PLAnetary Transits and Oscillations of stars
(PLATO) is a space observatory under development
by the European Space Agency for launch in
2026.
The mission goals are to search for planetary
transits across up to one million stars, and
to discover and characterize rocky extrasolar
planets around yellow dwarf stars (like our
sun), subgiant stars, and red dwarf stars.
The emphasis of the mission is on earth-like
planets in the habitable zone around sun-like
stars where water can exist in liquid state.
It is the third medium-class mission in ESA's
Cosmic Vision programme and named after the
influential Greek philosopher Plato, the founding
figure of Western philosophy, science and
mathematics.
A secondary objective of the mission is to
study stellar oscillations or seismic activity
in stars to measure stellar masses and evolution
and enabling the precise characterization
of the planet host star, including its age.
== History ==
PLATO was first proposed in 2007 to the European
Space Agency (ESA) by a team of scientists
in response to the call for ESA's Cosmic Vision
2015–2025 programme.
The assessment phase was completed during
2009, and in May 2010 it entered the Definition
Phase.
Following a call for missions in July 2010,
ESA selected in February 2011 four candidates
for a medium-class mission (M3 mission) for
a launch opportunity in 2024.
PLATO was announced on 19 February 2014 as
the selected M3 class science mission for
implementation as part of its Cosmic Vision
Programme.
Other competing concepts that were studied
included the four candidate missions EChO,
LOFT, MarcoPolo-R and STE-QUEST.In January
2015 ESA selected Thales Alenia Space, Airbus
DS, and OHB System AG to conduct three parallel
phase B1 studies to define the system and
subsystem aspects of PLATO, which were completed
in 2016.
On 20 June 2017, ESA has adopted PLATO in
the Science Programme, which means that the
mission can move from a blueprint into construction.
In the coming months industry will be asked
to make bids to supply the spacecraft platform.
The PLATO Mission Consortium that is responsible
for the payload and for major contributions
to the science operations is led by Prof.
Heike Rauer at the German Aerospace Center
(DLR) Institute of Planetary Research.
The design of the Telescope Optical Units
is made by an international team from Italy,
Switzerland and Sweden and coordinated by
Roberto Ragazzoni at INAF (Istituto Nazionale
di Astrofisica) Osservatorio Astronomico di
Padova.
The Telescope Optical Unit development is
funded by the Italian Space Agency, the Swiss
Space Office and the Swedish National Space
Board.PLATO is an acronym, but also the name
of a philosopher in Classical Greece; Plato
(428–348 BC) was looking for a physical
law accounting for the orbit of planets (errant
stars) and able to satisfy the philosopher's
needs for "uniformity" and "regularity".
== Objective ==
The goal is to find planets like Earth, not
just in terms of their size but in their potential
for habitability.
By using 26 separate small telescopes and
cameras, PLATO will search for planets orbiting
from 300,000 to one million stars.
The main objective of PLATO is to elucidate
the conditions for planet formation and the
emergence of life.
To achieve this objective, the mission has
these goals:
Discover and characterize a large number of
close-by exoplanetary systems, with a precision
in the determination of the planet radius
up to 3%, of stellar age up to 10%, and of
the planet mass up to 10% (the latter in combination
with on-ground radial velocity measurements)
Detect and characterize Earth-sized planets
and super-Earths in the habitable zone around
solar-type stars
Discover and characterize a large number of
exoplanetary systems to study their typical
architectures, and dependencies on the properties
of their host stars and the environment
Measure stellar oscillations to study the
internal structure of stars and how it evolves
with age
Identify good targets for spectroscopic measurements
to investigate exoplanet atmospheresPLATO
will differ from the COROT and Kepler space
telescopes in that it will study relatively
bright stars (between magnitudes 4 and 11),
enabling a more accurate determination of
planetary parameters, and making it easier
to confirm planets and measure their masses
using follow-up radial velocity measurements
on ground-based telescopes.
Its dwell time will be longer than that of
the TESS NASA mission, making it sensitive
to longer-period planets.
== Optics ==
The PLATO payload is based on a multi-telescope
approach, involving a set of 24 "normal cameras"
working at a readout cadence of 25 seconds
and monitoring stars fainter than apparent
magnitude 8, plus two "fast cameras" working
at a cadence of 2.5 seconds, and observing
stars between magnitude 4 to 8.
The cameras are refracting telescopes using
six lenses; each camera has an 1,100 deg2
field and a 120 mm lens diameter.
Each camera is equipped with its own CCD staring
array, consisting of four CCDs of 4510 x 4510
pixels.
The 24 "normal cameras" will be arranged in
four groups of six cameras with their lines
of sight offset by a 9.2° angle from the
+ZPLM axis.
This particular configuration allows surveying
a total field of about 2,250 deg2 per pointing.
The satellite will rotate around the mean
line of sight once a year, delivering a continuous
survey of the same region of the sky.
== Launch ==
The satellite is planned to launch in 2026
from Guiana Space Centre with a Soyuz rocket
to the Earth-Sun L2 Lagrangian point.
== See also ==
Cosmic Vision, ESA program (2015-2025)
List of projects of the European Space Agency
List of space telescopes
Transiting Exoplanet Survey Satellite (TESS),
NASA, launched in 2018
