Secrets of Saturn Keep Coming
By Amanda Jermyn

Though the Cassini Mission ended in September 2017 with the spacecraft’s spectacular planned plunge into Saturn’s atmosphere, the data it collected is the gift that keeps on giving. Recent analysis of some of this data enabled a research team from the Free University of Berlin, led by Nozair Khawaja, to discover new kinds of organic compounds, potential building blocks of life, in the ice particles ejected in plumes from volcanoes on Saturn’s moon, Enceladus.

While its icy crust is extremely cold, Enceladus generates internal heat through the decay of internal radioactive elements, as well as through tidal heating. Because Saturn’s gravity pulls with different strengths on either side of Enceladus it squeezes the moon, which generates friction and heats it.

Some of this heat is released when hydrothermal vents eject material from Enceladus’ core. This material mixes with water from the moon’s subsurface ocean, before being released into space as plumes of water vapor and ice particles. These ice particles feed Saturn’s E ring, a wide band of dust and ice particles that is home to Enceladus’ orbit.

The research team used data from Cassini’s Cosmic Dust Analyzer, or CDA, which detected the ice particles ejected from Enceladus into the E ring. The CDA’s mass spectrometer measurements enabled the researchers to determine the composition of organic materials discovered in the ice particles. These materials were found to be nitrogen- and oxygen-bearing compounds, similar to ones found on Earth that form amino acids, the building blocks of life.

According to the research team, these organic materials first dissolved in Enceladus’ subsurface ocean, then evaporated from the water surface before condensing and freezing onto ice particles inside fractures in the moon’s crust. They were then ejected into space through the volcanic plumes, ending up in Saturn’s E ring.

On Earth, hydrothermal vents on the ocean floor provide the energy that fuels the chemical reactions that convert similar organic compounds into amino acids. If the hydrothermal vents on Enceladus function the same way then it is possible that amino acids might form there too, creating conditions conducive to life. According to Khawaja, “We don’t yet know if amino acids are needed for life beyond Earth, but finding the molecules that form amino acids is an important piece of the puzzle.”

Hopefully future missions to Enceladus will tell us more about its potential for life. NASA has twice proposed the Enceladus Life Finder, or ELF, to assess the habitability of the subsurface ocean of Enceladus, but it has yet to be selected. The proposed mission would have an orbiter fly several times through Enceladus’ plumes to analyze ice samples for evidence of microbial life. And so the tantalizing search for life beyond our planet continues.

Join the Springfield Stars Club on Tuesday, January 28th at 7:00pm at the Springfield Science Museum for a planetarium show by Jack Megas on “The Mystery of the Disappearing Dinosaurs” and a tour of the meteorites in the museum’s Astronomy Hall. Jack is an astronomy educator at the Science Museum’s Seymour Planetarium, and a retired laboratory hematologist at Baystate Medical Center. He is a past president of the Springfield Stars Club and the Naturalist Club. Refreshments will be served, and the public is welcome. The meeting is free of charge for members, with a suggested donation of $2 per non-member.

Also, on Friday February 7th at 7:30pm, the Stars Club and the Springfield Science Museum will host “Stars over Springfield,” an astronomy adventure for the whole family. Jack Megas will repeat his planetarium show on “The Mystery of the Disappearing Dinosaurs” and give a tour of the meteorites in the museum’s Astronomy Hall. A fee of $3 for adults and $2 for children under 18 will be charged.