The spacecraft S approaches the planet Mars along a trajectory b-b in the orbital plane...

The spacecraft S approaches the planet Mars along a trajectory b-b in the orbital plane of Mars with an absolute velocity of 19 km/s. Mars has a velocity of 24.1 km/s along its trajectory a-a. Determine the angle β between the line of sight S-M and the trajectory b-b when Mars appears from the spacecraft to be approaching it head on.