A look at the glittering journey of NASA’s Saturn orbiter Cassini before it plunges to its death
Cassini’s final dive will end a mission that provided groundbreaking discoveries that included seasonal changes on the Saturn system.science Updated: Sep 14, 2017 11:02 IST
NASA’s Cassini spacecraft is closing in on the end of its epic 20-year journey in space, as it prepares to take the final plunge into the atmosphere of Saturn.
Cassini’s final dive will end a mission that provided groundbreaking discoveries that included seasonal changes on Saturn, the moon Titan’s resemblance to a primordial Earth, and a global ocean on the moon Enceladus with ice plumes spouting from its surface.
“The mission has been insanely, wildly, beautifully successful,” said Curt Niebur, Cassini program scientist.
The spacecraft will provide near real-time data on the atmosphere until it loses contact with Earth at 4:54am PDT on September 15.
Here’s a look at the glorious journey of the spacecraft through space:
- October 15, 1997
Titan IVB/Centaur carrying Cassini and European Space Agency’s Hugyens probe launches from Cape Canaveral.
- April 25, 1998
Cassini-Hugyens flies by Venus from within 284km of the planet. The gravity assist accelerates Cassini by about 4 miles per second to help it reach Saturn.
- June 24, 1999
Cassini-Hugyens flyby Venus for the second time for the gravity assist, this time within 600 km of the planet.
- December 1999 - April 2000
Cassini-Hugyens becomes the 7th spacecraft to fly in the asteroid belt. Scientists use the Cosmic Dust Analyzer to study the asteroid belt region, which is not considered a hazard for a spacecraft.
- December 30, 2000
Cassini-Hugyens makes its closest approach to Jupiter, at 10 million km from the largest planet in the solar system. With Galileo spacecraft, it provides insight into Jovian system.
- October 31, 2002
Twenty months before arriving near Saturn, Cassini captures the first image of the planet from a distance of 285 million km -- twice the distance between Earth and Sun.
- May 31, 2004
Cassini discovers two new moons of Saturn: Methone and Pallene. Saturn’s moon count is now 60.
- June 10, 2004
Cassini flies by 2000 km of Saturn’s dark moon Phoebe. In 1981, Voyager 2 flew by Phoebe at a distance of 2.2 million km, 1000 times farther away.
- July 1, 2004
Cassini becomes first probe to orbit Saturn at 9:12 pm UTC.
- October 24, 2004
Cassini comes within 1200 km of Titan, another Saturn moon, and beams back information and pictures.
- December 23, 2004
ESA’s probe Hugyen that was attached to Cassini, mostly in ‘sleep’ mode, detaches from the orbiter seven years after its launch. Hugyens begins its three-week journey to Titan.
- February 16, 2005
Cassini’s magnetometer discovers something is pushing against Saturn’s magnetic field around its moon Enceladus. It could be an atmosphere. There is evidence that gases may be coming from the moon’s interior or its surface.
- Cassini’s Cosmic Dust Analyzer records thousands of particles -- dust or ice -- coming from a cloud around Enceladus or from the adjacent E-Ring, the ring where the moon orbits. The team plans to take a second look at Enceladus.
- July 13, 2005
Cassini captures detailed images of the south polar region of Enceladus on a flyby. The tiny icy moon, which was supposed to be cold and dead, instead displays evidence for active ice volcanism. Cassini finds a cloud of water vapour over the moon’s south pole, and scientists say cracks from which the evaporating ice possibly supply the vapour cloud.
- March 8, 2006
Scientists announce evidence of liquid water reservoirs on Enceladus, possibly in the form of geysers.
- July 21, 2006
Cassini discovers lakes on Titan that were between 1km to 30km wide.
- September 14, 2006
Cassini sees previously unseen rings around Saturn as the planet shelters the spacecraft from the Sun’s blinding glare.
- September 9, 2007
Cassini reveals the yin and yang surface of Lapetus, another moon of Saturn. One hemisphere of the moon resembles snow and the other is as dark as tar.
- March 12, 2008
Cassini flies by Enceladus, going through icy water geyser-like jets. The spacecraft takes samples that might point to a water ocean or organics inside the little moon.
- May 31, 2008
Cassini completes its primary mission, with scientists discovering more about the giant planet.
- December 14, 2008
Scientists get a closer look of Enceladus after a Cassini flyby. New high-resolution images show that the moon’s south polar surface changes over time, including evidence of Earth-like tectonics.
- March 2, 2009
Spacecraft discovers Saturn’s smallest moon Aegaeon in the G-Ring.
- June 23, 2009
Sodium salts are found in Saturn’s outermost ring, suggesting that Enceladus might have an ocean under its surface. In July, their assumption strengthens after scientists recognise Ammonia in plume originating from Enceladus.
- February 2, 2010
NASA extends Cassini-Hugyens mission to 2017.
- September 26, 2010
Cassini’s mission to observe seasonal changes in the Saturn system begins.
- November 28, 2010
Cassini detects the moon Rhea’s exosphere which is infused with oxygen and carbon dioxide. This is first time a spacecraft has directly captured particles of an oxygen atmosphere outside the Earth’s.
- March 1, 2012
Cassini ‘sniffs’ molecular oxygen ions around Dione, Saturn’s icy moon.
- April 12, 2012
Scientists detect strange objects that punch through Saturn’s F-Ring and leave a glittering trail behind.
- July 18, 2013
Cassini takes picture of Earth from millions of kilometres away.
- March 5, 2014
Cassini goes for its 100th flyby of Titan. Scientists say Titan is like early Earth "in deep freeze".
- July 27, 2014
The orbiter identifies 100 geysers on Enceladus, suggesting water can spout from underground sea to the moon’s surface.
- December 18, 2015
Cassini passes Enceladus for the last time, at a distance of nearly 5000 km.
- March 23, 2016
Cassini reveals Titan’s highest peak, at 3,337 metres height.
- May 5, 2016
Cassini observes a bright star passing behind a plume of gas and dust from Enceladus, which means some of the moon’s jets blast off with more power when it is farther from Saturn.
- April 12, 2017
Cassini captures closest-ever taken images of Saturn’s moon Atlas, which looks like a flying saucer.
- Data collected reveals presence of hydrogen gas pouring in to the subsurface ocean of Enceladus from the seafloor. Hydrogen gas may potentially provide the chemical energy source of life.
- April 26, 2017
Cassini makes first contact with Earth after its first dive through the narrow gap between Saturn and its rings.
- The Grand Finale begins
Cassini ends its mission with 22 ‘daring’ loops, passing through the gap between Saturn and its outermost ring.
- May 24, 2017
Cassini looks at Saturn’s solstice, which occurs once in 15 years.
- June 29, 2017
After 20 years, Cassini is halfway through the final phase of its journey.
- September 15, 2017
Cassini will dive into Saturn’s atmosphere, burn up and disintegrate like a meteor, ending its two-decade journey through space.
(Source: NASA, agencies)
First Published: Sep 14, 2017 10:58 IST