Orwell Astronomical Society (Ipswich)
JUICE Mission, 15 May 2023
On 14 April 2023, the JUpiter ICy moons Explorer (JUICE) mission was launched by an Ariane 5 rocket from French Guiana. It is currently en route towards Jupiter and is due to make observations of three of the planet’s four Galilean moons, Ganymede, Europa and Callisto, during the period 2031-35.
Initially, my prospects of imaging JUICE within a few days or weeks of launch were not promising. It was cloudy over the UK on the evening of launch and then I was away from home for a while. By the time I returned home, JUICE was at a considerable distance from Earth. In addition, true darkness lasted less than two hours a night, making it difficult to image a very faint object. I therefore planned to wait for JUICE to return to the neighbourhood of Earth, during the Earth/Moon flyby in August 2024, before attempting to image it.
However, On 09 May, Milan Antoš of the Czech Republic posted an image of JUICE taken using a 250 mm scope. The following day, Nick James of Chelmford posted on the BAA forum that JUICE was much brighter than expected, at around magnitude 18. So perhaps the craft could be imaged after all...
On 15 May, the spacecraft was at a distance of 7.5 million km. It crossed the meridian in the evening nautical twilight at a declination of -4° moving at a rate of only 0.2 arcseconds per minute. I did not know if it was still at magnitude 18 but, in any case, I pressed ahead with imaging. I followed the spacecraft for 2½ hours until it started to get cloudy.
JUICE is not visible in individual 60 s exposures but can be seen in a stack of 20 minutes' worth of images. A video produced from the images shows a faint, slow-moving object very close to the location predicted by JPL Horizons. I was surprised and delighted that I was able to record a man-made object at such a vast distance. No doubt the large solar array, 85 m2 in area, helps in this regard!
Nigel Evans