Red dust, gaping craters, and rocky terrain seem frozen to the outside of Mars, but what’s hidden beneath the windswept surface? NASA’s The lander Insight may have discovered this before it died in the dust storm.
It has long been debated whether the core of Mars is solid or liquid. There is no direct way to observe the core of Mars, but InSight has attempted to do so. Its seismometer SEIS was the first instrument to find possible evidence of a liquid core. Meanwhile, its RISE (Rotation and Internal Structures Experiment) instrument was measuring minute changes in the planet’s rotation and “wobble” on its axis caused by the gravitational push and pull of the Sun during its orbit.
“Our analysis of InSight’s radio-tracking data denies the existence of a solid inner core, reveals the shape of the core, and indicates that there are internal mass anomalies deep in the mantle,” said the device. The researchers write in their paper. study Recently published in Nature.
slow to rise
RISE works by sending radio signals to Earth. By tracking changes in these signals, researchers can detect extremely small changes in position relative to the receiver. These changes are caused by a wobble in Mars’ rotation called the Nutation. The distance and direction traveled by these nutation axes can be used to infer information about the internal composition of Mars.
the red planet had long been suspected Confirm that there is a liquid core based on seismic measurements. However, detecting these changes based on radio signals proved difficult. It took a while for the signal to emerge from the noise of the planet’s motion. Mars is also swirling with dust storms, and the storms that occurred before and after InSight landed briefly altered the planet’s rotation speed. Its axis of rotation also undergoes slight changes due to the gravitational forces exerted by the moons Phobos and Deimos.
For the RISE experiment to be successful, researchers needed to know exactly where InSight landed on Mars. The lander plans a landing site, but it’s not exactly that. Even the scientists tracking the lander won’t know exactly where the landing site is until they interpret the first data the lander sends to Earth.
The initial RISE data was processed by radio scientist Sébastien Le Mestre of the Royal Observatory of Belgium, and the position estimate was uploaded to the Mars Reconnaissance Orbiter (MRO), which photographed the position. This image showed that InSight was located with amazing accuracy.
Rotation has nutation
After RISE figured out exactly where the lander was on Mars, how did the detected nutation suggest a liquid core? up) or retrograde (vice versa). Le Mestre and his team found that if Mars does indeed have a liquid core beneath a solid mantle, that would mean that the axis wobbles in retrograde motion, causing the core to move slightly more than it would in a solid. I already knew that it must be I tested this against InSight data and it matched.
“Nutation analysis based on radiometry [the] properties of the Mars core,” the researchers also said. study.
Further analysis reveals that the core of Mars is likely made of an alloy of liquid iron and sulfur, with constant convection, hot fluid rising and cold fluid sinking. . It is also believed to be completely liquid, unlike the core of the Earth. Earth’s outer core is a liquid iron-nickel alloy, while the inner core is solid and made up mostly of iron.
Scientists say Mars’ lower mantle may also be melting, which would affect the size and shape of its core. As the mantle melts, it can create subsurface mass anomalies, regions where matter is more or less dense than the surrounding matter. It turns out that one of these anomalies appears to be located far below the surface of the earth than the other. The slight flattening of both the surface and core of Mars as it rotates around its axis may be partly explained by the anomaly.
In the future, Le Mestre hopes to analyze more RISE data on the same dataset that revealed the anomaly and liquid core. We still have a huge amount of data from InSight waiting to learn more about Mars. “RISE is not just about inner depth, it’s about atmosphere and rotation,” he said in an article. press release. “[It can] Provides orientation and rotation models for reference in the scientific community. ”
Nature, 2023. DOIs: 10.1038/s41586-023-06150-0
Elizabeth Laine is a writing creature. Her work has been featured in SYFY WIRE, Space.com, Live Science, Grunge, Den of Geek and Forbidden Futures. When she’s not writing, she transforms, paints, and cosplays characters no one has heard of. Follow her on her Twitter @quothravenrayne.
