Tuesday, December 05, 2023

SPACE

Can signs of life be detected from Saturn’s frigid moon?


Enceladus’ ice plumes may hold the building blocks of life

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - SAN DIEGO

Saturn's icy moon, Enceladus 

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THIS ARTISTIC RENDERING SHOWS ICE PLUMES BEING EJECTED FROM ENCELADUS AT SPEEDS OF UP TO 800 MILES/HOUR.

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CREDIT: NASA




As astrophysics technology and research continue to advance, one question persists: is there life elsewhere in the universe? The Milky Way galaxy alone has hundreds of billions of celestial bodies, but scientists often look for three crucial elements in their ongoing search: water, energy and organic material. Evidence indicates that Saturn’s icy moon Enceladus is an ‘ocean world’ that contains all three, making it a prime target in the search for life.

During its 20-year mission, NASA’s Cassini spacecraft discovered that ice plumes spew from Enceladus’ surface at approximately 800 miles per hour (400 m/s). These plumes provide an excellent opportunity to collect samples and study the composition of Enceladus’ oceans and potential habitability. However, until now it was not known if the speed of the plumes would fragment any organic compounds contained within the ice grains, thus degrading the samples. 

Now researchers from the University of California San Diego have shown unambiguous laboratory evidence that amino acids transported in these ice plumes can survive impact speeds of up to 4.2 km/s, supporting their detection during sampling by spacecraft. Their findings appear in The Proceedings of the National Academy of Sciences (PNAS).

Beginning in 2012, UC San Diego Distinguished Professor of Chemistry and Biochemistry Robert Continetti and his co-workers custom-built a unique aerosol impact spectrometer, designed to study collision dynamics of single aerosols and particles at high velocities. Although not built specifically to study ice grain impacts, it turned out to be exactly the right machine to do so.

“This apparatus is the only one of its kind in the world that can select single particles and accelerate or decelerate them to chosen final velocities,” stated Continetti. “From several micron diameters down to hundreds of nanometers, in a variety of materials, we’re able to examine particle behavior, such as how they scatter or how their structures change upon impact.” 

In 2024 NASA will launch the Europa Clipper, which will travel to Jupiter. Europa, one of Jupiter’s largest moons, is another ocean world, and has a similar icy composition to Enceladus. There is hope that the Clipper or any future probes to Saturn will be able to identify a specific series of molecules in the ice grains that could point to whether life exists in the subsurface oceans of these moons, but the molecules need to survive their speedy ejection from the moon and collection by the probe. 

Although there has been research into the structure of certain molecules in ice particles, Continetti’s team is the first to measure what happens when a single ice grain impacts a surface. 

To run the experiment, ice grains were created using electrospray ionization, where water is pushed through a needle held at a high voltage, inducing a charge that breaks the water into increasingly smaller droplets. The droplets were then injected into a vacuum where they freeze. The team measured their mass and charge, then used image charge detectors to observe the grains as they flew through the spectrometer. A key element to the experiment was installing a microchannel plate ion detector to accurately time the moment of impact down to the nanosecond.

The results showed that amino acids — often called the building blocks of life — can be detected with limited fragmentation up to impact velocities of 4.2 km/s.

“To get an idea of what kind of life may be possible in the solar system, you want to know there hasn’t been a lot of molecular fragmentation in the sampled ice grains, so you can get that fingerprint of whatever it is that makes it a self-contained life form,” said Continetti. “Our work shows that this is possible with the ice plumes of Enceladus.”

Continetti’s research also raises interesting questions for chemistry itself, including how salt affects the detectability of certain amino acids. It is believed that Enceladus contains vast salty oceans — more than is present on Earth. Because salt changes the properties of water as a solvent as well as the solubility of different molecules, this could mean that some molecules cluster on the surface of the ice grains, making them more likely to be detected.

“The implications this has for detecting life elsewhere in the solar system without missions to the surface of these ocean-world moons is very exciting, but our work goes beyond biosignatures in ice grains,” stated Continetti. “It has implications for fundamental chemistry as well. We are excited by the prospect of following in the footsteps of Harold Urey and Stanley Miller, founding faculty at UC San Diego in looking at the formation of the building blocks of life from chemical reactions activated by ice grain impact.”

This work was supported by the Air Force Office of Science Research (MURI-22, grant FA9550-22-0199) and the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (grant 80NM0018D0004).

Dark galactic region nicknamed "The Brick" explained with Webb telescope findings


UF astronomer Adam Ginsburg harnesses the James Webb Space Telescope to explore a galactic enigma


Peer-Reviewed Publication

UNIVERSITY OF FLORIDA






In a recent study led by University of Florida astronomer Adam Ginsburg, groundbreaking findings shed light on a mysterious dark region at the center of the Milky Way. The turbulent gas cloud, playfully nicknamed “The Brick” due to its opacity, has sparked lively debates within the scientific community for years.

To decipher its secrets, Ginsburg and his research team, including UF graduate students Desmond Jeff, Savannah Gramze, and Alyssa Bulatek, turned to the James Webb Space Telescope (JWST). The implications of their observations, published in The Astrophysical Journal, are monumental. The findings not only unearth a paradox within the center of our galaxy but indicate a critical need to re-evaluate established theories regarding star formation.

The Brick has been one of the most intriguing and highly studied regions of our galaxies, thanks to its unexpectedly low star formation rate. It has challenged scientists’ expectations for decades: as a cloud full of dense gas, it should be ripe for the birth of new stars. However, it demonstrates an unexpectedly low star formation rate.

Using the JWST’s advanced infrared capabilities, the team of researchers peered into the Brick, discovering a substantial presence of frozen carbon monoxide (CO) there. It harbors a significantly larger amount of CO ice than previously anticipated, carrying profound implications for our understanding of star formation processes.

No one knew how much ice there was in the Galactic Center, according to Ginsburg. “Our observations compellingly demonstrate that ice is very prevalent there, to the point that every observation in the future must take it into account,” he said.

Stars typically emerge when gases are cool, and the significant presence of CO ice should suggest a thriving area for star formation in the Brick. Yet, despite this wealth of CO, Ginsburg and the research team found that the structure defies expectations. The gas inside the Brick is warmer than comparable clouds.

These observations challenge our understanding of CO abundance in the center of our galaxy and the critical gas-to-dust ratio there. According to the findings, both measures appear to be lower than previously thought.

“With JWST, we're opening new paths to measure molecules in the solid phase (ice), while previously we were limited to looking at gas,” said Ginsburg. “This new view gives us a more complete look at where molecules exist and how they are transported. “

Traditionally, the observation of CO has been limited to emission from gas. To unveil the distribution of CO ice within this vast cloud, the researchers required intense backlighting from stars and hot gas. Their findings move beyond the limitations of previous measurements, which were confined to around a hundred stars. The new results encompass over ten thousand stars, providing valuable insights into the nature of interstellar ice.

Since the molecules present in our Solar System today were, at some point, likely ice on small dust grains that combined to form planets and comets, the discovery also marks a leap forward toward understanding the origins of the molecules that shape our cosmic surroundings.

These are just the team’s initial findings from a small fraction of their JWST observations of the Brick. Looking ahead, Ginsburg sets his sights on a more extensive survey of celestial ices.

“We don't know, for example, the relative amounts of CO, water, CO2, and complex molecules,” said Ginsburg. “With spectroscopy, we can measure those and get some sense of how chemistry progresses over time in these clouds.”

With the advent of the JWST and its advanced filters, Ginsburg and his colleagues are presented with their most promising opportunity yet to expand our cosmic exploration.

In a recent study led by University of Florida astronomer Adam Ginsburg, groundbreaking findings shed light on a mysterious dark region at the center of the Milky Way. The turbulent gas cloud, playfully nicknamed “The Brick” due to its opacity, has sparked lively debates within the scientific community for years.

To decipher its secrets, Ginsburg and his research team, including UF graduate students Desmond Jeff, Savannah Gramze, and Alyssa Bulatek, turned to the James Webb Space Telescope (JWST). The implications of their observations, published in The Astrophysical Journal, are monumental. The findings not only unearth a paradox within the center of our galaxy but indicate a critical need to re-evaluate established theories regarding star formation.

The Brick has been one of the most intriguing and highly studied regions of our galaxies, thanks to its unexpectedly low star formation rate. It has challenged scientists’ expectations for decades: as a cloud full of dense gas, it should be ripe for the birth of new stars. However, it demonstrates an unexpectedly low star formation rate.

Using the JWST’s advanced infrared capabilities, the team of researchers peered into the Brick, discovering a substantial presence of frozen carbon monoxide (CO) there. It harbors a significantly larger amount of CO ice than previously anticipated, carrying profound implications for our understanding of star formation processes.

No one knew how much ice there was in the Galactic Center, according to Ginsburg. “Our observations compellingly demonstrate that ice is very prevalent there, to the point that every observation in the future must take it into account,” he said.

Stars typically emerge when gases are cool, and the significant presence of CO ice should suggest a thriving area for star formation in the Brick. Yet, despite this wealth of CO, Ginsburg and the research team found that the structure defies expectations. The gas inside the Brick is warmer than comparable clouds.

These observations challenge our understanding of CO abundance in the center of our galaxy and the critical gas-to-dust ratio there. According to the findings, both measures appear to be lower than previously thought.

“With JWST, we're opening new paths to measure molecules in the solid phase (ice), while previously we were limited to looking at gas,” said Ginsburg. “This new view gives us a more complete look at where molecules exist and how they are transported. “

Traditionally, the observation of CO has been limited to emission from gas. To unveil the distribution of CO ice within this vast cloud, the researchers required intense backlighting from stars and hot gas. Their findings move beyond the limitations of previous measurements, which were confined to around a hundred stars. The new results encompass over ten thousand stars, providing valuable insights into the nature of interstellar ice.

Since the molecules present in our Solar System today were, at some point, likely ice on small dust grains that combined to form planets and comets, the discovery also marks a leap forward toward understanding the origins of the molecules that shape our cosmic surroundings.

These are just the team’s initial findings from a small fraction of their JWST observations of the Brick. Looking ahead, Ginsburg sets his sights on a more extensive survey of celestial ices.

“We don't know, for example, the relative amounts of CO, water, CO2, and complex molecules,” said Ginsburg. “With spectroscopy, we can measure those and get some sense of how chemistry progresses over time in these clouds.”

With the advent of the JWST and its advanced filters, Ginsburg and his colleagues are presented with their most promising opportunity yet to expand our cosmic exploration.

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