In 2005, the Huygen spacecraft descended to a smooth landing on an alien moon that, on its surface, does not look so different from a landscape on Earth as seen in dim lighting. It has mountains, plains, rivers, and lakes. The atmosphere is hazy enough to make it difficult to view the surface from space and capable of supporting winds and precipitation, which means that Huygens’ landing on Titan took two and a half hours. Titan does have its differences, though. Its lakes and rivers are made of liquid ethane and methane. Ice is as solid as rocks. This is, of course, a function of its location in orbit around Saturn, about 900 million miles away from the sun.
That was in 2005, only a few months after the Cassini spacecraft had pulled into orbit around Saturn. In September 2017, NASA has slated Cassini’s demise with a spectacular plunge into Saturn’s atmosphere.
Cassini is a joint project between NASA, the ESA and the Italian Space Agency that was launched in 1997 to explore Saturn and attempt the first landing on Titan. It reached Saturn on July 1, 2004, and launched Huygen in January 2005. Huygen successfully landed and its short-lived mission revealed liquid ethane and methane, as well as evidence of an underground liquid water ocean. Further observations of Titan in 2006 revealed several dozen lakes that could be as large as 30 kilometers long.
Cassini’s primary mission was declared complete on June 1, 2008, and its mission has been extended twice since then. Its discoveries included two previously unknown moons that were named Methone and Pallene, and a hexagonal shape on Saturn’s south pole, and further observations of moons like Titan, Enceladus and Iapetus.
Cassini has taken several popular pictures while in orbit around Saturn, including an image of Earth as seen from Saturn. Later this year, Cassini will end a successful 20-year mission by making a few orbits within Saturn’s innermost ring, and then plunging into Saturn’s atmosphere. The space agencies behind Cassini chose to do this to protect moons like Titan, which may be able to support life.
Whatever Happened To Huygen?
During the ESA-built Huygen’s decent, the built-in instruments took measurements of the wind and organic chemistry in the atmosphere and took several pictures of the landscape. Once it landed, Huygen was only able to transmit for about 70 minutes before losing its battery power. It may still be sitting in the floodplain where it landed. In the minutes before Cassini lost its ability to communicate with Huygen with a line-of-sight connection, Huygen sent back pictures and data that indicated that Titan has all the ingredients necessary to support life.
While it’s unlikely that a future stranded astronaut may resurrect Huygen and use it as a communication device, any future visitors to Titan may choose to salvage it as a museum piece or turn its landing site into a historic landmark, as well as check whether it may have any untransmitted data in its memory banks.
The Future of Outer Solar System Exploration
Will there be future missions to Saturn and its moons? As planetary scientist Sarah Hörst told National Geographic, “Titan is so active and has so many Earth-like processes, it’s such a good test for our fundamental understanding of how planets work.”
Currently, NASA’s only other spacecraft to orbit a world in the outer solar system is Juno, which entered Jupiter orbit on July 4, 2016. Planned missions include a mission to Jupiter’s moon, Europa, which is slated to launch in the 2020s. At this time, however, NASA apparently has no plans to replace Cassini despite the desire of planetary scientists like Hörst to learn more about Titan and its capacity to support carbon-based life.