What Europa’s Glow Can Tell Us!

Europa is a key contender for bodies that have potential to host extraterrestrial life. With excitement, recent research revealed that Europa glows & that this glow may tell us about the composition of the water on Europa!

Sections:
  1. An Introduction to Europa
  2. NASA’s Europa Clipper Program
  3. Studying Europa’s Glow! (the Experiments)
  4. Implications of Europa’s Glow
(TL;DR, Glossary, and a Video Resource at the bottom 😊)
Approximate Read Time:  5 minutes!

An Introduction to Europa

Europa is one of Jupiter’s 79 confirmed moons. Europa’s surface is thought to be composed of mostly water ice (with liquid water under) mixed with various salts, and consequently, Europa is often considered “one of the most promising places to look for extraterrestrial life in our solar system!” 

FIG 1: Artist rendition of a glowing Europa

For more specific information on Europa, check this link out!


NASA’s Europa Clipper Program

NASA’s Europa Clipper Program is projected to launch in 2024. The goal of this mission is to study Europa’s water-rich composition and assess the moon’s potential to host life. 

The program will achieve this goal by passing by Europa many times and taking pictures of the moon’s surface and atmosphere.

FIG 2: An early design of the Europa Clipper spacecraft

However, there is a challenge the program must face: Europa’s liquid water lies far below the icy surface, making it harder to study the water’s composition. Scientists are hoping that there will be geysers that release bits of the water into space that can be analyzed by NASA’s machinery, but if no geysers are present, good remote sensing technology is essential. 

To capitalize on remote sensing technology, scientists at NASA have been looking into how ice behaves in Jupiter’s high radiation environment, in hopes that taking images of Europa’s surface and atmosphere will be enough to study the planet’s composition.


Studying Europa’s Glow! (the Experiments)

Why does Europa’s ice glow? 

Jupiter’s magnetic fields absorb charged particles released by Jupiter itself and accelerate them. Some of these accelerated charged particles hit Europa and deposit energy at Europa’s icy surface. In other words, the accelerated charged particles excite molecules at Europa’s surface that then release energy at visible wavelengths, resulting in a glowing Europa!

To more closely study the impact of these charged particles hitting Europa’s (water-salt) ice surface, Murthy Gudipati (NASA), Bryana Henderson (NASA), and Fred Bateman (NIST) froze ice samples with various combinations of salts to a temperature of 100 Kelvin. 

The scientists then bombarded the ice samples with electrons for ~20 seconds, and then measured the emissions from each ice sample.

What were the results?

All of the ice samples glowed white because they were emitting light from many different wavelengths. But the specific emission spectra and glow intensities differed based on the composition of the ice samples.

“We never imagined that we would see what we ended up seeing. When we tried new ice compositions, the glow looked different. And we all just stared at it for a while and then said, ‘This is new, right? This is definitely a different glow?’ So we pointed a spectrometer at it, and each type of ice had a different spectrum.”

Bryana Henderson, co-author of the study, also of NASA’s JPL

The following is a table of how different salts affected the ice samples’ emissions compared to a no-salt only-water ice slab that had a peak emission of blue/green wavelengths with a wide shoulder on the red end of the visible spectrum.

SaltEffect on Ice Sample’s Emission
Sodium sulfateEnhanced the red wavelengths, decreased the blue wavelengths
Sodium chlorideDecreased all wavelengths evenly
Sodium carbonateDeleted all emissions except those near the infrared region
Magnesium sulfateEnhanced all wavelengths, especially in the red-green area
TABLE 1
FIG 3: Emission spectra for different ice samples. Blue wavelengths are towards the left of the wavelength spectrum, red wavelengths are towards the right.

The researchers also determined that as electron radiation increased, the glow intensity of the ice increased as well. This presented the question of implications of this study towards Europa, as Europa is constantly bombarded by electrons for a lot longer than 20 seconds (as was in the experiment):

“Is there ever a point where you might break down the salts, and this glow stops happening?”

Jennifer Hanley, a planetary scientist at Lowell Observatory in Flagstaff, AZ

Implications of Europa’s Glow

Biggest takeaway of the study? The glow of Europa’s icy surface may give us information regarding the salt content / composition of Europa’s water!

For example, areas with less glow could suggest sodium-rich regions, while brighter glow areas may be rich in magnesium [Table 1, Figure 3].

Furthermore, knowledge of the composition of Europa’s water would lead to further implications regarding Europa (including learning more about its potential for habitability!):

“[The water’s composition] has implications for the temperature of that liquid water — the freezing point; it has implications for the thickness of the ice shell; it has implications for the habitability of that liquid water.”

Jennifer Hanley, a planetary scientist at Lowell Observatory in Flagstaff, AZ

This study applies to NASA’s Europa Clipper Program we discussed earlier by presenting a new approach to remotely (passing by the moon) study Europa’s composition! This allows for new equipment to be prepared for the mission.

In terms of next steps, the scientists hope to study the effects of components other than electrons (such as sulfur, oxygen, and hydrogen ions) on the ice samples’ emissions, as Europa is bombarded with much more than just electrons.

What are you excited to find out about Europa in the future?

Thank you for reading this piece. I hope you enjoyed it & will further ponder the knowledge it brings to light. I encourage you to leave a comment and/or start a discussion in the section below! 

Feel free to contact me at brainsproutblog@gmail.com and follow the blog @brainsproutblog on Instagram or Twitter for updates!


TL;DR:
  • Europa is one of Jupiter’s moons. Europa’s surface is thought to be composed of mostly water mixed with various salts, and consequently, Europa is considered “one of the most promising places to look for extraterrestrial life in our solar system!”
  • NASA’s Europa Clipper Program is projected to launch in 2024. The goal of this mission is to study Europa’s water-rich composition and assess the moon’s potential to host life. 
  • Europa glows, as its icy surface is constantly bombarded by accelerated particles that excite Europa’s molecules. To study this glow, scientists bombarded ice samples with various salt combinations with electrons and then measured the ice’s emission.
  • Biggest takeaway of the study? The glow of Europa’s icy surface may give us information regarding the salt content / composition of Europa’s water!
  • This study applies to NASA’s Europa Clipper Program by presenting a new approach to remotely (passing by the moon) study Europa’s composition
Glossary:
  • Electron: a stable subatomic particle with a charge of negative electricity that is found in all atoms
  • Radiation: the process in which energy is emitted as particles or waves
  • Visible spectrum: the portion of the electromagnetic spectrum that is visible to the human eye; wavelengths from about 380 to 750 nanometers
Video Resource:
Read more (sources!) 
  1. https://arstechnica.com/science/2020/11/europa-probably-glows-in-the-dark-and-that-may-tell-us-whats-in-it/
  2. https://www.nature.com/articles/s41550-020-01248-1
  3. https://www.sciencenews.org/article/jupiter-moon-light-europa-glow-dark-ice 
  4. https://www.space.com/jupiter-moon-europa-glows-in-the-dark 
  5. https://physicsworld.com/a/jupiters-moon-europa-could-glow-in-the-dark/ 
  6. https://solarsystem.nasa.gov/moons/jupiter-moons/europa/overview/ 
Image Sources:
  1. https://arstechnica.com/science/2020/11/europa-probably-glows-in-the-dark-and-that-may-tell-us-whats-in-it/
  2. https://www.sciencenews.org/article/jupiter-moon-light-europa-glow-dark-ice

2 thoughts on “What Europa’s Glow Can Tell Us!

  1. Oh wow I’m so out of the loop with these things so had no idea of this..imagine if there was life on there..the thought of that terrifies me if I’m being honest😂😂
    A really great post and a great read by the way❤️

    Like

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