Dust storms on Mars are larger than anticipated, even spreading into space. According to a recent article in the journal JGR Planets, Mars is releasing huge clouds of dust, filling a huge volume of the inner solar system with dust.
This can be seen with the naked eye. The bright triangle in this image, taken by the Haleakala Observatory in Hawaii, is Martian dust.
It’s called Zodiacal light, and astronomers have long wondered what causes it. Usually the dim triangle is sunlight scattered by dust in the plane of our solar system. The dust, it turns out, comes from Mars.
NASA’s Juno spacecraft flew through a dust cloud on its way to Jupiter between 2011 and 2016. Dust grains slammed into Juno at about 10,000 miles per hour, breaking off sub-millimeter pieces of the spacecraft. Juno’s huge solar panels proved to be excellent dust detectors, registering up to 200 hits a day.
According to one Zodiacal light theory, asteroids were thought to be the culprits. However, as Juno flew through the asteroid belt toward Jupiter, the number of collisions dropped dramatically, sometimes to zero. Asteroids were not the right answer. Instead, scientists realized that the dust was coming from Mars.
Mars is the dustiest place in the solar system, with dust storms enveloping the entire planet for months. But how does this dust escape? During storms, dust sometimes rises to very high heights in the Martian atmosphere; researchers call it “rocket dust. However, in order to leave Mars, you need to travel at ~5 km/sec, and even “rocket dust” has a hard time handling that. Rocket dust would be easier to launch from Phobos and Deimos, but these small moons don’t produce enough dust to account for the zodiacal light.
Thus, there is still a mystery here. Mars has dust, but researchers have yet to figure out how Mars ejects it in such gigantic quantities into the solar system. The lead author of the study, John Leif Jorgensen (Technical University of Denmark), and his colleagues hope that other scientists will help them solve this last piece of the puzzle.