Out Of The Syllabus
After two decades of thrilling exploration, the Cassini spacecraft ended its mission on September 15th, 2017, marking the end of the most successful space expeditions in NASA's history.
Designed to explore the Saturnian system from the orbit, it completed its primary mission in 2008 and went on to perform a dozen more flybys of Titan, Enceladus and the other icy moons of Saturn.
Artist's concept of Cassini's orbit insertion around saturn
Source: Wikimedia Commons
The achievements of the mission speak for how successful it was. Amongst the most phenomenal discoveries were the environmental features of Titan - the largest moon of Saturn, geysers erupting on Enceladus and the dynamic effects of it. Cassini's observations of Titan, has given scientists/researchers a look into the past conditions on Earth.
During its expedition, it has beamed back more than 500 gigs of scientific data, resulting in publication of more than 3000 scientific reports. It has completed 206 orbits along with 132 close flybys of Saturn's moon and took 332,000 images. Here's what the timeline says.
Some of its top accomplishments and discoveries during this journey are:
- The Huygens probe landing on the moon - Titan in the outer solar system
- Discovering lakes, rivers, seas and rains of liquid methane.
- Discovering active, icy plumes on the Saturnian moon Enceladus
- Discovering the hidden moons of Saturn
- Describing Saturn's rings as active and dynamic, shedding info on formation of planets.
- Describing the space between Saturn and its rings as 'empty'
- Studying Saturn's great northern storm of 2010-11
- Testing General Relativity theory
- Revealing the fact that radio-wave patterns are not tied to Saturn's interior orientation
- Studying prebiotic chemistry on Titan
- Solving the mystery of the dual, bright-dark surface of the moon Lapetus
- Completing the first view of the north polar hexagon and discovery of giant hurricanes at both Saturn's poles
Cassini, during it's launch. Oct 15, 1997 | Source: Link
Named after Giovanni Cassini and Christian Huygens, the Cassini-Huygens mission commonly known as just 'Cassini', was a joint mission by the National Aeronautics and Space Administration (NASA), the European Space Agency (ESA), and the Italian Space Agency (ASI) to gather information on the Saturnian system as a whole - including the rings and its natural satellites. Launched on October 15, 1997, from the Cape Canaveral Air Force Station's Space Launch Complex 40 using a U.S. Air Force Titan IVB/Centaur rocket, the Flagship-class spacecraft comprised of both NASA's probe and ESA's Huygens lander, to be landed on Titan. This made Cassini the fourth probe to visit Saturn, while first to enter its orbit. Managed by NASA's Jet Propulsion Laboratory (JPL) a joint team comprising of scientists and researchers from 17 countries were responsible for the designing, building, flying and collecting data from the orbiter and the probe.
Including the orbiter and the probe, the Cassini spacecraft is considered to be the second-largest unmanned interplanetary spacecraft built. It was powered by 32.7kg of Plutonium-238 (the heat from the material's radioactive decay was turned into electricity). The orbiter had a mass of 2150kg and the probe, 350kg. With the launch vehicle adapter and propellants weighing 3132kg, the spacecraft had a launch mass of 5712kg. With 1630 interconnected electrical components, 22,000 wire connections and about 14kms of cabling, it was undoubtedly one of the most complex spacecrafts ever built. The main propulsion system consisted of one prime and one backup R-4D bipropellant rocket engine, each of whose thrust was 490Newtons. The total spacecraft delta-v (Δv) was calculated to be around 7344km/hr.
The Cassini probe continued to orbit Saturn at a distance of between 8.2 and 10.2 astronomical units from the Earth. And it took 68-84 minutes for radio signals to travel from Earth to the spacecraft and vice versa. Here's a brief description of the instruments used.
The Day The Earth Smiled
Source: Wikimedia Commons
The Day the Earth smiled:
The Day the earth smiled refers to July 19, 2013, on which the Cassini spacecraft was pointed towards Earth to capture images of Earth and the Moon and the entire Saturn system during an eclipse of The Sun. This happened twice before (in 2006 and 2012) in its previous nine years in orbit. The name refers to the event as well as the mosaic photograph created from it. The photograph includes Earth, Mars, Venus and many Saturnian moons.
The Grand Finale
In late 2016, the Cassini spacecraft began performing a daring set of tasks. The end involved a series of close Saturn passes, flying just outside its narrow F ring. It probed the water-rich plume of the active geysers on the planet's intriguing moon Enceladus. As the spacecraft flew past Saturn, it collected some incredibly rich and valuable information, making detailed maps of Saturn's gravity and magnetic fields, revealing how the planet is composed in the inside and eventually helping us understand the origins.
No other mission has explored this unique region so close to the planet. The accomplishments speak for its greatness. At the end of the journey, Cassini falls into Saturn's atmosphere on purpose, completing its thrilling 20-year mission, ensuring that the biologically interesting worlds Enceladus and Titan could never be contaminated by hardy microbes that might have stowed away and survived the journey intact.
Cassini entering Saturn's atmosphere | Source: NASA/JPL
With the end of Cassini, NASA still has a spacecraft probing another planet, the giant one, Jupiter. The spacecraft known as Juno, has been orbiting Jupiter since last summer. The 1.1billion dollar Juno mission was launched in August 2011. Its mission is to gather data about the structure and composition of Jupiter's atmosphere, as well as the planet's gravity and magnetic fields. Along with Juno, New Horizons, another interplanetary space probe, launched in 2006 is currently on its mission's 'Science Phase', observing the Kuiper Belt Objects. Few more missions like the Europa Clipper and JUICE is scheduled to lift off in 2022.
JUNO spacecraft | Source: NASA
Below are few images captured by Cassini:
Lakes On Titan | Source: NASA/JPL
Saturn's Hexagon | Source: NASA/JPL
Rose like structure in between Saturn's Hexagon | Source: NASA/JPL
Saturn's shadows cast on its rings | Source: NASA/JPL
Goodbye Cassini! | Source: NASA/JPL
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