What is CHEOPS ? | An European Space Agency mission (Part-2)

Link for Part-1 : https://ikanlife16.blogspot.com/2019/04/cheops-european-space-agency-mission.html

Use of space based telescopes

Discovery of exoplanets was boosted by the use of space based telescopes because on earth there are disturbances due to atmosphere & many other factors, using satellites help to continuous target a particular area & it is easy to keep a sight over them.

One of the very first space sensitive telescope mission was CNES- led convection, Rotation & Planetary transits mission CoRoT (2006-13). Main objectives of this mission were:

• To look out for extra solar planets with short orbital periods (in days or with hours) .
• To measure oscillations in stars.

Using the transits method CoRoT mission has discovered 37 planets till now, NASA's 2009 Kepler mission is another one of the most famous missions & it has discovered almost three quarters of total planets we have discovered till now. Kepler looked at a fixed patch of space for a long period of time & it discovered a lot of exoplanets & stars, thus giving us an idea of how many planets exist out there in this never ending universe.

The latest addition to exoplanet mission fleet is the NASA's Transiting Exoplanet Survey Satellite(TESS) launched in April 2018 for detecting small planets with bigger host stars.

Some space observatories have also played a bigger role in helping us to discover exoplanets,some of these are :

• NASA/ESA Hubble telescope (used for calculating the transit measurements & atmosphere of some exoplanets).
• NASA's Spitzer (observing the change in infrared light during exoplanet's transit).
• ESA's Gaia mission (collecting the data-bank by doing a space survey from which we may discover some more exoplanets).

Enter CHEOPS

ESA plans to launch three exoplanet specific satellites in the next decade named CHEOPS, PLATO, ARIEL.

Main focus of CHEOPS

Previous observations have shown that most sun like stars host planets with wide ranges of size, masses & orbital parameters and are surprisingly around everywhere, around half of the size of sun like stars host planets with the size of in between Earth & Neptune. The number of small planets revolving around these stars were not predicted by the theories & this is one of the main focus points for CHEOPS.

Cheops will observe bright, nearby stars that are already known to host exoplanets, focusing particularly on those with (smaller) Earth- to Neptune-sized planets. With the precision & stability of the telescope CHEOPS will be able to measure the transit depths using the Transit Photometry method. It will also help the astronomers to accurately & precisely find out the sizes of these exoplanets.

By knowing when and where to point in order to catch

transits, CHEOPS will maximise the time it spends monitoring

actual transit events. It will point at stars over most of the sky,

returning to observe multiple transits over the course of the

mission, thus building up the accuracy of measurement of

planet sizes.

For planets which we are already having a mass measurement,

combining this with CHEOPS data will make it possible to

determine the density of the planet, with which we can know

about their composition and structure. This first-step

characterisation of these worlds – many with no Solar System

equivalents – is a critical step towards understanding the

formation, origin and evolution of these small exoplanets.

I will continue after this in next part.

Peace☮