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Cassini collects dust in bid to study Hyperion

Morgan Rehnberg, Correspondent
Aug 8, 2015, 1:01 UTC

Sen—The stunning, otherworldly close-ups offered by Cassini’s powerful cameras can make us feel as if we are right in the face of some of the Solar System’s most amazing objects, but in reality, the spacecraft captures these views from thousands or even millions of kilometers away. So how can we understand what makes up these faraway objects? That was the challenge facing astronomers this week as the robotic explorer swung past Saturn’s moon Hyperion.

Cassini, in orbit about Saturn for more than 11 years, has a variety of tools at its disposal; spectroscopy and gravitational mapping are common, but what is perhaps the most immediately-obvious approach is also one of the best: collecting pieces of the surface itself. The spacecraft is not designed to land, though, so scientists have to be clever.

Bits of space debris, called micrometeoroids, are constantly pelting all the objects in the Solar System (ones that hit Earth can cause shooting stars!). Each little impact into Hyperion blasts off a bit of its surface and some of this material escapes the moon’s feeble gravity and is lost to space. As Cassini swoops by, its Cosmic Dust Analyzer (CDA) can collect these particles from afar to take a peek at what makes up Hyperion.

The composition of this moon is particularly interesting because Hyperion’s unusual shape has long puzzled astronomers. The CDA is capable of providing some basic compositional information about collected grains, but even the simplest details can provide valuable clues. How much dust envelops Hyperion, for example, may itself help shed light on the moon’s strange surface.

The Cassini-Huygens mission is a collaborative effort between NASA, ESA, and the Italian Space Agency. Launched in 1997, it reached Saturn in 2004 and has since been studying the planet, its moons, and its rings. In 2005, the Huygens probe made the first landing on Titan, Saturn’s largest moon. After completing its second mission extension in 2017, Cassini will make a series of close passes to the planet and then end its time at Saturn by plunging into the planet’s atmosphere.