Spacecraft prepares for icy shower near Saturn
The Cassini spacecraft is about to get an icy shower. This will happen as it orbits Saturn.
On Wednesday, Cassini will storm through a jet of water vapor and frozen particles. The water vapor and frozen particles erupt from the south pole of Enceladus. Enceladus is one of Saturn's many moons. The spacecraft will zoom within 30 miles of the pole. This will provide the best sampling yet of its underground ocean.
Cassini will be traveling 19,000 mph. It should take just an instant to enter the plume.
A global liquid ocean is thought to exist beneath Enceladus' frozen crust. Enceladus is 300 miles wide. Wednesday's dive will be the deepest one yet through the continuous plumes. This makes the mission a bit riskier than usual.
Cassini was launched in 1997. It is not built to detect life. But scientists hope Wednesday's flyby will provide clues as to the possibility of it.
Wednesday's feat is a "a very big step in a new era of exploring ocean worlds in our solar system." That is according to NASA program scientist Curt Niebur.
There are other probable extraterrestrial ocean worlds. Those include Saturn's largest moon, Titan. It also includes Jupiter's moons, Europa, Ganymede and Callisto. Others might possibly be dwarf planets Pluto and Ceres.
"These are worlds with huge bodies of liquid water underneath their surfaces. The bodies have great potential to provide oases for life throughout our solar system," Niebur said Monday. "It is a journey in understanding about what makes a world habitable. It is a journey where we might find life. And where we might one day live ourselves."
Researchers are eager to nail down the chemical makeup of Enceladus' plumes. They also hope to confirm whether the eruptions are tight columns or curtains of jets running along fractures in the south pole.
In particular, the spacecraft will be looking to identify hydrogen molecules in the plume. This would help quantify hydrothermal activity occurring on the ocean floor. That, in turn, would help characterize the potential for life in this slightly salty ocean.
More missions would be needed for confirmation of life. Life might range from microscopic algae to little fish.
The action unfolds late Wednesday morning Eastern Time. It will take several hours to confirm success and start returning the information.
Spilker expects it will take a week to get a quick look at the scientific data. It will take many more weeks for a proper analysis.
Close-up pictures of Enceladus should be ready much sooner. Cassini will snap pictures of Enceladus. Pictures will be taken before, during and after the close encounter. The images will be smeared because of Cassini's speed. But the team hopes to remove the blurs. They hope to have some dramatic shots by Thursday night or Friday. Saturnshine is like our moonshine. It will provide the only lighting for the cameras.
This will be the 21st flyby of Enceladus by Cassini. "It is not our last, but arguably this one is going to be our most dramatic." That is according to project manager Earl Maize.
Cassini has come closer to Enceladus but never dipped so low through a plume. It skimmed 15 1/2 miles above the surface in 2008.
Scientists were tempted to fly even lower Wednesday. But they did not want to waste fuel. Cassini's orbit around Saturn will not be disturbed by the plume penetration. The U.S.-European spacecraft has two years of life remaining. Then it will plunge into Saturn's atmosphere and vaporize.