Answer:
Flybys. Â
Explanation:
Of the given options the cheapest type of mission of a robotic spacecraft is
Flybys. Â
Flybys are gravity assisted( they are accelerated by the force of gravity of Earth or the planet they are meant to orbit ) and hence require less fuel. NASA's Juno Mission to Jupiter in 2011 was a flyby. The spacecraft is studying planets composition, gravity field, magnetic field, etc.