The Extremely Large Telescope is soon to be completed. It will be one of the most powerful instruments for studying exoplanets. It is quite possible that it will be able to find life on one of them very quickly.
Capabilities of the Extremely Large Telescope
The Extremely Large Telescope (ELT), now under construction in northern Chile, will give scientists a better view of the Milky Way than any ground-based astronomical instrument before it. It’s hard to overstate how transformational this will be.
The ELT’s primary mirror array will have an effective diameter of 39 meters. It will collect an order of magnitude more light than previous telescopes and give us images 16 times sharper than the Hubble Space Telescope. The telescope is scheduled to launch in 2028, and results could start coming in just overnight, according to a recent study published on the arXiv preprint server.
Study of exoplanet spectra
One of the ELT’s most powerful capabilities will be to capture faint atmospheric spectra from the atmospheres of exoplanets. This usually happens when a planet passes in front of its star from our observation point. A small fraction of starlight passes through the planet’s atmosphere to reach us, and by analyzing the absorption spectra, we can identify molecules in the planet’s atmosphere, such as water, carbon dioxide, and oxygen. The James Webb Space Telescope, for example, has collected data on several exoplanet atmospheres.
But sometimes the transit data we can gather is inconclusive. For example, when James Webb searched for atmospheres on the planets of the TRAPPIST-1 system, it appeared that planets b and c were airless, but there was not enough data to rule out the presence of an atmosphere. There may be thin atmospheres with spectral lines too faint for JWST observations. The greater sensitivity of the ELT should solve this issue.
More interestingly, the new telescope will be able to collect spectra not only of exoplanets that pass by their star, but also of exoplanets that don’t, using reflected starlight. To determine how powerful ELT would be, the new study modeled the results for several scenarios.
Searching near red dwarfs
The scientists have focused on planets orbiting red dwarf stars, as this is the most common type of exoplanets, and have looked at four test cases: a non-industrial Earth rich in water and photosynthesizing plants, an early Archean Earth where life is just beginning to flourish, an Earth-like world where the oceans have evaporated, similar to Mars or Venus, and a pre-biotic Earth capable of life but where there is none. For comparison, the team also examined Neptune-sized worlds, which should have much thicker atmospheres.
The idea was to see if ELT could distinguish the difference between different Earth-like worlds, and more importantly, if the data could fool us by giving a false positive or false negative. That is, whether the uninhabited world will appear to have life in it, or whether the living world will appear to be barren.
Based on their simulations, the authors concluded that we should be able to clearly and accurately distinguish between neighboring star systems. For the nearest star, Proxima Centauri, we could detect life on an Earth-like world in just 10 hours of observation. For a world the size of Neptune, the ELT could capture the spectra of the planets in about an hour.
So, it seems that if life exists in a neighboring star system, the ELT should be able to detect it. The answer to perhaps the biggest question in human history may be answered in just a few years.
According to phys.org
