The rotating blades of a Mars helicopter could create an electric field or cause the surrounding air to glow at dusk


Rotating blades on a drone flying over Mars could cause tiny electrical currents to flow through the planet’s atmosphere, according to a NASA study.These currents, if large enough, could cause the air around the helicopter to glow.This process occurs naturally on a larger scale on Earth, as sometimes seen by passengers on planes and ships during electrical storms known as St. Elmo’s Fire, for example.William Farrell, of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said: “The faint glow is most noticeable in the late afternoon when the background sky is darker.”He is the lead author of a paper on the study published in the Journal of Planetary Science.”NASA’s experimental Ingenuity helicopter is not flying during this time, but future drones can be allowed to fly at night and look for this glow.””The currents generated by the rapidly rotating blades on the DRONE are too small to pose a threat to the vehicle or the Martian environment, but they provide an opportunity to do some additional scientific work to improve our understanding of an electric charge buildup called ‘triboelectrification,'” Farrell added.The team applied laboratory measurements and used computer modeling to study how electrical charges build up on the drone’s rotors.Charge accumulation also occurs on helicopter blades on land, especially in dusty environments, so the team also used explanations and modeling of land helicopter charging as a basis for understanding the Mars case.They found that as the drone’s blades rotated, they hit tiny dust particles in the Martian air, especially when the helicopter came close to the surface and blew the dust around.When the blades hit the dust particles, the charge is transferred, building up on the blades and creating an electric field.When the charge builds up to high levels, the atmosphere conducts electricity, a process known as “atmospheric breakdown,” creating a swarm of electrons that create an enhanced current that dissipates or neutralizes the charge buildup on the rotorcraft.The team found that the breakdown began with an invisible “electron avalanche.”Electrons are very small particles with a negative charge.Charge causes electrons to respond to electric fields — attracted by the field generated by the positive charge and repelled by the field generated by the negative charge.Free electrons — those that do not bond to atoms — are responsible for the flow of electricity in conductive materials such as copper wire.The atmosphere can also have free electrons, a few of which in the Martian air feel the force of the electric field from the rotorcraft and smash into carbon dioxide molecules in the atmosphere.The impact releases more electrons from carbon dioxide molecules, amplifying the current.Mars has a very thin atmosphere, about one hundredth as dense as Earth’s.This very low pressure makes collapse more likely.On Mars, the molecules that make up the atmosphere are farther apart than atmospheres like Earth’s because they are less dense.Think of the electric field pushing the free electrons much like a car starting a towing race.If there are many large obstacles along the way, an accelerating car may hit them and slow down (or stop).The collision limits the speed of the car and keeps it relatively slow.However, if the obstacles are very far apart, the same car will now accelerate to high speed before hitting the obstacles.Similarly, the extra space in the Martian air gives free electrons a wider acceleration path before they “crash” into a molecule, so they can reach the speed needed to kick other electrons away from the CARBON dioxide molecule and start an “electron avalanche” at a relatively low electric field.On Earth, the same “electron avalanche” can occur, but in the denser atmosphere, the electric field would have to be much larger.Although the currents produced by drones flying through the atmosphere are small, they could be large enough to start an “electron avalanche” in the air around the blades and other parts of the vehicle, perhaps even glowing blue-purple.However, the researchers acknowledge that their results are a prediction and that sometimes nature has other plans.”In theory, there should be some effect, but whether electron avalanches are strong enough to produce a glow, and whether any faint glow can be observed during the operation, remains to be determined on future drone flights to Mars,”In fact, people can even place small electronic gauges near the blades and on their legs to monitor the effect of any charging.”This electrical monitor can have both scientific value and provide a critical input to the health of the uav during flight.”

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