Unlocking Secrets in Ice with The James Webb Space Telescope

When people think of space, they often picture a vast, empty void. But space is far from empty. The interstellar medium (ISM)—the gas and dust that fills the space between stars—is rich with the ingredients for stars, planets, and possibly life itself. These tiny grain particles are like cosmic laboratories, where complex molecules form and evolve. Now, with the James Webb Space Telescope (JWST), scientists can peer into these hidden regions of space to uncover the secrets of ice species, the frozen building blocks of chemistry in space.

JWST’s cutting-edge instruments detect infrared light, which can pass through dense clouds of dust that block visible light. Infrared light is key to studying the ISM because it reveals molecules that absorb and emit specific wavelengths of light, each acting like a fingerprint. JWST’s precision allows scientists to detect even faint traces of these molecules, revealing the chemical makeup of regions where stars and planets are born.

What is Ice Made of in Space?

In space, ice isn’t just frozen water like what you’d find in a cold drink. It’s a mix of various frozen molecules, often referred to as “ice species.” These include water (H₂O), carbon dioxide (CO₂), methane (CH₄), ammonia (NH₃), and carbon monoxide (CO). In addition to these simple compounds, more complex organics like methanol (CH₃OH), formaldehyde (H₂CO), and even precursors to amino acids can freeze onto dust grains. These icy particles often serve as the starting point for chemical reactions that lead to larger, more intricate molecules.

Figure 1: An illustration of a dust grain in space. On these dust grains, molecules form via various grain-surface chemistry mechanisms and are released into the gas-phase through a process called desorption. Credit: Rachel Gross

JWST’s Breakthroughs in Ice Detection

Before JWST, detecting these icy molecules was extremely difficult because their faint signals are often drowned out or obscured by dust. But JWST’s advanced infrared cameras, like NIRCam and MIRI, can now detect these ices with unprecedented sensitivity. 

Astrochemists are now using JWST to study ice in diverse environments, from the dense clouds where stars are born to the icy surfaces of comets and moons in our solar system. These studies help answer big questions: How do these ices evolve over time? Can they seed life by delivering complex molecules to young planets?

Far from being empty, space is a vast chemical playground where frozen molecules hold the key to understanding the origins of stars, planets, and life itself. With JWST’s unparalleled capabilities, scientists are finally beginning to unlock the secrets hidden within cosmic ice.