NASAのインスタグラム(nasagoddard) - 9月15日 04時14分

In honor of Cassini's Grand Finale at Saturn tomorrow, we're looking back on a very big discovery on a very small moon.

When Cassini arrived at Enceladus, one of Saturn's moons, it saw curtains of icy material venting into space. Then, using the Composite Infrared Spectrometer aboard the spacecraft, scientists discovered that Enceladus's south pole was much warmer than expected. The strange temperature patterns on Enceladus suggested that the small, icy moon was up to something. After years of analyzing data from the CIRS instrument and others, it was clear that Enceladus harbors a liquid-water ocean beneath its surface.

Later evidence indicated that this remarkable moon might have hydrothermal vents — something previously known to exist only on Earth. As Enceladus travels in its elliptical orbit about Saturn, the moon flexes as it gets nearer to its parent planet, then farther, then nearer again. Four great cracks near its south pole — “tiger stripes," seen here in blue — spread, then squeeze and grind. Warm salt water, gases and minerals erupt through those fractures in the miles-thick ice shell and blast into space, exiting the moon's surface at 800 miles per hour.

When the Cassini orbiter plunges into the atmosphere of Saturn on Sept. 15, a group of NASA Goddard scientists will be among those waiting for the spacecraft’s last long-distance ping. That bittersweet signal will mark the end of an era for the team, which has devoted two decades to operating the CIRS instrument.
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Credit: NASA/JPL/Space Science Institute
#Cassini #GrandFinale #Saturn #NASA #Enceladus #space #science

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