Mission, launch date, main objective

PLATO just got a little closer to the future. The next exoplanet-hunting mission being developed by the European Space Agency (ESA) is named after the Greek philosopher. Like its namesake, it will research the physical laws underlying planetary motion.

ESA announcement on January 14, PLATO had reached a critical milestone in the review of the PLATO spacecraft and payload, allowing the development of the telescope’s exoplanet-hunting observatory to move forward with a planned launch in the current of 2026.

When launched, PLATO will join a host of other exoplanet hunting and characterization missions, including NASA’s James Webb Space Telescope. But PLATO has a specific role to play: to find and characterize rocky Earth-like planets in the habitable zones around Sun-like stars, worlds that have the greatest chance of sustaining life that resembles what we know.

What is PLATO?

PLATO is an ESA space telescope mission being developed by ESA to search for exoplanets around distant stars. It is one of four ESA missions planned or launched focus in whole or in part on exoplanets.

The ESA-characterizing ExOPlanets satellite (CHEOPS) was launched in 2019 and is currently hunting Earth-sized exoplanets at Neptune from a solar-synchronous orbit around Earth.

NASA’s James Webb Space Telescope, on which ESA has been a major partner, will conduct extensive studies of exoplanets once it becomes operational over the summer, including targets characterized for the first time by CHEOPS. Webb will operate approximately 1 million kilometers from Earth in orbit around Lagrange Point 2 (L2).

ESA’s Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL) study will be launched in 2028 and will investigate the chemical constituents of distant exoplanets from its orbit around L2.

Existing and future exoplanets study ESA missions. ESA

What does PLATO mean?

PLATO stands for PLANetary Transits and Oscillations, referring to PLATO’s use of the transit method to detect exoplanets.

Distant exoplanets are incredibly dim compared to their host stars, making them extremely difficult, if not impossible, to see directly. The transit method uses changes in starlight to detect orbiting exoplanets.

By closely monitoring a star for dips in brightness associated with an exoplanet passing between the star and the telescope — a transit — astronomers can not only detect the existence of an exoplanet, but also gauge its size based on starlight attenuation. And by watching for a second transit, astronomers can measure the orbital period of the exoplanet.

What is the main objective of PLATO?

ESA designed PLATO to discover and characterize rocky Earth-like exoplanets in the habitable zones of Sun-like stars and determine if these exoplanets are habitable. To achieve this primary goal, PLATO will determine the mass and radius of exoplanets and study the stars of these planets to better understand the evolution of other solar systems with potentially habitable worlds.

What type of telescope is PLATO?

While the Hubble Space Telescope has a large primary mirror and the James Webb Space Telescope has an even larger primary mirror made up of 18 segments, PLATO will consist of 26 separate telescopes, each with its own camera.

The payload module and some of the 26 eyes of PLATO, ESA’s exoplanet-hunting space telescopeESA

Plato telescopes are also refracting telescopes, using a series of lenses to collect and focus light rather than a set of mirrors like Webb and Hubble.

What is the launch date of the PLATO mission?

PLATO is currently expected to launch towards the end of 2026, although much further testing and development remains to be done before the mission takes off. For example, another critical review, this time of the spacecraft design, will be a must-do deal for PLATO in 2023.

But recent history suggests it’s worth taking your time when deploying sophisticated science instruments in deep space. While admittedly much larger than PLATO, the long-awaited James Webb Space Telescope has been repeatedly delayed during its development years and before its December 25, 2021 launch. But as noted by some scientists who have worked on Webb for decades, all of that testing and caution has paid off, with the Webb sailing smoothly so far to orbit L2.

How will PLATO be different from TESS?

PLATO and NASA’s Transiting Exoplanet Survey Satellite (TESS) share some mission similarities, but are designed for different purposes.

Launched in 2018, TESS, like PLATO, uses the transit method to detect exoplanets. But TESS was designed to take full-sky surveys of nearby bright stars in its hunt for exoplanets, which prevents it from spending enough time staring at a few patches of sky long enough to detect Earth-sized exoplanets. around Sun-like stars.

How will PLATO work with ARIEL?

By the time ARIEL is in space and operational, PLATO may already have targets to study for the exoplanet chemistry mission. PLATO can also provide targets for Webb, which will be a powerful instrument for studying the atmospheric chemistry of exoplanets using its infrared spectroscopy instruments.

But Webb is also a versatile tool that will be used to study distant galaxies, dark matter, and even planets in our own solar system. With two space missions dedicated to Earth-like exoplanets and their chemistry, ESA will be able to spend more time studying distant worlds that could turn out to be very similar to our own.

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