Briefly: there’s a meeting on the Extremely Large Telescope going on right now, the Vienna ELT Science + Simulations Workshop, at the University of Vienna Observatory.
https://astarvienna.github.io/websites/ELTWorkshopSept2025.html
This is the second Vienna meeting, #2: “Spatial resolution”.
(If you aren’t already aware: the ELT will be a 39-meter telescope, the world’s largest, when it is completed in 2029. By comparison, the current recordholder is, arguably, the 10.4m GTC or 11.8m LBT. Truly, the ELT will be a leap forward.)
In preparation for 2029, astronomers are lining up their early observations, and ongoing plans. Instruments that can take advantage of 39 meters of aperture are also being built, and they, too, need to be included in observation preparations. These meetings keep astronomers up to speed with the construction and completion, so that the observatory will be nice and productive from the start.
And now a few highlights. One of the key benefits of 39 meters of aperture is infrared studies; though Earth’s atmosphere is unsteady, blurring out small details, having 39 meters goes a long way towards image sharpening, through raw photon collecting area alone. Another benefit is that adaptive optics (“AO”) has not reached any fundamental limits yet. Active correction of the telescope glass can be used to compensate for unsteadiness of the atmosphere; the ELT will present a new challenge but currently, it seems like we can keep pace using faster, better correction procedures. Two of the instruments being built, then, are METIS (Mid-infrared ELT Imager and Spectrograph) and MICADO (Multi-AO Imaging Camera for Deep Observations).
Joel Vernet – “ELT Overview”
Ric Davies – “MICADO: the start of integration”
Wolfgang Brandner – “METIS Overview”
Frédéric Merlin – “Solar system investigation using ELT-MICADO”
Camille Chatenet – “Trans-Neptunian Objects with MICADO”
The leap forward via METIS is that, space telescopes aside, infrared astronomy is just cumbersome and annoying from the ground. It’s possible to do, but exposures are long, and not a great use of a scope’s precious time. Meanwhile, space telescopes are expensive, rare, and oversubscribed. Having ELT on the job means one more tool in our toolbox, looking at asteroids in the infrared.
Then, with MICADO, and the AO built into the ELT, we may (after some adjustment period) use the 39 meter aperture to directly image some of the bigger/closer asteroids. That’s right, some percent of asteroids will become more than just dots. A greater number will still be individual dots, but we will spot asteroid satellites- a second dot in orbit around the brighter dot. Binary systems are handy to have, since we can use Kepler’s Laws to take the masses of the asteroids.
2029: a big year for advancing science and knowledge. Can’t wait.