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NASA-Funded Studies Explain How Climate Is Changing Earth’s Rotation
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater) The Arctic is captured in this 2010 visualization using data from NASA’s Aqua satellite. A new study quantifies how climate-related processes, including the melting of ice sheets and glaciers, are driving polar motion. Another study looks at how polar meltwater is speeding the lengthening of Earth’s day.NASA’s Scientific Visualization StudioResearchers used more than 120 years of data to decipher how melting ice, dwindling groundwater, and rising seas are nudging the planet’s spin axis and lengthening days.
Days on Earth are growing slightly longer, and that change is accelerating. The reason is connected to the same mechanisms that also have caused the planet’s axis to meander by about 30 feet (10 meters) in the past 120 years. The findings come from two recent NASA-funded studies focused on how the climate-related redistribution of ice and water has affected Earth’s rotation.
This redistribution occurs when ice sheets and glaciers melt more than they grow from snowfall and when aquifers lose more groundwater than precipitation replenishes. These resulting shifts in mass cause the planet to wobble as it spins and its axis to shift location — a phenomenon called polar motion. They also cause Earth’s rotation to slow, measured by the lengthening of the day. Both have been recorded since 1900.
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The animation, exaggerated for clarity, illustrates how Earth’s rotation wobbles as the location of its spin axis, shown in orange, moves away from its geographic axis, which is shown in blue and represents the imaginary line between the planet’s geographic North and South poles.NASA’s Scientific Visualization StudioAnalyzing polar motion across 12 decades, scientists attributed nearly all of the periodic oscillations in the axis’ position to changes in groundwater, ice sheets, glaciers, and sea levels. According to a paper published recently in Nature Geoscience, the mass variations during the 20th century mostly resulted from natural climate cycles.
The same researchers teamed on a subsequent study that focused on day length. They found that, since 2000, days have been getting longer by about 1.33 milliseconds per 100 years, a faster pace than at any point in the prior century. The cause: the accelerated melting of glaciers and the Antarctic and Greenland ice sheets due to human-caused greenhouse emissions. Their results were published July 15 in Proceedings of the National Academy of Sciences.
“The common thread between the two papers is that climate-related changes on Earth’s surface, whether human-caused or not, are strong drivers of the changes we’re seeing in the planet’s rotation,” said Surendra Adhikari, a co-author of both papers and a geophysicist at NASA’s Jet Propulsion Laboratory in Southern California.
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The location of Earth’s spin axis moved about 30 feet (10 meters) between 1900 and 2023, as shown in this animation. A recent study found that about 90% of the periodic oscillations in polar motion could be explained by melting ice sheets and glaciers, diminishing groundwater, and sea level rise.NASA/JPL-Caltech Decades of Polar MotionIn the earliest days, scientists tracked polar motion by measuring the apparent movement of stars. They later switched to very long baseline interferometry, which analyzes radio signals from quasars, or satellite laser ranging, which points lasers at satellites.
Researchers have long surmised that polar motion results from a combination of processes in Earth’s interior and at the surface. Less clear was how much each process shifts the axis and what kind of effect each exerts — whether cyclical movements that repeat in periods from weeks to decades, or sustained drift over the course of centuries or millennia.
For their paper, researchers used machine-learning algorithms to dissect the 120-year record. They found that 90% of recurring fluctuations between 1900 and 2018 could be explained by changes in groundwater, ice sheets, glaciers, and sea level. The remainder mostly resulted from Earth’s interior dynamics, like the wobble from the tilt of the inner core with respect to the bulk of the planet.
The patterns of polar motion linked to surface mass shifts repeated a few times about every 25 years during the 20th century, suggesting to the researchers that they were largely due to natural climate variations. Past papers have drawn connections between more recent polar motion and human activities, including one authored by Adhikari that attributed a sudden eastward drift of the axis (starting around 2000) to faster melting of the Greenland and Antarctic ice sheets and groundwater depletion in Eurasia.
That research focused on the past two decades, during which groundwater and ice mass loss as well as sea level rise — all measured via satellites — have had strong connections to human-caused climate change.
“It’s true to a certain degree” that human activities factor into polar motion, said Mostafa Kiani Shahvandi, lead author of both papers and a doctoral student at the Swiss university ETH Zurich. “But there are natural modes in the climate system that have the main effect on polar motion oscillations.”
Longer DaysFor the second paper, the authors used satellite observations of mass change from the GRACE mission (short for Gravity Recovery and Climate Experiment) and its follow-on GRACE-FO, as well as previous mass-balance studies that analyzed the contributions of changes in groundwater, ice sheets, and glaciers to sea level rise in the 20th century to reconstruct changes in the length of days due to those factors from 1900 to 2018.
Scientists have known through historical eclipse records that length of day has been growing for millennia. While almost imperceptible to humans, the lag must be accounted for because many modern technologies, including GPS, rely on precise timekeeping.
In recent decades, the faster melting of ice sheets has shifted mass from the poles toward the equatorial ocean. This flattening causes Earth to decelerate and the day to lengthen, similar to when an ice skater lowers and spreads their arms to slow a spin.
The authors noticed an uptick just after 2000 in how fast the day was lengthening, a change closely correlated with independent observations of the flattening. For the period from 2000 to 2018, the rate of length-of-day increase due to movement of ice and groundwater was 1.33 milliseconds per century — faster than at any period in the prior 100 years, when it varied from 0.3 to 1.0 milliseconds per century.
The lengthening due to ice and groundwater changes could decelerate by 2100 under a climate scenario of severely reduced emissions, the researchers note. (Even if emissions were to stop today, previously released gases — particularly carbon dioxide — would linger for decades longer.)
If emissions continue to rise, lengthening of day from climate change could reach as high as 2.62 milliseconds per century, overtaking the effect of the Moon’s pull on tides, which has been increasing Earth’s length of day by 2.4 milliseconds per century, on average. Called lunar tidal friction, the effect has been the primary cause of Earth’s day-length increase for billions for years.
“In barely 100 years, human beings have altered the climate system to such a degree that we’re seeing the impact on the very way the planet spins,” Adhikari said.
News Media ContactsAndrew Wang / Jane J. Lee
Jet Propulsion Laboratory, Pasadena, Calif.
626-379-6874 / 818-354-0307
andrew.wang@jpl.nasa.gov / jane.j.lee@jpl.nasa.gov
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NASA Awards Launch Excitement for STEM Learning Nationwide
NASA awards inspire the next generation of explorers by helping community institutions like museums, science centers, libraries, and other informal education institutions and their partners bring science, technology, engineering, and mathematics (STEM) content to their communities. NASA’s Next Generation STEM project has expanded the Teams Engaging Affiliated Museums and Informal Institutions (TEAM II) program to include a new tier of funding and provide even more opportunities to informal educational institutions across the country.
The new STEM Innovator tier will fund awards of approximately $250,000, the Community Anchor tier will continue to offer awards up to $50,000, and the highest award level will be designated the National Connector and fund initiatives up to $900,000. Fiscal year 2024 solicitations will target the Community Anchor and the new STEM Innovator award levels. Community Anchor and National Connector awards will be the focus for the fiscal year 2025 solicitation.
The TEAM II program was first expanded to include Community Anchors in 2022. Since then, the program has designated over 50 institutions across 29 states as NASA Community Anchors. These awards support proposals that strengthen the STEM impact of many community organizations, including:
5th-8th Graders from Whiting Village School join Flight Director Tyson as they embark on a Destination Mars Virtual Mission from their two-room schoolhouse in rural Maine.NASAThe Challenger Learning Center of Maine reached more than 960 K-8 students statewide through 58 virtual programs touching 27 mainland schools and four island schools, hosted a STEM community night for residents of rural Whiting, Maine, and held two virtual programs featuring NASA women engineers for girls across the state.
“NASA’s funding allowed Challenger Maine to provide this Mars mission experience for free to schools, no matter their size,” said Kirsten Hibbard, executive director of the Challenger Learning Center of Maine. “We’ve connected with new schools and become this resource, literally a community anchor of STEM, for these schools.”
Youth at the Standing Arrow Powwow on the Flathead Reservation experience remote sensing content with virtual reality.NASAThe University of Montana spectrUM Discovery Area engaged western Montana’s rural and tribal communities in understanding the role NASA and its partners play in sensing and responding to fire. SpectrUM developed the Montana Virtual Reality Fire Sensing Experience. Using ClassVR headsets, visitors learned about NOAA’s (National Oceanic and Atmospheric Administration) Joint Polar Satellite System satellites, JPSS-1 and JPSS-2, and how they are used to remotely sense the Earth.
SpectrUM collaborated with its community advisory group, SciNation on the Flathead Reservation, to incorporate fire and Earth science curricula developed by the Confederated Salish and Kootenai Tribes into their field trip and educational programs, impacting hundreds of students.
A student from Barksdale Air Force Base in Louisiana is excited to complete an activity in the “Aeronautics Museum in a Box” kit developed by NASA’s Aeronautics Research Mission Directorate; Community Anchor grantee Sci-Port Discovery Center in Shreveport, Louisiana; and Central Creativity, an education center in Laurel, Mississippi.NASASci-Port Discovery Center Shreveport, Louisiana introduced middle and high school students to NASA aeronautics content through their Aeronautics Museum in a Box kits. The kits were developed in collaboration with NASA’s Aeronautics Research Mission Directorate, Sci-Port, and Central Creativity. The kits include fun, hands-on activities focusing on the parts of an airplane, principles of flight, airplane structure and materials, propulsion, future of flight, careers, and more. Students and families from underserved communities across Northwest Louisiana tested the kits and shared feedback with developers.
“Museum in a Box brought our participants to new heights beyond their imagination. They see themselves as teachers for their children, as a source of guidance for STEM careers instead of gangs,” said Dr. Heather Kleiner, director, Northwest LaSTEM Innovation Center, Sci-Port Discovery Center.
U.S. informal education institutions interested in proposing for these awards are invited to attend an optional pre-proposal webinar Thursday, July 25, or Tuesday, August 13. Event times and connection details are available here.
More information about funding opportunities can be found on NASA’s TEAM II Grant Forecasting webpage.
To learn more about TEAM II Community Anchors, visit:TEAM II Community Anchors – NASA
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NASA Sets Briefings for Crew-9 Mission to Space Station
NASA will host a pair of news conferences Friday, July 26, from the agency’s Johnson Space Center in Houston to highlight upcoming crew rotation missions to the International Space Station.
NASA will host a mission overview news conference at 12 p.m. EDT and provide coverage on NASA+, NASA Television, the NASA app, YouTube, and the agency’s website. The news conference will cover NASA’s SpaceX Crew-9 mission to the microgravity laboratory and Expeditions 71 and 72.
NASA also will host a crew news conference at 2 p.m., and provide coverage on NASA+, NASA Television, the NASA app, YouTube, and the agency’s website, followed by individual astronaut interviews at 3 p.m. Learn how to stream NASA TV through a variety of platforms, including social media.
The Crew-9 mission, targeted to launch in mid-August, will carry NASA astronauts Zena Cardman, Nick Hague, Stephanie Wilson, and cosmonaut Alexsandr Gorbunov of Roscosmos to the orbiting laboratory. A SpaceX Falcon 9 rocket will launch the crew aboard a Dragon spacecraft from Launch Complex 39A at NASA’s Kennedy Space Center in Florida on the company’s ninth crew rotation mission for NASA.
These events will be the final media opportunity to speak to the Crew-9 astronauts before they travel to NASA Kennedy for launch. United States-based media seeking to attend in person must contact the NASA Johnson newsroom no later than 5 p.m., Thursday, July 25, at 281-483-5111 or jsccommu@mail.nasa.gov. U.S. and international media interested in participating by phone must contact NASA Johnson by 9:45 a.m. the day of the event.
U.S. or international media seeking remote interviews must submit requests to the NASA Johnson newsroom by 5 p.m., Thursday, July 25. A copy of NASA’s media accreditation policy is online.
Briefing participants are as follows (all times Eastern and subject to change based on real-time operations):
12 p.m.: Mission Overview News. Conference
- Steve Stich, manager, Commercial Crew Program, NASA Johnson
- Dana Weigel, manager, International Space Station Program, NASA Johnson
- Sarah Walker, director, Dragon Mission Management, SpaceX
- Sergei Krikalev, executive director of Human Space Flight Programs, Roscosmos
2 p.m.: Crew News Conference
- Zena Cardman, spacecraft commander, NASA
- Nick Hague, pilot, NASA
- Stephanie Wilson, mission specialist, NASA
- Alexsandr Gorbunov, mission specialist, Roscosmos
3 p.m.: Crew Individual Interview Opportunities
- Crew-9 members available for a limited number of interviews
The Crew-9 mission will be the first spaceflight for Cardman, who was selected as a NASA astronaut in 2017. The Williamsburg, Virginia, native holds a bachelor’s degree in Biology and a master’s in Marine Sciences from the University of North Carolina at Chapel Hill. At the time of selection, she was a doctoral candidate in geosciences. Cardman’s research focused on geobiology and geochemical cycling in subsurface environments, from caves to deep sea sediments. Since completing initial training, Cardman has supported real-time station operations and development for lunar surface exploration. Follow @zenanaut on X and @zenanaut on Instagram.
With 203 days logged in space, this will be Hague’s third launch and second mission to the orbiting laboratory. During his first launch in 2018, Hague and his crewmate, Roscosmos cosmonaut Alexey Ovchinin, experienced a rocket booster failure, resulting in an in-flight launch abort and safe landing for their Soyuz MS-10 spacecraft. Five months later, Hague launched aboard Soyuz MS-12 and served as a flight engineer aboard the space station during Expeditions 59 and 60. Hague conducted three spacewalks to upgrade space station power systems and install a docking adapter for commercial spacecraft. As an active-duty colonel in the U.S. Space Force, Hague completed a developmental rotation at the Department of Defense in Washington, where he served as the USSF director of test and evaluation from 2020 to 2022. In August 2022, Hague resumed duties at NASA, working on the Boeing Starliner Program until this flight assignment. Follow @astrohague on X and @astrohauge on Instagram.
A veteran of three spaceflights aboard space shuttle Discovery, Wilson has spent 42 days in space. During her first mission, STS-121, in July 2006, she and her crewmates spent 13 days in orbit. Wilson served as the robotic arm operator for spacecraft inspection, the installation of the “Leonardo” Multi-Purpose Logistics Module, and spacewalk support. In October 2007, Wilson and her STS-120 crewmates delivered the Harmony module to the station and relocated a solar array. In April 2010, Wilson and her STS-131 crewmates completed another resupply mission to the orbiting complex, delivering a new ammonia tank for the station cooling system, new crew sleeping quarters, a window observation facility, and a freezer for experiments. During nearly 30 years with NASA, Wilson served as the integration branch chief for NASA’s Astronaut Office, focusing on International Space Station systems and payload operations. She also completed a nine-month detail as the acting chief of NASA’s Program and Project Integration Office at the agency’s Glenn Research Center in Cleveland. Follow @astro_stephanie on X.
This will be Gorbunov’s first trip to space and the station. Born in Zheleznogorsk, Kursk region, Russia, he studied engineering with qualifications in spacecraft and upper stages from the Moscow Aviation Institute. Gorbunov graduated from the military department with a specialty in operating and repairing aircraft, helicopters, and aircraft engines. Before being selected as a cosmonaut in 2018, he worked as an engineer for Rocket Space Corporation Energia and supported cargo spacecraft launches from the Baikonur Cosmodrome.
Learn more about how NASA innovates for the benefit of humanity through NASA’s Commercial Crew Program at:
https://www.nasa.gov/commercialcrew
-end-
Joshua Finch / Jimi Russell
Headquarters, Washington
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joshua.a.finch@nasa.gov / james.j.russell@nasa.gov
Leah Cheshier / Sandra Jones
Johnson Space Center, Houston
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leah.d.cheshier@nasa.gov / sandra.p.jones@nasa.gov
Hubble Studies a Potential Galactic Merger
3 min read
Hubble Studies a Potential Galactic Merger This NASA/ESA Hubble Space Telescope image captures the dwarf irregular galaxy NGC 5238. ESA/Hubble & NASA, F. AnnibaliThis NASA/ESA Hubble Space Telescope image features the dwarf irregular galaxy NGC 5238, located 14.5 million light-years from Earth in the constellation Canes Venatici. Its unexciting, blob-like appearance seems to resemble an oversized star cluster more than a classic image of a galaxy. Its lackluster appearance belies its complicated structure, which is the subject of a great deal of research. As the image reveals, Hubble is able to pick out the galaxy’s countless stars, as well as its associated globular clusters — glowing, bright spots both inside and around the galaxy swarmed by even more stars.
Astronomers theorize that NGC 5238 may have had a close encounter with another galaxy as recently as a billion years ago. NGC 5238’s distorted shape provides evidence for this interaction. As the two galaxies interacted, their gravity caused distortions in the distribution of stars in each galaxy. There’s no nearby galaxy which could have caused this disturbance, so astronomers think NGC 5238 devoured a smaller satellite galaxy. Astronomers look for traces of the consumed galaxy by closely examining the population of stars in NGC 5238, a task made for Hubble’s excellent resolution. One tell-tale sign of the smaller galaxy would be groups of stars with different properties from most of NGC 5238’s other stars, indicating they were originally formed in a separate galaxy. Another sign would be a burst of star formation that occurred abruptly at around the same time the two galaxies merged. The Hubble data used to create this image will help astronomers determine NGC 5238’s history.
Despite their small size and unremarkable appearance, it’s not unusual for dwarf galaxies like NGC 5238 to drive our understanding of galaxy formation and evolution. One main theory of galaxy evolution is that galaxies formed ‘bottom-up’ in a hierarchical fashion: star clusters and small galaxies were the first to form out of gas and dark matter. Over time, gravity gradually assembled these smaller objects into galaxy clusters and superclusters, which explains the shape of the largest structures we see in the universe today. A dwarf irregular galaxy like NGC 5238 merging with a smaller companion is just the type of event that might have started the process of galaxy assembly in the early universe. Hubble’s observations of tiny NGC 5238 may help test some of our most fundamental ideas of how the universe evolves!
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From One Crew to Another: Artemis II Astronauts Meet NASA Barge Crew
Members of the Artemis II crew met with the crew of NASA’s Pegasus barge prior to their departure to deliver the core stage of NASA’s SLS (Space Launch System) rocket to the Space Coast.
NASA astronaut and pilot of the Artemis II mission Victor Glover met the crew July 15.
From left to right: Ashley Marlar, Jamie Crews, Nick Owen, Jeffery Whitehead, Scott Ledet, Jason Dickerson, John Campbell, NASA astronaut Victor Glover, Farid Sayah, Kelton Hutchinson, Terry Fitzgerald, Bryan Jones, and Joe Robinson.NASA/Brandon HancockNASA astronaut Reid Wiseman, commander, and CSA (Canadian Space Agency) astronaut Jeremy Hansen, mission specialist, visited the barge July 16 shortly before the flight hardware was loaded onto it.
The Pegasus crew and team, from left, includes Kelton Hutchinson, Jeffery Whitehead, Jason Dickerson, Arlan Cochran, John Brunson, NASA astronaut Reid Wiseman, Marc Verhage, Terry Fitzgerald, Scott Ledet, CSA astronaut Jeremy Hansen, Wil Daly, Ashley Marlar, Farid Sayah, Jamie Crews, Joe Robinson, and Nick Owen.NASA/Sam LottPegasus is currently transporting the SLS core stage from NASA’s Michoud Assembly Facility in New Orleans to NASA’s Kennedy Space Center in Florida, where it will be integrated and prepared for launch. During the Artemis II test flight, the core stage with its four RS-25 engines will provide more than 2 million pounds of thrust to help send the Artemis II crew around the Moon.
Pegasus, which was previously used to ferry space shuttle tanks, was modified and refurbished to ferry the SLS rocket’s massive core stage. At 212 feet in length and 27.6 feet in diameter, the Moon rocket stage is more than 50 feet longer than the space shuttle external tank.
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Members of NASA’s Pegasus barge crew meet with Artemis II crew members at NASA’s Michoud Assembly Facility in New Orleans July 15 and 16. NASA/Eric Bordelon Members of NASA’s Pegasus barge crew meet with Artemis II crew members at NASA’s Michoud Assembly Facility in New Orleans July 15 and 16. NASA/Eric Bordelon Members of NASA’s Pegasus barge crew meet with Artemis II crew members at NASA’s Michoud Assembly Facility in New Orleans July 15 and 16. NASA/Brandon Hancock Members of NASA’s Pegasus barge crew meet with Artemis II crew members at NASA’s Michoud Assembly Facility in New Orleans July 15 and 16.NASA/Evan DeRocheNASA is working to land the first woman and first person of color on the Moon under Artemis. SLS is part of NASA’s backbone for deep space exploration, along with the Orion spacecraft, advanced spacesuits and rovers, the Gateway in orbit around the Moon, and commercial human landing systems. SLS is the only rocket that can send Orion, astronauts, and supplies to the Moon in a single launch.