Special Parallelograms Geometry Unit 12, Day 3 Mr. Zampetti.
Thermogravimetry: a technique for planetary in-situ missions A. Longobardo 1,F. Dirri 2, E. Palomba...
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Transcript of Thermogravimetry: a technique for planetary in-situ missions A. Longobardo 1,F. Dirri 2, E. Palomba...
Thermogravimetry: a technique for planetary in-situ missions
A. Longobardo1,F. Dirri2, E. Palomba1, A. Zinzi3, E. Zampetti4, S. Pantalei4, D. Biondi1, B. Saggin5, A.Bearzotti4 and A. Macagnano4
1IAPS-INAF, Via Fosso del Cavaliere 100, 00133 Rome, Italy2Dipartimento di Fisica, Università La Sapienza, Rome, Italy
3DISAM, Università Parthenope, Naples, Italy4IMM-CNR, Rome, Italy
5Politecnico di Milano, Milan, Italy
Outline
i. Introduction to Thermogravimetry
ii. Planetary applications
iii. The VISTA project
iv. Laboratory measurements
v. Conclusions
21/04/23 EPSC 2012, Madrid 2
Basic principlesThermogravimetry is a widely used technique to study absorption, sublimation and condensation processes.The instrument core is a Piezoelectric Crystal Microbalance (PCM), whose oscillation frequency increases at decreasing deposited mass: once the material is deposited onto the sensor it is possible to measure the amount of weight change as a function of increasing temperature due to the release of more volatile species. The temperature is increased by an appropriate heater.
Abundance volatile compound
Composition volatile compound
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Application fields
• Detection and analysis of volatiles compounds in the studied samples, i.e. adsorbed/included in the molecular structure, or in the studied environment
• Analysis of condensable species, i.e. discrimination between different phases (gas/liquid/solid).
The Thermo-Gravimetric Analysis (TGA) can be performed in two temperature regimes, depending on the purpose:
• ACT (Ambient to Cryogenic Temperatures Regime): <300 K• AHT (Ambient to High Temperatures Regime): >300 K
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Techniques for volatile measurements
• Attenuated Total Reflectance (ATR)- mass not lower than 200 g
- power of few watts required
• Gas Cromatography/Mass Spectroscopy (GC-MS) / GC-MS- instrument size of cm3
- problems about interface between GC and MS
• ThermoGravimetric Analysis (TGA) / TGA
- low mass (25 g)
- low size (cm3)
- low requested power (<1 W)21/04/23 EPSC 2012, Madrid 5
Outline
i. Introduction to Thermogravimetry
ii. Planetary applications
iii. The VISTA project
iv. Laboratory measurements
v. Conclusions
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Moon
• Water ice detection
• Measurement of water, organics and other volatiles content in the lunar regolith
• Analysis of electrical properties of regolith
Scientific goals in a lunar lander scenario
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Asteroids and comets
• Measurement of water and organic content in the asteroid regolith (asteroid taxonomy)
• Detection of cometary activity (measuring flux and dust/ice ratio)
Scientific goals in a in-situ mission on asteroids or comets
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Icy satellites
• Discrimination between water ice and clathate hydrates (not possible by means of spectral analysis)
• Determination of non-ice materials composition (solphates, carbonates, H2O2), characterised by different sublimation temperatures
• Detection of possible organic presence
Scientific goals in a in-situ mission on a icy satellite (e.g. Europa and Ganimede)
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Mars
• Measurement of water frost point, i.e. relative humidity
• Detection of possible ice falls
• Measurement of dust settling rate
• Measurement of water, organics and carbonates content in the Martian dust (related to habitability of the planet)
Scientific goals in a martian lander scenario
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Venus
Scientific goals in a aerostatic balloon mission on Venus
• Dew point (i.e. partial pressure) measurement of cloud condensable species
• Discrimination of volatile and refractory species in aerosols
• Analysis of areosol electrical properties
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Titan
Scientific goals in a aerostatic balloon mission on Titan
• Measurement of methan dew point (i.e. mixing ratio)
• Measurement of organics content (e.g. ethane, acetylene, benzene) in cloud aerosols (possible thanks to their different volatility and partial pressure)
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Outline
i. Introduction to Thermogravimetry
ii. Planetary applications
iii. The VISTA project
iv. Laboratory measurements
v. Conclusions
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Volatile In-Situ Thermogravimetry Analyser
VISTA is the thermogravimeter developed by a consortium of Italian institutes, led by IAPS-INAF and coordinated by Dr. Ernesto Palomba.
• Light (25 grams)
• Small (2x2x3 cm3)
• Low power-consuming (60 mW for T=60° K in vacuum)
• High sensitivity (10-100 ppm)
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Instrument concept
VISTA has a heater and a thermistor integrated onto the crystal.The thermistor can act as additional heater, in parallel to the other heater. In this configuration the required voltage to obtain a certain T decreases of 50%.
Simulation: V=1 V, I=50 mA P=50 mW in air
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The lunar version: MOVIDAMOon Volatile, Ice and Dust Analyser
Legend
Lunar surface
Capacitor
Microbalance
Dust particle
The microbalance is placed inside a capacitor held at a voltage V. Dust particles passing through the capacitor will deposit on the PCM in a time t depending on their charge-to-mass ratio q/m:
q/m= 2/(V t2)
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VISTA and ESA Cosmic Vision
Different VISTA configurations have been studied for Phase A of the following ESA Cosmic Vision (2015-2025) missions:
MARCO POLOTarget: primitive asteroid
MARCOPOLO-RTarget: primitive asteroid
Penetrator for EJSMTarget: Europa and Ganimede
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Outline
i. Introduction to Thermogravimetry
ii. Planetary applications
iii. The VISTA project
iv. Laboratory measurements
v. Conclusions
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Water desorption from clay (1)
The mass of a clay sample has been measured
1. Before the controlled hydration
2. After the controlled hydration
3. After the TGA
In the two performed tests, the TGA measures show a very good agreeement between the amount of water absorbed from clay during its hydration and the amount of released water after the heating (Zinzi et al., Sensor and Actuators A, 2011).
Controlled hydration camera21/04/23 EPSC 2012, Madrid 19
Water desorption from clay (2)Three kinds of experiments performed, differing on humid flux exposure time
Exposition time(hours)
Adsorbed water(% wt.)
Desorbed water(% wt.)
Measure 1 3 3.0 ± 0.2 2.5 ± 0.2
Measure 2 16 2.0 ± 0.2 1.8 ± 0.2
Measure 3 1 5.5 ± 0.2 5.5 ± 0.2
Average 6.7 3.5 ± 0.2 3.3 ± 0.2
No dependence on exposure time
Images from Zinzi et al., Sensor and Actuators A, 2011
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21/04/23 EPSC 2012, Madrid
Enthalpy of sublimation of adipic acid in vacuum (1)
Adipic acid has been heated at different temperatures and hence deposited on a cold PCM (TPCM = -25°C)
21
21/04/23 EPSC 2012, Madrid
Enthalpy of sublimation of adipic acid in vacuum (1)
Adipic acid has been heated at different temperatures and hence deposited on a cold PCM (TPCM = -25°C)
Becker containing adipic acid
PCM
Copper shield
Plate
22
Enthalpy of sublimation of adipic acid in vacuum (2)
Deposition rates of adipic acid at different temperatures have been measured. Enthalpy of sublimation has been inferred by Van’t Hoff relation:
H : enthaply of sublimationT1 and T2 : adipic acid temperaturesR1 and R2 : deposition rates at temperatures T1 and T2
R : gas constant
21/04/23 EPSC 2012, Madrid 23We found H = 131 kJ/mol, in agreement with
the literature value (129.3±2.5) kJ/mol
1 1 2
2 1 2
ln( )( )R TT
H RR T T
Outline
i. Introduction to Thermogravimetry
ii. Planetary applications
iii. The VISTA project
iv. Laboratory measurements
v. Conclusions
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Conclusions
• Thermogravimetry can find application in many planetary environments
• An instrument based on TGA (i.e. VISTA) is under study and development for space applications: it is very light, small and low-power consuming
• A VISTA laboratory breadboard has been tested by performing measurements of water desorption and enthalpy of sublimation
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