5 min read<\/p>\n
Preparations for Next Moonwalk Simulations Underway (and Underwater)<\/h1>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n![\"The](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2025\/11\/1-mars-south-polar-cap.jpg?w=2048\")
<\/a><\/figure>\nThe European Space Agency\u2019s Mars Express orbiter captured this view of Mars\u2019 south polar ice cap Feb. 25, 2015. Three years later, the spacecraft detected a signal from the area to the right of the ice cap that scientists interpreted as an underground lake.<\/div>\nESA\/DLR\/FU Berlin, CC BY-SA 3.0 IGO<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nResults from an enhanced radar technique have demonstrated improvement to sub-surface observations of Mars.<\/em>\u00a0<\/p>\nNASA\u2019s Mars Reconnaissance Orbiter (MRO) has revisited and raised new questions about a mysterious feature buried beneath thousands of feet of ice at the Red Planet\u2019s south pole. In a recent study, researchers conclude from data obtained using an innovative radar technique that an area on Mars suspected of being an underground lake is more likely to be a layer of rock and dust.\u00a0\u00a0<\/p>\n
The 2018 discovery of the suspected lake set off a flurry of scientific activity, as water is closely linked with life in the solar system. While the latest findings indicate this feature is not a lake below the Martian surface, it does suggest that the same radar technique could be used to check for subsurface resources elsewhere on Mars, supporting future explorers.\u00a0<\/p>\n
The paper, published in Geophysical Research Letters<\/a> on Nov. 17, was led by two of MRO\u2019s Shallow Radar (SHARAD) instrument scientists, Gareth Morgan and Than Putzig, who are based at the Planetary Science Institute in Tucson, Arizona, and Lakewood, Colorado, respectively.\u00a0<\/p>\nThe observations were made by MRO with a special maneuver that rolls the spacecraft 120 degrees. Doing so enhances the power of SHARAD, enabling the radar\u2019s signal to penetrate deeper underground and provide a clearer image of the subsurface. These \u201cvery large rolls<\/a>\u201d have proved so effective that scientists are eager to use them at previously observed sites where buried ice might exist<\/a>.\u00a0<\/p>\n\n\n\n![\"This](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2025\/11\/e1-vlr-paper-lake-location.jpg?w=2048\")
<\/a><\/figure>\nThis map shows the approximate area where in 2018 ESA\u2019s Mars Express detected a signal the mission\u2019s scientists interpreted as an underground lake. The red lines show the path of NASA\u2019s Mars Reconnaissance Orbiter, which flew both directly overhead as well as over an adjacent region.
\nCredit: Planetary Science Institute\n<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nMorgan, Putzig, and fellow SHARAD team members had made multiple unsuccessful attempts to observe the area suspected of hosting a buried lake. Then the scientists partnered with the spacecraft\u2019s operations team at NASA\u2019s Jet Propulsion Laboratory in Southern California, which leads the mission, to develop the very large roll capability.\u00a0<\/p>\n
Because the radar\u2019s antenna is at the back of MRO, the orbiter\u2019s body obstructs its view and weakens the instrument\u2019s sensitivity. After considerable work, engineers at JPL and Lockheed Martin Space in Littleton, Colorado, which built the spacecraft and supports its operations, developed commands for a 120-degree roll \u2014 a technique that requires careful planning to keep the spacecraft safe \u2014 to direct more of SHARAD\u2019s signal at the surface.<\/p>\n
Bright signal<\/strong>\u00a0\u00a0<\/h2>\nOn May 26, SHARAD performed a very large roll to finally pick up the signal in the target area, which spans about 12.5 miles (20 kilometers) and is buried under a slab of water ice almost 1 mile (1,500 meters) thick.\u00a0\u00a0<\/p>\n
When a radar signal bounces off underground layers, the strength of its reflection depends on what the subsurface is made of. Most materials let the signal slip through or absorb it, making the return faint. Liquid water is special in that it produces a very reflective surface, sending back a very strong signal (imagine pointing a flashlight at a mirror).\u00a0<\/p>\n
That\u2019s the kind of signal that was spotted from this area in 2018 by a team working with the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument aboard the ESA (European Space Agency) Mars Express orbiter. To explain how such a body of water could remain liquid under all that ice, scientists have hypothesized it could be a briny lake, since high salt content can lower water\u2019s freezing temperature.\u00a0<\/p>\n
\n\n\n![\"\"](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2025\/11\/e2-pia04918.jpg?w=2048\")
<\/a><\/figure>\nAn antenna sticks out like whiskers from NASA\u2019s Mars Reconnaissance Orbiter in this artist\u2019s concept depicting the spacecraft, which has been orbiting the Red Planet since 2006. This antenna is part of SHARAD, a radar that peers below the Martian surface.<\/div>\nNASA\/JPL-Caltech<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\n\u201cWe\u2019ve been observing this area with SHARAD for almost 20 years without seeing anything from those depths,\u201d said Putzig. But once MRO achieved a very large roll over the precise area, the team was able to look much deeper. And rather than the bright signal MARSIS received, SHARAD detected a faint one. A different very-large-roll observation of an adjacent area didn\u2019t detect a signal at all, suggesting something unique is causing a quirky radar signal at the exact spot MARSIS saw a signal.\u00a0<\/p>\n
\u201cThe lake hypothesis generated lots of creative work, which is exactly what exciting scientific discoveries are supposed to do,\u201d said Morgan. \u201cAnd while this new data won\u2019t settle the debate, it makes it very hard to support the idea of a liquid water lake.\u201d<\/p>\n
Alternative explanations<\/strong><\/h2>\nMars\u2019 south pole has an ice cap sitting atop heavily cratered terrain, and most radar images of the area below the ice show lots of peaks and valleys. Morgan and Putzig said it\u2019s possible that the bright signal MARSIS detected here may just be a rare smooth area \u2014 an ancient lava flow, for example.\u00a0<\/p>\n
Both scientists are excited to use the very large roll technique to reexamine other scientifically interesting regions of Mars. One such place is Medusae Fossae, a sprawling geologic formation on Mars\u2019 equator that produces little radar return. While some scientists have suggested it\u2019s composed of layers of volcanic ash, others have suggested the layers may include heaps of ice deep within.\u00a0<\/p>\n
\u201cIf it\u2019s ice, that means there\u2019s lots of water resources near the Martian equator, where you\u2019d want to send humans,\u201d said Putzig. \u201cBecause the equator is exposed to more sunlight, it\u2019s warmer and ideal for astronauts to live and work.\u201d\u00a0<\/p>\n
More about MRO<\/h2>\n
NASA\u2019s Jet Propulsion Laboratory in Southern California manages MRO for the agency\u2019s Science Mission Directorate in Washington as part of NASA\u2019s Mars Exploration Program portfolio. Lockheed Martin Space in Denver built MRO and supports its operations. SHARAD was provided to the MRO mission by the Italian Space Agency (ASI).<\/p>\n<\/p>\n
News Media Contacts<\/strong><\/p>\nAndrew Good\u00a0
Jet Propulsion Laboratory, Pasadena, Calif.\u00a0
818-393-2433\u00a0
andrew.c.good@jpl.nasa.gov<\/a>\u00a0<\/p>\n<\/p>\nKaren Fox \/ Molly Wasser\u00a0
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov<\/a>\u202f\/ molly.l.wasser@nasa.gov<\/a><\/p>\n2025-130<\/p>\n
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![\"The](\"https:\/\/www.nasa.gov\/wp-content\/uploads\/2025\/11\/1-mars-south-polar-cap.jpg\")
<\/a><\/figure>Results from an enhanced radar technique have demonstrated improvement to sub-surface observations of Mars.<\/em>\u00a0<\/p>\n NASA\u2019s Mars Reconnaissance Orbiter (MRO) has revisited and raised new questions about a mysterious feature buried beneath thousands of feet of ice at the Red Planet\u2019s south pole. In a recent study, researchers conclude from data obtained using an innovative radar technique that an area on Mars suspected of being an underground lake is more likely to be a layer of rock and dust.\u00a0\u00a0<\/p>\n The 2018 discovery of the suspected lake set off a flurry of scientific activity, as water is closely linked with life in the solar system. While the latest findings indicate this feature is not a lake below the Martian surface, it does suggest that the same radar technique could be used to check for subsurface resources elsewhere on Mars, supporting future explorers.\u00a0<\/p>\n The paper, published in Geophysical Research Letters<\/a> on Nov. 17, was led by two of MRO\u2019s Shallow Radar (SHARAD) instrument scientists, Gareth Morgan and Than Putzig, who are based at the Planetary Science Institute in Tucson, Arizona, and Lakewood, Colorado, respectively.\u00a0<\/p>\n The observations were made by MRO with a special maneuver that rolls the spacecraft 120 degrees. Doing so enhances the power of SHARAD, enabling the radar\u2019s signal to penetrate deeper underground and provide a clearer image of the subsurface. These \u201cvery large rolls<\/a>\u201d have proved so effective that scientists are eager to use them at previously observed sites where buried ice might exist<\/a>.\u00a0<\/p>\n Morgan, Putzig, and fellow SHARAD team members had made multiple unsuccessful attempts to observe the area suspected of hosting a buried lake. Then the scientists partnered with the spacecraft\u2019s operations team at NASA\u2019s Jet Propulsion Laboratory in Southern California, which leads the mission, to develop the very large roll capability.\u00a0<\/p>\n Because the radar\u2019s antenna is at the back of MRO, the orbiter\u2019s body obstructs its view and weakens the instrument\u2019s sensitivity. After considerable work, engineers at JPL and Lockheed Martin Space in Littleton, Colorado, which built the spacecraft and supports its operations, developed commands for a 120-degree roll \u2014 a technique that requires careful planning to keep the spacecraft safe \u2014 to direct more of SHARAD\u2019s signal at the surface.<\/p>\n On May 26, SHARAD performed a very large roll to finally pick up the signal in the target area, which spans about 12.5 miles (20 kilometers) and is buried under a slab of water ice almost 1 mile (1,500 meters) thick.\u00a0\u00a0<\/p>\n When a radar signal bounces off underground layers, the strength of its reflection depends on what the subsurface is made of. Most materials let the signal slip through or absorb it, making the return faint. Liquid water is special in that it produces a very reflective surface, sending back a very strong signal (imagine pointing a flashlight at a mirror).\u00a0<\/p>\n That\u2019s the kind of signal that was spotted from this area in 2018 by a team working with the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument aboard the ESA (European Space Agency) Mars Express orbiter. To explain how such a body of water could remain liquid under all that ice, scientists have hypothesized it could be a briny lake, since high salt content can lower water\u2019s freezing temperature.\u00a0<\/p>\n \u201cWe\u2019ve been observing this area with SHARAD for almost 20 years without seeing anything from those depths,\u201d said Putzig. But once MRO achieved a very large roll over the precise area, the team was able to look much deeper. And rather than the bright signal MARSIS received, SHARAD detected a faint one. A different very-large-roll observation of an adjacent area didn\u2019t detect a signal at all, suggesting something unique is causing a quirky radar signal at the exact spot MARSIS saw a signal.\u00a0<\/p>\n \u201cThe lake hypothesis generated lots of creative work, which is exactly what exciting scientific discoveries are supposed to do,\u201d said Morgan. \u201cAnd while this new data won\u2019t settle the debate, it makes it very hard to support the idea of a liquid water lake.\u201d<\/p>\n Mars\u2019 south pole has an ice cap sitting atop heavily cratered terrain, and most radar images of the area below the ice show lots of peaks and valleys. Morgan and Putzig said it\u2019s possible that the bright signal MARSIS detected here may just be a rare smooth area \u2014 an ancient lava flow, for example.\u00a0<\/p>\n Both scientists are excited to use the very large roll technique to reexamine other scientifically interesting regions of Mars. One such place is Medusae Fossae, a sprawling geologic formation on Mars\u2019 equator that produces little radar return. While some scientists have suggested it\u2019s composed of layers of volcanic ash, others have suggested the layers may include heaps of ice deep within.\u00a0<\/p>\n \u201cIf it\u2019s ice, that means there\u2019s lots of water resources near the Martian equator, where you\u2019d want to send humans,\u201d said Putzig. \u201cBecause the equator is exposed to more sunlight, it\u2019s warmer and ideal for astronauts to live and work.\u201d\u00a0<\/p>\n NASA\u2019s Jet Propulsion Laboratory in Southern California manages MRO for the agency\u2019s Science Mission Directorate in Washington as part of NASA\u2019s Mars Exploration Program portfolio. Lockheed Martin Space in Denver built MRO and supports its operations. SHARAD was provided to the MRO mission by the Italian Space Agency (ASI).<\/p>\n<\/p>\n News Media Contacts<\/strong><\/p>\n Andrew Good\u00a0 Karen Fox \/ Molly Wasser\u00a0 2025-130<\/p>\n<\/a><\/figure>
\nCredit: Planetary Science Institute\n<\/div>\n<\/figcaption><\/div>\n<\/div>\n<\/div>\nBright signal<\/strong>\u00a0\u00a0<\/h2>\n
<\/a><\/figure>Alternative explanations<\/strong><\/h2>\n
More about MRO<\/h2>\n
Jet Propulsion Laboratory, Pasadena, Calif.\u00a0
818-393-2433\u00a0
andrew.c.good@jpl.nasa.gov<\/a>\u00a0<\/p>\n<\/p>\n
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov<\/a>\u202f\/ molly.l.wasser@nasa.gov<\/a><\/p>\nShare<\/h2>\n<\/p><\/div>\n