VISTA Payload for ESA RAMSES Mission

The 2029 close approach of near-Earth asteroid (99942) Apophis offers a rare and scientifically valuable opportunity to study the physical and compositional response of a small body to intense tidal forces. The European Space Agency’s RAMSES (Rapid Apophis Mission for SpacE Safety) mission will rendezvous with Apophis and observe its evolution before, during, and after the Earth flyby. The objectives of RAMSES are to measure of the characteristics of Apophis before its closest approach to Earth and to observe the effect of Earth’s tidal forces during the approach [1]. The design of RAMSES is similar to the Hera mission, including a main spacecraft and two CubeSats.On board Cubesat-1, in charge of Tyvak International, is the VISTA instrument (Volatile In-Situ Thermogravimeter Analyser), a dust and volatile analyser. The instrument design is based on VISTA for ESA Hera Mission [2]. The instrument core is composed by two quartz crystals, mounted in a sandwich-like configuration, its Proximity Electronics (PE) and the Thermal Control System  (TCS) (two built-in controlled heaters and RT detectors, and a Thermo-Electric Cooler). The technical characteristics are listed in Table 1.Table 1. VISTA technical characteristic and FE Model design view.In the framework of RAMES Mission, VISTA payload will monitor ejecta production, dust lofting, and potential regolith mobilization induced by tidal stresses or rotational excitation [3]. VISTA can also monitor any raised particles ejected due to meteor/micrometeorites impacts and due to any spacecraft manoeuvres, that influences Apophis surface (e.g. OSIRIS-APEX may use its thrusters to stir up rocks and dust on the surface of Apophis). These observations will provide critical insights into surface cohesion, mechanical response, and mass loss processes in response to planetary encounters. Combined with high-resolution imaging [4] and spectral data from other RAMSES payloads, VISTA will contribute to detect the presence of µm and sub-µm particles size and provide insight on the asteroid composition by using the TGA (Thermo-Gravimetric Analysis) and using the following operational modes (Fig.2):Accumulation mode: this consists of passive collection of dust and volatiles. ACTIVE MODE (Heating mode): it is the QCM warming up to the volatile desorption temperature. ACTIVE MODE (Cooling mode): it is the QCM cooling down (5-10K) to favour the dust/volatiles accumulation.   Figure 2. VISTA operational Modes during each expected phase of RAMSES Mission. References[1] Michel P. et al., “Science Objectives of RAMSES: ESA’s Rapid Apophis Mission for SpacE Safety”, Apophis T-4 Years 2025 (LPI Contrib. No. 3083)[2] Palomba E. et al., “VISTA payload on-board Milani Cubesat for Hera space mission for the study and characterization of Didymos binary system”, 45th COSPAR Scientific Assembly 2024[3] Scheeres et al., 2005; Icarus, Volume 178, Issue 1, p. 281-283[4] Palomba et al., “Monitoring surface evolution of Apophis during its 2029 Earth flyby: the role of HAMLET on ESA’s RAMSES Mission”, EPSC 2025