SETI at Home Upgrade

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SETI, the Search for Extraterrestrial Intelligence, is looking for more recruits to hunt for aliens with their home computers.


Stepping up the search for ET. I'm Bob Hirshon and this is Science Update.

Right now, hundreds of thousands of people are looking for extraterrestrials with their personal computers. The project's called SETI at Home, and it uses a free screensaver to sift through radio waves from space for signs of alien intelligence. Now, chief scientist Dan Wertheimer wants a million more recruits—thanks to a major upgrade in the giant radio telescope in Arecibo, Puerto Rico, that collects the signals.


It has a very good receiver, much more sensitive than the one we used before, and that's why we're asking more volunteers to help us analyze this data.

The new receiver also covers more of the sky and more radio bandwidth than ever. By spring of 2008, the researchers expect to be processing 500 times more data than they used to—provided they get enough help. Find the link to sign up at: [SETI@home]. I'm Bob Hirshon, for AAAS, the science society.

Making Sense of the Research

Are we alone in the universe? That's one of the great scientific mysteries of all time. But many scientists believe the odds are excellent that other intelligent life forms exist. Why? Well, according to recent estimates, there are about 70 sextillion (70,000,000,000,000,000,000,000) stars in the universe. Now, suppose, for example, that one in a million of those stars has planets orbiting around it, like our sun does, and that one in a million of those orbiting planets supports some kind of life. That would still mean that 70 billion other planets could be teeming with extraterrestrials. Nobody knows what the real numbers are, but this shows why many researchers think it's incredibly unlikely that extraterrestrial life doesn't exist.

So where are all these aliens, and why haven't we heard from them? Probably the same reason they haven't heard from us: They're too far away. Consider the fact that humans, with our seemingly advanced technology, have never set foot anywhere beyond the moon—the nearest extraterrestrial destination. The most distant unmanned spacecraft, Voyager 1 and 2, were launched over twenty years ago and only recently reached the outer edge of our solar system. And our entire solar system is just a speck compared to the universe as a whole. In fact, in order to get past the nearest handful of stars within a human lifetime, we'd have to build a spacecraft that could travel at the speed of light or even faster—which doesn't look possible anytime soon.

So SETI, the Search for Extraterrestrial Intelligence, isn't looking for alien spaceships. Instead, it's looking for radio waves that might be being sent, probably unintentionally, by other civilizations. (Our own radio and television signals, which leak from Earth and drift across the universe, have already passed by thousands of stars; if there are any alien civilizations in those neighborhoods, they could theoretically be watching early Earthling TV shows like I Love Lucy.)

SETI looks specifically for something called “narrow band transmissions,” which as far as we know can be produced only by artificial equipment. No matter where you are in the universe, these transmissions will be most efficient at broadcasting signals that can be received at the other end. So SETI believes that even extraterrestrials who are very different from us will probably make use of these radio waves for communication, if they have the intelligence and technology to do so.

However, it's very hard to look for these narrow band transmissions, because we produce so many of them here on Earth. Sifting out all that noise, along with natural radio waves that bounce around in space, is a task that the world's biggest supercomputers couldn't manage. So instead, SETI at Home taps into a source of even bigger computing power: ordinary PCs and laptops around the world. Although each computer can process only small amounts of data on its own, hundreds of thousands of computers working together can do a whole lot of work. And since almost every personal computer on Earth sits idle some of the time, the SETI at Home project can use them without disrupting anyone's life.

Here's how it works: You download a screensaver from SETI at Home. It's actually a software program that waits until the computer isn't being used, then starts downloading and processing data from SETI, analyzes it, and sends the results back to SETI. It keeps doing this until you come back or shut down the computer, whether it's thirty seconds or twelve hours later. Using this technique, called parallel distributed computing, SETI scientists have essentially created the world's most powerful supercomputer.

Now, however, they need even more volunteers, because the giant radiotelescope in Arecibo, Puerto Rico, has been retooled to look at more of the sky than ever. If you're interested, try out the program. It's a longshot, but your computer might just make one of the greatest discoveries in human history.

Now try and answer these questions:

  1. What is SETI looking for?
  2. What is parallel distributed computing and how does SETI use it?
  3. Do you think aliens exist? If so, why don't we have proof of their existence yet? If you don't think they exist, why not?

You may want to check out the January 25, 2008, Science Update Podcast to hear further information about this Science Update and the other programs for that week. This podcast's topics include: Space Research Update: the 11-year solar storm cycle returns, the MESSENGER spacecraft reports back from Mercury, and the search for intelligent life in the universe continues with the help of your computer. Also: Unique animal and plant adaptations.

For Educators

Visit the SETI at Home website to learn more and download the free software.

Another parallel distributed computing project, the Screensaver Lifesaver, recently finished creating a massive database of potential cancer-fighting molecules.

In the Access Excellence lesson plan Project SETI, students learn to look for life in outer space.

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