Image copyright NASA Image caption Jake O’Sullivan of NASA’s Jet Propulsion Laboratory has called for a new guiding principle for the search for life
Space scientists have called for a new guiding principle to guide the search for alien life.
Some, including Jake O’Sullivan, have suggested it could come in the form of a picture, like Kepler or Spitzer space missions.
This, they say, would capture evidence about microorganisms in distant worlds.
Others, like Ernst Kuhn, have suggested an atmosphere as an important data point.
The US space agency has created a new science roadmap that runs from 2016 to 2025, outlining how to tackle the thorny, global challenge of finding life beyond our own planet.
The roadmap, published in Science magazine, sets out how, with special attention to the concept of habitability, the United States can tackle the latest technological challenges in space exploration.
This includes discussing where the search for life is going next, and what emerging technologies could play a part.
The new ideas did not come up in isolation. Mr O’Sullivan of NASA’s Jet Propulsion Laboratory told BBC News that data gathered by satellite telescopes “is more and more interesting and more and more relevant”.
“It’s becoming increasingly clear that it isn’t just planets with water, but one could just as well be in the presence of these organisms,” he said.
He suggested the finding of life in the distant solar system orbiting a dying star as a possible starting point for such investigations.
“I guess at one point it could be the atmosphere of that planet,” Mr O’Sullivan said.
Image copyright NASA Image caption The light from a distant planet may be slowly bleaching it as it takes up more of its host star’s light, NASA scientists believe
In a study published in September last year, US researchers suggested that life on Earth might have evolved “proximately on the edge of the solar system’s habitable zone, on a planet like Uranus or Neptune that orbits the Sun at a slight angle”.
They proposed a picture that captured images of the surface of the planet, similar to how Spitzer or Kepler space telescopes used light as a proxy for an atmosphere.
However, a number of authors of the article in Science acknowledged that collecting valuable data is harder than it sounds.
Image copyright NASA Image caption The prediction comes from the same researchers who, last year, reported that life was more likely to be “unfragmented” in a hard-to-detect, “fuzzy” phenomenon called an insulator, where heat from the planet is absorbed by molecules below.
“Where will the explosion of data come from in the future?” asked the senior author of the study in Science, Mirko Stecker, of the California Institute of Technology in Pasadena.
“The host stars of the future may be different from those of the past. So which instrument will be able to take us there? Will it be the same instrument from the past?”
US scientists have also emphasised the importance of Earth-like planets.
“For life to persist and likely be found elsewhere in the universe, we must look at habitable worlds that are like Earth, but more accurately, our sun,” said Joseph Nuth, of the University of Minnesota.
The findings in Science, in a section called the high impact chapters, are also at the heart of an opinion piece about the importance of life that published in the journal Scientific Reports last week.
Scientists surveyed 65 billion Earth-like planets found in the Milky Way galaxy by looking at the gravitational fields of stars.
They found there were about 700 “polarities” in the galaxies: the edges of a star in space that orbit at distances beyond the pull of the planets around them.
Image copyright NASA Image caption Five of the planets within the ‘habitable zone’ have liquid water, a key requirement for life to exist on a planet
This tells them that about seven Earth-like planets, with liquid water around them, would be protected from the worst of the harmful effects of a star like our sun.