Research Byte

Published in the RSAA Lunations
Vol1 Issue29 1–30 June 2022

 At the intersection of astrophysics and philosophy lies the existential question: “Are we alone in the Universe?”. Society at large is often fascinated with the Drake equation and the Fermi paradox, which offer indirect clues as to humanity’s origin and ultimate demise. Exoplanetary science, especially through the Kepler mission, has found that 5-50% of solar-like stars have rocky planets capable of having surface liquid water. However, there are lots of reasons that such a planet would not, in fact, have any liquid water, and if it did, it may not have life. No current mission can ask these questions – JWST may be able to ask the question for transiting planets around very low mass stars, which may not be habitable for other reasons. 

There are currently 2-3 mission concepts that can search for signs of liquid water and photosynthetic life.  In the USA, there is LUVOIR, which is much more expensive than planned NASA budgets, and HabEx, which only has sensitivity to probe the very nearest stars. The European effort is the Large Interferometer for Exoplanets (LIFE: life-space-mission.com), which has a lower launch mass but at least 5 spacecraft, with an intended launch date around 2045. 

ANU teams co-led by Mike Ireland are developing photonic technology for LIFE, and developing the robotic formation flying prototype interferomer Pyxis, which will be gradually going on-sky over the coming year in the AITC carpark.  PhD student Jonah Hansen has also led one accepted and one submitted paper on re-visiting the mission architecture 13 years after large NASA and ESA teams finished their final report. We find that the 4-telescope “Emma X-Array" configuration (illustrated here, from Cockell et al. 2009), long assumed to be optimal, is not as good at detecting or characterising terrestrial exoplanets as a 5-telescope array, even where each telescope has 4/5 of the collecting area (see figure). The optical design is not much more complex, and unlike the 4-telescope array, the 5-telescope array still completes much of the mission if 1 telescope fails. Read more: https://arxiv.org/abs/2201.04891 and https://arxiv.org/abs/2204.12291.  

Mike Ireland