VISTA: a piezoelectric microbalance for the ESA Hera mission

Asteroids are a population of millions of small bodies that can be found all over the Solar System, ranging in size from hundreds of kilometers to meter-sized, mainly concentrated between Mars and Jupiter. Asteroid compositions vary from metallic cores of once-molten bodies to primitive and ice-rich mixtures. Therefore, the understanding of asteroids is crucial to improve our understanding on the history and evolution of the Solar System. A few tens of thousands Near-Earth Asteroids (NEA), whose orbits are close to the Earth’s orbit (less than 1.3 AU), have been found. Some of them, also called Potentially Hazardous Asteroids (PHAs), could potentially make threatening close approaches to the Earth. For this reason, in the last decades several space agencies have studied NEAs, in particular those that could potentially impact with our planet, and investigated different techniques to avoid an Earth impact event. This led to the development of the first planetary defense mission, an international collaboration of NASA DART and ESA Hera space missions. The target of both missions is the binary asteroid system of Didymos, whose secondary moon Dimorphos was successfully impacted by DART in September 2022. Hera, launched in October 2024, is currently on its way to Didymos, with the objective of investigating the asteroid system in details, such as evaluate its subsurface and internal properties and measure in great detail the outcome of the kinetic impactor test of DART. The goal of this research activity consists in the development and experimental characterization of the VISTA instrument for the ESA Hera Mission, one of the payload on board the CubeSat Milani. VISTA is based on the concept of piezoelectric microbalances and aims at analysing the dust environment around the Didymos system and at providing information on the contamination on board.