And this is it. On Friday 15 September, after 20 years in space, 13 of which spent in Saturn’s system, Cassini plunged into the gas giant’s atmosphere. NASA made this choice to prevented it crashing into and contaminating the moons Titan or Enceladus, which could host alien microbial life. The end was quick: as described in details in this National Geographic’s article, “the spacecraft’s thrusters failed, overwhelmed by gravity and intense atmospheric friction. It began to tumble, lost sight of Earth, and went silent forever around 4:55 a.m. PTThough scientists couldn’t observe the action, they knew that one or maybe two minutes after Cassini’s signal vanished, Saturn tore the spacecraft apart. The probe shed flaming pieces into the planet’s atmosphere, streaking through the alien sky like a crumbling meteor.”
Cassini’s discoveries during this long mission were amazing, and this article summarises the oddest ones. An example: the discovery that the moon Hyperion is charged with static electricity, the first time the phenomenon had been seen on a moon of another planet in our solar system. The fact itself is important, offering hints to design spacecrafts that can survive in harsh, electrically charged, environments.
Also, Cassini literally witnessed the birth of a new moon in 2014. “NASA released images of the edge of Saturn’s A ring, one of the bright and wide outer regions. Cassini got pictures of an arc that was 20 percent brighter than its surroundings, 750 miles (about 1,200 kilometers) long and 6 miles (10 km) wide.The mission scientists also saw what looked like unusual irregularities on the edge of the ring: small bulges caused by the gravitational pull of something nearby. The arc and protuberances on the ring could have been a small moon accreting from bits of icy material, a replay of the birth process of Saturn’s larger moons, researchers said. NASA said there was no expectation that the object, which they named Peggy, would get bigger — it’s less than a mile across — and it may even fall apart. But seeing it illuminates much of the process of moon-building, scientists said. The study describing the discovery was published in April 14, 2014, issue of the journal Icarus.”
Below: this is Cassini’s final image in natural colour “created using images taken with red, green and blue spectral filters of Cassini’s Solid-State Imaging system, is the last image taken by the spacecraft. It looks toward the planet’s night side, lit by reflected light from the rings, and shows the location at which the spacecraft would enter the planet’s atmosphere hours later.” (Read the long version at the Planetary Society blog)
And if you want to see the moment Cassini’s signal went dead from the Deep Space Network….here it is.
The good thing? Now Cassini has become part of the planet it has been studying for so long. It sounds like a homecoming – or a love embrace.