Failed observations of a specific target using the JWST have generated something a lot more fascinating.
In the belt of asteroids that drifts between Jupiter and mars, the space telescope spotted a previously unknown, and exceptionally small, asteroid. The yet-unnamed chunk of rock measures just 100 to 200 meters (328 to 656 feet) across and it is quite possibly the smallest item yet detected by the JWST.
It is not merely a brilliant demonstration of the JWST’s features, it indicates those skills could be used to better categorize the countless pieces of rubble lurking in the Main Belt.
“We – absolutely unexpectedly – detected a small asteroid in publicly accessible MIRI calibration observations,” says astronomer Thomas Müller of the Max Planck Institute for Extraterrestrial Physics in Germany.
“The measurements are some of the very first MIRI measurements focusing on the ecliptic plane and the work of ours suggests that many new objects will likely be detected with this instrument.”
As the JWST metaphorically opened up its golden honeycomb eye in July 2022, scientists started putting it through its paces, calibrating its instrumentation, ensuring everything was running as it needs to. One of the instruments is definitely the Mid Infrared Instrument, or MIRI.
MIRI’s calibration target became a much bigger asteroid in the Main Belt called (10920) 1998 BC1, discovered in 1998 and measuring 15.7 kilometers (9.75 miles) across. Unfortunately, the JWST observations weren’t particularly good ones: the telescope wasn’t quite oriented correctly, and the images of the target were way too brilliant and blown out.
It was not a complete bust as far as 10920 was concerned; the images obtained by the JWST allowed the researchers to test some techniques for constraining the size and orbit of asteroids, combined with data from other ground- and space based telescopes.
The research has been published in Astronomy & Astrophysics.