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World's Largest Digital Sky Survey Issues Biggest Astronomical Data Release Ever
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By NASA
Explore This Section Overview Science Science Findings Juno’s Orbits Spacecraft People Stories Multimedia JunoCam Images Jupiter hosts the brightest and most spectacular auroras in the Solar System. Near its poles, these shimmering lights offer a glimpse into how the planet interacts with the solar wind and moons swept by Jupiter’s magnetic field. Unlike Earth’s northern lights, the largest moons of Jupiter create their own auroral signatures in the planet’s atmosphere — a phenomenon that Earth’s Moon does not produce. These moon-induced auroras, known as “satellite footprints,” reveal how each moon interacts with its local space environment.
Juno capturing the marks on Jupiter of all four Galilean moons. The auroras related to each are labeled Io, Eur (for Europa), Gan (for Ganymede), and Cal (for Callisto). NASA/JPL-Caltech/SwRI/UVS team/MSSS/Gill/Jónsson/Perry/Hue/Rabia Before NASA’s Juno mission, three of Jupiter’s four largest moons, known as Galilean moons — Io, Europa, and Ganymede — were shown to produce these distinct auroral signatures. But Callisto, the most distant of the Galilean moons, remained a mystery. Despite multiple attempts using NASA’s Hubble Space Telescope, Callisto’s footprint had proven elusive, both because it is faint and because it most often lies atop the brighter main auroral oval, the region where auroras are displayed.
NASA’s Juno mission, orbiting Jupiter since 2016, offers unprecedented close-up views of these polar light shows. But to image Callisto’s footprint, the main auroral oval needs to move aside while the polar region is being imaged. And to bring to bear Juno’s arsenal of instruments studying fields and particles, the spacecraft’s trajectory must carry it across the magnetic field line linking Callisto and Jupiter.
These two events serendipitously occurred during Juno’s 22nd orbit of the giant planet, in September 2019, revealing Callisto’s auroral footprint and providing a sample of the particle population, electromagnetic waves, and magnetic fields associated with the interaction.
Jupiter’s magnetic field extends far beyond its major moons, carving out a vast region (magnetosphere) enveloped by, and buffeted by, the solar wind streaming from our Sun. Just as solar storms on Earth push the northern lights to more southern latitudes, Jupiter’s auroras are also affected by our Sun’s activity. In September 2019, a massive, high-density solar stream buffeted Jupiter’s magnetosphere, briefly revealing — as the auroral oval moved toward Jupiter’s equator — a faint but distinct signature associated with Callisto. This discovery finally confirms that all four Galilean moons leave their mark on Jupiter’s atmosphere, and that Callisto’s footprints are sustained much like those of its siblings, completing the family portrait of the Galilean moon auroral signatures.
An international team of scientists led by Jonas Rabia of the Institut de Recherche en Astrophysique et Planétologie (IRAP), CNRS, CNES, in Toulouse, France, published their paper on the discovery, “In situ and remote observations of the ultraviolet footprint of the moon Callisto by the Juno spacecraft,” in the journal Nature Communications on Sept. 1, 2025.
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Last Updated Sep 02, 2025 Related Terms
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By European Space Agency
Less than three weeks since the first MetOp Second Generation weather satellite, MetOp-SG-A1, was launched, this remarkable new satellite has already started transmitting data from two of its cutting-edge instruments, offering a tantalising glimpse of what’s to come.
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By NASA
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Preparations for Next Moonwalk Simulations Underway (and Underwater)
Scientists believe giant impacts — like the one depicted in this artist’s concept — occurred on Mars 4.5 billion years ago, injecting debris from the impact deep into the planet’s mantle. NASA’s InSight lander detected this debris before the mission’s end in 2022.NASA/JPL-Caltech Rocky material that impacted Mars lies scattered in giant lumps throughout the planet’s mantle, offering clues about Mars’ interior and its ancient past.
What appear to be fragments from the aftermath of massive impacts on Mars that occurred 4.5 billion years ago have been detected deep below the planet’s surface. The discovery was made thanks to NASA’s now-retired InSight lander, which recorded the findings before the mission’s end in 2022. The ancient impacts released enough energy to melt continent-size swaths of the early crust and mantle into vast magma oceans, simultaneously injecting the impactor fragments and Martian debris deep into the planet’s interior.
There’s no way to tell exactly what struck Mars: The early solar system was filled with a range of different rocky objects that could have done so, including some so large they were effectively protoplanets. The remains of these impacts still exist in the form of lumps that are as large as 2.5 miles (4 kilometers) across and scattered throughout the Martian mantle. They offer a record preserved only on worlds like Mars, whose lack of tectonic plates has kept its interior from being churned up the way Earth’s is through a process known as convection.
A cutaway view of Mars in this artist’s concept (not to scale) reveals debris from ancient impacts scattered through the planet’s mantle. On the surface at left, a meteoroid impact sends seismic signals through the interior; at right is NASA’s InSight lander.NASA/JPL-Caltech The finding was reported Thursday, Aug. 28, in a study published by the journal Science.
“We’ve never seen the inside of a planet in such fine detail and clarity before,” said the paper’s lead author, Constantinos Charalambous of Imperial College London. “What we’re seeing is a mantle studded with ancient fragments. Their survival to this day tells us Mars’ mantle has evolved sluggishly over billions of years. On Earth, features like these may well have been largely erased.”
InSight, which was managed by NASA’s Jet Propulsion Laboratory in Southern California, placed the first seismometer on Mars’ surface in 2018. The extremely sensitive instrument recorded 1,319 marsquakes before the lander’s end of mission in 2022.
NASA’s InSight took this selfie in 2019 using a camera on its robotic arm. The lander also used its arm to deploy the mission’s seismometer, whose data was used in a 2025 study showing impacts left chunks of debris deep in the planet’s interior.NASA/JPL-Caltech Quakes produce seismic waves that change as they pass through different kinds of material, providing scientists a way to study the interior of a planetary body. To date, the InSight team has measured the size, depth, and composition of Mars’ crust, mantle, and core. This latest discovery regarding the mantle’s composition suggests how much is still waiting to be discovered within InSight’s data.
“We knew Mars was a time capsule bearing records of its early formation, but we didn’t anticipate just how clearly we’d be able to see with InSight,” said Tom Pike of Imperial College London, coauthor of the paper.
Quake hunting
Mars lacks the tectonic plates that produce the temblors many people in seismically active areas are familiar with. But there are two other types of quakes on Earth that also occur on Mars: those caused by rocks cracking under heat and pressure, and those caused by meteoroid impacts.
Of the two types, meteoroid impacts on Mars produce high-frequency seismic waves that travel from the crust deep into the planet’s mantle, according to a paper published earlier this year in Geophysical Research Letters. Located beneath the planet’s crust, the Martian mantle can be as much as 960 miles (1,550 kilometers) thick and is made of solid rock that can reach temperatures as high as 2,732 degrees Fahrenheit (1,500 degrees Celsius).
Scrambled signals
The new Science paper identifies eight marsquakes whose seismic waves contained strong, high-frequency energy that reached deep into the mantle, where their seismic waves were distinctly altered.
“When we first saw this in our quake data, we thought the slowdowns were happening in the Martian crust,” Pike said. “But then we noticed that the farther seismic waves travel through the mantle, the more these high-frequency signals were being delayed.”
Using planetwide computer simulations, the team saw that the slowing down and scrambling happened only when the signals passed through small, localized regions within the mantle. They also determined that these regions appear to be lumps of material with a different composition than the surrounding mantle.
With one riddle solved, the team focused on another: how those lumps got there.
Turning back the clock, they concluded that the lumps likely arrived as giant asteroids or other rocky material that struck Mars during the early solar system, generating those oceans of magma as they drove deep into the mantle, bringing with them fragments of crust and mantle.
Charalambous likens the pattern to shattered glass — a few large shards with many smaller fragments. The pattern is consistent with a large release of energy that scattered many fragments of material throughout the mantle. It also fits well with current thinking that in the early solar system, asteroids and other planetary bodies regularly bombarded the young planets.
On Earth, the crust and uppermost mantle is continuously recycled by plate tectonics pushing a plate’s edge into the hot interior, where, through convection, hotter, less-dense material rises and cooler, denser material sinks. Mars, by contrast, lacks tectonic plates, and its interior circulates far more sluggishly. The fact that such fine structures are still visible today, Charalambous said, “tells us Mars hasn’t undergone the vigorous churning that would have smoothed out these lumps.”
And in that way, Mars could point to what may be lurking beneath the surface of other rocky planets that lack plate tectonics, including Venus and Mercury.
More about InSight
JPL managed InSight for NASA’s Science Mission Directorate. InSight was part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supported spacecraft operations for the mission.
A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), supported the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors.
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Last Updated Aug 28, 2025 Related Terms
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By European Space Agency
According to the newly released 35th State of the Climate report, 2024 saw record highs in greenhouse gas concentrations, global land and ocean temperatures, sea levels, and ocean heat content. Glaciers also suffered their largest annual ice loss on record. Data records from ESA’s Climate Change Initiative helped underpin these findings.
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By NASA
NASA’s Nancy Grace Roman Space Telescope will be a discovery machine, thanks to its wide field of view and resulting torrent of data. Scheduled to launch no later than May 2027, with the team working toward launch as early as fall 2026, its near-infrared Wide Field Instrument will capture an area 200 times larger than the Hubble Space Telescope’s infrared camera, and with the same image sharpness and sensitivity. Roman will devote about 75% of its science observing time over its five-year primary mission to conducting three core community surveys that were defined collaboratively by the scientific community. One of those surveys will scour the skies for things that pop, flash, and otherwise change, like exploding stars and colliding neutron stars.
These two images, taken one year apart by NASA’s Hubble Space Telescope, show how the supernova designated SN 2018gv faded over time. The High-Latitude Time-Domain Survey by NASA’s Nancy Grace Roman Space Telescope will spot thousands of supernovae, including a specific type that can be used to measure the expansion history of the universe.Credit: NASA, ESA, Martin Kornmesser (ESA), Mahdi Zamani (ESA/Hubble), Adam G. Riess (STScI, JHU), SH0ES Team Called the High-Latitude Time-Domain Survey, this program will peer outside of the plane of our Milky Way galaxy (i.e., high galactic latitudes) to study objects that change over time. The survey’s main goal is to detect tens of thousands of a particular type of exploding star known as type Ia supernovae. These supernovae can be used to study how the universe has expanded over time.
“Roman is designed to find tens of thousands of type Ia supernovae out to greater distances than ever before,” said Masao Sako of the University of Pennsylvania, who served as co-chair of the committee that defined the High-Latitude Time-Domain Survey. “Using them, we can measure the expansion history of the universe, which depends on the amount of dark matter and dark energy. Ultimately, we hope to understand more about the nature of dark energy.”
Probing Dark Energy
Type Ia supernovae are useful as cosmological probes because astronomers know their intrinsic luminosity, or how bright they inherently are, at their peak. By comparing this with their observed brightness, scientists can determine how far away they are. Roman will also be able to measure how quickly they appear to be moving away from us. By tracking how fast they’re receding at different distances, scientists will trace cosmic expansion over time.
Only Roman will be able to find the faintest and most distant supernovae that illuminate early cosmic epochs. It will complement ground-based telescopes like the Vera C. Rubin Observatory in Chile, which are limited by absorption from Earth’s atmosphere, among other effects. Rubin’s greatest strength will be in finding supernovae that happened within the past 5 billion years. Roman will expand that collection to much earlier times in the universe’s history, about 3 billion years after the big bang, or as much as 11 billion years in the past. This would more than double the measured timeline of the universe’s expansion history.
Recently, the Dark Energy Survey found hints that dark energy may be weakening over time, rather than being a constant force of expansion. Roman’s investigations will be critical for testing this possibility.
Seeking Exotic Phenomena
To detect transient objects, whose brightness changes over time, Roman must revisit the same fields at regular intervals. The High-Latitude Time-Domain Survey will devote a total of 180 days of observing time to these observations spread over a five-year period. Most will occur over a span of two years in the middle of the mission, revisiting the same fields once every five days, with an additional 15 days of observations early in the mission to establish a baseline.
This infographic describes the High-Latitude Time-Domain Survey that will be conducted by NASA’s Nancy Grace Roman Space Telescope. The survey’s main component will cover over 18 square degrees — a region of sky as large as 90 full moons — and see supernovae that occurred up to about 8 billion years ago.Credit: NASA’s Goddard Space Flight Center “To find things that change, we use a technique called image subtraction,” Sako said. “You take an image, and you subtract out an image of the same piece of sky that was taken much earlier — as early as possible in the mission. So you remove everything that’s static, and you’re left with things that are new.”
The survey will also include an extended component that will revisit some of the observing fields approximately every 120 days to look for objects that change over long timescales. This will help to detect the most distant transients that existed as long ago as one billion years after the big bang. Those objects vary more slowly due to time dilation caused by the universe’s expansion.
“You really benefit from taking observations over the entire five-year duration of the mission,” said Brad Cenko of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, the other co-chair of the survey committee. “It allows you to capture these very rare, very distant events that are really hard to get at any other way but that tell us a lot about the conditions in the early universe.”
This extended component will collect data on some of the most energetic and longest-lasting transients, such as tidal disruption events — when a supermassive black hole shreds a star — or predicted but as-yet unseen events known as pair-instability supernovae, where a massive star explodes without leaving behind a neutron star or black hole.
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This sonification that uses simulated data from NASA’s OpenUniverse project shows the variety of explosive events that will be detected by NASA’s Nancy Grace Roman Space Telescope and its High-Latitude Time-Domain Survey. Different sounds represent different types of events, as shown in the key at right. A single kilonova seen about 12 seconds into the video is represented with a cannon shot. The sonification sweeps backward in time to greater distances from Earth, and the pitch of the instrument gets lower as you move outward. (Cosmological redshift has been converted to a light travel time expressed in billions of years.) Credit: Sonification: Martha Irene Saladino (STScI), Christopher Britt (STScI); Visualization: Frank Summers (STScI); Designer: NASA, STScI, Leah Hustak (STScI) Survey Details
The High-Latitude Time-Domain Survey will be split into two imaging “tiers” — a wide tier that covers more area and a deep tier that will focus on a smaller area for a longer time to detect fainter objects. The wide tier, totaling a bit more than 18 square degrees, will target objects within the past 7 billion years, or half the universe’s history. The deep tier, covering an area of 6.5 square degrees, will reach fainter objects that existed as much as 10 billion years ago. The observations will take place in two areas, one in the northern sky and one in the southern sky. There will also be a spectroscopic component to this survey, which will be limited to the southern sky.
“We have a partnership with the ground-based Subaru Observatory, which will do spectroscopic follow-up of the northern sky, while Roman will do spectroscopy in the southern sky. With spectroscopy, we can confidently tell what type of supernovae we’re seeing,” said Cenko.
Together with Roman’s other two core community surveys, the High-Latitude Wide-Area Survey and the Galactic Bulge Time-Domain Survey, the High-Latitude Time-Domain Survey will help map the universe with a clarity and to a depth never achieved before.
Download the sonification here.
The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA’s Jet Propulsion Laboratory in Southern California; Caltech/IPAC in Pasadena, California; the Space Telescope Science Institute in Baltimore; and a science team comprising scientists from various research institutions. The primary industrial partners are BAE Systems, Inc. in Boulder, Colorado; L3Harris Technologies in Melbourne, Florida; and Teledyne Scientific & Imaging in Thousand Oaks, California.
By Christine Pulliam
Space Telescope Science Institute, Baltimore, Md.
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Last Updated Aug 12, 2025 EditorAshley BalzerLocationGoddard Space Flight Center Related Terms
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