Oct. 8 (UPI) — New analysis of observations made during Cassini’s “Grand Finale” plunge suggests Saturn’s rings are surprisingly complex in their chemical composition.
The data also suggests chemical-coated dust grains from Saturn’s innermost D ring are raining down on the gas giant’s upper atmosphere. Over time, scientists predict, the flow of chemicals could alter the composition of Saturn’s atmosphere.
During its final pass through Saturn’s rings and into the planet’s atmosphere, Cassini’s spectrometer sampled and analyzed a variety of chemicals. The instrument’s data revealed the surprising presence of water, methane, ammonia, carbon monoxide, molecular nitrogen and carbon dioxide.
Researchers shared their survey of the Cassini data this week in the journal Science.
“What the paper is describing is the environment in the gap between the inner ring and upper atmosphere, and some of the things found were expected, such as water,” Thomas Cravens, a professor of physics and astronomy at the University of Kansas, said in a news release. “What was a surprise was the mass spectrometer saw methane — no one expected that. Also, it saw some carbon dioxide, which was unexpected.”
Until now, scientists assumed Saturn’s rings were mostly composed of water molecules.
“But the innermost rings are fairly contaminated, as it turns out, with organic material caught up in ice,” said Cravens.
Because the rings are spinning faster than Saturn’s atmosphere, many of these contaminants are flung inward toward the atmosphere’s upper layers. The discovery revealed a new type of interaction between satellite materials and planetary atmospheres.
“This could help us understand: How does a planet get rings? Some do, some don’t,” Cravens said. “What’s the lifetime of a ring? And what’s replenishing the rings? Was there a time when Saturn didn’t have rings?”
According to the Cassini data, so much material is being shed by the D ring, it’s likely the ring’s lifespan will be shorter than previously estimated.
And because the chemical-coated grains are traveling at high speeds, scientists think their impacts on the upper atmosphere are considerable.
“These dust grains moving at satellite speed, depositing energy that can dissociate the atmosphere,” Cravens said. “Per atom, it’s pretty energetic stuff because of the speed differentiation between the rings and the atmosphere. We think it may be heating the upper atmosphere, changing its composition.”
