Giada: Its Status After the Rosetta Cruise Phase and on-Ground Activity in Support of the Encounter With Comet 67p/Churyumov-Gerasimenko

Abstract

GIADA (Grain Impact Analyser and Dust Accumulator) on-board the Rosetta mission to comet 67P/Churyumov-Gerasimenko was designed to study the physical and dynamical properties of dust particles ejected by the comet during the encounter. In this paper we report the results of the analysis of data collected by GIADA during the past seven years of the cruise phase. During this period the GIADA detection subsystems were switched on for periodic in-flight payload checkouts to monitor their stateof-health including potential changes in its performance that could affect its data collection. Only slight variations in sensitivity and dynamical range were identified that will not affect the GIADA measurement capability during the Rosetta comet encounter and rendezvous phase. The GIADA microbalance system detected the presence of low-volatility material over a period of about 169 days when the GIADA cover remained partially opened. It is highly probable that this material originated from the spacecraft itself, as a spacecraft's outgassing was observed by the ROSINA mass spectrometer (on-board Rosetta) during the cruise phase.The identification of the low-volatility mass deposited on the microbalances as self-contamination will allow us to evaluate the mass rate background to be subtracted from the GIADA science data. These results obtained from GIADA cruise data analysis coupled with laboratory calibration data obtained from measurements using the GIADA spare model for selected cometary dust analogs will be the basis for the interpretation of the GIADA scientific data.

Laboratory simulations of the Vis-NIR spectra of comet 67P using sub-µm sized cosmochemical analogues

“…Instruments onboard Rosetta have provided information on the physics of 67P dust in the coma, including dust size and velocity distribution. The Grain Impact Analyser and Dust Accumulator (GIADA, Della Corte et al, 2014)) measured sizes from 100 μm to millimetres and characterised the dust flux Della Corte et al, 2016;Fulle et al, 2016b). The Cometary Secondary Ion Mass Analyser (COSIMA, Henkel et al, 2003) measured sizes from tens of micrometres to millimetres .…”

Density and Charge of Pristine Fluffy Particles From Comet 67p/Churyumov–gerasimenko

“…From 2014 August 1 to September 15, the Grain Impact Analyzer and Dust Accumulator (GIADA) instrument on board ESA's Rosetta Mission (Colangeli et al 2007;Della Corte et al 2014) collected compact particles, which constrained 67P's dust mass loss rate and dust/gas ratio at heliocentric distances >3.4 AU (Rotundi et al 2015). Up to 2015 January 14, GIADA has detected a total of 193 compact particles: 81 by both the GDS (laser curtain) and IS (impact sensor) subsystems (GDS+IS) and 112 by IS only.…”

GIADA performance during Rosetta mission scientific operations at comet 67P

“…The GIADA instrument and its performances are described in Colangeli et al (2007) and in Della Corte et al (2014), here we recall the main characteristics of the sensors of the three GIADA subsystems. The GDS is made up of four SDLO-4001 InGaAs CW (continuous-wave) laser diodes (λ= 915 nm), operated in pair pulsed mode at 100 kHz, i.e.…”

“…a signal detected by another PZT creates an undesired effect on PZT2. The analysis of the time delays measured during the cruise phase for the GIADA in flight PZT2 (Della Corte et al, 2014) provided first evidence that it was affected by electrical cross-talk. In order to verify this behaviour, we performed a dedicated test on GIADA in flight, reproducing the tests performed on GIADA PFM in the laboratory.…”

“…Temperature variations are induced by Rosetta spacecraft -Sun distance changes and by specific observational geometries. It is pivotal to monitor the behaviour of the three GIADA subsystems, as done by Della Corte et al (2014) during the Rosetta cruise phase.…”