The discovery of TRAPPIST-1 was exciting news to be sure. Astronomers marveled at the idea of seven Earth-size planets potentially capable of sustaining life. It sounded like a gold mine. Maybe a little too good to be true. And it sort of was. The distant star system may not be the life refuge astronomers previously hoped it might be.
The star from which these planets orbit was originally thought to be much younger (around 500 million years) however new research suggests that the star might actually be between 5.4 and 9.8 billions years old. The upper end is over twice the age of our solar system.
Why does the age of the star matter? TRAPPIST-1 has a relatively stable dwarf star, and the close orbit of the seven planets allows for the potential of life to flourish, but the extended life span means the planets have experienced a prolonged exposure to radiation.
“Our results really help constrain the evolution of the TRAPPIST-1 system,” says Adam Burgasser, an astronomer from the University of California. “…because the system has to have persisted for billions of years. This means the planets had to evolve together, otherwise, the system would have fallen apart long ago.”
The bad news, the radiation is most likely to have boiled off the atmosphere. Also, the close orbit has the potential to make these planets tidally locked, leading to temperature extremes. In other words, the TRAPPIST-1 planets may more closely resemble Venus or Mars than Earth. Of course, the only way to find out for certain is to visit the system. Unfortunately, the TRAPPIST-1 group is 229 trillion miles away. Traveling at the speed of light it would take 39 years to get there. Considering space craft travel much slower than the speed of light, a science expedition would take much longer. If we were to point Voyager, Earth’s most distant spacecraft, traveling at 38,000 mph, it would reach the TRAPPIST-1 system in 685,000 years. So, a long time to wait for an answer.
“If there is life on these planets, I would speculate that it has to be hardy life because it has to be able to survive some potentially dire scenarios for billions of years,” Burgasser said.
All the planets in the TRAPPIST-1 system have much lower densities than Earth. So, it is still possible that thick atmospheres could protect the TRAPPIST-1 planets from the harsh radiation. Although, it seems more likely that these planets are just sterile wastelands, and life is still a rarity.