Observations of Europa’s leading hemisphere reveal elevated H2O2 in the warmer, low latitude chaos terrains compared to the colder, polar regions.
![A: Schematic of the ultra-high vacuum chamber used for electron irradiation experiments of Europan ice analogs. B: Shift in the resonant frequency of the QCM during co-deposition of H2O and CO2 ice from dedicated gas dosers. We first condense CO2 [1] from a doser at a constant rate of (0.25 ± 0.01) Hz/s (zoomed in the inset). We then admit water vapor [2] through a second doser which increases the deposition rate to (4.8 ± 0.2) Hz/s. When the film approaches the desired thickness (2.8 µm, which corresponds to a frequency shift of ∼ 21, 000 Hz), we terminate H2O gas deposition first [3] and continue with CO2 condensation briefly to ensure the terminal CO2 rate did not drift significantly from the initial value (< 10%). The CO2 doser is shut off at [4]. This co-deposition scheme using multiple gas dosers with QCM gravimetry allows for producing mixed ices with precisely tailored composition. This film has CO2 intimately mixed with water ice at (2.5 ± 0.1)% (by number) concentration. -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2025/06/Laboratory-Investigation-Of-CO2-Driven.png?resize=1200%2C733&ssl=1)
Observations of Europa’s leading hemisphere reveal elevated H2O2 in the warmer, low latitude chaos terrains compared to the colder, polar regions.