8 mins read 08 Oct 2020

An Exoplanetary Twinkle in USQ’s eye

How do you study the atmosphere of an alien world, orbiting a distant star? By looking for the twinkle in the host star’s light! A new space telescope, currently scheduled to launch in 2023 or 2024, will do just that -- and today, it was announced that Australian researchers at the University of Southern Queensland will be a core part of the new and exciting mission.

Twinkle, Twinkle, Little Star ... revealing planets from afar ....

Over the past thirty years, or so, we have been witness to a great scientific revolution - the dawn of the Exoplanet Era. Where once we wondered if the Solar system was unique, we now know that planets are ubiquitous - that virtually every star in the sky is accompanied by a planetary retinue. 

In recent years, the number of alien worlds (exoplanets) we have found has skyrocketed - primarily thanks to the amazing NASA space observatories Kepler and, more recently, TESS (the Transiting Exoplanet Survey Satellite). Those instruments have revealed thousands of new exoplanets that transit their host stars - passing directly between us and their stars every single time they complete another orbit around them. 

Whilst we have found a panoply of alien worlds (4284 confirmed to date, a number that is rising on a weekly basis), our knowledge of those planets remains very limited. Based on the amount of light they block as they transit their star, we can work out their size (bigger planets block more light), and if we can measure how their gravity makes their star wobble (using instruments like USQ’s MINERVA-Australis), we can work out their mass (a more massive planet causes a bigger wobble). But that’s about it. 

What astronomers really want to be able to do is to take the next step - to begin to characterise these newly discovered alien worlds, to study their atmospheres, and, eventually, to find those that could be the most promising targets in the search for alien life.

A twinkle in the atmosphere from another world

An artist’s impression of the kind of data Twinkle will obtain - showing the absorption of a star’s light at infra-red wavelengths as a result of that light passing through the atmosphere of an alien world. Credit: Twinkle Press Pack; Twinkle, UCL, SSTL, Blue Skies Space Ltd.

That’s where Twinkle comes in. When a planet transits its host star, some of the star’s light will pass through the planet’s atmosphere, before carrying on to eventually reach the Earth. Whilst passing through the planet’s atmosphere, that light will gain a spectral fingerprint that reveals the atmosphere’s makeup. The gasses in the planet’s atmosphere will absorb light at certain specific wavelengths, with each gas imprinting a unique absorption fingerprint on the spectrum of the star’s light.

Now, most of the star’s light will miss the atmosphere of the planet (since the planet is much smaller than the star), so the signal of the planet’s atmosphere will be a tiny change superimposed on the star’s usual spectrum. But Twinkle is designed to be able to measure that tiny change, to reveal the make-up and structure of the atmospheres of the planets it observes. 

At the same time, Twinkle will also obtain amazing measurements of how the brightness of the planet-hosting star dips, allowing astronomers to refine their knowledge of the planet’s size. When it isn’t busy staring at stars to unveil the atmospheres of their planets, it will also perform observations studying objects in our own Solar system, from the comets and asteroids that whizz across the orbits of the planets, to the atmosphere of our own, homegrown planets (and their moons).  

A space telescope at a bargain price

Artist’s impression of the Twinkle Space Telescope in orbit around the Earth, studying a distant alien world. Credit: Twinkle, UCL, SSTL, Blue Skies Space Ltd.

Historically, the great space observatories have all been government/space agency funded. Telescopes like Hubble, Kepler, and TESS were all built and run by NASA, whilst the European Space Agency, ESA, gave us incredible facilities such as Hipparcos and Gaia. All those telescopes were huge endeavours, built at a cost that only NASA and ESA could afford.

But times change. Thanks to the revolution of commercial launches, putting payloads into space is now far, far cheaper than was ever the case before. At the same time, it has now become possible to build satellites using off-the-shelf components, greatly reducing the cost required to put your very own spacecraft together.

Twinkle takes advantage of both these revolutions to put together a cutting-edge space telescope for a fraction of the cost of the great observatories of the past. In space terms, it will be ‘cheap’ - costing ‘just’ tens of millions of dollars. By contrast, the forthcoming James Webb Space Telescope, NASA’s next great space observatory, is currently running on a budget in excess of $10 billion - more than two orders of magnitude more costly than Twinkle. 

Twinkle is actually being developed under a relatively unique model for a space observatory. Rather than being funded by a single government agency, it is instead being funded by a number of international partners. Those partners have bought into the mission, contributing some of its cost, in return for guaranteed time with the telescope, once it is launched. 

And that’s where Australia comes into the picture.

An Australian Team with a Twinkle in its eye

University of Southern Queensland PhD student Nataliea Lowson will play a leading role in Australia’s participation in the Twinkle space telescope. Image credit: D. Martinelli/University of Southern Queensland.

The University of Southern Queensland today announced their buy-in to the Twinkle space observatory, as founder members of the mission consortium. In doing so, they have guaranteed that Australia will have a piece of the action in this revolutionary new observatory. 

Australia has been a key player in the global search for alien worlds since the late 1990s - and in recent years, USQ has taken the lead in Australian Exoplanetary research. The team at USQ are currently working with NASA, and with colleagues around the globe, following up on the wealth of planet candidates being discovered by TESS. 

USQ hosts the southern hemisphere’s only dedicated exoplanet follow-up facility, MINERVA-Australis, specifically designed to allow researchers to build on TESS’ discoveries, and to learn more about newly discovered alien worlds.

The MINERVA-Australis telescope located at the Mt. Kent Observatory, just outside Toowoomba. Credit: David Martinelli/USQ.

By joining the global Twinkle consortium, USQ researchers will get guaranteed time on the new space observatory, allowing them to focus the spacecraft on the most exciting targets they detect using MINERVA-Australis. The work will go hand-in-hand with the work of other USQ researchers, whose work is focussed on studying the stars those planets orbit - allowing the team to build a cohesive picture of newly discovered alien worlds and the stars that host them.

In addition to getting guaranteed observing time, once Twinkle launches, USQ plans to send staff and students (initially, Dr Duncan Wright and Nataliea Lowson) to the UK to work with the team from Blue Skies Space Ltd. who are constructing Twinkle. This will mean that Australian researchers get to shape the construction of the new space observatory - and will also mean that those staff and students can bring back expertise that should help Australia to build our own satellites, in the years to come!

Towards the search for life

We live in a galaxy that likely contains millions of planets that could resemble Earth - and in the coming decades, we will discover hundreds, if not thousands of them. The search for life beyond the Solar system will then begin in earnest. Credit: NASA, ESA, and G. Bacon (STScI).

In the longer term, Twinkle is a stepping stone towards the next generation of space-based exoplanet observatories. If we want to search for any evidence of life beyond the Solar system, studies of the atmospheres of Earth-like planets will prove vital. Such studies will help us to identify the most promising targets for that search (helping us to identify hot-house hellscapes, like Venus, that would otherwise be considered ‘Earth-like’). 

Once the most promising targets are chosen for the search for alien life, Twinkle’s successors will focus in, carrying out what will be the most challenging observations ever attempted. They will attempt to look for anything unusual, anything out-of-place, on those alien worlds, and in their atmospheres (such as phosphine, which was recently, to much acclaim, found in Venus’ atmosphere). 

Extraordinary claims require extraordinary evidence, and Twinkle’s successors will have to spend thousands of hours staring continually at a few choice exoplanets, trying to hunt down the tenuous signs of alien life. By joining the Twinkle consortium, USQ (and Australia) is guaranteed to be part of the ongoing journey towards those observations - with the goal of one day answering the ultimate question: are we alone?

And of course, we’ll make that journey with a Twinkle in our eyes!

Video Credit: System Sounds

Prof. Jonti Horner

Jonti got hooked on astronomy at the age of five, after seeing part of an episode of "The Sky At Night". He joined his local astronomical society in the UK, WYAS, and remains a member (and honourary president) to this day! He studied Physics and Astronomy at the University of Durham, before doing his DPhil at the University of Oxford, studying 'The Behaviour of Small Bodies in the Outer Solar System.'.

After leaving Oxford, Jonti spent a nomadic decade, working in Bern (Switzerland), Milton Keynes and Durham (in the UK) and Sydney (Australia), before finally moving to Toowoomba, in 2014, to take a post at the University of Southern Queensland. Jonti is now Professor of Astrophysics at USQ, where his research interests range from studying the Solar system's small bodies, to finding planets around other stars, and trying to quantify the different factors that could make one alien world more promising as a target for the search for life than another. He is an enthusiastic science communicator, and can be heard regularly on ABC Queensland, talking about all things Space and Astronomy.

Twitter: @JontiHorner