NASA MAVEN (Mars Atmosphere and Volatile Evolution) mission scientists have uncovered a key puzzle piece in understanding certain types of auroras on Mars, finding that they form in a similar way to Earth-based auroras.
 
Results published Thursday in Nature Communications show the same mechanism that circulates and catapults charged particles into Earth’s atmosphere is happening at Mars on much smaller scales because of differences in the two planets’ magnetic fields.
 
The MAVEN spacecraft, in orbit around Mars, experienced a loss of signal with ground stations on Earth on Dec. 6, 2025. On June 3, NASA declared the mission had concluded after finding the spacecraft to be unrecoverable. However, data from the mission is still being used to inform NASA science and future missions to Mars.
 
When the Sun’s magnetic field lines get close to Earth’s magnetosphere, the large magnetic bubble protecting the planet, they can reconnect and inject energy and mass throughout Earth’s magnetosphere and magnetotail, ultimately firing electrons back into the atmosphere to generate Earth’s auroras. This process, called the Dungey cycle, drives electrical currents, accelerates charged particles that create auroras, and controls the circulation of plasma in Earth’s magnetosphere and ionosphere.
 
This new study shows that a miniature version of the Dungey cycle is happening over Mars’ strong crustal magnetic fields, which gives scientists a better look into the physics of Martian auroras.
 
“We knew that magnetic reconnection was happening at Mars but did not expect it to be like the Dungey cycle,” said Shaosui Xu, lead author of the study and associate research physicist at the Space Sciences Laboratory at the University of California, Berkeley.
 
Mars does not have a global magnetic field like Earth. Earth’s magnetic field is created by our planet’s churning core, while Mars has numerous miniature magnetospheres that arise from intensely magnetized crust scattered around the planet.  These regions were formed around 4 billion years ago when lava cooled in the presence of Mars’ ancient global magnetic field, which has since disappeared due to intense solar wind stripping the planet’s atmosphere.
 
The MAVEN mission has observed highly localized auroras over these crustal fields, similar to Earth’s auroras at the poles, but it wasn’t until now that scientists could fully understand the physics of how they form. The study used several instruments aboard the MAVEN spacecraft to build up a picture of the Dungey-like behavior: the Magnetometer and Solar Wind Electron Analyzer instruments, which were used to determine the magnetic configuration and derive electrical currents, and the STATIC (Suprathermal and Thermal Ion Composition) instrument, which was used to measure plasma flows in the ionosphere.
 
“We really pushed the limit of STATIC to get the data we needed,” said Xu. “It was the final piece to the puzzle in understanding these localized auroras.”
 
The realization that a Dungey-like cycle was happening within these crustal magnetic fields answered the question of how the electrons were being energized to create the auroras. It also shows that a Dungey-like mechanism can happen on both large and small scales, giving more insight into where in the solar system this process could be taking place.
 
“This is a remarkable result that changes how we think of Martian auroras and is another important step toward understanding why Mars and Earth have evolved so differently despite being governed by the same underlying physics.” said Shannon Curry, MAVEN’s principal investigator and a research scientist at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. “I am incredibly proud of our team’s work on this discovery and excited to uncover new insights into the Red Planet and its evolution.”
 
By finding out more about this process, scientists also are gaining a better understanding of how the solar environment interacts with the Red Planet as a whole, which is essential for future robotic and crewed missions.
 
“I remember in graduate school discussing with my advisor how the cycling of crustal magnetic fields could work at Mars,” said Xu. “It’s incredible to be part of the team that found the answer to that question.”
 
The MAVEN mission is part of NASA’s Mars Exploration Program portfolio. The mission’s principal investigator is based at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder, which also is responsible for managing science operations and public outreach and communications. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN mission. Lockheed Martin Space built the spacecraft and is responsible for mission operations. NASA’s Jet Propulsion Laboratory in Southern California provides navigation and Deep Space Network support.
 
For more information on NASA’s MAVEN mission, visit:
 
https://science.nasa.gov/mission/maven/
 
Karen Fox / Alana Johnson
Headquarters, Washington
240-285-5155 / 202-672-4780
karen.c.fox@nasa.gov / alana.r.johnson@nasa.gov
 
Lonnie Shekhtman
NASA’s Goddard Space Flight Center, Greenbelt, Md.
lonnie.shekhtman@nasa.gov

 

Background

Human exploration of Mars will expose crews to a persistent, fine particulate environment whose physicochemical properties and health implications remain only partly understood. Because no samples of authentic Martian airborne dust have been returned to Earth, NASA must rely on lunar dust toxicology, Martian regolith simulants, and extensive rover/lander geochemical and mineralogical datasets to develop an initial, risk‑informed Permissible Exposure Limit (PEL). The Johnson Space Center (JSC) Lunar and Martian Dust Risk Custodian, the JSC Toxicology group, and the OCHMO Standards team worked together to draft a preliminary standard for incorporation into NASA-STD-3001 NASA Spaceflight Human-System Standard, Volume 2: Human Factors, Habitability, and Environmental Health.

The Martian Dust Limit Working Group was assembled to review this draft standard and associated evidence. Across two working sessions in February 2026, panel members reviewed mission architecture drivers, the current scientific understanding of Martian dust composition, and the toxicological evidence base supporting the establishment of a Mars dust PEL. Discussions emphasized the critical interplay between dust standards and Mars mission design elements including Extravehicular Activity (EVA) cadence, dust ingress characteristics, and the performance of habitat environmental control systems; these features highlight the need for a limit that is conservative, verifiable, and adaptable as the Mars architecture evolves. Panel members for the Working Group were David Damby, Claire Horwell, Brian Hynek, Shaunna Morrison, and Joyce Tsuji; NASA presenters were Katie Borremans, Elizabeth Rampe, and Torin McCoy; the OCHMO organizers/moderators were Douglas Ebert, David Francisco, and Kim Lowe. The Working Group meetings were also attended by members of Space Medicine and Operations group and JSC Toxicology.

The Martian Dust Limit Working Group Primary Goals

Evaluate NASA’s proposed derivation of this initial standard

The panel concluded that NASA’s approach to deriving a 30‑day continuous PEL of 0.1 mg/m³ is reasonable and appropriately conservative for early short‑stay missions. This value originates from the established lunar 30‑day PEL (0.4 mg/m³), reduced by a 3x database uncertainty factor to account for knowledge gaps in Martian dust toxicity, higher iron content, amorphous constituents, and differences between simulants and actual dust. Members supported this framework, noting that a continuous limit applied using measured time‑weighted averages is more practical than making assumptions tied to fixed dust clearance rates given the diversity of spacecraft designs. They also acknowledged that near‑term exposures will be peak‑driven (e.g., post‑EVA suit ingress) and therefore recommended that the standard explicitly address the need to manage short‑duration spikes.

Identify chemical constituents requiring further scrutiny

The panel affirmed that overall dust mass remains the primary near‑term engineering concern, but several chemical constituents warrant attention. Chromium 6⁺, manganese, and perchlorate were all considered low‑risk in the context of inhaled Martian dust, provided the overall dust PEL is applied (see below). However, perchlorate was recommended for broader agency‑level exposure management across multiple intake routes (e.g., ingestion due to in situ crop growth). Iron was discussed in detail due to its high abundance in Martian regolith and its potential to generate Reactive Oxygen Species (ROS), though current toxicology shows no clear link between iron‑driven ROS and pulmonary harm; still, knowledge gaps led the panel to prioritize iron for further study and potential Spacecraft Maximum Allowable Concentration (SMAC) development. Arsenic was judged unlikely to pose meaningful risk at present.

Weigh the merits of an overall dust limit versus separate SMACs

Chemical constituents embedded within Martian dust were evaluated with respect to whether independent SMACs are warranted. Based on rover observations indicating predominantly trivalent chromium, low airborne perchlorate, and manganese concentrations well below conservative SMAC thresholds at the proposed PEL, the group agreed that the overall dust limit is likely sufficiently protective for expected 30‑day missions. However, panel members advised that SMACs be maintained for select constituents such as perchlorate and manganese for mission‑planning crosschecks. From the requirement perspective, an overall Martian dust PEL approach was favored for practicality and clarity, with constituent-specific SMACs retained or developed only where they add tangible operational value.

Refine the standard’s technical language for operational use

The working group also refined the standard language to ensure clarity and consistency in implementation. Members recommended that the limit apply to a specified time‑weighted average measurement period but also making it explicit that the requirement is for protection during continuous exposure. They encouraged incorporation of peak‑exposure management within the rationale, and highlighted uncertainties related to iron content, nanophase iron, and oxidative potential so that future revisions can incorporate emerging scientific insight.

Martian Dust Contamination Limits

The new requirement established for NASA-STD-3001 is as follows:

[V2 6253] The system shall limit the concentrations of Martian dust particles less than 10 μm in size in the habitable atmosphere below a 24-hour time-weighted average of 0.1 mg/m3 during exposure scenarios lasting up to 30 days in duration.

Conclusions

Taken together, the working group’s deliberations reinforce that an initial Martian dust standard must balance conservatism with operational feasibility while accommodating architectural and scientific uncertainty. The proposed requirement provides a defensible, evidence‑informed foundation for design, verification, and risk communication. As additional Martian data and toxicological research become available, this standard should be periodically revisited to ensure continued protection of crew health during human exploration of Mars.

For more information on the results of the working group, see link to the special publication below:

NASA’s Perseverance Mars rover has uncovered evidence that a 245-foot-thick (75-meter-thick) stack of ancient rock on the rim of Jezero Crater was built by repeated asteroid impacts. Referred to as the “Broom Point member” by the rover’s science team, this sequence of layered bedrock is likely more than 3.9 billion years old, making it among the oldest terrain ever examined by a Mars rover.  

Released Wednesday in the Journal of Geophysical Research: Planets, the findings offer a window into one of the most tumultuous chapters in the history of the solar system.  

“Since leaving Jezero, Perseverance has been exploring a brand-new frontier, both geographically and geologically — a chapter of Martian time that predates the crater itself,” said Ken Farley, Perseverance deputy project scientist at Caltech in Pasadena, California. “On Earth, our earliest geologic history has been fundamentally broken up, deformed, and erased by plate tectonics. Because Mars lacks plate tectonics to recycle its crust, this ancient record remains intact, giving us a rare glimpse into a geological time period that doesn’t exist on our own planet.” 

Reading between layers 

After ascending the western rim of Jezero Crater in late 2024, Perseverance began examining surrounding locations with its science instruments. Their data at Broom Point revealed six distinct rock types, including breccias — rocks composed of angular fragments — alternating with layers of fine-grained, pulverized rock dust. Rock fragments within the breccias are pocked with gas-bubble cavities, indicating they were once molten. 

The presence of tiny, dark, glassy beads within the layers offered an important clue about how these rocks formed. While volcanoes can produce similar glassy droplets, they rarely occur in such high abundance, pointing to asteroid impacts, instead, as the primary architect. In fact, the largest beads rival those flung out by the dinosaur-killing Chicxulub asteroid’s impact on Earth. 

The repetition of these distinct rock types multiple times throughout this thick sequence of rock indicates that high-energy impact events happened again and again across this region of early Mars. 

“The different rock layers are a record of variable-sized impacts occurring at different distances from where this rock sequence was accumulating,” said Alex Jones, a Ph.D. student in planetary geology at Imperial College London and lead author of the paper. “Some large impacts took place very far away, some small impacts nearby. Their debris all ended up landing here, constructing this thick section of rock.”  

How these layers formed may suggest an interaction with water or ice. Several of the layers look like they may have been formed by fast, ground-hugging debris flows. On Earth, these powerful, fluidlike surges can occur when molten rock hits water or ice that instantly flashes into steam.  

Cosmic one-two punch 

Some of Broom Point’s layers tilt at angles exceeding 80 degrees — nearly vertical — which is far too steep to be caused by the impact that created Jezero Crater.  

Instead, scientists suspect a cosmic “one-two punch” shaped this landscape long ago. First, a colossal asteroid impact created the 1,200-mile-wide (1,900-kilometer-wide) Isidis Basin, one of the largest impact basins on Mars, upending and tilting the once-flat rock layers. Later, a second asteroid likely struck, forming Jezero Crater, which measures 28 miles (45 kilometers) across. This second impact fractured and uplifted the already-tilted rocks into the dramatic formations the rover sees today.  

To pin down exactly when these events took place, the Perseverance team collected two core samples, dubbed “Bell Island” and “Main River.” If a future mission were to return them to Earth, laboratory dating could determine when and how often impacts were occurring on early Mars — and, by extension, the infant Earth, whose own early impact record has been erased by billions of years of plate tectonics. 

“During this violent era, it wasn’t rain or snow falling from the sky, but an almost constant barrage of molten rock droplets and pulverized dust kicked up by asteroid impacts,” said Jones. “If we can pin down the ages of these layers, it would be like reading a cosmic weather report from 4 billion years ago.” 

More about Perseverance 

NASA’s Jet Propulsion Laboratory in Southern California, which is managed for the agency by Caltech, built and manages operations of the Perseverance rover on behalf of the agency’s Science Mission Directorate in Washington, as part of NASA’s Mars Exploration Program portfolio. Arizona State University leads the operations of the rover’s Mastcam-Z instrument, working in collaboration with Malin Space Science Systems in San Diego, on the design, fabrication, testing, and operation of the cameras. SuperCam is led by Los Alamos National Laboratory in New Mexico, where the instrument’s Body Unit was developed. The rover’s SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) instrument was built at NASA JPL, and its WATSON (Wide Angle Topographic Sensor for Operations and eNgineering) camera was built at Malin Space Science Systems.

For more information on NASA’s Perseverance, visit:

https://science.nasa.gov/mission/mars-2020-perseverance

News Media Contacts

DC Agle 
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov  

Karen Fox / Alana Johnson
NASA Headquarters, Washington
240-285-5155 / 202-672-4780
karen.c.fox@nasa.gov / alana.r.johnson@nasa.gov

2026-045

This close-up view shows fragments of sulfur crystals — the first ever seen on the Red Planet. The crystals were found after NASA’s Curiosity Mars rover happened to drive over a rock and crush it on May 30, 2024. Several days later, Curiosity used a camera on the end of its robotic arm to take this image.

A recent paper in Science suggests that the sulfur formed when magma deep below the surface released fluids or gases that deposited sulfur on the Red Planet’s surface about 3 billion years ago.

Image credit: NASA/JPL-Caltech/MSSS

A predawn Moon-and-planets meetup, a returning comet, a great chance to see the Milky Way, and Saturn’s rings at a new angle.

Skywatching Highlights

• July 7: Last Quarter Moon
• July 11 + 12: Dawn alignment of the Moon, Mars, Saturn, and Uranus
• July 14: New Moon; best dark-sky window for Comet 10P/Tempel 2 and the Milky Way
• Later in July: Saturn’s unusually thin rings are a rewarding telescope target
• July 21: First Quarter Moon
• July 29: Full Moon

Transcript

An early morning hangout with the Moon and planets, a comet swings by, prime time for the Milky Way, and Saturn’s rings shine at a new angle. That’s What’s Up for July.

Before sunrise on July 11 and 12, look toward the eastern sky for a lineup of the Moon and planets. On these mornings, the waning crescent Moon helps point the way to Mars, with Saturn shining nearby in the morning sky.

Uranus is in the same general part of the sky, too, but it is much fainter, so you will need binoculars or a telescope to see it.

Mars will look like a small reddish point of light, Saturn is brighter and easier to spot, and the Moon makes the whole scene easy to locate.

Around the New Moon on July 14, Comet 10P/Tempel 2 swings by.

This is a short-period comet, meaning it returns to the inner solar system on a regular orbit. In this case, it comes back about every 5½ years. It is not a dramatic comet that you see just by looking up at the sky, though.

Through binoculars or a telescope, find the constellation Capricornus and look for a small fuzzy glow nearby, possibly with a brighter central knot and a short, broad, fan-shaped tail.

For the best chance to view the comet, head somewhere dark, away from city lights. Start looking once the sky is fully dark, ideally about 45 to 60 minutes after sunset.

Those same dark nights around the July 14 New Moon are also the best time this month to look for the Milky Way.

From a dark location, away from city lights, the Milky Way appears as a pale, cloudy band across the summer sky. The bright, cloudy region of the Milky Way marks the direction of the galactic center. It looks so dense because we’re looking toward one of the most crowded parts of our galaxy, where countless stars glow behind dark clouds of cosmic dust.

Late in the evening, look low in the southern sky for a group of stars shaped like a big hook or scorpion tail. That’s Scorpius. The bright, cloudy part of the Milky Way is nearby, close to another group of stars called Sagittarius.

For the best chance to see the Milky Way, go somewhere dark, give your eyes time to adjust, and try not to look at your phone.

Later in July, Saturn is a rewarding target for telescope users.

Saturn’s rings are still tilted at a very shallow angle from our point of view, making them look unusually thin. The rings aren’t disappearing, but how they appear from Earth is changing. It’s a great reminder that our view of the solar system is always in motion.

Here are the phases of the Moon for July.

You can stay up to date on all of NASA’s missions exploring the solar system and beyond at science.nasa.gov. I’m Raquel Villanueva from NASA’s Jet Propulsion Laboratory, and that’s What’s Up for this month.