A day on Earth last about 24 hours. The word “about” in that sentence does a lot of heavy lifting because Earth’s rate of rotation changes all the time. Not by much, only fractions of milliseconds, but it means our common 24-hour day only really applies at human scales.
There are several things that can change the Earth’s rotation. The gravitational tug of the Moon and tides are gradually slowing Earth over millions of years. The melting of ice in the polar regions, the tectonic shift of the Earth’s crust during earthquakes, and even the draining of water from the aquifer. Earth is a geologically and biologically active world, so it’s only natural that Earth’s rotation rate is also dynamic. But a recent study shows that the rotation of Mars is also changing, which is a bit of a surprise.
The Zhurong rover has operated on the surface of Mars for over a year since it deployed on May 22nd, 2021. Before the rover suspended operations on May 20th, 2022, due to the onset of winter and the approach of seasonal sandstorms, Zhurong managed to traverse a total distance of 1.921 km (1.194 mi). During the first kilometer of this trek, the rover obtained vital data on Mars’ extremely weak magnetic fields. According to a new study by researchers from the Chinese Academy of Science (CAS), these readings indicate that the magnetic field is extremely weak beneath the rover’s landing site.
How thick is the crust of Mars? This question is what a recent study published in Geophysical Research Letters attempted to answer as it reported on data from a magnitude 4.7 marsquake recorded in May 2022 by NASA’s InSight lander, which remains the largest quake ever recorded on another planetary body. As it turns out, this data helped provide estimates of Mars’ global crustal thickness, along with a unique discovery regarding the crust in the northern and southern hemispheres, and how the interior of Mars produces its heat.
Exploring Mars is hazardous work. Robotic missions that are sent there have to contend with extreme temperatures, dust storms, intermittent sunlight, and rough terrain. In recent years, two robotic missions were lost due to dust alone, and all that roving around has done a number on the Curiosity rover’s treads. It’s understandable why mission teams are pleasantly surprised when their missions make it through a rough patch. This was the case with the Ingenuity team when they discovered that the rotorcraft, which has been exploring Mars alongside Perseverance, survived the night and is back in working order.
Testing how robotic helicopters fair in the Martian environment is one of the objectives of Ingenuity, which is the first mission of its kind on Mars. On May 3rd, 2022, the mission team learned that Ingenuity had lost power after trying to keep itself warm during the cold Martian night. Luckily, there was enough sunlight the following morning for the little rotorcraft to power up its batteries again and resume normal operations. This was a welcome relief, given that the Opportunity rover and InSight lander were both lost to the extreme cold and dust that characterize a Martian winter.
There’s no way to sugarcoat it: Mars has a “dust problem.” The surface of the Red Planet is covered in particulate matter consisting of tiny bits of silica and oxidized minerals. During a Martian summer in the southern hemisphere, the planet experiences dust storms that can grow to encompass the entire planet. At other times of the year, dust devils and dusty skies are a persistent problem. This hazard has claimed robotic explorers that rely on solar panels to charge their batteries, like NASA’s Opportunityrover and the InSightlander, which ended their missions in 2018 and 2022, respectively.
Martian dust has also been a persistent challenge for the Ingenuity helicopter, the rotorcraft that has been exploring Mars alongside NASA’s Perseverance rover since February 2021. Luckily, the way it has kicked up dust has provided vital data that could prove invaluable for rotorcraft sent to explore other extraterrestrial environments in the future. Using this data, a team of researchers (with support from NASA) has completed the first real-world study of Martian dust dynamics, which will support missions to Mars and Titan (Saturn’s largest moon) in this and the next decade.
The InSight lander might have transmitted its last picture from the surface of Mars. It looks like the lander is succumbing to Mars’ dusty conditions, as its ability to generate energy from its solar panels has been declining in recent weeks.
It’s always sad and somehow poignant when a lander or a rover falls silent. Each of them has a personality that goes along with their mission. But we’ve known for months this day was coming.
Billions of years ago, Mars was a much different place than it is today. Its atmosphere was thicker and warmer, liquid water flowed on its surface, and the planet was geologically active. Due to its lower gravity, this activity led to the largest volcanoes in the Solar System (Olympus Mons and the Thetis Mons region) and the longest, deepest canyon in the world (Valles Marineris). Unfortunately, Mars’ interior began to cool rapidly, its inner core solidified, and geological activity largely stopped. For some time, geologists have believed that Mars was essentially “dead” in the geological sense.
However, recent studies have provided seismic and geophysical evidence that Mars may still be “slightly alive.” In a recent study, scientists from the University of Arizona (ASU) challenged conventional views of Martian geodynamic evolution by discovering evidence of an active mantle plume pushing its way through the crust, causing earthquakes and volcanic eruptions. Combined with some serious marsquakes recorded by NASA’s InSight lander, these finding suggests that there is still some powerful volcanic action beneath the surface of Mars.
However, a research team led by ETH Zurich recently analyzed a cluster of more than 20 recent marsquakes, which revealed something very interesting. Based on the location and spectral character of these events, they determined that most of Mars’ widely distributed surface faults are not seismically active. Nevertheless, most of the 20 seismic events observed originated in the vicinity of Cerberus Fossae, a region consisting of rifts (or graben). These results suggest that geological activity and volcanism still play an active role in shaping the Martian surface.
Space science doesn’t always go as planned. Sometimes when scientists think they’ve made a remarkable discovery that will make human expansion into the cosmos easier, they are just flat-out wrong. But the beauty of science is that it corrects itself in the presence of new data. The people responsible for planning future Mars missions will have to make just such a correction as new data has come in on the availability of water on the red planet. There’s not as much of it as initially thought. At least not around the equator where InSight landed.