The footprints and rover tracks on the Moon will be there for millions of years, as there is no wind to blow them away. But Mars is a different story. Researchers looking at the tracks left by the two Mars Exploration Rovers, Spirit and Opportunity have found that Mars wind storms can quickly erase any evidence the rovers had been there.
“It is humbling, said Paul Geissler, lead author of a recent paper on eolian — or wind — processes on Mars. “We make kilometer-long human graffiti on the surface of another planet and then Mars just wipes the slate clean for the next visitors!”
Geissler and his team were interested in how the Martian wind affects the surface, in the mechanisms and time-scales for the surface changes that could be seen across the globe.
Each of the rovers have left a trail of tracks in the soil that could be seen by orbiting spacecraft – the Mars Global Surveyor (no longer functioning) and the Mars Reconnaissance Orbiter – as well as in images from the rovers themselves.
From the images, the team was able to document the formation of the tracks and also their eventual erasure through the action of Martian winds.
They were a little surprised at the results.
“We anticipated that we would be able to see the rovers’ tracks in MRO HiRISE images and we *might* see some changes,” Geissler told Universe Today in an email, “ but I was surprised at how quickly the tracks disappeared!”
Geissler said that when he wrote his original proposal for the research (which was before MRO arrived at Mars), he thought it was likely they would not see any changes in the tracks over the duration of the mission.
“I expected the tracks to be slowly buried by dust settling out of the atmosphere or overprinted by dust-devils in Gusev crater,” he said. “Instead they are blown away by gusts of wind during episodic storms that only last a few days! I think the mechanisms of track erasure are interesting and somewhat surprising.”
While it might be sad for most of us to know the rover tracks are being erased, the scientists see it a little differently.
“I will confess to not feeling sad about it at all,” said Jim Bell, lead the lead scientist for the Panoramic cameras on the rovers, and a member of the Geissler’s research team. “Rather, it’s cool that the Martian environment is so dynamic, and tracking the tracks provides a neat science experiment to understand the role of dust and sand transport in modifying the current surface. So don’t be sad, be glad!
Read the team’s paper: “Gone with the wind: Eolian erasure of the Mars Rover tracks”
Hat tip to Scott Maxwell (@marsroverdriver) on Twitter.