Within a minute of the time Cassini’s final transmission was expected, the probe burnt up in Saturn’s hydrogen-dense atmosphere. Thus ended the nearly 20 year Cassini-Huygens mission, one likely to have a significant impact on future exploration to those far reaches of our solar system.
Indeed, the very reason NASA decided to destroy the probe, launched in 1997, touches on the significant gains in knowledge gained from the mission, one that produced a body of research so surprising it has altered our perception of some of the most significant cosmic events – even to the origins and possibilities of life itself. Two of Saturn’s moons, Titan and Enceladus, were far more conducive to the conditions we understand to be instrumental to life than was expected. While the European Space Agency’s Huygen lander was never sanitized, by the time it had touched down on Titan, there was nothing to be done about it. Some microbes can survive in space far longer than was previously believed, as has been demonstrated by experiments on the International Space Station. So, in a perfect confluence of great-for-life but bad-for-science possibilities, Huygens could have accidentally seeded Titan with life, or affected any life the moon may have already harbored – an outcome so unexpected no one has had time to explore the scientific and ethical ramifications.
The fear that Cassini could harbor its own microorganisms and, after finally running out of power nine years past its expected mission life, crash into and potentially contaminate Enceladus led to the decision to terminate the probe while it was still under control. In so doing, engineers at the Jet Propulsion Laboratory in Pasadena guided the probe into the interior of the planet’s famous ice rings and into the vast space between the rings and the planet’s atmosphere, with its final plummet occurring early this morning, at 3:30 a.m. PST.
The probe’s imaging systems were turned off to enable other sensors to transmit, and it’s expected that the information collected in Cassini’s final moments as it plunged toward Saturn might provide us with some of the most significant information about Saturn to date.
While interplanetary travel is both too expensive and can boast far to few financial returns for commercial space companies to have an interest in exploring them, many of the launchers and other systems being built by private companies such as SpaceX could be used to boost NASA’s probes in the future. Additionally, as techniques for in-situ resource exploitation are developed, commercial missions and incentives could develop, especially considering some of the data Cassini-Huygens provided about Saturn’s moons: Titan was found to have liquid oceans of methane. Enceladus is thought to have ice volcanoes and seas of liquid water under a top layer of ice. Some have even speculated that Saturn might experience rains of diamonds.
For now, though, it is incumbent on public exploration to determine when (and whether) to return to Saturn, Titan, and Enceladus. Whatever future missions find, the Cassini-Huygens mission will live on as one of the most important and startling exploration endeavors ever undertaken by humankind.