In a bold call to action, Australian astronomers Dr. Charley Lineweaver and PhD student Aditya Chopra from the Australian National University have declared that the search for planets capable of supporting life beyond our solar system should be a top priority. Their insights, published in the Annual Reviews of Earth and Planetary Sciences, emphasize that understanding what makes a planet habitable is crucial for the survival of humanity.

Since the first exoplanet was discovered orbiting another star in 1995, the count has surged to over 750. Yet, only a handful of these worlds are classified as ‘Earth-like’. Lineweaver describes the quest to determine the habitability of these planets as the new “holy grail” of astronomy, a complex challenge that will occupy planetary scientists for the next couple of decades.

“Determining whether these planets are habitable has become one of the biggest, most confusing, and important issues that planetary scientists are going to have to deal with in the next 10 to 20 years,” says Lineweaver.

Lineweaver argues that exploring habitable planets is essential for establishing future human colonies. He likens the current reluctance to venture beyond Earth to the skepticism faced by Columbus when he proposed his transatlantic journey in 1450.

“It’s a bit like the Europeans in 1450 saying ‘Hey, what does it matter whether we go exploring the rest of the world?'”

Key Factors for Habitability

Lineweaver and Chopra’s review highlights two critical factors for life: the presence of water and a temperature range between -20°C and 122°C. They point out that recent explorations of Earth have revealed life in extreme environments previously thought uninhabitable, suggesting that similar extraterrestrial environments may also harbor life.

“Over the past few decades, our exploration of the Earth has turned up life in all kinds of weird environments where we didn’t think life could be,” Lineweaver explains.

The duo also introduces the concept of the “abiogenesis habitable zone,” which refers to the specific conditions necessary for life to form, a much narrower range than those required for life to survive.

“Life, by managing its own environment, makes a planet habitable,” Lineweaver adds. “It’s kind of like an adult can live in a higher range of temperatures than a baby can.”

Future Observations and Discoveries

Looking ahead, Lineweaver is optimistic about the capabilities of observation programs like the Kepler telescope, which has been extended through at least 2015. These programs are expected to continue unveiling Earth-like planets.

“The next step will be to develop a satellite that can look at the atmospheres of these planets, which will be able to give us some information about whether there is life there or not,” he states.

As we stand on the brink of a new era in space exploration, the implications of finding habitable planets could be monumental. If we discover an Earth-like planet, Lineweaver suggests that the next logical step would be to send an interstellar probe to explore it. Conversely, he warns that failing to find such a planet could lead to dire consequences for humanity.

“If we don’t find one, maybe we’ll go extinct,” he concludes.

As we have seen in other explorations on this site, space radiation may be deadly enough to keep us on earth. If so, this could be the only host planet we get in this particular simulation. That does not mean we should not try, however.