Exploring Mars

By Scott Hamilton

The Perseverance rover was launched on July 30, 2020, on an Atlas V-541 rocket. It left the pad at Launch Complex 41 in Cape Canaveral Air Force Station, Fla., at 7:50 a.m. The Atlas-V is among the largest of interplanetary rockets and is the same type used to carry two previous rovers, Insight and Curiosity, to Mars.

One instrument on board Perseverance that makes this rover unique is the microphone attached to the rover’s mast. For the first time, we will be able to hear the sounds of Mars. Microphones are not a normal component on space rovers, due mainly to the high cost and weight limit restrictions on sending rovers 58.942 million miles to Mars. It is difficult for scientists to justify the cost of adding the additional weight and space requirements for microphones.

In fact, there are rules in place that require a solid scientific reason for adding any instrument to a rover. So you might be curious, how did the scientists justify the addition of a microphone to Perseverance? Surprisingly it is related to the study of rocks in the Martian desert. They are able to measure the hardness of rocks up to 20-feet away from the rover by firing a laser at the rock and measuring the frequency of the sound that is picked up by the microphone. Softer rocks are damaged more by the laser, resulting in a different “popping” sound from the laser hitting the rock.

The microphone will also be used to monitor sounds from the rover itself, for example, the motor sounds of the rover’s arm moving, the wheels turning in the dust, and the other instruments in use on the rover. These sounds can help engineers in the event of system failures to diagnose the issues based on the sounds rather than relying only on what can be seen by the cameras.

The microphone will take recordings about 3.5 minutes in length during the rock measuring experiments, and scientists fully expect to hear sounds other than that of the laser vaporizing the rocks. They expect to hear grains of sand scraping across the Martian landscape, wind rolling over and around the rover, and the “howls” of dust devils in the near distance, which have been observed by previous rovers but never heard before.

There is the expectation, based on atmospheric measurements, that the sounds will be much different on the Martian surface than we expect. The Martian atmosphere is much thinner, which will result in lower pitched sounds than on Earth. While we have successfully landed eight spacecrafts on Mars, Perseverance will be the first equipped with a microphone, provided it makes a safe landing in February 2021.

The last two attempts to place a microphone on Mars were failures. In 1999, NASA’s Mars Polar Lander mission crash-landed, destroying the craft. The second attempt to record the sounds of Mars flew with the Phoenix lander, which landed flawlessly in 2008, but the microphone was turned off before landing due to technical problems. Hopefully, Perseverance will provide the first sounds from Mars in February. If you are interested in more information on Mars and space exploration, you can sign up for NASA’s Mars Newsletter at http://mars.nasa.gov.

Until next week, stay safe and learn something new.