Stopping the stars from twinkling: Unlocking the potential of ground-based telescopes for astronomy and free-space optical communication

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Aim: To build robust 3D models of both local and global atmospheric turbulence, in order to i) routinely characterise the atmospheres of small transiting exoplanets and ii) improve satellite communication by supporting the transition from traditional radio waves to faster, cheaper and more secure Free Space Optical Communication (FSOC).Ground-based astronomy and FSOC are both currently limited by the Earth's turbulent atmosphere. By pioneering new concepts in atmospheric characterisation and correction, I will: 1. enable astronomical observations from ground-based telescopes to be comparable to, and potentially better than, space telescopes2. enable regular, robust and sustained FSOC links between the ground and orbiting satellites.These innovative techniques have multiple applications, including:1. learning about small Earth-like exoplanets orbiting distant stars2. retrieving data from space science satellites used for Earth observation, inter-planetary and deep space missions. There are many reasons to study exoplanets. These range from trying to understand how solar systems form and evolve, to the search for extra-terrestrial life. The former will allow us to explore the vast diversity of worlds that exist and to discover the physical universe on a whole new level. The latter being incredibly exciting with implications for the whole of humanity.Simply detecting an exoplanet is not enough, we must also characterise these planets in order to ascertain what they are like. There are several ways to characterise exoplanets. One of the most powerful and certainly the most productive is the transit method. As a planet passes in front of a star it blocks some of the light. This reduction in intensity is observable by telescopes and is used to deduce the presence of an exoplanet orbiting a distant star and a wealth of information about it. The amount of light absorbed or emitted by the planet in several wavelengths gives us a detailed impression of the temperature distribution, dynamics, composition and weather systems of the exoplanet's atmosphere.Several large transits surveys such as TESS and NGTS and the radial-velocity surveys of HARPS and HARPS-N, together with future space satellites such as CHEOPS and PLATO, will provide abundant interesting targets which will require precise follow-up. The extra precision attainable by using the large collecting areas and the accessibility of multiple ground-based telescopes would allow the routine and targeted characterisation of the atmospheres of distant small exoplanets. However, this is beyond current capabilities.The Earth's atmosphere causes intensity fluctuations, called scintillation, which can be seen as twinkling by the naked eye. This twinkling limits the sensitivity of ground-based observations to that of exoplanets many times larger than the Earth.In addition to astronomy, the recently expanding field of FSOC has very similar problems. The large bandwidth of using optical wavelengths, as opposed to conventional radio communication, will enable 10-100 times more data to be retrieved from space science satellites used for Earth observation, inter-planetary and deep space missions. This increase in transmission rates is analogous to moving from traditional copper cables to fibre optics. In addition, by transitioning to optical wavelengths, we can meet demands for higher capacity data transmissions that societies around the world have become accustomed to. Through a combination of characterising the Earth's atmospheric turbulence using novel instrumentation, with a numerical global turbulence forecast model, which I am developing, I will assess the implications of the Earth's atmosphere on astronomy and FSOC and develop new correction mechanisms, including tomographic scintillation correction. It is only with the combination of these themes can we truly unlock the full potential of ground-based telescopes.