NASA/JPL-Caltech
To say Mars is a strange planet might be an understatement. It has very little atmosphere, an unstable liquid metal core that constantly wobbles on its axis, and the fact that it is a frozen desert is a contradiction in itself. As if Mars wasn’t so strange, data from NASA’s InSight Lander (RIP) reveal that the red planet’s rotation is getting faster every year.
The increased spin was unknown until the research team found evidence of acceleration through InSight. rise (Experiments of Rotation and Internal Structures) Apparatus. The same team, led by radio scientist Sebastien Le Mestre of the Royal Observatory of Belgium, who is also the principal investigator of RISE, had previously found that the core of Mars was most likely a lump of molten metal. A closer look at his RISE data, obtained by InSight during his first 900 days on Mars, showed that Mars’ rotation accelerated by a fraction of a millisecond per (Earth) year, or about 0.76 milliseconds. It turns out that there is Mars days are getting shorter. but why?
what is below or what is above
The main purpose of RISE was to see how much Mars wobbles when its orbit is pushed and pulled by the Sun’s gravity. This determines whether the core is likely solid or liquid. But RISE also had another mission: to measure the length of a day on Mars. A Martian day, known as a sol, is about 30 minutes longer than an Earth day, or 24 hours and 37 minutes. RISE used reflected radio waves to measure Mars’ rotational speed and wobble. When receiving radio signals from NASA’s Deep Space Network (DSN), the radio waves are reflected directly back to Earth. The difference between the frequency of the signal sent by the DSN and the signal reflected back to Earth gave his InSight team an idea of how the lander was moving with Mars.
Changes in the frequency of reflected radio waves reveal orbital wobble and the length of a day on the Red Planet, making RISE more accurate than ever for daylength changes, five times more accurate than a Viking lander. Measured in There was also another way RISE found evidence that the days on Mars are getting slightly shorter. We also tracked changes in carbon dioxide at the poles.2 It sublimates when the earth warms in spring and summer and condenses when the earth cools in autumn and winter.
ice cream, ice baby
We know why the Earth’s rotation has slowed for billions of years and our days are getting longer, but scientists aren’t sure exactly why Mars’s rotation is accelerating and its days are getting shorter. Not positive. But it’s entirely possible that it has something to do with changes in the Red Planet’s ice sheets.
When the Martian ice cap loses its carbon dioxide ice through sublimation during the warm season, the areas it once covered are almost ice-free. Le Mestre and his team suggest that post-glacial repulsion and/or ice accumulation will cause Mars’ mass to move closer to its axis as it rotates, albeit in different ways. This can occur when atmospheric carbon dioxide condenses into ice and accumulates in polar ice caps very close to the Earth’s axis. Alternatively, postglacial repulsion can deform the planet as glaciers sublime and land masses return to the gaps left behind.
Alternatively, researchers believe Mars could accelerate. Coupling of core and mantlewhich involves the transfer of momentum from the liquid core to the mantle.
“Evidence that the rotation speed of Mars is slowly accelerating” [could] It’s a result of the internal dynamics of Mars, or long-term trends in the atmosphere and ice sheets,” the researchers said in their paper. study Recently published in Nature.
Finding such subtle variations in the data has been a tedious task. Researchers had to wait a painfully long time to get enough data while the lander was still operating, and when they finally got that data, things like water could interfere with the results. I had to rule out all possible sources of possible noise. And the solar wind may have slowed down the reflected radio signal from InSight as it travels from Mars to Earth.
InSight was wiped out by a dust storm, but Le Mestre hopes to continue learning from the data and find out what’s causing the shorter stays on Mars.
Nature, 2023. DOIs: 10.1038/s41586-023-06150-0