Image of planets in space

CIRCLING SATURN: Enceladus is one of Saturn’s 146 moons.

SHUTTERSTOCK.COM (SPACE); NASA (SATURN); NASA/JPL/SPACE SCIENCE INSTITUTE (ENCELADUS)

STANDARDS

NGSS: Core Idea: ESS1.B, PS1.A, LS1.C

CCSS: Writing: 1

TEKS: 6.3A, 7.9A, 7.9C., 8.3A, ASTR.11D, ASTR.16C

Could Aliens Live Here?

Saturn’s moon Enceladus has all the necessary ingredients for life

AS YOU READ, THINK ABOUT the physical and chemical features a world needs for life to exist there.

At first glance, Saturn’s moon Enceladus doesn’t seem like a great place to live. Its entire surface is covered in ice, and temperatures hover at a bone-chilling -201°C (-330°F). It also has more than 100 active ice volcanoes, which blast a never-ending spray of ice, dust, and gases into the air.

Deep below Enceladus’s icy crust lies a totally different environment: a warm underground ocean (see Hidden Sea). Scientists have discovered that this vast sea has an abundance of organic molecules. These molecules contain the element carbon (C), which is the main building block for all living things on Earth. Researchers studying the ocean on Enceladus have also detected compounds that contain the elements hydrogen (H), nitrogen (N), oxygen (O), sulfur (S)—and, most recently, phosphorus (P).

Scientists consider these six elements essential for life as we know it. That’s led many researchers to believe Enceladus might be the best place to search for alien life in our solar system.

At first glance, Enceladus doesn’t seem like a great place to live. This moon of Saturn is completely covered in ice. Temperatures stay around a bone-chilling -201°C (-330°F). It also has more than 100 active ice volcanoes. They blast a never-ending spray of ice, dust, and gases into the air.

A totally different environment lies deep below Enceladus’s icy crust. It’s a warm underground ocean (see Hidden Sea). Scientists have discovered an abundance of organic molecules in this vast sea. These molecules contain the element carbon (C). It’s the main building block for all living things on Earth. Researchers have also detected other compounds in Enceladus’s ocean. They contain the elements hydrogen (H), nitrogen (N), oxygen (O), and sulfur (S). And recently, researchers have detected phosphorus (P).

Scientists say these six elements are necessary for life as we know it. That makes Enceladus interesting to many researchers. They believe it might be the best place to search for alien life in our solar system.

WATERY WORLD

Enceladus is the sixth largest of Saturn’s 146 moons. Even so, it’s only 504 kilometers (313 miles) across—about one-seventh the diameter of Earth’s moon. A handful of other moons in our solar system have large amounts of liquid water. But Enceladus stands out for one reason: Scientists have been able to study its hidden ocean.

Enceladus’s ice volcanoes spray liquid from the moon’s underground sea. The water shoots hundreds of miles above the moon’s surface. Between 2008 and 2015, NASA’s Cassini spacecraft flew through these plumes and collected several samples. Their chemical makeup revealed a surprising amount about Enceladus’s ocean.

Saturn has 146 moons. Enceladus is the sixth largest. But it’s only 504 kilometers (313 miles) across. That’s about one-seventh the diameter of Earth’s moon. A few moons in our solar system have large amounts of liquid water. But Enceladus stands out for one reason: Scientists have actually studied the contents of its hidden ocean.

Enceladus’s ice volcanoes spray liquid from the moon’s underground sea. The water shoots hundreds of miles above the moon’s surface. Between 2008 and 2015, NASA’s Cassini spacecraft flew through these plumes. It collected several samples. Their chemical makeup revealed many things about Enceladus’s ocean.

NASA/JPL

PLANETARY PROBE: The Cassini spacecraft spent 13 years studying Saturn and its moons.

“We learned a lot from Cassini,” says Frank Postberg, a planetary scientist at the Free University of Berlin in Germany. For example, Enceladus’s ocean is salty, like Earth’s oceans. But in addition to sodium chloride, or table salt, the water on Enceladus is rich in sodium bicarbonate. This type of salt is also known as baking soda. The samples collected by Cassini also provided evidence that Enceladus’s ocean is heated by hydrothermal vents. These cracks in the seafloor release water that’s been heated within the moon. In Earth’s deep oceans, these same types of vents provide heat and nutrients for many marine creatures.

It’s these similarities with oceans on Earth that first made Enceladus a strong candidate for harboring life. The idea was further strengthened by the fact that Enceladus’s ocean also contains many elements necessary for life. There was only one problem: A key element—phosphorus—was missing. But then, in 2023, Postberg and his team used more advanced techniques to analyze Cassini’s water samples. They found phosphorus, which had previously gone undetected.

“We learned a lot from Cassini,” says Frank Postberg. He’s a planetary scientist at the Free University of Berlin in Germany. For example, Enceladus’s ocean is salty. Like Earth’s oceans, it contains sodium chloride, or table salt. But the water on Enceladus is rich in sodium bicarbonate too. This type of salt is also known as baking soda. The samples collected by Cassini also showed that Enceladus’s ocean is heated by hydrothermal vents. These cracks in the seafloor release hot water. The water was heated within the moon. Earth’s deep oceans have these same types of vents. They provide heat and nutrients for many sea creatures.

These similarities with Earth’s oceans sparked the idea that life could exist on Enceladus. Then researchers found that Enceladus’s ocean also contains many elements necessary for life. That strengthened the idea. There was only one problem. A key element was missing. It was phosphorus. But Postberg and his team analyzed Cassini’s water samples again in 2023. This time, they used more advanced techniques and found phosphorus. It had gone undetected before.

VITAL ELEMENT

SHUTTERSTOCK.COM

The element phosphorus, which was recently found on Enceladus, is essential for life as we know it.

All creatures on Earth need phosphorus to grow and function. Phosphorus is a crucial part of DNA—the molecule that carries organisms’ hereditary material. Beyond Earth, the element is rare. The small amount present on other worlds is usually trapped in rocks, where organisms can’t access it. That limits where life could exist.

But Postberg’s discovery showed that Enceladus’s ocean is teeming with an unusually high level of phosphorus—as much as a thousand times more than Earth’s oceans contain. The scientists wanted to know why. To find out, they partnered with researchers at the Tokyo Institute of Technology in Japan to build a simulation of Enceladus’s ocean in a lab. They then examined how the moon’s waters might interact with the rocks that made up its seafloor. “Normally, phosphorus is locked up in rock and doesn’t like to dissolve,” explains Postberg. “But when we added a lot of baking soda to the water in our experiment to mimic Enceladus’s ocean, this allowed the phosphorus to dissolve from the rock into the water.”

That’s exciting news for astronomers, because the kind of rock thought to make up Enceladus’s seafloor is found throughout the outer solar system. So it’s likely that oceans on other moons in the region could also contain phosphorus. That means many worlds may be packed with this vital ingredient for life.

All creatures on Earth need phosphorus to grow and function. The element is a vital part of DNA. This molecule carries organisms’ hereditary material. Beyond Earth, phosphorus is rare. A small amount is present on other worlds. But it’s usually trapped in rocks, and organisms can’t use it. That limits where life could exist.

But Postberg found an unusually high level of phosphorus in Enceladus’s ocean. It’s as much as a thousand times more than Earth’s oceans contain. The group wanted to know why. So they partnered with scientists at the Tokyo Institute of Technology in Japan. Together, they built a model of Enceladus’s ocean in a lab. Then they examined how the moon’s waters and its rocky seafloor might interact. “Normally, phosphorus is locked up in rock and doesn’t like to dissolve,” explains Postberg. “But when we added a lot of baking soda to the water in our experiment to mimic Enceladus’s ocean, this allowed the phosphorus to dissolve from the rock into the water.”

That’s exciting news for astronomers. They think Enceladus’s seafloor is made of a certain type of rock. And that type is found throughout the outer solar system. So oceans on other moons in the region likely contain phosphorus. That means many worlds may be packed with this vital ingredient for life.

THE SEARCH IS ON

This year, NASA plans to send an orbiting spacecraft to study another lunar ocean on Jupiter’s moon Europa. The Europa Clipper will arrive at the moon in 2030. It’s equipped with instruments that will allow scientists to see if the moon’s ocean also has conditions that are suitable for life. There are hints that Europa, like Enceladus, has ice volcanoes that shoot up ocean particles. If it does, Clipper will be able to collect samples. “Of course, we’ll be checking for phosphorus,” says Postberg.

NASA and the European Space Agency have also flagged Enceladus for another major space mission in the future. But it will take time to design and build a spacecraft—and then almost 10 years for it to travel to faraway Saturn. “That means if you’re a kid reading this now who decides to become a planetary scientist, the mission to Enceladus will be arriving just when you are beginning your scientific career,” says Postberg. Who knows: You could be the first person to discover alien life on another world!

This year, NASA plans to send an orbiting spacecraft to Jupiter’s moon Europa. The Europa Clipper will arrive at that moon to study its ocean in 2030. Are conditions on Europa suitable for life? The spacecraft’s instruments will allow scientists to examine that question. Enceladus has ice volcanoes that shoot up ocean particles. It looks like Europa has them too. If it does, Clipper will collect a sample. “Of course, we’ll be checking for phosphorus,” says Postberg.

NASA and the European Space Agency are planning another major space mission to Enceladus. But it will take time to design and build a spacecraft. Then the spacecraft will need almost 10 years to reach faraway Saturn. “That means if you’re a kid reading this now who decides to become a planetary scientist, the mission to Enceladus will be arriving just when you are beginning your scientific career,” says Postberg. Who knows? You could be the first person to discover alien life on another world! 

CONSTRUCTING EXPLANATIONS: Explain why scientists think Enceladus could be one of the best places to look for alien life in our solar system.

What does your class think?

Do you think Saturn’s moon Enceladus harbors alien life?

Please enter a valid number of votes for one class to proceed.

Do you think Saturn’s moon Enceladus harbors alien life?

Please select an answer to vote.

Do you think Saturn’s moon Enceladus harbors alien life?

0%
0votes
{{result.answer}}
Total Votes: 0
Thank you for voting!
Sorry, an error occurred and your vote could not be processed. Please try again later.
videos (1)
Skills Sheets (4)
Skills Sheets (4)
Skills Sheets (4)
Skills Sheets (4)
Lesson Plan (2)
Lesson Plan (2)
Text-to-Speech