In 2025, we may discover the first signs of life outside our solar system.
Crucial to this potential breakthrough is 6.5 meter diameter James Webb Space Telescope (JWST). JWST, launched aboard an Ariane 5 rocket from the coastal town of Kourou in French Guiana in 2021, is the largest space telescope to date. Since it began collecting data, the telescope has allowed astronomers to observe some of the darkest objects in the universe, such as ancient galaxies and black holes.
Perhaps more importantly, in 2022, telescopes will provide the first glimpse of a rocky exoplanet with an interior that astronomers call its habitable zone. This is a region around a star where the temperature is just right for liquid water, one of the key building blocks of life as we know it, to exist on the planet’s rocky surface. This Earth-sized planet was discovered orbiting a small red star. Trappist-1It is a star 40 light years away and has 1/10th of the sun’s mass. Red stars are cooler and smaller than our yellow sun, making it easier to detect Earth-sized planets orbiting them. Nonetheless, signals detected from exoplanets are typically weaker than those emanating from their much brighter host stars. Discovering this planet was a very difficult technological achievement.
The next step, detecting molecules in planetary atmospheres, will be an even more challenging astronomical feat. Whenever a planet passes between us and a star (as it passes), starlight is filtered by the planet’s atmosphere and hits molecules in its path, creating spectral absorption features that we can search for. These features are very difficult to identify. To accomplish this, JWST will need to collect enough data from multiple planetary transits to suppress signals from their host stars and amplify molecular signatures in the rocky exoplanet’s incredibly thin atmosphere (if these planets are scaled down to size). For an apple, for example, at that scale the atmosphere would be thinner than the fruit’s skin. But with a space telescope as powerful as JWST, 2025 could finally be the year we can detect these molecular signatures.
But TRAPPIST-1’s detection of water on exoplanets is not the only opportunity to find life on distant exoplanets. For example, in 2024, JWST also revealed potential signs of carbon dioxide and methane in the atmosphere. K2-18bA planet located 124 light years from Earth. But K2-18b is not an Earth-like rocky planet orbiting its star in the habitable zone. Instead, it’s more likely to be a giant ball of gas with oceans similar to Neptune’s (though smaller). This means that if there is life on K2-18b, it may be in a completely different form from life as we know it on Earth.
In 2025, JWST will provide more information about these sweet detections and hopefully confirm for the first time whether there is life on extraterrestrial worlds light years away from us.
