Image copyright NASA Image caption Astronomers are using telescopes on Mars to search for molecules like water that could be molecules of life
If the secret to life on other planets beyond our solar system is not found soon, it will become one of the biggest discoveries of this century, a group of scientists say.
A new report says scientists could have to redouble their efforts to find any hints of life on other worlds in the next decade.
It blames climate change as one of the biggest threats to this possible discovery.
Researchers say there is no point searching for life on Earth, because it is already common – just in different places.
The authors say future discoveries will have to take other planets into account, and that the new searches will have to be much more targeted.
Being able to choose and test the right types of material will also be crucial. And the report published in the Proceedings of the National Academy of Sciences recommends focusing on environments where hydrogen is believed to exist, including ice sheets and plate tectonics.
“Finding information about the history of life on Earth and studying it from various environments outside our solar system opens up fundamental questions about the origin of life,” said study co-author Carl Murray from the University of Oxford.
“We will have to double our efforts to discover the life that lives in other solar systems.”
The report says if climate change continues unchecked, the atmosphere of another planet, even one completely free of life, might start to warm up.
That would mean surface conditions would be different from those on Earth.
A trend in which young planets reach as warm as an Earth-sized world will stop, and if a giant planet like Jupiter or Saturn releases enough greenhouse gases, life will become “significantly exposed”.
If that discovery happened in the next decade, it could be “promising evidence for life”, the report says.
“The best that we can do for now is to redouble our efforts to find such evidence,” it concludes.
Other difficulties include questions of distance – an object that has undergone intense gravitational tugs could appear moving rather than travelling through space. This too might give away the information of life on Earth.
There are also uncertainties about what signals could be detected, the authors suggest.
They say it is not clear what radio signals might be extracted from a distant planet and tested to make sure they come from a species of life, rather than anything else.
Image copyright NASA Image caption The Cassini probe also discovered chemicals that could indicate the presence of life on Saturn’s moon Titan
And finding living creatures will be complicated by natural disasters.
The largest life forms on Earth were long thought to have originated in hot, violent volcanic environments, but the authors write that today “sustainability of Earth-based life is being threatened by a series of environmental events” – many caused by global warming.
They point to the now-defunct “asteroid bombardment window” by the asteroid Apophis in 2029 as one such event.
“Asteroid collisions are increasingly likely to damage cities and threaten infrastructure in space, like communications satellites, in the years to come. How fast will nature act to destroy us?”