Toolmarks on Mars Leave a Trail of Robotic Graffiti

Our robots are equipped tools that leave behind distinctive marks on the fourth planet from the Sun. Here’s how those tools have changed over time to leave a more lasting impression on Mars, and what we can expect from the robots of the future.

Nuzzles from Sojourner

The Pathfinder Lander’s deployable mini-rover Sojourner was equipped with a spectrometer to determine rock composition, but didn’t have any fancy tools to collect samples. Instead, it bumped up against points of interest and carefully deployed its instrument kit against the rocks. Although it might have left marks on Mars, its tiny tire tracks caused far more of a fuss than its tools.

Rock Abrasion from the Opportunity and Spirit Rovers

An abraded circle at the London target inside Endurance Crater from June 2004. Image credit: NASA/JPL/Cornell

The Opportunity and Spirit rovers are each equipped with a simple abrasion tool designed to grind away surface layers. This is enough to expose a fresh, unweathered surface in a circle 4.5 centimeters (1.8 inches) in diameter, and offer the smallest possible glance into the rock’s interior. The rovers left behind a trail of shallow marks, just enough to expose fresh rock. Yet like the breadcrumbs of Hansel and Gretel, their trails were likely quickly erased behind them by scouring wind.

Scoop and Rasp from the Phoenix Mars Lander

Shallow holes cut into icy soil at Snow White in July 2008. Image credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University

The Phoenix Mars Lander brought a motorized rasp to the north pole of Mars. It scraped clear an area with the front-edge blade of the scoop, then used the rasp to penetrate even-harder frozen soil. The four-by-four rasp array created a grid of holes 5 centimeters (2 inches) wide; the 3 cubic centimeters (half teaspoon) of material was collected into the scoop. Concentrated all in one location ringing the lander’s fixed position, these shallow marks might still remain sheltered from the wind by the robot’s bulk, but they, too, will slowly fade over time.

Brush and Drill by the Curiosity Mars Rover

Full-depth drillhole and preliminary mini-hole at John Klein in February 2013. Image credit: NASA/JPL-Caltech/MSSS

The Curiosity Rover brushes dust off of rocks, then drills into them. Flutes on the drillbit pull tailings up to the surface, providing easily-accessible powder for sieving and feeding into an onboard sampling suite. The drillhole is 1.6 centimeters (0.63 inches) wide and up to 6.4 centimeters (2.5 inches) deep. These are the first serious marks we’ve left on Mars, holes deep enough that they could qualify as geological vandalism. Although too widely spaced to make a traceable trail, these drillholes scream loudly that something artificial was here.

Although loaded with different scientific equipment, the yet-unnamed Mars 2020 Rover will have the same chassis so will be leaving behind a very similar trail of holes on the surface.

The Tools of the Future

The InSight Lander launching in 2016 will be taking these piddly little scratches at the surface and amping them up with our first-ever subsurface exploration. Along with surface seismic probes, the lander is equipped with a heat flow probe that will be hammered meters deep into the planet. While only a single hole, it will also be the deepest mark we’ve left on Mars.

Top image: Toolmarks from Opportunity rover’s rock abrasion tool [left]; the Phoenix lander’s rasp [center]; and the Curiosity rover’s drill [right]. Credit: NASA/JPL-Caltech