Cassini is once more lord of the rings, after surviving seventh Saturn dive
NASA's Cassini spacecraft has beamed back some stunning views of Saturn's rings, taken on June 4, as the probe sped through the 1,500-mile (2,400-km) gap separating the gas giant's uppermost cloud layers and innermost rings. With the seventh dive complete, Cassini is nearly a third of the way through the Grand Finale phase of its mission, the culmination of which will see the probe fly directly into Saturn's atmosphere on September 15.
As Cassini passed high over Saturn's northern hemisphere, it made detailed scans of the gas giant's intricate main rings using its Composite Infrared Spectrometer (CIRS). Data harvested by the instrument will help scientists to build a greater understanding of the composition and temperature of the different elements of the breath-taking structures.
The veteran probe also took the opportunity to scan Saturn's A ring, right through to its C ring, with its RADAR instrument. Originally designed to scour the surface of Saturn's enigmatic moon Titan, RADAR is also proving useful in characterizing the gas giant's rings.
RADAR allows Cassini to bombard a target with radio waves, and then capture the waves that bounce back off a hard surface, such as the particles that make up Saturn's rings. The instrument can reveal the disposition of solid particles, as well as how rough or smooth they are, in addition to their temperature.
For Cassini's seventh dash through Saturn's ring plane, which occurred at 6:38 p.m. PDT, the spacecraft was moving at over 76,000 mph (122,000 km/h). The probe passed within 2,420 miles (3,890 km) of the planet's upper cloud layers, where the pressure is roughly the equivalent to that at sea level back on Earth.
During the ring passage, Cassini passed through Saturn's incredibly faint D ring. In order to protect the spacecraft from any potential ring collisions, the probe's handlers reorientated Cassini's 4-meter-wide (13-ft) high-gain antenna to face the direction of travel, creating a makeshift shield.
The downside of this approach is that it significantly constrains how and when Cassini can use its scientific payload, as it is unable to reorientate itself at will.
This protective measure is only planned to be employed out of two of the remaining 15 crossings, as data recorded by the spacecraft's Radio and Plasma Wave Science Instrument (RPWS), has revealed a surprisingly low population of particles in the Saturn-ring gap.
Cassini's eighth ring crossing is set to take place on June 10.