Hubble and the Unexpected Asteroids

Image (Credit): This Hubble image is a mosaic of many exposures where some asteroids appear multiple times. (NASA, ESA, and B. Sunnquist and J. Mack/STScI)

The Hubble Space Telescope’s old data still holds some secrets. The European Space Agency (ESA) has reported that astronomers have found 1,031 unidentified asteroid trails in earlier data from the NASA/ESA Hubble Space Telescope. The asteroids were located by the Hubble Asteroid Hunter project, which defines the project in this way:

…we use archival images made by the Hubble Space Telescope to find asteroids observed by chance. The ESASky team compared the observation epoch and field of view of these images with the computed orbits of asteroids, to identify possible observations. The positions predicted by the algorithm, nevertheless, have some associated uncertainty because the ephemerides are not always known to great precision. This uncertainty increases with the amount of time between the last observation date and the date we predict the position for. Identifying the asteroids in the images (if present) and marking the exact position of their trail allows us to update the ephemerides and help us better characterise these objects.

More than 11,000 volunteers studied about 37,000 composite images taken by the Hubble between April 2002 and March 2021. The volunteers found about 1,000 asteroid trails, which when combined with other images spotted using artificial intelligence added to 1,701 asteroid trails. Of these, 1,031 are unidentified trails most likely associated with smaller asteroids. The analysis of these unidentified trails will continue.

This is a great example of the public assisting with astronomy and allowing for more timely results. It’s a helpful model for future astronomy endeavors.