dips in stellar brightness—the telltale signs of planetary orbits. Although more than 300 planets outside the solar system have already been found using this method, among other techniques, Kepler's strength will lie in its instruments' sensitivity to smaller, cooler planets more hospitable to life and more like our own.

In a new book, planetary scientist Alan Boss, who studies stellar and planetary formation at the Carnegie Institution of Washington and is a member of the Kepler scientific team, argues that the mission should throw open the door to finding life outside the solar system. With any luck, Boss says, Kepler should indicate that billions of habitable planets exist in our galaxy alone, with an almost unfathomable tally of sextillions across the entire universe. (Where are Jules Verne and H. G. Wells when you need them?) We spoke to Boss about the thesis of his book.


[An edited transcript of the interview follows.]

Your new book is called The Crowded Universe. What does the title mean?
The point of the book is to show why one can claim that the universe is likely to be teeming with life. I make the argument throughout the book that we already know that Earths are likely to be incredibly common—every solar-type star probably has a few Earth-like planets, or something very close to it. To my mind, at least, if one has so many habitable worlds sitting around for five billion or 10 billion years, it's almost inevitable that something's going to start growing on the majority of them.

If they've got water on them, and they've got some comets coming in dumping in some amino acids and other interesting prebiotic chemicals, how are you going to keep those things from growing some sort of life?

Life is so tenacious and willing to seek out a toehold anywhere it can, my feeling is that it is going to originate anywhere it has a chance. It may not necessarily be little creatures like in a Steven Spielberg movie, but there will be some kind of archaealike or bacterialike microbes crawling around or bubbling along. Those are going to be creating output like oxygen and methane, and those are things we can see in the atmosphere. We may not be able to tell if a planet has intelligent life or dinosaurs, but we can at least tell if it has slime mold. So we're going for the slime mold.

Source: Scientific American

South Korea goes SETI

The Gwacheon National Science Museum said its brand new 7.2-meter telescope, to be activated this month, will be used to search for signs of extraterrestrial intelligence.

Local astronomers are analyzing radio signals detected by the telescope, which is now under a test run, according to Lee Kang-hwan, who will head the museum’s SETI (search for extra-terrestrial intelligence) program.

The telescope’s targets will include the Milky Way and about 250 planetary systems, Lee said.

"Our radio telescope is one of the first instruments of its kind specializing in finding indications of alien life,’’ Lee said.

"There’ve been consistent efforts in several countries to search for radio signals produced by extra-terrestrial life, but no substantial results have been reported. Science needs more research in this area, and we are glad to be part of the process,’’ he said.

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