melting probe review simon sheridan melting probe reviewgraz 11 april 2006 simon sheridan a...

Simon SheridanMelting Probe Review

Simon SheridanGraz 11 April 2006

Melting Probe Review

A MINIATURE MASS SPECTROMETER AS A MELTING PROBE PAYLOAD

INSTRUMENT

S. SheridanPlanetary and Space Sciences Research

Institute, Open University, Milton Keynes,

MK7 6AA, U.K. [email protected]




Talk overview

Context: PSSRI research and instrumentation• Previous missions• Mass spectrometry background

Proposed payload for a melting probe

Results

Future work and conclusions




PSSRI instrument heritageFrom sample analysis

• Lunar samples• Meteorites• Stardust, Genesis…

…to in-situ instruments• Cassini-Huygens

– SSP, HASI, CDA• Beagle 2

– ESS, GAP• Rosetta

– Ptolemy, MUPUS, GIADA

And also enabling research:• Medical/life sciences • Next generation instruments• MEMS




The Gap instrument

GAP on Beagle2 (6 kg)

High precision (<<1%)

•Solid sample inlet (carousel, MPAe)

•Chemical sample processing

•Chemical / getter pumps

•Onboard reference material

•Magnetic sector mass spectrometer (2kg, 5W)

•VERY complex sample preparation




The Ptolemy instrument

Ptolemy on Rosetta lander (<5 kg)

Medium precision (1 to 5 %)•Solid sample inlet (carousel, MPAe)

•Chemical sample processing

•3-4 channel gas chromatograph

•Ion trap mass spectrometer (500 g, 1 W)• MEMS field emission electron source

(CCLRC RAL)• Digital ion counting (no noise)• m/z 10-200 • C, H, N, O, (S?)

•VERY complex sample preparationQM Post Vibration Test: E-Box Panels Removed to Reveal PCBs




•Simple device:

• Low mass, low power & rugged• 3 electrodes

– 3D trapping field

– r.f. (approximately 1 MHz)

• Electron multiplier detector• Ion source

•Fast scanning (m/z 10-250 in 100 ms)

•Operates under poor vacuum (1x10-3 mbar)

•Software control of one parameter (r.f.)

Limitations:

•Requires sophisticated drive electronics

The Ion trap Mass Spectrometer




PSSRI Ion trap interests

•Melting probe instrument• terrestrial (Lake vostock)• Europa, Mars poles

•EVITA for an Instrumented mole

•Active EDLS – measuring atmospheric properties (pressure, density, composition during descent e.g. to Mars)

•Monitoring breathing air

•Venus Entry Probe, balloon, • 100 gram microprobes

– A batch of MEMS traps (due in next few weeks)

•PhD student (1 Oct 2006-) sub-1 kg MS for planetary missions

•Ongoing work in support of the Rosetta mission

•Wellcome trust project - Breath analyser




The EVITA instrument

•EVITA Evolved Volatiles Ion Trap Analyser

•Initially developed for instrumented mole deployment

• Modular system• Mission specific sampling method• Airless bodies:

– Bepicolombo– NEO missions– Luna missions

• Mars missions– Miniature Turbo pump (130 grams)




Ion trap on a Melting ProbeInstrument proposal:

•Miniature ion trap (EVITA type) mass spectrometer• m/z of 10-200 amu

• measurement of – either gaseous volatile compounds (if sampling in a non-aqueous environment)– or dissolved organic compounds (if sampling in an aqueous environment)– the above measurements to PPM levels

•Use technology derived from previous projects•Low mass (<500 g) and low power (<1 W)




Sample inlet / preparation (1)

•Direct sampling of the environment •Feedback enables constant pressure (flow)

> 1x10-10 to 1x10-4 mbar l sec-1

•Very simple - a variable capillary leak•Pressure tested to 150 bar (Helium)

> Used on the Ptolemy instrument•Will allow evacuation during cruse phase

Limitations:

•no selective control of sample species> Lets everything into the mass spectrometer

•problem with aqueous environment> large gas load - Pumping requirement

(1) Thermally actuated proportional valve




Sample inlet / preparation (2)

•Membrane is the interface between the liquid and the vacuum of the mass spectrometer •very low gas load in aqueous environments

>minimal pumping required •Rugged / simple devices•Negate extensive sample preparation•Continuous monitoring possible

Limitations:

•Sensitivity depends on hydrophobicity and volatility of the analyte.

2) Membrane inlet




Ion trap for a Melting Probe




The prototype ion trapPrototype electronics Prototype hardware




Future work• More representative system

• A vacuum vessel has been designed and is under construction to allow testing of the Ion trap with a MIMS and a direct inlet system

– Sampling from liquids

– investigation of pressure effects / length of operation with the mini chemical getter pump

• Replace the Filament used in the prototype ion trap:• A batch of MEMS nanotip electron sources is being manufactured by RAL

– testing and characterisation of these devices with the ion trap system

• A alternative batch of miniature, rugged and low power electron sources has been procured.

– A testing programme is currently underway to evaluate these devices with the Ion trap

• Development of new electron multiplier devices

• Further development of the Ion trap drive electronics is now required:• Funds required to enable a study to evaluate / design and manufacture an ASIC.




Conclusions• PSSRI has an active, ongoing programme of missions and technology

development involving small ion trap mass spectrometers and the associated inlet systems

• A prototype Ion trap instrument has been developed which is low mass, small, flexible in operation and could be carried by the proposed melting probe

• Two sampling methods have been discussed which are compatible with the envisaged environment in which the melting probe will operate

• Ongoing characterisation / development of the system is currently underway• Further development of the electronics, with the aim of designing and the

eventual manufacture of an ASIC solution (maybe part of a common electronics solution???)

• Looking for funding opportunities to achieve this




Acknowledgements

The PSSRI space instrumentation mass spectrometry group:

A.D. Morse

G.H.Morgan

S.J.Barber

I.P.Wright

M.Javis

melting probe review simon sheridan melting probe reviewgraz 11 april 2006 simon sheridan a...

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