NASA tried to phone aliens
Finding ET 'central' to agency's plans despite warning from Hawking
Cosmologist Stephen Hawking says it's too risky to try to talk to space aliens, but he's too late -- NASA has already tried it.
The US space agency and others have already beamed messages into deep space, trying to phone extraterrestrials.
NASA, which two years ago broadcast the Beatles song 'Across The Universe' into the cosmos, discussed its latest search strategy for life beyond Earth.
"The search for life is really central to what we should be doing next in the exploration of the solar system," said Cornell University planetary scientist Steve Squyres, chairman of a special National Academy of Sciences panel advising NASA on future missions.
The panel is looking at 28 possible missions, from Mars to the moons of Jupiter and Saturn. And NASA is focused on looking for simple life like bacteria in Earth's solar system rather than fretting about alien overlords coming here.
Just days ago, Prof Hawking said on his new TV show that a visit by extraterrestrials to Earth would be like Christopher Columbus arriving in the Americas, "which didn't turn out very well for the Native Americans".
The world-renowned physicist speculated that while most extraterrestrial life would be similar to microbes, advanced life forms would probably be "nomads, looking to conquer and colonise".
The comment reinvigorated a three-year debate festering behind the scenes in the small community of astronomers who look for extraterrestrial life, said Seth Shostak, a senior astronomer at the SETI Institute, which looks for aliens.
While some people think broadcasting into the universe is "like shouting in a jungle, not necessarily a good idea", Mr Shostak asked: "Are we to forever hide under a rock? That to me seems like no way to live."
There is a big difference of opinion about the issue, says Mary Voytek, a senior astrobiology scientist at NASA.
"We're prepared to make discoveries of any type of life, of any form," she said.
The SETI Institute in Mountain View, California, takes a passive approach, listening for any signals from aliens.
For more than a quarter of a century, however, various groups have been sending out signals to other worlds. Four NASA space probes -- Pioneer 10 and 11 and Voyager 1 and 2 -- carry plaques and recordings that say hello from Earth and give directions on how to get here.
Those probes, launched in the 1970s, are at the edges of the solar system.
But Massachusetts Institute of Technology planetary scientist Sara Seager does not rate the broadcasts to space, because so far they are pointed at random, not towards potential Earth-like planets.
"We wouldn't even know where to send our message, it's so vast out there," she said.