A whole new world: NASA’s pioneering search for life

Jonathan Stark explains how the TESS satellite will help us find new life


On the evening of Wednesday 18thApril 2018, NASA launched a new space telescope which will orbit around the Earth and help astronomers find habitable planets outside of our solar system. The Transiting Exoplanet Survey Satellite, or TESS, will join the veteran Kepler telescope, which has discovered over 2000 planets since its launch in 2009. NASA hopes that TESS will identify planets which have a similar size to Earth, which can then be investigated further to see if they might support life.

TESS was carried up by one of SpaceX’s reusable Falcon 9 rockets, which have become fairly standard for NASA launches in recent years. The telescope is planned to scan all of the sky over its first two years in orbit, focusing on individual regions for 27 days at a time to eventually cover all of the Southern Hemisphere in its first year and all of the Northern Hemisphere in its second.

As it carries out its scanning, NASA’s researchers will be looking out for planets that are only a few times larger than Earth, orbiting around M dwarf stars, which are a little dimmer than the Sun. With large planets and relatively small stars, the planets will dim their stars’ light as they pass in front of them. Warm, habitable planets will be found in close, short orbits around these small stars – meaning that they are more likely to be spotted passing over their stars during TESS’s 27 day viewing periods.

TESS has been designed to identify planets that are roughly the same size and temperature as Earth. However, that’s just the beginning of the story. After TESS’s first two years of investigation, the planets that have been found will be further investigated using a larger, more powerful telescope: the James Webb Space Telescope.

Webb is hailed by NASA as “the premier observatory of the next decade”, and set to be launched in 2020. It will use its massive 6.5m mirror to capture images which researchers can use to study the creation of the universe, the formation of galaxies and star systems, and many other questions of astronomy as well as taking a closer look at TESS’s exoplanets.

The Webb Telescope should help identify what gases are in the atmospheres of the Earth-like planets detected by TESS, which is a key factor in whether or not they might support life. Different gases absorb different wavelengths of light, and while TESS will mainly just be able to spot these planets, Webb will be sensitive enough to see exactly which wavelengths dim the most when a planet passes in front of its star – and thus, tell us what their atmospheres are made of. NASA hopes that they can keep TESS running beyond its initial two-year mission, so that the two telescopes can be used together to identify and analyse potentially Earth-like worlds.

The search for life-supporting worlds – and possibly even life itself – out in space is one of the most engaging ventures in astronomy, and has consistently grabbed headlines in science magazines, major newspapers and tabloids alike for decades. Newspapers are still running stories about Curiosity discovering ‘Life on Mars’, seven years after the rover touched down. Recently, the discovery of large lakes deep under ice in Canada ignited new discussion about the possibility of life on Jupiter’s frozen moon, Europa, which has a similar subglacial sea. And now, NASA has stepped up the search for life amongst the thousands of planets that we can see outside of our own solar system.

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