NASA’s Cassini spacecraft has begun transmitting data and images from the mission’s final close flyby of Saturn’s active moon Enceladus. Cassini passed Enceladus at a distance of 3,106 miles (4,999 kilometres) on Saturday, 19 December at 5:49pm GMT (12:49pm EST).
“This final Enceladus flyby elicits feelings of both sadness and triumph,” said Earl Maize, Cassini project manager at JPL. “While we’re sad to have the close flybys behind us, we’ve placed the capstone on an incredible decade of investigating one of the most intriguing bodies in the solar system.”Cassini will continue to monitor activity on Enceladus from a distance, through the end of its mission in September 2017. Future encounters will be much farther away — at closest, more than four times farther than this latest encounter.
This was the 22nd Enceladus encounter of Cassini’s mission. The spacecraft’s discovery of geologic activity there, not long after arriving at Saturn, prompted changes to the mission’s flight plan to maximise the number and quality of flybys of the icy moon.“We bid a poignant goodbye to our close views of this amazing icy world,” said Linda Spilker, the mission’s project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “Cassini has made so many breathtaking discoveries about Enceladus, yet so much more remains to be done to answer that pivotal question, ‘Does this tiny ocean world harbour life?'”
After revealing Enceladus’ surprising geologic activity in 2005, Cassini made a series of discoveries about the material gushing from warm fractures near its south pole. Scientists announced strong evidence for a regional subsurface sea in 2014, revising their understanding in 2015 to confirm that the moon hosts a global ocean beneath its icy crust.
Engineers believe a piece of foreign object debris may be intermittently stalling a motor needed to place the Curiosity Mars rover’s drill bit onto rocks, and the robot’s ground team is assessing the source of the potential contamination.
Skywatchers in the UK looking to the south-southeast shortly before midnight on Friday 9 June can see the rising full Moon just 2½ degrees above Saturn, the pair fitting comfortably in the same field of view of binoculars and telescopes magnifying less than 20×. Saturn is closest to the Earth for this year on 15 June, so here is our quick observing guide to the ringed planet at its best.
Supermassive black holes do not give off any of their own light, hence the word “black” in their name. However, many black holes pull in surrounding material and emit powerful bursts of X-rays. Collectively, these active black holes can be thought of a cosmic choir, singing in the language of X-rays. Their “song” is what astronomers call the cosmic X-ray background.