Astronomy
Einstein was right about the way matter plunges into black holes
Einstein was right about the way matter plunges into black holes
Linking Organic Molecules to Hydrothermal Vents on Enceladus
Despite the vast distance between us and Saturn’s gleaming moon Enceladus, the icy ocean moon is a prime target in our search for life. It vents water vapour and large organic molecules into space through fissures in its icy shell, which is relatively thin compared to other icy ocean moons like Jupiter’s Europa. Though still out of reach, scientific access to its ocean is not as challenging as on Europa, which has a much thicker ice shell.
The presence of large organic molecules isn’t very controversial. But they don’t necessarily signify that something alive lurks in its ancient, unseen ocean. Instead, hydrothermal processes could produce them. The complexity arises because hydrothermal processes are also linked to the emergence of life.
Understanding the abiotic processes that produce these molecules is important not just for Enceladus. It could serve as a baseline for understanding the results of a future mission to the frozen moon and any biosignatures it might detect.
New research in the journal Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences examines this issue. It’s titled “Laboratory characterization of hydrothermally processed oligopeptides in ice grains emitted by Enceladus and Europa.” The lead author is Dr. Nozair Khawaja from the Institute of Space Systems (IRS) at the University of Stuttgart.
Scientists postulate the life on Earth got started at hydrothermal events on the ocean floor. These vents provide mineral-rich fluids. At deep ocean vents under extreme pressure, these minerals can react with seawater to produce the building blocks of life.
This image shows a black smoker hydrothermal vent discovered in the Atlantic Ocean in 1979. It’s fueled from deep beneath the surface by magma that superheats the water, and the plume delivers minerals to the sea. Courtesy USGS.“In research, we also speak of a hydrothermal field,” explains lead author Khawaja. “There is convincing evidence that conditions prevail in such fields that are important for the emergence or maintenance of simple life forms.”
Much of what we know about Enceladus comes from the Cassini mission. Scientists are still working with Cassini’s data even though it ended in 2017. Although much of the data was low resolution, it’s still valuable.
Professor Frank Postberg from the Freie Universität (FU) Berlin is one of the study’s co-authors. “In 2018 and 2019, we encountered various organic molecules, including some that are typically building blocks of biological compounds,” Postberg said. “And that means it is possible that chemical reactions are taking place there that could eventually lead to life.”
There’s a missing link between the hydrothermal vents and the molecules vented into space. Scientists aren’t certain if the vents are responsible for the molecules or in what way. Is life involved?
This image shows the detection of hydrothermally altered biosignatures on Enceladus. Image Credit: SWRI/NASA/JPLTo answer these questions, the researchers simulated an Enceladus hydrothermal vent in their laboratory.
“To this end, we simulated the parameters of a possible hydrothermal field on Enceladus in the laboratory at the FU Berlin,” said lead author Khawaja. “We then investigated what effects these conditions have on a simple chain of amino acids.” Amino acids are the basic building blocks of proteins and the basis of all Earth life. There are hundreds of them, and 22 of them are in all living cells. They’re the precursors to proteins and they show that life on Earth is all connected.
The researchers subjected amino acids to conditions thought to persist at Encledadus’ ocean floor. “Here, we present results from our newly established facility to simulate the processing of ocean material within the temperature range 80–150°C and the pressure range 80–130 bar, representing conditions suggested for the water-rock interface on Enceladus,” they write in their paper. Under those conditions, the chains of amino acids behaved characteristically.
But that’s in a lab. Can we devise a space probe that can detect these types of changes on Enceladus? The changes themselves are obscured, but do they produce byproducts or markers that are emitted into space?
Cassini’s Cosmic Dust Analyzer (CDA) detected the organic molecules in Enceladus’ plumes by watching collisions between rapidly moving particles that shatter molecules and vapourize their contents. Some particles, stripped of their electrons, become positively charged and are attracted to a negative electrode on the instrument. The less massive they are, the faster they reach the electrode.
By combining a large amount of this type of data, the CDA revealed a lot about the original molecules.
But this can’t be replicated in a lab.
“Instead, we employed an alternative measurement method called LILBID for the first time on ice particles containing hydrothermally altered material,” Khawaja explains. LILBID stands for laser-induced liquid beam ion desorption, a different type of mass spectrometry than the CDA performs. Though the method is different, it produces results similar to Cassini’s CDA instrument.
“This delivers very similar mass spectra to the Cassini instrument. We used this to measure an amino acid chain before and after the experiment. In the process, we came across characteristic signals that were caused by the reactions in our simulated hydrothermal field,” Khawaja said.
Specifically, the researchers examined the hydrothermal processing of the triglycine (GGG) peptide. GGG is a tripeptide, the most common one. Scientists often use GGG to study amino acids, peptides, and proteins, analyzing the molecular interactions and physicochemical parameters of all three.
“Differences observed between mass spectra of hydrothermally processed and unprocessed triglycine can be regarded as a spectral fingerprint to identify processed GGG in ice grains from icy moons in the solar system,” the authors wrote in their research.
These two panels from the research compare the mass spectra of hydrothermal unprocessed triglycine (left) to hydrothermally processed triglycine (right.) There are some clear differences between the two. Image Credit: Khawaja et al. 2024.“This delivers very similar mass spectra to the Cassini instrument. We used this to measure an amino acid chain before and after the experiment. In the process, we came across characteristic signals that were caused by the reactions in our simulated hydrothermal field,” Khawaja said.
The researchers intend to repeat this experiment with other organic molecules under extended geophysical conditions in Enceladus’ ocean. “With this new laboratory setup, we will simulate a range of hydrothermal conditions, from the high pressures and temperatures associated with greater depths into the core, to the milder conditions in the ocean water near the water-rock interface,” the authors write in their paper.
The results will allow them to search through Cassini’s data for similar markers. It can also work for future missions to Enceladus and would be further proof of hydrothermal activity on the frozen ocean moon.
If scientists can confirm hydrothermal vents on Enceladus, the excitement that moon generates will only increase.
The post Linking Organic Molecules to Hydrothermal Vents on Enceladus appeared first on Universe Today.
A Star Became 1,000 Times Brighter, and Now Astronomers Know Why
Astronomers were surprised in 1937 when a star in a binary pair suddenly brightened by 1,000 times. The pair is called FU Orionis (FU Ori), and it’s in the constellation Orion. The sudden and extreme variability of one of the stars has resisted a complete explanation, and since then, FU Orionis has become the name for other stars that exhibit similar powerful variability.
The star in question is called Orionis North, and it’s the central star of the pair. Astronomers see its brightening behaviour in old stars but not in young stars like FU Ori. The young star is only about 2 million years old.
Astronomers working with ALMA (Atacama Large Millimetre-submillimetre Array) have discovered the reason behind Fu Ori’s variability. They’ve published their research in the Astrophysical Journal. It’s titled “Discovery of an Accretion Streamer and a Slow Wide-angle Outflow around FU Orionis,” and the lead author is Antonio Hales, deputy manager of the North American ALMA Regional Center and scientist with the NRAO.
Here’s what scientists do know about FU Ori (FUor) stars and their variability. They brighten when they attract gas gravitationally into an accretion disk. Too much mass at once can destabilize the disk, and as material falls into the star, it brightens. But what they didn’t understand was why and how this happened.
“FU Ori has been devouring material for almost 100 years to keep its eruption going. We have finally found an answer to how these young outbursting stars replenish their mass,” explained lead author Hales. “For the first time we have direct observational evidence of the material fueling the eruptions.”
ALMA is the world’s largest radio telescope. It’s an interferometer with 66 separate antennae, which can be moved across the ground to give the observatory a ‘zoom-in’ effect. This powerful observatory has driven a lot of astronomical science.
In this research, ALMA identified a long streamer of carbon monoxide that appears to be falling into FU Ori. The researchers don’t think this streamer has enough material to sustain the star’s current outburst. But it could be the remnant from a past episode. “It is possible that the interaction with a bigger stream of gas in the past caused the system to become unstable and trigger the brightness increase,” explained Hales.
This figure from the research shows 12CO and 13CO emissions as detected by ALMA. The colours denote velocity. The CO streamer of infalling gas is labelled. “The elongated feature has a connection neither to the larger-scale molecular outflow nor to the inner disk rotation and is more similar to accretion streamers recently reported around young stellar objects,” the authors explain. Image Credit: Hales et al. 2024.The current outburst creates strong stellar winds that interact with a leftover envelope of material from the star’s formation. The wind shocks the envelope, sweeping up carbon monoxide with it. The CO is what ALMA detected.
Artist’s impression of the large-scale view of FU~Ori. The image shows the outflows produced by the interaction between strong stellar winds powered by the outburst and the remnant envelope from which the star formed. The stellar wind drives a strong shock into the envelope, and the CO gas swept up by the shock is what the new ALMA revealed. The inset image is an artist’s impression of the streamer of CO feeding mass into FU Ori. Image Credit: NSF/NRAO/S. DagnelloALMA’s ability to operate in different configurations and wavelengths played a role in this work. It allowed the team to detect different types of emissions and to detect the mass flowing into FU Ori. They compared the observations to models of mass flow and accretion streamers. “We compared the shape and speed of the observed structure to that expected from a trail of infalling gas, and the numbers made sense,” said Aashish Gupta, a Ph.D. candidate at European Southern Observatory (ESO). Gupta is a co-author of this work, and he developed the methods used to model the accretion streamer.
This image from the research shows the model results (green line) overlain on ALMA data. The streamer modelling closely matches the data. “The fitting results suggest that the morphology and the velocity profile of the observed streamer emission can be well represented as a trail of infalling gas,” the authors write in their published research. Image Credit: Hales et al. 2024.The researchers measured the amount of material flowing into FU Ori through the streamer. About 0.07 Jupiter Masses per Myr?1 flow into the young star. Jupiter is about 318 times more massive than Earth. This means that FU Ori’s infall streamer rate is lower than infall around other Class 0 protostars. “This would suggest that the observed streamer will require ?100 Myr to replenish disk masses, which is at least an order of magnitude greater than the typical disk lifetimes,” the authors point out.
The infall streamer and its effect on the star are complex. Not enough material comes in via the streamer to trigger the outbursts. “The streamer needs to be more massive to sustain FU Ori’s outburst accretion rates (by several orders of magnitude). The estimated streamer mass infall rate is not even sufficiently massive to sustain quiescent stellar accretion rates,” the authors explain.
Instead, the infalling material causes disk instability, which in turn delivers enough material to FU Ori to trigger outbursts. “Anisotropic infall, cloudlet capture events, the inhomogeneous delivery of material, and the building up of material around dust traps can all lead to the disk instabilities that could trigger accretion outbursts,” Hales and his co-authors write. They can’t say for sure if this is what’s happening. That would require more modelling, which is outside the scope of this work.
ALMA also spotted another streamer of slow-moving CO. This one is coming from the star rather than falling into it. Hales and his colleagues think this streamer is similar to streamers coming from other young protostellar objects and isn’t related to the brightening. “The ALMA observations reveal the presence of large-scale, wide-angle bipolar outflows for the first time around the class prototype FU Ori,” the researchers write in their paper.
Curiously, astronomers have detected these outflows from other FUor stars but never at FU Ori itself. It’s coming from Fu Ori North, the star that experiences the powerful brightening.
“Prior searches for molecular outflows around FUors, mainly using single-dish telescopes, reported outflowing material from many FUors but failed to detect flows emerging from the FUor class prototype,” the researchers write in their paper. “These nondetections instigated the belief that there were no molecular outflows around the FU Ori system. Our discovery ends the mystery by clearly demonstrating the presence of a molecular outflow from FU Ori itself.”
Understanding young stars is critical because their behaviour governs planet formation. FU Ori’s brightening could have a defining effect on the planets that form around the star.
“By understanding how these peculiar FUor stars are made, we’re confirming what we know about how different stars and planets form,” Hales explained. “We believe that all stars undergo outburst events. These outbursts are important because they affect the chemical composition of the accretion discs around nascent stars and the planets they eventually form.”
For the authors, their research demonstrates how the powerful ALMA observatory makes a unique contribution to astronomical research. “These results demonstrate the value of multiscale interferometric observations to enhance our understanding of the FU Ori outbursting system and provide new insights into the complex interplay of physical mechanisms governing the behaviour of FUor-type and the many other kinds of outbursting stars,” the authors conclude.
The post A Star Became 1,000 Times Brighter, and Now Astronomers Know Why appeared first on Universe Today.
Huge, solar flare-launching sunspot has rotated away from Earth. But will it return?
How do you forecast a solar storm? Space weather experts explain
Cosmic butterfly or interstellar burger? This planet-forming disk is the largest ever seen
New Answers for Mars’ Methane Mystery
Planetary scientists perk up whenever methane is mentioned. Methane is produced by living things on Earth, so it’s considered to be a potential biosignature elsewhere. In recent years, MSL Curiosity detected methane coming from the surface of Gale Crater on Mars. So far, nobody’s successfully explained where it’s coming from.
NASA scientists have some new ideas.
Ever since Curiosity landed on Mars in 2012, it’s been sensing methane. But the methane displays some odd characteristics. It only comes out at night, it fluctuates with the seasons, and sometimes, the amount of methane jumps to 40 times more than the regular level.
The ESA’s ExoMars Trace Gas Orbiter entered a science orbit around Mars in 2018, and scientists fully expected it to detect methane in the planet’s atmosphere. But it didn’t, and it has never been detected elsewhere on Mars’ surface.
If life was producing the methane, it appears to be restricted to the subsurface under Gale Crater.
There’s no convincing evidence that life exists on Mars. It may have in the past, and it’s possible that some extant life clings to a tenuous existence in subsurface brines or something. But we lack evidence, so life is basically ruled out as the methane source. Especially since the evidence shows life would have to be under Gale Crater and nowhere else.
Scientists have been trying to determine the source of methane, but so far, they haven’t come up with a specific answer. It has something to do with subsurface geological processes involving water, most likely.
This image illustrates possible ways methane might get into Mars’ atmosphere and also be removed from it: microbes (left) under the surface that release the gas into the atmosphere, weathering of rock (right), and stored methane ice called a clathrate. Ultraviolet light can work on surface materials to produce methane as well as break it apart into other molecules (formaldehyde and methanol) to produce carbon dioxide. Credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan“It’s a story with a lot of plot twists,” said Ashwin Vasavada, Curiosity’s project scientist at NASA’s Jet Propulsion Laboratory in Southern California, which leads Curiosity’s mission.
Alexander Pavlov is a planetary scientist at NASA’s Goddard Space Flight Center who leads a group of NASA scientists studying the Martian Methane Mystery. In recent research, they suggested that the methane is stored underground. They didn’t explain what produced it, but they showed that methane can be sealed underground by salt solidified in the Martian regolith.
This figure from research published in 2024 illustrates how a salt cap could form and trap methane under the Martian surface. There’s strong evidence of subsurface water on Mars, and it can migrate to the surface and evaporate. Some of the salt in the ground is transported to the surface with the water. Once the water or ice is gone, the salt is left behind in the upper few centimetres of soil. The researchers hypothesized that the salt can become cemented into the same type of duricrust that the InSight lander struggled with. Image Credit: Pavlov et al. 2024.They suggested that the methane could be released from its subsurface reservoir by the weight of the Curiosity rover itself. The rover’s weight could break the salt seal and release methane in puffs. That’s an interesting proposition, but it doesn’t explain the seasonal and diurnal fluctuations. That makes sense since the Gale Crater is one of only two regions where a rover is working. The other is Jezero Crater, where the Perseverance Rover is working, but it doesn’t have a methane detector. (Neither will the ESA’s Rosalind Franklin rover, which is scheduled to land on Mars in 2029.)
The research group addressed those fluctuations by suggesting that seasonal and daily heating could also break the seal and release methane.
Their potential explanations stem from research Pavlov conducted in 2017. He grew bacteria called halophiles, which grow in salty conditions, in simulated Martian permafrost. The simulated soil was infused with salt, replicating conditions on much of Mars. The microbe growth was inconclusive, but the researchers noticed something else. As the salty ice sublimated, a layer of solidified salt remained, forming a crust.
“We didn’t think much of it at the moment,” Pavlov said.
But he remembered it when MSL Curiosity detected an unexplained burst of methane on Mars in 2019.
“That’s when it clicked in my mind,” Pavlov said. Then, he and a team of researchers began testing conditions that could form the hardened salt seals and then break them open.
Perchlorate is a chemical salt that’s widespread on Mars. Pavlov and his fellow researchers recreated different simulated Martian permafrosts with varying amounts of perchlorate. Inside a Mars simulation chamber, they subjected the samples to different temperatures and atmospheric pressures to see if they would form seals.
In their experiments, they used neon as a methane analog and injected it under the soil. Then, they measured the gas pressure below and above the soil. They found that the pressure was higher under the soil, meaning the gas was being trapped by the salty permafrost. Furthermore, they found that seals formed in samples containing as little as 5% or 10% perchlorate, and they formed within 3 to 13 days. Those are compelling results.
This image shows one of the Mars analog samples with a hardened crust of salt sealing the surface. The lighter colour is where the sample has been scratched. The lighter colour indicates drier soil, and once it was exposed to air outside the Mars Chamber, it quickly absorbed moisture and turned brown. Image Credit: Pavlov et al. 2018.While 5-10% perchlorate doesn’t sound like much, it’s actually a higher concentration than in Gale Crater, where the methane has been detected. But perchlorate isn’t the only salt in Martian regolith. It also contains sulphates, another type of salt mineral. Pavlov says he and his team will test sulphates next for their ability to form a seal.
The Martian Methane Mystery is commanding a lot of attention. It’s a juicy mystery, and once it’s solved, our understanding of methane as a biosignature or false positive will be much improved. NASA’s 2022 Planetary Mission Senior Review recommended that the issue of methane production and destruction at Mars be investigated further.
The type of work that Pavlov and his colleagues are doing is important, but it’s being held back. Pavlov says that they need more consistent methane measurements. The problem is that Curiosity’s SAM (Sample Analysis at Mars) instrument, which senses the methane, is busy with other tasks. It only checks for methane a few times per year. It’s mostly occupied with drilling samples and testing them, a critical and time-consuming part of the rover’s mission.
The Tunable Laser Spectrometer is one of the tools within the Sample Analysis at Mars (SAM) laboratory on NASA’s Curiosity Mars rover. By measuring the absorption of light at specific wavelengths, it measures concentrations of methane, carbon dioxide and water vapour in Mars’ atmosphere. (Image Credit: NASA/JPL-Caltech)“Methane experiments are resource intensive, so we have to be very strategic when we decide to do them,” said Goddard’s Charles Malespin, SAM’s principal investigator.
Curiosity’s mission wasn’t designed to measure methane fluctuations. In 2017, NASA said its SAM instrument only sampled the atmosphere 10 times in 20 months. That’s a very inconsistent sample that leaves lots of unanswered questions.
Scientists think another mission is needed to advance their understanding of Martian methane. Rather than one sensor taking irregular methane readings from one location, we need multiple testing stations on the surface that regularly monitor the atmosphere. Nothing like it is in the works.
“Some of the methane work will have to be left to future surface spacecraft that are more focused on answering these specific questions,” Vasavada said.
The post New Answers for Mars’ Methane Mystery appeared first on Universe Today.
