NASA's Curiosity Rover has been cruising around on Mars for about four years now, shooting rocks and singing "Happy Birthday" to itself every year. Therefore, the space agency thought it was about time the robot got a bit of an upgrade: the ability to choose which rocks to shoot on its own.

This development marks the first time an instrument of this kind has been autonomously operated on any robotic planetary mission, according to NASA.

So, who does the Curiosity Rover have to thank for this upgrade? The upgrade comes courtesy of software developed at NASA's Jet Propulsion Laboratory in Pasadena, Calif., called Aegis (Autonomous Exploration for Gathering Increased Science). The software allows the rover to use its various on-board laser and telescopic cameras, which are part of the Curiosity Chemistry and Camera (ChemCam) instrument, to identify potential targets based on certain criteria, such as a rock's size or reflectivity, set by staff back on Earth.

"This autonomy is particularly useful at times when getting the science team in the loop is difficult or impossible," said NASA robotics engineer Tara Estlin in a press statement. "[I]n the middle of a long drive, perhaps, or when the schedules of Earth, Mars and spacecraft activities lead to delays in sharing information between the planets."

As evidenced in Estlin's statement, NASA's scientists are still the ones that actually pull the trigger, with the new software finding its value when it's not possible for scientists to give any instructions.

For what it's worth, the Aegis software is by no means new. It has been used before in Curiosity's predecessor, the Mars rover Opportunity, which has been in operation since 2004. However with Opportunity, the software was used less often and used mainly for analyzing images taken with a wide-angle camera to help identify rocks that should be more thoroughly imaged, rather than blasting.

So, why is the Curiosity blasting away at rocks, anyway? Well, the laser is used to analyze the chemical composition of rocks and soil by hitting them with a tiny pulse, and then scrutinizing the gas produced using a spectrometer. This tool records the color wavelength of the plasma generated by the laser shots, which, in turn, can be used by NASA to determine the target's chemical composition.

This laser has been used plenty of times in the past — 350,000 total laser shots at about 1,400 targets in all, and now, with the introduction of Aegis, things are poised to become a lot easier and increase in efficiency.

"Due to their small size and other pointing challenges, hitting these targets accurately with the laser has often required the rover to stay in place while ground operators fine tune pointing parameters," Estlin said. "Aegis enables these targets to be hit on the first try by automatically identifying them and calculating a pointing that will center a ChemCam measurement on the target."