NASA Mars spacecraft flip maneuver questions theory of underground lake

On February 25, 2015, the European Space Agencys Mars Express orbiter captured a detailed image of Mars south polar ice cap. Three years later, scientists noticed unusual radar signals near the ice cap, initially interpreted as evidence of an underground lake.

Planetary researchers are gaining fresh insights into this long-debated Martian phenomenon after NASAs spacecraft executed an uncommon maneuver to investigate the possible presence of subsurface water.

In 2018, Mars Express identified unusually strong radar reflections beneath the south polar ice cap, raising excitement because the readings resembled those from modern subglacial lakes on Earth. Despite this, confirming the lakes existence has been difficult, leaving the theory unproven but widely discussed.

On November 17, scientists using NASA's Mars Reconnaissance Orbiter (MRO) published new research in Geophysical Research Letters with data from MROs Shallow Radar (SHARAD) instrument. Their results challenge the idea of a subglacial lake in this region.

Previous SHARAD observations had been unsuccessful because the radar antenna, located on MRO's rear, was partially blocked by the spacecrafts body. To solve this, engineers at NASA's Jet Propulsion Laboratory and Lockheed Martin devised a maneuver to roll MRO by 120 degrees, effectively flipping the spacecraft. This allowed SHARAD to directly scan a circular area roughly 12.5 miles wide beneath nearly a mile of ice.

If liquid water existed there, a strong radar reflection would have been expected. Instead, the May observations revealed only a faint signal, weakening the argument for a subglacial lake and prompting new questions about the composition of the ice-covered region.

An animation illustrates MRO performing the very large roll, which enhances SHARADs ability to study subsurface features. (Credit: NASA)

A similar large-roll scan of an adjacent area detected no signal, indicating that the previous radar reflections may have been caused by something unusual, said Than Putzig, SHARAD instrument scientist at the Planetary Science Institute.

While the mystery of the south polar signals remains unsolved, NASA notes that this maneuver opens possibilities for future radar investigations of other Martian regions where hidden ice or unusual subsurface structures might exist.

Analysis: New Findings Cast Doubt on Subglacial Lake Theory on Mars

Recent developments in the study of Mars’ south polar region have led to a significant shift in our understanding of its subsurface. While earlier observations from the European Space Agency’s Mars Express and NASA’s Mars Reconnaissance Orbiter (MRO) hinted at the presence of a possible underground lake beneath the Martian ice, new data challenges this theory. In particular, the results of a groundbreaking maneuver executed by the MRO have raised new questions about the composition of the region's ice-covered terrain.

Initially, strong radar signals detected beneath the ice suggested the existence of liquid water, similar to subglacial lakes found on Earth. This idea captivated planetary scientists and stirred hopes of uncovering evidence of Martian life or past habitability. However, the results from the MRO’s latest observations, made possible by a unique 120-degree roll maneuver, showed only faint radar reflections, significantly weaker than what would be expected from liquid water.

The new data calls into question the earlier interpretation of radar signals and suggests that the signals previously detected may have been caused by other subsurface features or unusual ice properties. These findings mark an important moment in the ongoing exploration of Mars, where even the most promising theories can be upended by new technological advancements and refined methods of data collection.

Despite the setback in confirming the subglacial lake hypothesis, this new maneuver opens up exciting possibilities for future research on Mars. The ability to conduct more precise radar scans could reveal hidden ice deposits or other subsurface anomalies across different Martian regions. As scientists continue to probe the Martian surface, they remain hopeful that new insights will emerge, shedding light on the planet's potential to support life and its geological history.

Sources:

• NASA Mars spacecraft flip maneuver challenges theory of underground lake