Orbitrap mass analyser for in situ characterisation of planetary environments: Performance evaluation of a laboratory prototype
Introduction
It is a major goal of space exploration to decipher the origin and evolution of Solar System bodies in relation to the primordial conditions of the solar nebula, the chemical fingerprints of the formation of the Solar System, the evolutionary processing of minerals, volatiles and organic compounds, as well as to elucidate the source and evolution of organic matter, its relevance for the origin of life, and to explore other possible modern habitats with suitable conditions to sustain life. The knowledge of the molecular, elemental and isotopic composition of Solar System bodies and of their environments is therefore central in space research. For instance, to understand the evolutionary processes, planetary sciences require in situ measurements of noble gas concentrations, their isotopic abundances, and the distribution of volatiles species such as H2O, HCN… Recently, in the frame of in situ measurements at bodies with potential relevance for astrobiology (Titan, Europa, Enceladus, comets, and asteroids), the need to develop a new generation of in situ space instruments able to handle and analyse the diversity and complexity of organics, their isotopic composition, and their potential interaction with inorganic material has emerged. This fosters the continuous effort to develop in situ analytical tools that are up to the analytical challenges of space exploration.
Mass spectrometry is arguably among the most desirable tool for in situ space exploration given its ability to analyse the composition of gaseous, liquid or solid samples, and its extreme sensitivity, versatility, and by the potential of extensive miniaturisation. Common mass spectrometers (MS) are made of independent units: (i) the ion source for generating charged (and optionally deliberately fragmented) species representative of the analysed sample, (ii) the mass analyser for sorting the ions by their mass to charge ratios (m/z), and (iii) the detector, which produces electronic signals related to the abundances of each ionic species. The availability of several types of mass analysers, as well as different samples preparation apparatus and data processing software, yields a wide diversity of MS instruments.
Mass spectrometers have been employed in space for two applications (Palmer and Limero, 2001): air monitoring in inhabited spacecraft and space stations like Apollo, Mir and the International Space Station, and the in situ characterisation of the chemical composition of Solar System environments (Niemann and Kasprzak, 1983). To date, almost all the classical technologies of mass analysers have been adapted and used for space exploration: magnetic or electromagnetic sector deflectors (Balsiger et al., 2007, Biemann et al., 1976, Niemann et al., 1980), radio frequency quadrupole mass filters (Istomin et al., 1979, Istomin et al., 1982, Mahaffy et al., 2012, Mahaffy et al., 2014, Niemann et al., 1992, Niemann et al., 1998, Waite et al., 2004) or radio frequency ion traps (Wright et al., 2007), and time-of-flight (TOF) (Balsiger et al., 2007, Gloeckler et al., 1992, Goesmann et al., 2007, Kissel and Krueger, 1987, Kissel et al., 2007, Scherer et al., 2006, Srama et al., 2004).
Interplanetary dust particles have been analysed in situ by mass spectrometry in previous space missions by two methods, depending upon the relative dust velocity with respect to the spacecraft. In the case of low relative velocity, i.e. up to 0.2 km s−1, the dust particles can be non-destructively collected and analysed with a dedicated ionisation method such as an ion gun in the case of COSIMA (Cometary Secondary Ion Mass Analyzer) on-board the Rosetta orbiter (Hilchenbach et al., 2016, Kissel et al., 2007, Schulz et al., 2015). At impacts at velocities above 1.5 km s−1 direct mass spectrometry of the plasma cloud created by the impact of dust has been successfully used on Giotto, Vega, Stardust and Cassini (Kempf et al., 2012, Koschny and Grün, 2001, Krivov et al., 2003, Krüger et al., 1999). This technique even permits the study of planetary surface or sub-surface micrometric fragments (Postberg et al., 2009, Postberg et al., 2011).
Requirements for in situ characterisation of extra-terrestrial surfaces and atmospheres (essentially in the context of the exploration of bodies with expected chemical complexity) led to the development of new instruments. These instruments aim to characterise bulk materials (Briois et al., 2008, Briois et al., 2013, Cottin et al., 2010, Tulej et al., 2014) (potentially containing organic matter), and to this end their main figure of merit is their mass resolving power.
The mass resolving power of an analyser refers to its ability to separate ions that have similar m/z ratios. It is measured by the ratio m/Δm, where m is the mass of a measured ion, and Δm is the full width at half maximum of the peak. Depending on the analyser concept, the resolving power varies with m/z. To be fully descriptive, it is therefore necessary to quote the mass to charge ratio at which the mass resolving power is determined.
The chemical composition of comet 67P/Churyumov–Gerasimenko has recently been analysed by dedicated instruments on orbiter and lander (Philae) of the Rosetta mission that brought a wealth of information on the comet's composition (e.g. Capaccioni et al., 2015; Le Roy et al., 2015; Altwegg et al., 2015; Wright et al., 2015; Goesmann et al., 2015; Hilchenbach et al., 2016), but it is anticipated that the results can only partially assess the diversity of chemical species. Recently, tantalizing results on primitive meteorites and cometary organic matter analogues have been reported by high-resolution mass spectrometry (resolving power >200,000 at m/z 200) (Danger et al., 2013, Schmitt-Kopplin et al., 2010). In the near future, pristine samples are expected from small carbonaceous bodies of the Solar System (e.g. Hayabusa 2and OSIRIS-REx) and will be analysed with high performance instruments in the laboratory. Questions of contamination or volatile loss during Earth atmospheric entry are however an issue. Combining a sample return mission with a new generation of in situ analytical tools is therefore at the scale of the expected analytical challenge.
Mars is the most thoroughly explored extra-terrestrial body with currently six orbiters and two rovers collecting information about its atmosphere and surface. In particular, the Curiosity rover (Grotzinger et al., 2012) exploring the surface with solid sampling and Gas Chromatograph–MS (Mahaffy et al., 2012, Vasavada et al., 2014). However, although the presence of organic molecules at the Mars surface (Freissinet et al., 2015) and the past habitability of Gale crater have definitely been proven with the Curiosity rover, several key questions remain about the assessment of a prebiotic-like chemistry, which could have occurred in the past. Although the mass analysers allowed great advances, their limited mass resolving power did not prevent ambiguities in the attribution of ionic species, such as disambiguation between inorganic and organic material.
The Titan atmosphere hosts naturally occurring chemical processes leading to the synthesis of complex organic molecules, potentially prebiotic (Hörst et al., 2012). The Cassini–Huygens mission revealed an extraordinarily complex ionospheric composition. At an altitude of 1000 km, the Ion Neutral Mass Spectrometer (INMS) detected roughly 50 positive ions in the mass range 1–99 u (Cravens et al., 2006) while the CAssini Plasma Spectrometer (CAPS) provided evidence for positive ions reaching up to m/z ~350 (Waite et al., 2007) as well as negative ions with m/z up to ~10,000 (Coates et al., 2007). These complex ions are the precursors of the aerosols visible at lower altitude (Lavvas et al., 2013). Mass spectrometry is the best tool to analyse Titan's upper atmosphere, but the chemical identification is hampered by the limited mass-resolving power (m/Δm ≤500 at best) of the instruments (Waite et al., 2004, Young et al., 2004). It is clear that Instruments with a far better mass resolving power are to be developed. For example, the model payload for the Titan and Saturn System Mission included a polymer mass spectrometer to measure the densities of gases and aerosols (10–10,000 u), with a resolving power of ~10,000 (Coustenis et al., 2009).
Among all the mass spectrometers flown so far, the Rosetta mission hosts two MS instruments with the best resolving power achieved in space: the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) and COSIMA instruments, respectively dedicated to the chemical analysis of gaseous and to dust samples from the comet 67P/Churyumov–Gerasimenko. ROSINA includes a mass analyser based on an electromagnetic sector deflector called the Double-Focussing Mass Spectrometer (DFMS) with a mass resolving power better than 9000 at m/z 28 (Balsiger et al., 2007, Jäckel et al., 2011). COSIMA is a Time Of Flight - Secondary Ion Mass Spectrometer (TOF-SIMS) with a mass resolving power of 1400 at m/z 100 (Kissel et al., 2007).
Compared to state-of-the-art MS instruments on Earth, space borne in situ MS offers limited performance due to technical constraints related to the launch and journey of the space probes and their instrument in space, as well as the space operating conditions that can be sometimes far from those used on Earth. These constraints require in situ space instruments to be miniaturised to limit their weight, size, power consumption and data volume. They also need to be designed to survive harsh environmental conditions such as solar and cosmic radiation, pressure, temperature, to withstand mechanical stress related to the probe launch, the journey in space, and sometimes descent and landing on a Solar System body. All these constraints on space borne MS instruments challenge the mass resolving power, and the mass measurement accuracy.
“High-resolution mass spectrometry” denotes the ability to resolve the isobaric interferences by measuring the accurate mass to charge ratios of ions. This ability is related to the sum of the nuclear mass defects of all the constituting atoms. It implies to resolve better than the second decimal in the measurement of the ionic mass. Hence, increasing the mass resolving power gives access to plateaus of chemical information in the following manner:
- i)
m/Δm <2500 allows separation of peaks with different nominal masses (e.g., 28 u versus 29 u), or with small mass differences at small masses (e.g. discriminating 25Mg from 24MgH already requires a m/Δm of ~2000).
- ii)
2500<m/Δm<10,000 allows separation of peaks for isobaric molecular species (e.g., N2 versus CO at 28 u) but only with m/z below 50, e.g., major molecular entities in the Solar System, which could be identified by other spectroscopic methods.
- iii)
10,000<m/Δm<100,000 provides separation of isobaric species with masses up to m/z 500, i.e., it allows unequivocal identification and quantification of the building blocks of life, and discriminates against their potential interaction with inorganic material.
Significant efforts to develop further high-resolution mass spectrometers (HRMS) for space exploration are currently ongoing under Research and Technology (R&T) programs, but no HRMS instrument has flown yet on a space exploration probe. One can cite two different concepts based on extending the time-of-flight of the ions by multiple reflections. The first concept is the ion and neutral mass spectrometer MASPEX (MAss Spectrometer for Planetary EXploration), which is a Multi-Bounce high-resolution time-of-flight mass spectrometer. Its principle is based on the concept described by Wollnik and Przewloka (1990). It has achieved NASA Technology Readiness Level (TRL) 5 and has been recently selected for the future NASA discovery mission to Europa (www.jpl.nasa.gov/missions/europa-mission). At current best estimate, its length, average power consumption and mass are 48 cm, 36 W and 6.7 kg respectively, without harness and radiation shielding (Hässig et al., 2015a). It has proven a mass resolution of m/Δm=13,500 at m/z 28 after 12 cycles, that can be increased up to 59,000 in bunch mode (Libardoni and Synovec, 2013), but with a reduced mass range. The second concept is the MULti-TUrn time-of-flight Mass spectrometer, MULTUM (Shimma and Toyoda, 2012), which was the first laboratory model studied for the COSAC (COmetary SAmpling and Composition) experiment of the Rosetta mission (Matsuo et al., 1999). Its operation principle is described in Sakurai and Baril (1995). It consists of 4 cylindrical electrostatic sectors and 28 electric quadrupole lenses. The mass resolution increases according to the number of ion cycles. A resolving power up to 350,000 at m/z 28 has been reported after 1200 cycles (Toyoda et al., 2003). A portable version “MULTUM-S II“(70 dm3; 35 kg (including vacuum pump and electric circuits)), dedicated to greenhouse gases or polychlorobiphenyl analysis, reached a resolving power of ∼30,000 at m/z 44 after 50 cycles (Shimma et al., 2010).
Laboratory mass spectrometry has been revolutionized by access to Ultra High-Resolution Mass Spectrometers (UHRMS) (m/Δm better than 105). They are based on ion trapping and on Fourier Transform (FT) of the signal induced by their oscillations in the analyser. Initially, the trapping was achieved by a strong magnetic field and the ion cyclotron frequency was the signature of mass to charge ratio (so-called FT-ICR for Fourier Transform-Ion Cyclotron Resonance). Although very powerful, this concept requires high field magnets, which are heavy and thus not suitable for space exploration. In 2000, a new type of Fourier Transform Mass Spectrometry analyser based on a purely electrostatic field was demonstrated by Makarov (2000). This mass analyser, which has been marketed by Thermo Fisher Scientific as the Orbitrap™ analyser, confines ions in a compact volume, with all dimensions of the analyser electrodes smaller than 5 cm. Sophisticated mass spectrometers based on the Orbitrap mass analyser allow for UHRMS up to m/Δm ~106 at m/z 200 as achieved in the laboratory (Denisov et al., 2012). Several laboratory studies performed with commercially available LTQ Orbitrap mass spectrometers (which incorporate both the Orbitrap and quadrupole ion trap mass analysers) on planetary materials give a good illustration of the potential of this technique for space applications (Danger et al., 2013, Gautier et al., 2014, Hörst et al., 2012, Pernot et al., 2010, Somogyi et al., 2012, Vuitton et al., 2010).
Our team is conducting an R&T effort – called Cosmorbitrap – to bring the Orbitrap technology to spaceflight conditions, with the driving motivation to operate in space the first Fourier Transform Mass Spectrometry (FTMS) analyser.
The aim of this paper is to present the performance and capability tests conducted on a prototype set-up used as a first stage of the R&T Cosmorbitrap development, and the promising perspectives in the context of future Solar System exploration. In the following, a brief discussion of the Orbitrap mass analyser is provided followed by a description of the prototype set up, and evaluation of its performances.
Section snippets
Orbitrap mass analyser
The Orbitrap cell consists of four main electrodes: a central inner spindle-shaped electrode, two external outer electrodes and a deflection electrode (Fig. 1). The measurement principle is based on the pulsed injection of ions inside the cell, in which an electrostatic field is produced by polarising the central electrode at a high-voltage with respect to the outer electrodes, which are at floating ground, and act as the detector. A two-level high-voltage is applied on the central electrode.
Laboratory prototype
Since 2009, a series of R&T programs has been undertaken by a consortium of five French laboratories (LPC2E, Orléans; LISA, Créteil; LATMOS, Guyancourt; IPAG, Grenoble; CSNSM, Orsay) in order to evaluate the potential of the Orbitrap ultra high-resolution mass analyser as a viable key subsystem for the future generation of in situ space mass spectrometers (Briois et al., 2012, Briois et al., 2014, Carrasco et al., 2012, Thissen et al., 2011, Vuitton et al., 2014). The aim of the project is
Results and performance of the prototype
Experiments presented in this section were conducted using the LAb-Cosmorbitrap depicted in Fig. 4. Samples were inserted using a stainless steel sample holder rod (30 cm long and 1 cm diameter) through a primary vacuum (at about 10−2 mbar) injection airlock directly into the ion optic vacuum chamber. The testbed is based on a direct injection probe, allowing sample repositioning or exchange within few minutes. In order to characterise the ultimate mass resolution of the present prototype, tests
Conclusions
This paper presents the current performance of the prototype of the Cosmorbitrap subsystem mass analyser coupled with a laser ablation ionisation source. These reported tests demonstrate the capabilities of such subsystem. The LAb-Cosmorbitrap testbed is capable of providing mass resolving power as a function of m/z similar to the commercial instrument using the same type of Orbitrap cell, reaching 474,000 at m/z 9, with mass accuracy below 15 ppm, which is very unusual for space instrumentation
Acknowledgement
We thank all people involved in the development of Cosmorbitrap, and our international partners engaged with us in the development of a complete mass spectrometer instrument, and more particularly Dr. E. Denisov and C. Katz from Thermo Fisher Scientific. Authors gratefully acknowledge the financial support by the French Space National Agency, the Centre National des Etudes Spatiales (CNES), the Region Centre/Val de Loire, and the Labex ESEP (No. 2011-LABX-030) for its support and funding
References (83)
- et al.
Characterization of laboratory analogs of interstellar/cometary organic residues using very high resolution mass spectrometry
Geochim. Cosmochim. Acta
(2013) - et al.
Orbitrap mass spectrometry with resolving powers above 1,000,000
Int. J. Mass Spectrom.
(2012) - et al.
Nitrogen incorporation in Titan's tholins inferred by high resolution orbitrap mass spectrometry and gas chromatography-mass spectrometry
Earth Planet. Sci. Lett.
(2014) - et al.
Performance evaluation of a prototype multi-bounce time-of-flight mass spectrometer in linear mode and applications in space science
Planet. Space Sci.
(2015) - et al.
Linear high resolution dust mass spectrometer for a mission to the Galilean satellites
Planet. Space Sci.
(2012) - et al.
Impacts into ice-silicate mixtures: ejecta mass and size distributions
Icarus
(2001) - et al.
A space time-of-flight mass spectrometer for exobiologically-oriented applications
Adv. Space Res.
(1999) - et al.
Mass spectrometry in the U.S. Space Program: past, present, and future
J. Am. Soc. Mass Spectrom.
(2001) - et al.
Ion optics of a high resolution multipassage mass spectrometer with electrostatic ion mirrors
Nucl. Instrum. Methods Phys. Res. A
(1995) - et al.
A novel principle for an ion mirror design in time-of-flight mass spectrometry
Int. J. Mass Spectrom.
(2006)
Chemical ionization in the atmosphere? A model study on negatively charged “exotic” ions generated from Titan's tholins by ultrahigh resolution MS and MS/MS
Int. J. Mass Spectrom.
Time-of-flight mass spectrometers with multiply reflected ion trajectories
Int. J. Mass Spectrom. Ion Process.
Comet 67P/Churyumov–Gerasimenko, a true Kuiper belt comet as judged from its D/H in water
Science
The Ame2012 atomic mass evaluation (I)
Chin. Phys.
The Ame2012 atomic mass evaluation (II)
Chin. Phys.
ROSINA, Rosetta orbiter spectrometer for ion and neutral analysis
Space Sci. Rev.
Search for organic and volatile inorganic compounds in two surface samples from the Chryse Planitia region of Mars
Science
The organic-rich surface of comet 67P/Churyumov–Gerasimenko as seen by VIRTIS/Rosetta
Science
Discovery of heavy negative ions in Titan’s ionosphere
Geophys. Res. Lett.
TandEM: Titan and Enceladus mission
Exp. Astron.
Composition of Titan's ionosphere
Geophys. Res. Lett.
Organic molecules in the Sheepbed Mudstone, Gale Crater, Mars
J. Geophys. Res.: Planets
The solar wind ion composition spectrometer
Astron. Astrophys. Suppl. Ser.
COSAC, the cometary sampling and composition experiment on Philae
Space Sci. Rev.
Organic compounds on comet 67P/Churyumov–Gerasimenko revealed by COSAC mass spectrometry
Science
Mars Science Laboratory Mission and science investigation
Space Sci. Rev.
Comet 67P/Churyumov–Gerasimenko – close-up on dust particle fragments
Astrophys. J. Lett.
Formation of amino acids and nucleotide bases in a Titan atmosphere simulaton experiment
Astrobiology
The Orbitrap: a new mass spectrometer
J. Mass Spectrom.
Venera 11 and 12 mass spectrometry of the lower Venus atmosphere
Sov. Astron. Lett.
Mass spectrometry on the Venera 13 and 14 landers: preliminary results
Sov. Astron. Lett.
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