A thriller on Saturn’s moon Rhea might have lastly been solved. When NASA’s Cassini spacecraft flew previous the planet’s second-largest moon earlier than the tip of its mission in 2017, it noticed a mysterious compound. It seems, that compound could also be hydrazine, which is usually utilized in rocket gas.
As Cassini flew previous Saturn’s moons, it examined the daylight bouncing off their surfaces to find out what they’re fabricated from. On Rhea, in addition to a number of of the opposite moons, one thing on the floor absorbed a portion of that gentle within the ultraviolet vary of the spectrum.
“We seen there was this dip within the spectrum and questioned what it was, however we speculated that it is perhaps some sort of water ice,” says Amanda Hendrix on the Planetary Science Institute in California. “We puzzled over what it’s for a very long time.”
She and her colleagues noticed how gentle bounced off a number of compounds in laboratory experiments, and located two that appeared to match what Cassini noticed on Rhea: hydrazine and chlorine. Whereas both may very well be a match for Cassini’s observations, it’s laborious to give you a approach for chlorine to be produced on Rhea’s floor, Hendrix says.
Hydrazine, then again, may very well be made in reactions between chemical compounds that we all know exist on the icy moon. It might additionally float over from the thick ambiance of the neighbouring moon Titan. Although Cassini did use hydrazine as gas for its thrusters, these thrusters had been by no means fired close to Rhea, so the researchers are assured that it didn’t come from the spacecraft.
“It is a potential rationalization for the function on Rhea, however we nonetheless have work to do to determine why it happens on different moons,” says Hendrix. “It is a clue to some course of that’s occurring in the entire Saturn system, and doubtless elsewhere as properly.”
Journal reference: Science Advances, DOI: 10.1126/sciadv.aba5749
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