NASA’s Perseverance rover In 2021, Perseverance recorded unusual sounds as a dust devil passed over it, later identified as electrical discharges—akin to lightning-like zaps—caused by the separation of charged dust particles within the vortex. These electrified whirlwinds form when larger, positively charged dust particles fall to the ground while smaller, negatively charged particles are lifted, creating an electric field.
Here's a breakdown of what we know:
1. How Dust Devils Form and Electrify:
Dust devils on Mars form similarly to those on Earth: solar energy heats the surface, causing warm air to rise and create an updraft. Horizontal winds then cause this rising air to rotate, forming a vortex.
As dust particles churn and collide within these vortices, friction generates electrical charges.
Larger, positively-charged particles tend to settle at the bottom, while lighter, negatively-charged particles rise. This charge separation creates a strong electric field. When the electric field becomes strong enough and the Martian atmosphere (which is thinner and less conductive than Earth's) struggles to dissipate these charges, a sudden discharge can occur, akin to lightning.
2. Evidence of Electrical Activity:
While direct visual confirmation of large lightning strikes like those on Earth is still elusive, computer models show how charge buildup could lead to lightning within Martian dust devils.
Intriguingly, the SuperCam microphone on NASA's Perseverance rover has recorded sounds that some researchers believe could be consistent with thunder from electrical discharges within dust devils.
3. Potential Threat to Perseverance Rover:
The primary concern for rovers like Perseverance is that electrified dust can adhere to conducting surfaces such as wheels, solar panels, and antennas. This adherence can:
Diminish solar energy availability by obscuring solar panels.
Harm communications by affecting antennas.
Complicate the motion of rovers and robots due to dust accumulation on moving parts.
While the Martian atmosphere is too thin to support the massive, dramatic lightning strikes seen on Earth, smaller electrical discharges are still possible. These "lightning-like zaps" could potentially damage or disrupt the sensitive electronics aboard the rovers, shortening their operational lifespans.
4. NASA's Protection Measures:
NASA's rovers are designed to withstand harsh Martian environments, including dust storms and extreme temperatures.
They utilize robust designs, including: Rocker-bogie suspension systems for navigating rough terrain.
Radiation-hardened electronics and redundant computer systems.
Radioisotope heater units (RHUs) and electrical heaters to maintain optimal temperatures.
Insulation using materials like sputtered gold film and silica aerogel.
Regarding dust specifically, while dust accumulation is a known challenge for solar-powered rovers, "cleaning events" (dust removal by wind or dust devils themselves) have historically helped keep solar arrays relatively clear, extending mission lifespans.
NASA is also researching electrodynamic dust shield (EDS) technology to prevent dust accumulation on surfaces like solar panels, optical systems, and even spacesuits for future human missions.
This technology uses electric fields to repel dust particles.
The possibility of lightning in Martian dust devils adds a new dimension to the environmental challenges faced by Martian missions, highlighting the need for continued research and protective measures for current and future explorers of the Red Planet.