It may come as a surprise to learn that Mars rover Curiosity is an interplanetary litterbug.
During entry, descent and landing (EDL) on the red planet’s surface in August, the one-ton Mars Science Laboratory (MSL) shed its heat shield, back shell, parachute, and then its rocket-powered skycrane ditched into the Mars dirt — the impact marks were all documented by NASA’s Mars Reconnaissance Orbiter (MRO) shortly after Curiosity touched down.
But it didn’t stop there — the MRO’s Context Camera later spotted six fresh craters around 7.5 miles (12 kilometers) from the rover’s landing site created by the 55-pound (25-kilogram) solid tungsten counterweights that were ejected shortly before Curiosity’s parachute was deployed. When attached, these masses ensured the aeroshell was oriented correctly as it “glided” through the atmosphere.
However, during Curiosity’s interplanetary transit from Earth to the Martian atmosphere, there was another, rather chunky component that was jettisoned ten minutes before EDL and its debris field has just been imaged by the MRO’s High Resolution Imaging Science Experiment (HiRISE) camera. In addition, the impact craters of two heavier tungsten counterweights have also been spotted by HiRISE.
The chunky “cruise stage” was attached to Curiosity’s aeroshell (the capsule containing the rover composed of the backshell and heatshield) and was outfitted with solar panels to supply the rover with energy and thrusters to guide the spacecraft during transit after launch on Nov. 26, 2011.
With the help of HiRISE, four large impact craters have been spotted some 50 miles (80 kilometers) west of Curiosity’s landing site. These craters likely correspond to the cruise stage that split apart as it tumbled through the Martian atmosphere plus two 165-pound (75-kilogram) blocks of tungsten called “cruise balance mass devices” that were ejected two minutes after cruise stage separation. Smaller impact sites, likely caused by debris from the cruise stage breakup, have also been spotted in the Mars dirt.
Although the armada of Mars satellites have imaged many fresh naturally-occurring craters created by meteorites, scientists have little clue as to how big or heavy the meteoroids were before impact. Therefore, assumptions derived from craters’ size and shape have to be made. But in the case of man-made craters such as these, scientists already know the size, shape and trajectory of the “meteorites”, providing a unique opportunity to understand how objects interact with the Martian atmosphere and surface on impact.