It’s almost become expected that many space telescopes and probes can have “extended missions”. Both Voyagers are still sending data back 40+ years after their 5-year primary mission ended. But figuring out what to do with those spacecraft after their primary mission takes some negotiation. One such craft that will reach its end-of-mission in 2030 is Euclid, which is currently on a mission to map the “dark universe” of dark energy and dark matter. According to a new paper from Luigi “Rolly” Bedin of the Astronomical Institute of Padova, which is available in pre-print form on arXiv, for its second act we could turn Euclid into the most powerful astrometric telescope ever made.

Currently calculations give Euclid an extended life of about 8 years, thanks to the additional fuel the craft has on board. That would more than double the 6-year original mission, which is already well underway. With that additional time, Dr. Bedin suggests Euclid do something completely outlandish - do the exact same thing that it did for the first six-year mission.

Why on Earth would we use Euclid to do the same thing that it had just spent most of its lifetime completing? Because getting a second data point would allow us to see what moved in those six years - an astronomical value called “proper motion”. This is a calculation of how closer objects (such as stars in the Milky Way) move against a background of further objects (like distant galaxies) over time. But the key is that, in order to calculate proper motion, you need a very long time between data points to ensure the motion is significant enough to be calculated. According to Dr. Bedin, about 6 years should do the trick for Euclid.