Jupiter moon could be suitable for life: research

AUSTIN, Texas (KXAN) — The outer layer of one of Jupiter’s moons, Europa, is solid ice and strong evidence supports an ocean flowing below. New research led by the University of Texas at Austin is showing how oxygen could be making its way into the ocean — providing a link to the possibility of alien life there.

The researchers proposed that chemical elements can be transported through the ice by drainage of saltwater through the formation of chaotic terrains, a planetary area with clusters of ridges, cracks and plains.

They discovered this brine, or saltwater, percolates through the 10-15 mile thick ice within these channels. It’s a mechanism that could provide significant amounts of oxygen to the internal ocean, according to lead researcher Marc Hesse, a professor at UT’s School of Geosciences and Department of Geological Sciences.

At the high end of the estimates, the amount of oxygen making its way to Europa’s ocean could be comparable to the amount of oxygen in Earth’s ocean, according to Steven Vance, a research scientist at NASA’s Jet Propulsion Laboratory, or JPL, and group supervisor of its Planetary Interiors and Geophysics Group.

“And so of course on Earth we know that fish can swim around in the ocean and filter out oxygen from the water,” Steven Vance said. “So it’s easy to imagine just by analogy with Earth, microbes swimming around having lots of time to evolve… similar to how organisms evolved on Earth.”

This study is the first quantitative evaluation of the process of transporting oxygen through these tiny channels, called “oxidant transport by porous brine migration.” The team of researchers posed three conditions that would make this process possible, according to Hesse.

Are there large volumes of melted water at the surface of the ice?
Can the brines, or salt water, gradually filter through the ice before refreezing?
Do the brines carry oxidants from the surface before transporting together through the ice?

This research shows that all of these answers could be “yes.”

An artist’s interpretation of liquid water on the surface of the Europa spewing from cryovolcanoes (background) and pooling beneath chaos terrain (foreground). A recent study led by The University of Texas at Austin examined how water associated with chaos terrains could help transport oxygen from the moon’s surface to its liquid water ocean. (Courtesy NASA-JPL)

The study

Chaotic terrains cover approximately one-quarter of the surface on Europa and require the formation of large volumes of brine, according to the study. Hesse told Nexstar’s KXAN that despite the low surface temperatures, which are approximately 100 Kelvin or -279.67 Fahrenheit, several features of its surface show the requirement of near-surface melt.

Evidence was found in the observations of irradiated sodium chloride, which can be seen as an orange-brown color on the surface. The substance likely originated within the moon and was exposed by resurfacing, according to Hesse and his team of researchers.

This colorized image of Europa is a product of clear-filter grayscale data from one orbit of NASA’s Galileo spacecraft, combined with lower-resolution color data taken on a different orbit. The blue-white terrains indicate relatively pure water ice, whereas the reddish areas contain water ice mixed with hydrated salts, potentially magnesium sulfate or sulfuric acid. The reddish material is associated with the broad band in the center of the image, as well as some of the narrower bands, ridges and disrupted chaos-type features. (Courtesy NASA/JPL-Caltech/SETI Institute)

For these brines to drain, the underlying ice is likely to be partially molten. This is due to chaotic terrains forming over diapiric upwellings, or low topographic domes created by the penetration of overlapping ice. This leads to a plausible explanation that within the underlying ice there are amounts of liquid melt, researchers found.

The drainage of brines generated during the formation of chaotic terrains provides a possible scenario for how oxygen could move through the ice and to the internal ocean of Europa. If oxygen can make it to the ocean, Europa could have the potential to sustain life, according to this research.

Why Europa?

Life on Earth can’t exist without water. There used to be a question whether bodies of water on other planets existed, but that’s been answered by scientists with almost certainty through ground-based telescopes on Earth and space telescopes. And the icy moons of large planets, such as Europa, likely have large eternal oceans.

“For the search of life on other planets, step one is to look for water and oxygen,” Hesse said. “Once you have [those] the question becomes, ‘Could there be life in these oceans?’”

Scientists are almost certain that beneath the ice on Europa is a salt-water ocean that has the possibility of containing twice as much water as all of the Earth’s oceans, according to NASA.

Life requires three basic necessities: liquid water, an energy source and organic compounds. Europa could have all three of these, and its ocean may have existed for the entirety of the solar system, long enough for life to evolve there, according to NASA. This makes Europa a major candidate for scientists in the search for extraterrestrial life.

You can view a 3D model of Europa and learn more here.

Simulation Results

The team of researchers, including those at UT, are responsible for the first physics-based computer simulation of this transport of oxygen. Here is what they found:

The model shows the water drains downward through the outer ice and transports the oxidants in spherical “porosity waves,” or pulses of melt. The model estimates 86% of the oxidants under the chaotic terrain can travel to the internal ocean.

The physics-based simulation built by the researchers shows brine at Europa’s surface taking the form of a “porosity wave” (spherical shape) that causes pores in the ice to momentarily widen – allowing the brine and the oxygen it carries to pass through the moon’s ice shell until it arrives in the liquid water ocean. The chart shows time (in thousands of years) and ice shell depth (in kilometers). Red indicates higher levels of oxygen. Blue represents lower levels of oxygen. (Courtesy Hesse et al.)

The simulation showed the drainage of the water is fast enough to avoid refreezing despite the extremely cold surface temperatures. This means a significant portion of the water, and oxygen, at the surface makes it down through the chaotic terrains and into the liquid ocean.

Europa Clipper Mission

Launching in October 2024, the Europa Clipper spacecraft will travel to Europa and determine whether there are places below Europa’s ice shell that could support life.

While this is not a life detection mission, it will be measuring if the ingredients for life are present. The spacecraft will orbit around Jupiter, creating the opportunity to conduct nearly 50 flybys of Europa at different locations over the span of five and a half years.

The mission will place a spacecraft in orbit around Jupiter in order to perform a detailed investigation of Europa. The mission will last five and a half years and the spacecraft will orbit Jupiter. (Courtesy NASA/JPL-Caltech)

The Europa Clipper spacecraft will be NASA’s largest spacecraft made for a planetary mission. The spacecraft will be about 16 feet tall and more than 100 feet long when its solar arrays are deployed to its sides like wings.

The spacecraft will consist of 10 instruments, three of which have roots in Texas, according to Vance.

The Europa-UVS is the first science instrument to be completed for this mission and was developed by a team at Southwest Research Institute in San Antonio. The instrument will be used to search above the surface of Europa for signs of plumes, or water vapor venting from the surface.

“’Could there be life?’ is the first question. Where Europa-UVS fits into this is by measuring these gases coming off of the surface and potentially plumes, then understanding what their composition is made of,” said Kurt Retherford, the senior program manager at the Southwest Research Institute and NASA’s principal investigator of the Europa-UVS.

Engineers inspect Europa Clipper’s ultraviolet spectrograph (called Europa-UVS) in a cleanroom at NASA’s Jet Propulsion Laboratory in Southern California, following the delivery of the instrument from Southwest Research Institute (SwRI). (NASA/JPL-Caltech Photo)

There is one other instrument coming from the Southwest Research Institute in San Antonio, the MASPEX. This instrument will collect gases and convert them into ions, holding them within the instrument. This instrument will determine the ions’ mass, revealing each molecule’s identity which will help determine if Europa is habitable.

UT is responsible for developing the Radar for Europa Assessment and Sounding: Ocean to Near-surface, or REASON. It will use radio waves to detect objects from a distance. The instrument will use radar to search for water below the moon’s icy shell.

Hesse told KXAN, “The fact that as a country and as the world, we managed to put together these missions and go out there and investigate these questions is just amazing.”