For nearly half a century scientists have searched the sky for radio signals that clearly originated with intelligent life on another planet. All they needed was a glimpse, just a whimper, proving that we are not alone in the universe.
But in all those years, despite the undaunted and sincere efforts of some of astronomy's leading minds, they have found nothing. Not even a hint that E.T. is out there.
In recent years scientists have suggested alternative ways of searching -- analyzing the atmospheres of other planets to see evidence of life, for example -- but there's a new idea in the mix now that could have significant fringe benefits, including, quite possibly, saving the Earth from destruction.
"If we are going to find E.T., I think we are going to stumble across him," said electrical engineer John D. Mathews of Pennsylvania State University in a telephone interview.
Instead of searching specifically for alien intelligence, Mathews said, we need to rebuild the space program with unmanned self-replicating robots that could explore outer space, sending back data that would tell us far more than we now know about our galaxy.
In other words, give up on our current search. And in due time, he said, we just might meet E.T.
Mathews has laid out his ideas for space exploration in a provocative article in the Journal of the British Interplanetary Society. It seems like science fiction, with exploratory robots zipping off from a base on the moon, or an asteroid, to land eventually on other worlds, where they would mine minerals and build manufacturing plants to replicate themselves. The new clones, updated with the latest technology, would blast off again in search of distant planets on the fringes of the galaxy.
The idea itself is not all that new. The brilliant Hungarian-American mathematician John von Neumann envisioned self-replicating robotic explorers decades ago, which became central characters in hundreds of science fiction stories. Von Neumann, incidentally, also coined the term Mutually Assured Destruction (MAD) while working on the Manhattan Project in the development of the atomic bomb.
But if the vision of robots cloning and updating themselves seems impossible, many of the strange ideas that sprang from the fertile mind of von Neumann have proved true, including what many consider the first computer virus.
However, Mathews was attracted to the von Neumann world for reasons far more basic than searching for E.T., which he said "has been elevated to this almost magical, god-like status."
"Why do we want to be in space anyway?" he asked during the telephone interview. "There are two immediate answers. I would like to say it's because we want to go exploring and we like new frontiers and all of that, but I think the fact is we need to worry about getting hit on the head by an asteroid, and we need to worry about the fact that the near-space environment is full of junk."
In case anyone has forgotten, an asteroid is believed to have wiped out the dinosaurs. And some day a lot of the debris left over from the early days of exploration is going to come down, possibly with tragic results.
So we need to get our house in order on both those counts, Mathews argues, and the best way to do that is with robots that can mine necessary resources, manufacture fuel, and send back critical data while cleaning up the celestial neighborhood.
But could robots be self-sufficient enough to mine and manufacture whatever they need on some distant rock? Aren't we far away from that, if it's even possible?
"We are a very small step away from that right now," Mathews said. "We have 3-D printers (which could manufacture just about anything) and self- replicating systems right now."
We'll be there, he said, "within a couple of years at the most."
That's the starting gate, of course, not the encounter with E.T.. And that encounter will probably come about -- while we're doing other things -- simply because the communications system needed for a fleet of robots just might pick up something interesting.
Mathews has borrowed ideas from astrophysicist Gregory Benford of the University of California, Irvine, and his twin brother, James, a physicist specializing in high-powered microwave technology, as well as James's son, Dominic, a NASA scientist.
The Benfords have argued that the current search for E.T., based on transient signals from something like a television broadcast on another planet, was doomed because that signal would be so weak by the time it reached Earth that it would be undetectable. Most likely, they said, E.T. would use short "blips" of narrowly focused laser beams, probably in the near infrared, to communicate with its own spacecraft, which would most likely be self-replicating robots.
That's also likely to be the kind of communication system that earthlings will use to collect data from their future robots.
Mathews sees this scenario for finding E.T.: A robot belonging to Earth accidentally transits a narrow infrared beam in space. The robot's computer recognizes and captures the data in that short blip. Bingo. E.T. is calling home.
Mathews, and the Benfords, and many other scientists believe that may be how it happens, because any intelligent life would likely face obstacles like ours -- limited resources, many needs competing with space exploration, and problems at home.
"If they are like us, they too have a dysfunctional government and all the other problems plaguing us," Mathews said. "They won't want to spend a lot to communicate with us."
It could take decades, if not centuries, to develop the complete system envisioned by Mathews. But it may not take all that long to find E.T.
It's possible, he said, that extraterrestrial robots are already roaming the outer edge of our solar system. An unmanned spacecraft, with the right communications equipment, just might pick up an electronic bit of data that shouldn't be there.