Science
Separating out signals recorded at the seafloor
Roger Bryant and David Fike’s research reveals that pyrite sulfur isotopes mainly reflect local conditions, shifting fundamental understanding of oceanic environmental studies.
Last Updated on November 1, 2024 by Daily News Staff
Roger Bryant studied ocean floor core samples at the Secondary Ion Mass Spectrometry (SIMS) facility at Washington University in St. Louis during his PhD studies. Bryant and David Fike have used this data to prove a discovery that will fundamentally change how scientists use pyrite sulfur isotopes to study oceanic conditions.
« Separating out signals recorded at the seafloor
Newswise — Blame it on plate tectonics. The deep ocean is never preserved, but instead is lost to time as the seafloor is subducted. Geologists are mostly left with shallower rocks from closer to the shoreline to inform their studies of Earth history.
Signals from the Sea
“We have only a good record of the deep ocean for the last ~180 million years,” said David Fike, the Glassberg/Greensfelder Distinguished University Professor of Earth, Environmental, and Planetary Sciences in Arts & Sciences at Washington University in St. Louis. “Everything else is just shallow-water deposits. So it’s really important to understand the bias that might be present when we look at shallow-water deposits.”
One of the ways that scientists like Fike use deposits from the seafloor is to reconstruct timelines of past ecological and environmental change. Researchers are keenly interested in how and when oxygen began to build up in the oceans and atmosphere, making Earth more hospitable to life as we know it.
For decades they have relied on pyrite, the iron-sulfide mineral known as “fool’s gold,” as a sensitive recorder of conditions in the marine environment where it is formed. By measuring the bulk isotopic composition of sulfur in pyrite samples — the relative abundance of sulfur atoms with slightly different mass — scientists have tried to better understand ancient microbial activity and interpret global chemical cycles.
But the outlook for pyrite is not so shiny anymore. In a pair of companion papers published Nov. 24 in the journal Science, Fike and his collaborators show that variations in pyrite sulfur isotopes may not represent the global processes that have made them such popular targets of analysis.
Instead, Fike’s research demonstrates that pyritte responds predominantly to local processes that should not be taken as representative of the whole ocean. A new microanalysis approach developed at Washington University helped the researchers to separate out signals in pyrite that reveal the relative influence of microbes and that of local climate.
For the first study, Fike worked with Roger Bryant, who completed his graduate studies at Washington University, to examine the grain-level distribution of pyrite sulfur isotope compositions in a sample of recent glacial-interglacial sediments. They developed and used a cutting-edge analytical technique with the secondary-ion mass spectrometer (SIMS) in Fike’s laboratory.
“We analyzed every individual pyrite crystal that we could find and got isotopic values for each one,” Fike said. By considering the distribution of results from individual grains, rather than the average (or bulk) results, the scientists showed that it is possible to tease apart the role of the physical properties of the depositional environment, like the sedimentation rate and the porosity of the sediments, from the microbial activity in the seabed.
“We found that even when bulk pyrite sulfur isotopes changed a lot between glacials and interglacials, the minima of our single grain pyrite distributions remained broadly constant,” Bryant said. “This told us that microbial activity did not drive the changes in bulk pyrite sulfur isotopes and refuted one of our major hypotheses.”
“Using this framework, we’re able to go in and look at the separate roles of microbes and sediments in driving the signals,” Fike said. “That to me represents a huge step forward in being able to interpret what is recorded in these signals.”
In the second paper, led by Itay Halevy of the Weizmann Institute of Science and co-authored by Fike and Bryant, the scientists developed and explored a computer model of marine sediments, complete with mathematical representations of the microorganisms that degrade organic matter and turn sulfate into sulfide and the processes that trap that sulfide in pyrite.
“We found that variations in the isotopic composition of pyrite are mostly a function of the depositional environment in which the pyrite formed,” Halevy said. The new model shows that a range of parameters of the sedimentary environment affect the balance between sulfate and sulfide consumption and resupply, and that this balance is the major determinant of the sulfur isotope composition of pyrite.
“The rate of sediment deposition on the seafloor, the proportion of organic matter in that sediment, the proportion of reactive iron particles, the density of packing of the sediment as it settles to the seafloor — all of these properties affect the isotopic composition of pyrite in ways that we can now understand,” he said.
Importantly, none of these properties of the sedimentary environment are strongly linked to the global sulfur cycle, to the oxidation state of the global ocean, or essentially any other property that researchers have traditionally used pyrite sulfur isotopes to reconstruct, the scientists said.
“The really exciting aspect of this new work is that it gives us a predictive model for how we think other pyrite records should behave,” Fike said. “For example, if we can interpret other records — and better understand that they are driven by things like local changes in sedimentation, rather than global parameters about ocean oxygen state or microbial activity — then we can try to use this data to refine our understanding of sea level change in the past.”
Source: Washington University in St. Louis
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The Knowledge
Artemis II Crew Beams Stunning First Moon Flyby Images Back to Earth

Artemis II Astronauts Capture First Moon Flyby Images from Lunar Far Side
April 7, 2026 — NASA has released the first breathtaking images from the historic Artemis II mission, offering humanity a rare look at the Moon’s far side—including views never before seen by human eyes.
Captured during a seven-hour lunar flyby on April 6, the images were taken by astronauts aboard the Orion spacecraft as part of NASA’s first crewed mission to the Moon in more than 50 years.
🌕 A Historic View of the Moon
The newly released images reveal stunning details of the lunar surface, including impact craters, ancient lava flows, and fractured terrain that scientists will use to better understand the Moon’s geologic history.
Among the most remarkable visuals is a rare solar eclipse seen from space, where the Moon passes in front of the Sun, revealing the Sun’s outer corona. The images also captured an “earthset” and “earthrise”—moments where Earth appears to set and rise over the Moon’s horizon.
In one striking image, the Moon is backlit by the Sun, with Earth glowing at its edge, while distant planets like Saturn and Mars appear as bright points in the background.
📸 Thousands of Images, New Discoveries
The Artemis II crew—Reid Wiseman, Victor Glover, Christina Koch, and Canadian astronaut Jeremy Hansen—used a range of cameras to capture thousands of high-resolution images during the flyby.
In addition to photography, the astronauts reported observing six meteoroid impact flashes on the Moon’s surface, offering scientists a rare opportunity to study active lunar events in real time.
Researchers are now analyzing the images, audio, and telemetry data to refine their understanding of the Moon’s surface and compare findings with observations from Earth-based astronomers.
🔬 Science That Shapes the Future
According to NASA officials, the data collected during Artemis II will play a critical role in shaping future missions, including plans to establish a long-term human presence on the Moon.
“These images are not only visually stunning, but they are brimming with scientific value that will inspire generations to come,” said Dr. Nicky Fox, associate administrator for NASA’s Science Mission Directorate.
The mission also provides astronauts with a unique advantage—human observation. With four trained sets of eyes, the crew is able to analyze subtle differences in color, brightness, and texture across the lunar surface in ways robotic systems cannot.
🚀 More Than Halfway Home
Now more than halfway through its 10-day journey, Artemis II is heading back toward Earth. NASA is targeting a splashdown at 8:07 p.m. EDT on April 10 off the coast of San Diego.
Live coverage of the return will begin at 6:30 p.m. EDT on NASA+, with recovery teams ready to retrieve the crew and spacecraft following reentry.
🌍 A New Era of Exploration
The Artemis II mission marks a major step forward in NASA’s long-term vision of returning humans to the Moon and eventually sending astronauts to Mars.
With each image and data point sent back to Earth, the mission is not only rewriting the record books—but also expanding humanity’s understanding of our closest celestial neighbor.
Official Artemis II images are available through NASA’s digital platforms, including the Artemis Image Gallery and NASA Image and Video Library.
🔗 Related External Links
Explore official NASA resources and view the latest Artemis II Moon flyby images:
- NASA: Artemis II Mission Overview
- NASA Artemis Program (Return to the Moon)
- NASA Image and Video Library (Artemis II Photos)
- Artemis Image Gallery
- Orion Spacecraft Details
- Apollo 13 Mission History (Previous Distance Record)
Source: NASA Official Release – Artemis II Moon Flyby Images
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The Earth
PFAS are turning up in the Great Lakes, putting fish and water supplies at risk – here’s how they get there
PFAS “forever chemicals” are entering the Great Lakes through rivers, groundwater, and rain, threatening drinking water, fish, and one of the world’s largest freshwater systems.

Christy Remucal, University of Wisconsin-Madison
No matter where you live in the United States, you have likely seen headlines about PFAS being detected in everything from drinking water to fish to milk to human bodies.
PFAS, or per- and polyfluoroalkyl substances, are a group of over 10,000 synthetic chemicals. They have been used for decades to make products waterproof and stain- and heat-resistant – picture food wrappers, stain-resistant carpet, rain jackets and firefighting foam.
These chemicals are a growing concern because some PFAS are toxic even at very low levels and associated with health risks like thyroid issues and cancer. And some of the most common PFAS don’t naturally break down, which is why they are often referred to as “forever chemicals.”
Now, PFAS are posing a threat to the Great Lakes, one of America’s most vital water resources.
The five Great Lakes are massive, with over 10,000 miles of coastline (16,000 kilometers) across two countries and containing 21% of the world’s fresh surface water. They provide drinking water to over 30 million people and are home to a robust commercial and recreational fishing industry.
My colleagues at the University of Wisconsin-Madison and I study how chemicals like PFAS are affecting water systems. Here’s what we’re learning about how PFAS are getting into the Great Lakes, the risks they’re posing and how to reduce those risks in the future.
PFAS’ many pathways into the Great Lakes
Hundreds of rivers flow into the lakes, and each can be contaminated with PFAS from sources such as industrial sites, military operations and wastewater treatment plants in their watersheds. Some pesticides also contain PFAS, which can wash off farm fields and into creeks, rivers and lakes.
The concentration of PFAS in rivers can vary widely depending on these upstream impacts. For example, we found concentrations of over 1,700 parts-per-trillion in Great Lakes tributaries in Wisconsin near where firefighting foam has regularly been used. That’s more than 400 times higher than federal drinking water regulations for PFOS and PFOA, both 4 parts-per-trillion.
However, concentration alone does not tell the whole story. We also found that large rivers with relatively low amounts of PFAS can put more of these chemicals into the lakes each day compared with smaller rivers with high amounts of PFAS. This means that any effort to limit the amount of PFAS in the Great Lakes should consider both high-concentration hot spots and large rivers.
Groundwater is another key route carrying PFAS into the Great Lakes. Groundwater is a drinking water source for more than one-third of people in the U.S., and it can become contaminated when PFAS in firefighting foam and other PFAS sources seep into soil.
When these contaminated plumes enter the Great Lakes, they carry PFAS with them. We detected PFAS concentrations of over 260 parts-per-trillion in the bay of Green Bay in Lake Michigan. The chemicals we found were associated with firefighting foam, and we were able to trace them back to a contaminated groundwater plume.
PFAS can also enter the Great Lakes in unexpected ways, such as in rain and snowfall. PFAS can get into the atmosphere from industrial processes and waste incineration. The chemicals have been detected in rain across the world, including in states surrounding the Great Lakes.
Although PFAS concentrations in precipitation are typically lower than in rivers or groundwater, this is still an important contamination source. Scientists estimate that precipitation is a major source of PFAS to Lake Superior, which receives about half of its water through precipitation.
Where PFAS end up determines the risk
Much of the PFAS that enter Lake Superior will eventually make their way to the downstream lakes of Michigan, Huron, Erie and Ontario.
These chemicals’ ability to travel with water is one reason why PFAS are such a concern for drinking water systems. Many communities get their drinking water from the Great Lakes.
https://datawrapper.dwcdn.net/ovIHR/1
PFAS can also contaminate other parts of the environment.
The chemicals have been detected in sediments at the bottom of all the Great Lakes. Contaminated sediment can release PFAS back into the overlying water, where fish and aquatic birds can ingest it. So, future remediation efforts to remove PFAS from the lakes are about more than just the water – they involve the sediment as well.
PFAS can also accumulate in foams that form on lake shorelines during turbulent conditions. Concentrations of PFAS can be up to 7,000 times higher in natural foams compared with the water because PFAS are surfactants and build up where air and water meet, like bubbles in foam. As a result, state agencies recommend washing skin that comes in contact with foam and preventing pets from playing in foam.
Some PFAS bioaccumulate, or build up, within fish and wildlife. Elevated levels of PFAS have been detected in Great Lakes fish, raising concerns for fisheries.
High PFAS concentrations in fish in coastal areas and inland waters have led to advisories recommending people limit how much they fish they eat.
Looking ahead
Water cycles through the Great Lakes, but the process can take many years, from 2.6 years in Lake Erie to nearly 200 years in Lake Superior.
This means that PFAS that enter the lakes will be there for a very long time.
https://datawrapper.dwcdn.net/OOPxB/1
Since it is not possible to clean up the over 6 quadrillion gallons of water in the Great Lakes after they have been contaminated, preventing further contamination is key to protecting the lakes for the future.
That starts with identifying contaminated groundwater and rivers that are adding PFAS to the lakes. The Sea Grant College Program and the National Institutes of Water Resources, including the Wisconsin programs that I direct, have been supporting research to map these sources, as well as helping translate that knowledge into actions that policymakers and resource managers can take.
PFAS contamination is an issue beyond the Great Lakes and is something everyone can work to address.
- Drinking water. If you are one of the millions of people who drink water from the Great Lakes, find out the PFAS concentrations in your drinking water. This data is increasingly available from local drinking water utilities.
- Fish. Eating fish can provide great health benefits, but be aware of health advisories about fish caught in the Great Lakes and in inland waters so you can balance the risks. Other chemicals, such as mercury and PCBs, can also lead to fish advisories.
- Personal choice. Scientists have proposed that PFAS only be used when they have vital functions and there are no alternatives. Consumer demand for PFAS-free products is helping reduce PFAS use in some products. Several states have also introduced legislation to ban PFAS use in some applications.
Decreasing use of PFAS will ultimately prevent downstream contamination in the Great Lakes and around the U.S.
Christy Remucal, Professor of Civil and Environmental Engineering, University of Wisconsin-Madison
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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The Knowledge
Artemis II’s long countdown – a space historian explains why it has taken over 50 years to return to the Moon
Why has it taken 50+ years to return to the Moon? A space historian explains the technical, political, and financial complexities behind Artemis II’s long journey.

Emily A. Margolis, Smithsonian Institution
While I was leading a tour of the National Air and Space Museum in January 2026, a visitor posed this insightful question: “Why has it taken so long to return to the Moon?”
After all, NASA had the know-how and technology to send humans to the lunar surface more than 50 years ago as part of the Apollo program. And, as another tour guest reminded us, computers today can do so much more than they could back then, as evidenced by the smartphones most of us carry in our pockets. Shouldn’t it be easier to get to the Moon than ever before?
The truth is that sending humans into space safely continues to be difficult, especially as missions increase in complexity.
New technologies require years of study, development and testing before they can be certified for flight. And even then, systems and materials can behave in ways that surprise and worry engineers and mission planners; look no further than Boeing’s Starliner CFT mission or the performance of the Orion heat shield on Artemis I.
Issues with Starliner’s thrusters led NASA to return the spacecraft from the International Space Station without its crew. Unanticipated chipping of the Orion heat shield resulted in years of research, culminating in NASA altering the atmospheric reentry plans for the Artemis II mission.
NASA’s programs also require sustained political will and financial support across multiple presidential administrations, Congresses and fiscal years. As a historian of human spaceflight, I have studied the space agency’s efforts to engage the broader public to convince American taxpayers that their programs hold value for the nation.
NASA is now on the eve of the first crewed flight to the Moon since the Apollo era: Artemis II. A crew of four will conduct a lunar flyby, laying the groundwork, the agency hopes, for a landing on the Artemis IV mission.
The story of NASA’s effort to return humans to the Moon is long and winding, demonstrating the complexities of turning grand ambitions into real missions.
Post-Apollo
In early 1970, with two successful Moon landings on the books, President Richard Nixon sought to reduce NASA’s budget to better align with his administration’s priorities. This decision put the space agency in a difficult position, which ultimately led to the cancellation of three planned Apollo missions to conserve funding for its plans for long-term human activity in low Earth orbit.
NASA repurposed the third stage of a Saturn V rocket to create the first U.S. space station, Skylab, which operated from 1973 to 1974. The space agency used leftover Saturn IB rockets and Apollo command and service modules to send crews to the station.
Over the next three decades, NASA developed and operated the space shuttle. The fleet of space shuttle orbiters supported satellite deployment and microgravity research on orbital missions of up to 17 days. This work was meant to enable future long-duration human missions and provide benefits to people on Earth. For example, data from protein crystal growth experiments have informed the development of medicines.
The space shuttle program facilitated the construction, maintenance and staffing of a continuously inhabited research platform in orbit, the International Space Station. The first modules launched in late 1998.
Where to next?
As the new millennium approached, the Clinton administration tasked NASA to think beyond the space station. What could robots and humans do next in space? And where could they do it? Notably, the White House expressed an interest in locations beyond low Earth orbit.
NASA, it turned out, was well positioned to meet the administration’s request. NASA Administrator Daniel Goldin was already thinking about preparing proposals for the next presidential administration and had recently sponsored a human lunar return study. In 1999, he established a team to investigate new technologies, missions and destinations for the 21st century.
This work took on new significance following the tragic loss of the space shuttle Columbia crew in February 2003. Many people, including those in the new George W. Bush White House, wondered whether the human spaceflight program should continue – and, if so, how.
Administration discussions culminated in Bush’s Vision for Space Exploration in 2004, which directed NASA to retire the space shuttle after the completion of the space station. It called for returning humans to the Moon on a crew exploration vehicle designed for destinations beyond low Earth orbit.
It also called for continuing robotic exploration of Mars and engaging companies and international partners in space. Fifteen years earlier, President George H. W. Bush had also announced a Moon and Mars exploration program, but congressional concerns about cost kept space travelers close to home.
The Constellation program’s legacy
In December 2004, NASA began the process of finding a manufacturer for the crew exploration vehicle. By August 2006, the space agency awarded Lockheed Martin the contract to build the capsule, which it had named Orion – the same Orion planned to carry Artemis astronauts to the Moon.
Years of research, development and testing followed for Orion as well as the Ares I crew and Ares V cargo launch vehicles. Together, these technologies made up the Constellation program.
Constellation had two primary objectives: in the near term, to help transport crew to and from the space station after the space shuttle program ended; in the long term, to enable human lunar exploration.
Building systems that could work in both Earth orbit and around the Moon was supposed to save the time and cost of developing two vehicles. Similarly, adapting space shuttle program hardware could supposedly cut costs.
During the first months of Barack Obama’s presidency in 2009, the administration initiated an independent review of NASA’s human spaceflight plans. The Augustine Committee, chaired by retired aerospace executive Norman Augustine, found that the agency’s ambitions outstripped its limited budget, leading to significant delays. The first Orion spacecraft was likely to arrive after the space station ceased operations.
The committee proposed several paths forward at the current funding level, which prioritized space shuttle and space station programs. An additional annual investment of US$3 billion would allow for human exploration beyond low Earth orbit.
Ultimately, the Obama administration canceled Constellation, but two of its technologies lived on, thanks to U.S. senators from states that would have been affected by cuts.
The NASA Authorization Act of 2010 funded Orion’s continued development, shifting responsibility for space station crew transportation to commercial vehicles. It also directed NASA to develop the space launch system, a redesigned Ares V heavy booster, to send Orion to the Moon. The technical strategy had political benefits, too, preserving jobs in numerous congressional districts by providing continuity for aerospace contractors.
In December 2014, a Delta IV heavy rocket launched the first Orion capsule on a test flight, providing engineers with data on spacecraft systems and the heat shield. By October 2015, the space launch system had completed a critical design review, the last step before manufacturing could begin.
Introducing Artemis
In December 2017, the new Trump administration issued a policy directive shifting the focus of NASA’s human spaceflight program back to the Moon. The space agency would use Orion and the space launch system in a race to meet an ambitious 2024 landing date. NASA officially named the program Artemis in May 2019.
The 25-day Artemis I mission, launched in November 2022, was a major milestone for the program. This uncrewed flight was the first flight of the space launch system and the first to integrate SLS and Orion. It laid the groundwork for Artemis II, which will be the first crewed flight of the SLS.
Over more than 50 years, each new presidential administration has reassessed the place of spaceflight among its priorities, either encouraging or curtailing NASA’s efforts to return humans to the lunar surface.
Each crewed flight requires the alignment of technical expertise, political will and financial support over years if not decades. For the space fans who plan to watch the Artemis II launch, the wait for countdown may feel long. But it’s just a blink in NASA’s long journey back to the Moon.
Emily A. Margolis, Curator of Contemporary Spaceflight, National Air and Space Museum, Smithsonian Institution
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Dive into “The Knowledge,” where curiosity meets clarity. This playlist, in collaboration with STMDailyNews.com, is designed for viewers who value historical accuracy and insightful learning. Our short videos, ranging from 30 seconds to a minute and a half, make complex subjects easy to grasp in no time. Covering everything from historical events to contemporary processes and entertainment, “The Knowledge” bridges the past with the present. In a world where information is abundant yet often misused, our series aims to guide you through the noise, preserving vital knowledge and truths that shape our lives today. Perfect for curious minds eager to discover the ‘why’ and ‘how’ of everything around us. Subscribe and join in as we explore the facts that matter. https://stmdailynews.com/the-knowledge/
