The speed of sound in an ideal (calorically perfect) gas is given by
a = sqrt( gamma * R * T )
where gamma is the ratio of specific heats (thermodynamic property of a gas, which may vary with temperature), R is the individual gas constant, and T the temperature of the fluid. All of these are going to be different on Mars versus on Earth:
Earth:
R = R_atm = 287 J / (kg * K)
gamma = 1.44
T = 293 K (taking room temperature as an average temperature)
Mars:
R = R_CO2 = 188 J / (kg * K)
gamma = 1.37
T = 210 K (from a quick google, about -60 deg C)
If the Martian and Earth atmospheres were at the same temperature, then the speed of sound on Mars would be 80% that of the speed of sound on Earth. Given the temperature difference, the speeds of sound are
a_mars = 232 m/s
a_earth = 347 m/s
So yes, much of the difference is due to the composition: the Martian atmosphere has a higher atomic weight, which leads to a lower individual gas constant, and decreases the speed of sound. However, a substantial amount of the difference is simply due to the different temperatures on the surfaces of the two planets.
The speed of sound in an ideal (calorically perfect) gas is given by
where gamma is the ratio of specific heats (thermodynamic property of a gas, which may vary with temperature), R is the individual gas constant, and T the temperature of the fluid. All of these are going to be different on Mars versus on Earth: If the Martian and Earth atmospheres were at the same temperature, then the speed of sound on Mars would be 80% that of the speed of sound on Earth. Given the temperature difference, the speeds of sound are So yes, much of the difference is due to the composition: the Martian atmosphere has a higher atomic weight, which leads to a lower individual gas constant, and decreases the speed of sound. However, a substantial amount of the difference is simply due to the different temperatures on the surfaces of the two planets.