Linear Ion Trap Mass Spectrometer (LITMS) Instrument Field and Laboratory Tests as Part of the ARADS Field Campaigns

The highly compact Linear Ion Trap Mass Spectrometer (LITMS), developed at NASA Goddard Space Flight Center, combines Mars-ambient laser desorption-mass spectrometry (LD-MS) and pyrolysis-gas chromatography-mass spectrometry (GC-MS) through a single, miniaturized linear ion trap mass analyzer. The LITMS instrument is based on the Mars Organic Molecule Analyser (MOMA) investigation developed for the European Space Agency's ExoMars Rover Mission with further enhanced analytical features such as dual polarity ion detection and a dual frequency RF (radio frequency) power supply allowing for an increased mass range. The LITMS brassboard prototype underwent an extensive repackaging effort to produce a highly compact system for terrestrial field testing, allowing for molecular sample analysis in rugged planetary analog environments outside the laboratory. The LITMS instrument was successfully field tested in the Mars analog environment of the Atacama Desert in 2019 as part of the Atacama Rover Astrobiology Drilling Studies (ARADS) project, providing the first in situ planetary analog analysis for a high-fidelity, flight-like ion trap mass spectrometer. LITMS continued to serve as a laboratory tool for continued analysis of natural Atacama samples provided by the subsequent 2019 ARADS final field campaign.

The Mars Organic Molecule Analyzer (MOMA) Instrument: Characterization of Organic Material in Martian Sediments

The Mars Organic Molecule Analyzer (MOMA) instrument onboard the ESA/Roscosmos ExoMars rover (to launch in July, 2020) will analyze volatile and refractory organic compounds in martian surface and subsurface sediments. In this study, we describe the design, current status of development, and analytical capabilities of the instrument. Data acquired on preliminary MOMA flight-like hardware and experimental setups are also presented, illustrating their contribution to the overall science return of the mission. Key Words: Mars-Mass spectrometry-Life detection-Planetary instrumentation. Astrobiology 17, 655-685.

Unique capabilities of AC frequency scanning and its implementation on a Mars Organic Molecule Analyzer linear ion trap

AC frequency scanning in quadrupole ion traps enables unique scan modes.

A novel planar ion funnel design for miniature ion optics

The novel planar ion funnel (PIF) design presented in this article emphasizes simple fabrication, assembly, and operation, making it amenable to extreme miniaturization. Simulations performed in SIMION 8.0 indicate that ion focusing can be achieved by using a gradient of electrostatic potentials on concentric metal rings in a plane. A prototype was fabricated on a 35 × 35 mm custom-designed printed circuit board (PCB) with a center hole for ions to pass through and a series of concentric circular metal rings of increasing diameter on the front side of the PCB. Metal vias on the PCB electrically connected each metal ring to a resistive potential divider that was soldered on the back of the PCB. The PIF was tested at 5.5 × 10(-6) Torr in a vacuum test setup that was equipped with a broad-beam ion source on the front and a micro channel plate (MCP) ion detector on the back of the PIF. The ion current recorded on the MCP anode during testing indicated a 23× increase in the ion transmission through the PIF when electric potentials were applied to the rings. These preliminary results demonstrate the functionality of a 2D ion funnel design with a much smaller footprint and simpler driving electronics than conventional 3D ion funnels. Future directions to improve the design and a possible micromachining approach to fabrication are discussed in the conclusions.

Calibration of an in situ membrane inlet mass spectrometer for measurements of dissolved gases and volatile organics in seawater

Use of membrane inlet mass spectrometers (MIMS) for quantitative measurements of dissolved gases and volatile organics over a wide range of ocean depths requires characterization of the influence of hydrostatic pressure on the permeability of MIMS inlet systems. To simulate measurement conditions in the field, a laboratory apparatus was constructed for control of sample flow rate, temperature, pressure, and the concentrations of a variety of dissolved gases and volatile organic compounds. MIMS data generated with this apparatus demonstrated thatthe permeability of polydimethylsiloxane (PDMS) membranes is strongly dependent on hydrostatic pressure. For the range of pressures encountered between the surface and 2000 m ocean depths, the pressure dependent behavior of PDMS membranes could not be satisfactorily described using previously published theoretical models of membrane behavior. The observed influence of hydrostatic pressure on signal intensity could, nonetheless, be quantitatively modeled using a relatively simple semiempirical relationship between permeability and hydrostatic pressure. The semiempirical MIMS calibration developed in this study was applied to in situ underwater mass spectrometer (UMS) data to generate high-resolution, vertical profiles of dissolved gases in the Gulf of Mexico. These measurements constitute the first quantitative observations of dissolved gas profiles in the oceans obtained by in situ membrane inlet mass spectrometry. Alternative techniques used to produce dissolved gas profiles were in good accord with UMS measurements.