Researchers unveiled evidence of hydrogen plumes on Saturn's moon Enceladus that are similar to deep sea hydrothermal vents on Earth that support primitive life. According to Linda Spilker, a Cassini Project scientist at NASA's Jet Propulsion Laboratory:

Potential for life on Jupiter's moon Europa, too: Hubble Space Telescope discovered a water plume on the warmest part of Europa's surface.

Why it matters: The most likely locations for life beyond Earth in our solar system may be these two moons.

The discovery of these hydrothermal vents on Enceladus was made by the Cassini spacecraft, which has been in orbit around Saturn for 14 years. It made a dive through one of Enceladus' plumes in 2015 and used a mass spectrometer to analyze the particles in it to gather this evidence.

How it works: Hydrogen would essentially serve as food for any microbes that might be in Enceladus' ocean. As rocks are exposed to warm water, they undergo a process known as "serpentinization," in which certain minerals rich in iron react with the the ocean and new minerals are produced, forming mineral precipitates.

What's next:

• Enceladus: The Cassini mission is winding down this year, but researchers would like to confirm existence of phosphorous and sulfur and narrow down the pH on Enceladus.
• Europa: Researchers want to launch a similar dive into its water plume to give Europa the same treatment as Enceladus.