This image from NASA’s Curiosity rover shows what appears to be a sandy floral-like formation on Mars. But planetary scientist Abigail Fraemant says it’s actually a result of minerals and water interacting on the planet’s surface.
Human-made space debris, or space junk, poses a serious threat to our planet’s satellites. It includes nonfunctional spacecraft, old and failed rocket stages, abandoned mission-related devices, and fragmentation debris from explosions.
Every spacecraft, regardless of their purpose, has the potential to become a piece of space debris. And the proliferation of satellites from companies such as Elon Musk’s Starlink and OneWeb satellite constellations means that the amount of space junk near Earth will continue to grow.
This is particularly worrying because even small debris reentering the atmosphere at high speed can cause damage to nearby satellites or spacecraft. For example, in May 2021, a tiny fragment from a Chinese weather satellite hit the International Space Station, causing a 5mm hole.
To avoid these collisions, satellite operators use a variety of techniques to prevent debris from reaching their satellites and spacecraft. These include using space tug-like vehicles to drag debris to a safer orbit, modifying the shape and size of orbital objects to make them more likely to escape into space, and creating debris shields.
But all of these methods have their limitations. And they are only a start.
In addition to damaging satellites and spacecraft, debris can also pose a risk of causing physical harm to the people living on or near the space station. In fact, a team of researchers has calculated that there is a 10 percent chance that someone could be killed by falling debris over the next decade.
That is a frightening thought, especially given the number of dead and failed satellites littering low-Earth orbit today. Fortunately, the density of debris has been slowly reducing since the mid-20th century, and new mitigation strategies are being developed. But it is still a significant issue, and the proliferation of new satellites and other devices could lead to an unstoppable space junk problem.
Impact craters on Mars reveal evidence of the planet’s warmer, wetter past. The rocks ejected from impacts contain minerals that formed in the presence of water, and some craters show signs of ancient lakes. Layered sediments on the rim of these craters also add to the evidence.
Craters are the predominant landforms on a planetary surface and are important tools for dating its history. Crater morphology can provide clues about the nature of the surface, such as lobate ejecta blankets or central pit craters (a type of crater that’s common on Mars but uncommon on Earth).
There are more than 43,000 impact craters larger than 5 kilometers (3 miles) in diameter on Mars, and there are likely over a quarter of a million craters smaller than this. Scientists believe that most of these were formed by meteorite impacts early in Mars’ history.
But some of these craters could have been formed more recently by the large number of small meteors that hit Mars. Because Mars is closer to the asteroid belt, it’s more likely to be struck by meteors from that source.
That’s why researchers are so interested in the small craters on Mars. “It’s an overlooked part of the landscape,” said Crown.
This 150-metre-wide crater, found by the MRO, is near the northern hemisphere of the planet. Dr Miljkovic said it’s the largest fresh impact crater detected on Mars in the last 16 years.
This crater, which was spotted by InSight’s cameras this year, was also the source of a major impact recorded by the orbiter in December. That was a seismic event that looked similar to the earlier one.
Water once sweltered Mars, but it disappeared from the planet’s surface about three billion years ago. Scientists don’t know what happened to the water on the red planet, but one possibility is that it lost its atmosphere — a theory similar to Earth’s.
Mars’ atmospheric pressure is very low compared to that of Earth, so if any water tried to stay on the planet’s surface, it would boil away quickly. This means that most of the water on Mars is frozen as ice.
But some traces of liquid water are still visible on the planet today. Radar data from the Mars Express orbiter and the Mars Reconnaissance Orbiter indicate that there’s water ice in the planet’s north pole, and in mid-latitude regions.
These traces of liquid water are in the form of hydrated minerals, which are rocks that have been heated and incorporated with water. This research could help scientists figure out how to extract more water from the planet before humans arrive.
The hydrated minerals are able to hold more water than ordinary rocks because they contain other elements like oxygen and hydrogen. This could be the key to creating an artificial ocean on Mars, according to Dr Frances Butcher of the University of Sheffield in England.
The researchers used the FREND instrument on NASA’s Mars Reconnaissance Orbiter to measure the amount of hydrogen in Martian soil. They found that the hydrogen levels increased as they moved north and south from the equator, indicating that there was more water beneath the surface.
Martian dust devils, like their counterparts on Earth, appear when solar heating on the surface rises and causes warm air to rise. The wind generated from that rising air forms a vortex, or whirling column of wind. These are often short-lived, but sometimes they can last for hours.
On Mars, dust devils are especially common when the sun heats the ground. That’s a time when the winds are strongest and there’s more dust on the planet.
As these wind-blown dust grains move through the atmosphere, they suck up air particles and create an area of low pressure. It’s a bit like what you would see over a desert in the summer.
But unlike over Earth’s deserts, the area of low pressure on Mars is so thin that it doesn’t push back with as much force. The result is a whirling column of air that is weak but strong enough to lift particles off the surface.
The first record of a dust devil in Martian history was caught by NASA’s Perseverance rover on Sept. 27, 2021, at Jezero crater on the floor of the Red Planet’s southern hemisphere. The rover’s masthead camera, called SuperCam, recorded the sound of the wind, along with data from other sensors in its Mars Environmental Dynamics Analyzer instrument.
The microphone was turned on for a few seconds only eight times a month, but the recording is long enough to give a detailed picture of how dust devils work. It also picked up the sounds of small impacts from the dust grains as they were flung at the rover. By counting these tiny impacts, scientists were able to see how dense the dust was within the devil. This could help researchers better understand how the dust devils function and might even shed light on a possible mechanism for how they lift up particles from the Martian surface.
In this picture of mars, a thin ice layer resembling Swiss cheese is buried less than a meter beneath the planet’s surface. It’s been spotted by a radar on a European Space Agency orbiter called MARSIS, which beams down pulses of radio waves and listens for reflections. The ice is brighter than usual because it absorbs energy from the radio waves, which gives a clue that it’s water.
Scientists have long known that the polar caps of Mars are covered in water. But they’ve been unsure whether the ice was frozen all the way down to its bed, as is the case on Earth.
New research suggests that Mars might have some of this liquid water at its base today. In fact, a team of international researchers found evidence that there might be subglacial water under the south polar ice cap on Mars.
Using laser-altimeter data from NASA’s Mars Global Surveyor and HiRISE spacecraft, the researchers were able to detect subtle patterns on the ice cap’s height that are consistent with the predictions of computer models of how a body of water would affect the surface topography.
These findings suggest that ice is likely to be present under the south polar ice cap, and that Mars is probably geothermally active to maintain it at this depth. The ice is made of carbon dioxide, and the researchers believe that it is flowing as glaciers into basins on the slopes of the south polar ice cap.
These findings have a lot of implications for future explorations of the red planet, says Angel Abbud-Madrid, director of the Center for Space Resources at the Colorado School of Mines in Golden. These subsurface glaciers might offer the perfect landing sites for human bases, he says.