Cassini was a highly complex interplanetary spacecraft. Featuring 12 scientific instruments like imaging cameras, radar, spectrometers, magnetometers and spectrographs – its primary mission was to conduct in-depth studies of Saturn, its rings, and moons.
Its orbiter was powered by three radioisotope thermoelectric generators (RTGs). These produced electricity using plutonium-238 decay.
It was a joint NASA/ESA mission
The Cassini-Huygens mission was a bold robotic exploration of Saturn and its rings, moons, and magnetic environment. Launched on October 15, 1997 and reaching Saturn through gravity assists in July 2004, its orbiter bore the name Giovanni Domenico Cassini (1625-1712), while its probe Christiaan Huygens (1629-1695).
In January 2005, a spacecraft carrying a lander separated and launched towards Saturn’s largest moon, Titan. Once there, the lander transmitted data back to Earth via orbiter relayer; its instruments included imaging camera, radar antennas and spectrometers.
Scientists and engineers on this mission were determined to see it succeed, even if that meant working through holidays and into the night. Their enthusiasm kept them going during long years of operation that often required solving unexpected problems. Finally, on 15 September 2017 it came to an abrupt end when it conducted 22 ‘ring dives’ between Saturn’s rings and its atmosphere before plunging back into Saturn’s atmosphere itself.
It was a success
Cassini spent 13 years orbiting Saturn, during which time it discovered several moons including Enceladus and Titan. Scientists also learned that some of these moons may host simple forms of life; to prevent the craft crashing onto either Enceladus or Titan and potentially contaminating their surfaces with Earth microbes, NASA decided to intentionally end its mission by plunging Cassini into Saturn’s atmosphere.
Engineers working on this mission implemented a technique called gravity assist to increase momentum for their spacecraft. Over a series of 20 “ring-grazing” orbits over five months, it came within 1000 miles of Saturn’s rings every week – something unthinkable during previous missions!
Scientists used Cassini data to test Albert Einstein’s General Relativity theory, which states that massive objects bend space and time around them. Radio signals sent from Earth to the spacecraft allowed scientists to observe this effect; its telemetry data also enabled scientists to detect chemical composition of Saturn’s rings; University of Virginia planetary astronomer Anne Verbiscer helped interpret these measurements while publishing papers detailing discoveries made on Enceladus.
It was a disappointment
Cassini spent 13 years exploring Saturn and its rings, moons, and rings with exquisite detail and reinforcing the notion that life might exist anywhere in our solar system. After this amazing feat of spacecraft engineering, scientists at NASA’s Jet Propulsion Laboratory in California received their final data stream from Cassini.
The mission began with an ambitious flight that saw the spacecraft enter Saturn’s orbit and dive through its rings before remaining stationary to make 162 targeted flybys of moons and planets in its path.
Meteone and Pallene were discovered along with Janus and Epimetheus co-orbitals of Saturn’s rings; Hebes was even named. A major discovery was Enceladus’ geysers erupting from its surface, hinting that water or organic material may exist below – this discovery proved revolutionary because it suggested Saturn may contain an environment similar to Earth that might support life.
It was a failure
Cassini was the inaugural spacecraft to explore Saturn and its rings, as well as one of its most intriguing moons – Enceladus. Additionally, its discoveries provided evidence for extraterrestrial life around Saturn; these discoveries inspired later missions like Europa Clipper that will explore Jupiter’s icy moons.
Over its seven-year run, the mission only encountered four major issues. Engineers successfully addressed an optics issue on one narrow-angle camera by warming its optics in an exacting fashion – now performing better than it ever did at launch!
Another source of concern was Cassini’s diminishing fuel supply. To prevent any potentially catastrophic consequences arising from an uncontrolled and long-dead Cassini hitting and polluting Enceladus in its final moments, engineers found an effective and scientifically worthwhile way to end Cassini by entering “graveyard orbit.”