NASA’s Cassini space probe performed a close flyby of Saturn’s irregularly shaped moon Hyperion on 31 May 2015.
Cassini passed Hyperion on 31 May 2015 at a distance of about 21,000 miles (34,000 km). Mission scientists expect images from the encounter to arrive on Earth within 1-2 days. This view of the moon was obtained during Cassini’s flyby on 26 September 2005. It reveals crisp details across the strange, tumbling moon’s surface. Differences in color could represent differences in the composition of surface materials. Image credit: NASA / JPL-Caltech / Space Science Institute.
Hyperion, also known as Saturn VII, is a small moon of Saturn, with dimensions of 111 x 82 x 64 miles (180 x 133 x 103 km) and a mean radius of 82 miles (133 km).
It was discovered by astronomers William Cranch Bond, George Phillips Bond and William Lassell in 1848, and was named after one of the Titans from Greek mythology.
The moon has a bizarre, sponge-like appearance owing to its unusually porous interior. It rotates chaotically, essentially tumbling unpredictably through space as it orbits the gas giant.
Because of this, it’s challenging to target a specific region of the moon’s surface, and most of Cassini’s previous close approaches have encountered more or less the same familiar side of the moon.
Cassini’s closest-ever Hyperion flyby occurred on 26 September 2005, when the spacecraft passed within 323 miles (520 km) of the moon’s surface. According to the mission scientists, about six minutes before that approach, the space probe received the equivalent of a 200-volt electric shock from Hyperion’s electrostatically charged surface, even though the objects were over 1,200 miles (2,000 km) apart.
Cassini’s next notable flyby is slated for 16 June 2015, when the spacecraft will pass 321 miles (516 km) above icy Dione.
That flyby will represent the mission’s penultimate close approach to that moon.
In October 2015, the spacecraft will make two close flybys of Enceladus, coming as close as 30 miles (48 km) in the final pass.
In late 2015, the spacecraft will again depart Saturn’s equatorial plane – where moon flybys occur most frequently – to begin a year-long setup of the mission’s daring final year.
For its grand finale, Cassini will repeatedly dive through the space between Saturn and its rings.
