Space Jam: Cassini’s End


Rahul Rao

Undoubtedly the biggest space-related news of the last few weeks was the final end of Cassini. On the fifteenth of September, the unmanned spacecraft, which had been orbiting Saturn for thirteen years, reached the end of one final pass between the gas giant’s rings, plunged into the planet’s atmosphere, and burnt up.

Cassini was impressive for many reasons, not least of which was its longevity. The probe had been launched in 1997 before going through an elaborate sequence of flybys around other solar system bodies. Cassini flew past Venus, twice, back past Earth, and then past Jupiter, then finally reaching Saturn in 2004. (It may seem strange to go closer to the Sun in order to go further away from it, but the inner planets’ gravity gave Cassini additional speed that allowed it to reach Saturn with less fuel, and thus less cost, than a straight shot.) Cassini was initially slated to end in 2008, but the probe continued to operate long past that. Indeed, its mission was gradually ended until 2017, effectively doubling its lifetime.

During those long years, the Cassini mission helped produce a veritable treasure trove of knowledge about Saturn and its satellites. The probe took images and data of Saturn’s rings, moons, and atmosphere from closer than was ever previously possible; furthermore, data from Cassini helped astronomers discover at least seven previously unknown moons. Additionally, Cassini carried with it a smaller probe, Huygens, which in 2005 descended to the surface of Saturn’s moon Titan, unlocking what lay below its thick atmosphere. These sorts of details will find their way into astronomy classes within the next few years, and they are being uncovered now.

Scientific value aside, Cassini-Huygens was important for showing the power of international space cooperation. The mission was a collaboration between NASA and the European Space Agency. The Cassini probe, in fact one of the largest unmanned spacecraft ever built, and its companion Huygens were both international creations. Parts and scientific instruments and knowledge were provided by numerous countries. While a mission of this scale is certainly possible alone, it was made significantly easier by being a multinational effort. International cooperation such as this is the future of research, including at Vanderbilt.

Why couldn’t we have just left Cassini to drift around Saturn for an eternity? Since Cassini was built on and launched from Earth, it might still carry bacteria or other organisms from Earth. Such organisms have proven to be able to survive and thrive in the hostile environment of space. In the event that the probe ended up coming in contact with one of Saturn’s larger moons, they could even spread such organisms there and contaminate them. Particularly due to the fact that some of these worlds are candidates for life themselves, this is a risk that is not worth taking.

Furthermore, if Cassini returned to Earth, there is always a slight possibility that some alien life form might have hitched a ride and come back to contaminate Earth’s own biosphere. This may seem like an extremely remote possibility, and certainly, most of us would consider the idea of alien infection remote or in the realm of fiction. But it pays to be careful with the risks associated with space exploration.

Why is all this important to us? After all, again, all this is happening quite literally billions of miles removed from any of us. But that distance is exactly the point – this is a fantastic example of the limits science and technology are capable of pushing. One day, after all, humans ourselves might be living amongst the worlds that Cassini and Huygens explored.