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Cassini–Huygens is an unmanned spacecraft sent to Saturn and has been beaming back science since last 19 years.
Cassini is the Saturn orbiter, whereas Huygens, a lander for Saturn’s largest moon, Titan.
It is the fourth space probe to visit Saturn and the first one to enter orbit.
A joint endeavor of NASA, Italian Space Agency (ISA), ESA, Cassini-Huygens is sent to study the Saturnian system in detail.
C-H is designed to unravel the mysteries arising from previous observations as mentioned below;
- The origin of its rings
- Where do the colors of the rings come from?
- Enceladus, one of the moons of Saturn, has an abnormally smooth surface.
- The chemical reactions occurring in Titan’s atmosphere.
- Are there any oceans on Titan?
- What is the source of the abundant methane present in Titan’s atmosphere? It is a compound associated with biological activity on Earth.
C-H was launched on October 15th, 1997. It flew by Earth, Venus, Jupiter and finally arriving at Saturn on July 1, 2004.
Huygens separated from Cassini and landed on Saturn’s moon, Titan, on January 14th, 2005. Huygens was an atmospheric entry probe built by European Space Agency (ESA). It became the first spacecraft ever to land on Titan and the furthest landing from Earth a spacecraft has ever made.
Huygens was the first probe that landed on another world in the outer solar system. It was quite a breakthrough for mankind.
Here are some of the photos Huygens took when it landed on Titan;
This is the first colored view of the Titan’s surface. The two rock-like objects just below the middle of the image are about 15 centimeters (left) and 4 centimeters (center) across respectively, at a distance of about 85 centimeters from Huygens. Scientists noted that these objects had signs of erosion under them caused by fluvial activity.
It seems that Huygens landed in a dry riverbed, not of water but methane.
The image to the right was taken during the descent of Huygens to the surface of Titan from an altitude of about 8 kilometers with a resolution of about 20 meters per pixel.
Following image illustrates Cassini’s flight path to Saturn;
Scientists have never before studied the size, temperature, composition and distribution of Saturn’s rings from Saturn orbit. Cassini has captured extraordinary ring-moon interactions, observed the lowest ring-temperature ever recorded at Saturn, discovered that the moon Enceladus is the source for Saturn’s E ring, and viewed the rings at equinox when sunlight strikes the rings edge-on, revealing never-before-seen ring features and details.
A slideshow below shows some remarkable moments Cassini witnessed during its journey to Saturn.
The gif below shows a series of images of the super-sized Hexagon storm on Saturn’s north pole. The sides of the hexagon are about 13,800 km long…that’s more than the diameter of Earth!
A black and white version;
What is the power source of the probe?
Considering the distance from Sun to Saturn, it was decided that solar arrays won’t be feasible as power sources for the probe. To generate enough power, such arrays would have been too large and heavy. Cassini orbiter is powered by three radioisotope thermoelectric generators.
Let’s take a look at Cassini-Huygens’ life throughout these 20 long years…
The Cassini space probe performed two gravitational-assist flybys of Venus on April 26, 1998, and June 24, 1999. This momentum helped the probe to reach all the way out to the asteroid belt. This flyby gave Cassini a boost of about 4 miles/second which assisted it to reach Saturn.
Nearly 2 years after launch, Cassini-Huygens flew within 700 miles of Earth and picking up another boost of 3.4 miles/second in its speed.
To gain momentum already in flight, the Cassini mission included several such flybys.
Fun fact: If in any case this gravitational slingshot maneuver were to fail and the Cassini-Huygens probe happened to crash and collide with Earth, NASA’s estimated that, in the worst case (with an acute angle of entry in which Cassini would gradually burn up), a significant fraction of the 33 kg of plutonium-238 inside the RTGs would have been dispersed into the Earth’s atmosphere so that up to five billion people (i.e. almost the entire terrestrial population) could have been exposed, causing up to an estimated 5,000 additional cancer deaths, but the chance of that happening were less than one in one million.
Sorry! that wasn’t fun, my bad.
It was the 7th spacecraft ever to fly through the asteroid belt. Don’t worry, the asteroid belt is harmless to our spacecrafts even though it consists of a significant amount of asteroids. Scientists used Cassini-Huygens cosmic dust analyzer to study the region.
On December 30, 2000; the probe made its closest approach to Jupiter at a distance of 6.2 million miles.
On October 31, 2002; Cassini-Huygens’ camera test returned images of Saturn taken from a distance longer than the distance between Earth and the Sun.
May 31, 2004; Cassini spacecraft revealed two previously unknown moons of Saturn, Methone and Pallene.
Phoebe was the first moon among all that Cassini flew by during its mission around Saturn.
June 1, 2004
Cassini, still carrying the Huygens probe, became the first spacecraft to orbit Saturn.
Then came the first close encounter with Titan, Saturn’s largest moon. On Dec 23, 2004, the Huygens probe was detached from NASA’s Cassini orbiter to be sent to Titan. This implies that Huygens was mostly in sleep mode alongside the Cassini probe during their 7-year journey towards Saturn.
The next flyby was of Iapetus during which Cassini captured images of an unexpected equatorial ridge approx. 12 miles and 8 miles high.
January 14th, 2005
Huygens successfully landed on Titan’s surface after a descent of about 2 hours and 27 minutes. The probe was battery-powered and survived another 72 hours on Titan’s surface. The first ever landing of a probe on an unknown world.
Liquid water on Enceladus (one of the many moons of Saturn).
Cassini scientists announced evidence of liquid water reservoirs possibly in the form of geysers.
After countless such discoveries until the primary mission completion of Cassini, scientists decided to extend Cassini’s mission till 2017.
The Day the Earth Smiled
NASA informed the public that a long distance photo was being captured in advance. On July 19, 2013, the probe was pointed towards Earth to capture an image of the Earn and the Moon. The imaging team said they wanted the people to smile and wave to the skies.
On February 10, 2015, Cassini approached Rhea (moon) at a distance of about 47,000 km.
May 31, 2015, Cassini flew by Hyperion(moon) at a distance of 34,000 km
The last flyby of Dione(moon) performed by Cassini was on August 17, 2015, at a remarkably close distance of about 475 km.
April 21, 2017
The Grand Finale Begins
Cassini will end its historic mission with 22 daring loops passing through the gap between Saturn and the innermost ring. This will be the closest up until now we have reached to Saturn.
So why did they decide to end the mission?
The spacecraft is running out of juice used for adjusting its course. So instead of losing out on the control, they decided to give it an honorable departure. This, in turn, will avoid its possibility of collision with Saturn’s moon in the future, thus preventing the contamination of the moons with unwanted debris on the potentially life-sustaining surface on those moons.
Cassini will plunge into Saturn, fighting to keep its antenna pointed at Earth as it transmits its farewell. In the skies of Saturn, the journey ends as Cassini becomes part of the planet itself on 15th of September, 2017.
BOLDLY GO, Cassini.