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.
Astronomers are finding dozens of massive, so-called ‘runaway stars’ in our galaxy with the help of images from NASA’s Spitzer Space Telescope and Wide-field Infrared Survey Explorer, or WISE. When these speedy, massive stars plow through space, they can cause material to stack up in front of them, creating dramatic arc-shaped features called bow shocks.
Despite earlier reports of a possible detection, a joint analysis of data from ESA’s Planck satellite and the ground-based BICEP2 and Keck Array experiments has found no conclusive evidence of primordial gravitational waves.
Skywatchers in Western Europe and the UK should look low to the south-southwest at nautical dusk on 3 and 5 October 2019 to view the waxing Moon pass close to Jupiter and Saturn, the Solar System’s largest gas giant planets. Observers at northern temperate latitudes should make the most of any opportunities to view these planets before they are lost in twilight.