Stephanie Getty, Lucy Lim, Andrej Grubisic, Adrian Southard, Jerome Ferrance, Manuel Balvin, Xiang Li, Timothy Cornish, Jamie Elsila, Larry Hess, Carl Kotecki, John Hagopian, William Brinckerhoff
A number of new instrument capabilities are currently in maturation for future in situ use on planetary science missions. Moving beyond the impressive in situ instrumentation already operating in planetary environments beyond Earth will enable the next step in scientific discovery. The approach for developing beyond current instrumentation requires a careful assessment of science-driven capability advancement. To this end, two examples of instrument technology development efforts that are leading to new and important analytical capabilities for in situ planetary science will be discussed: (1) an instrument prototype enabling the interface between liquid separation techniques and laser desorption/ionization mass spectrometry and (2) an addressable excitation source enabling miniaturized electron probe microanalysis for elemental mapping of light and heavy elements.
Future astrobiology missions will focus on planets with significant astrochemical or potential astrobiological features, such as small, primitive bodies and the icy moons of the outer planets that may host diverse organic compounds. We have made significant progress in the laser desorption/ionization mass spectrometry area with advancement in the two-step laser tandem mass spectrometer (L2MS) instrument to deconvolve complex organic signatures. In this paper we will describe our development effort on a new laser architecture for the L2MS instrument. The laser provides two discrete mid-infrared and ultraviolet wavelengths on a single laser bench with a straightforward path toward space deployment.
Recent visible wavelength observations of Multiwalled Carbon Nanotubes (MWCNT) coatings have revealed
that they represent the blackest materials known in nature with a Total Hemispherical Reflectance (THR) of
less than 0.25%. This makes them exceptionally good as absorbers, with the potential to provide order-ofmagnitude
improvement in stray-light suppression over current black surface treatments when used in an optical
system. Here we extend the characterization of this class of materials into the infrared spectral region to further
evaluate their potential for use on instrument baffles for stray-light suppression and to manage spacecraft thermal
properties through radiant heat transfer process. These characterizations will include the wavelength-dependent
Total Hemispherical Reflectance (THR) properties in the mid- and far-infrared spectral regions (2-110 μm).
Determination of the temperature-dependent emittance will be investigated in the temperature range of 40 to
300 K. These results will be compared with other more conventional black coatings such as Acktar Fractal Black
or Z306 coatings among others.
The Bidirectional Reflectance Distribution Function (BRDF) at visible and near-infrared wavelengths of
Multi-Wall Carbon NanoTubes (MWCNTs) grown on substrate materials are reported. The BRDF measurements
were performed in the Diffuser Calibration Laboratory (DCaL) at NASA's Goddard Space Flight Center, and results
at 500nm and 900nm are reported here. In addition, the 8° Directional/Hemispherical Reflectance of the samples is
reported from the ultraviolet to shortwave infrared. The 8° Directional/Hemispherical Reflectance was measured in
the Optics Branch at NASA's Goddard Space Flight Center. The BRDF was measured at 0° and 45° incident angles
and from -80° to +80° scatter angles using a monochromatic source. The optical scatter properties of the samples as
represented by their BRDF were found to be strongly influenced by the choice of substrate. As a reference, the
optical scattering properties of the carbon nanotubes are compared to the BRDF of Aeroglaze Z306TM and Rippey
Ultrapol IVTM, a well-known black paint and black appliqué, respectively. The possibility, promise, and challenges
of employing carefully engineered carbon nanotubes in straylight control applications particularly for spaceflight
instrumentation is also discussed.
Observations of the Earth are extremely challenging; its large angular extent floods scientific instruments with high flux
within and adjacent to the desired field of view. This bright light diffracts from instrument structures, rattles around and
invariably contaminates measurements. Astrophysical observations also are impacted by stray light that obscures very
dim objects and degrades signal to noise in spectroscopic measurements. Stray light is controlled by utilizing low
reflectance structural surface treatments and by using baffles and stops to limit this background noise. In 2007 GSFC
researchers discovered that Multiwalled Carbon Nanotubes (MWCNTs) are exceptionally good absorbers, with potential
to provide order-of-magnitude improvement over current surface treatments and a resulting factor of 10,000 reduction in
stray light when applied to an entire optical train. Development of this technology will provide numerous benefits
including: a.) simplification of instrument stray light controls to achieve equivalent performance, b.) increasing
observational efficiencies by recovering currently unusable scenes in high contrast regions, and c.) enabling low-noise
observations that are beyond current capabilities. Our objective was to develop and apply MWCNTs to instrument
components to realize these benefits. We have addressed the technical challenges to advance the technology by tuning
the MWCNT geometry using a variety of methods to provide a factor of 10 improvement over current surface treatments
used in space flight hardware. Techniques are being developed to apply the optimized geometry to typical instrument
components such as spiders, baffles and tubes. Application of the nanostructures to alternate materials (or by contact
transfer) is also being investigated. In addition, candidate geometries have been tested and optimized for robustness to
survive integration, testing, launch and operations associated with space flight hardware. The benefits of this technology
extend to space science where observations of extremely dim objects require suppression of stray light.
A new nanoscale electric field sensor was developed for studying triboelectric charging in
terrestrial and Martian dust devils. This sensor is capable to measure the large electric fields for
large dust devils without saturation. However, to quantify the electric charges and the field
strength it is critical to calibrate the mechanical stiffness of the sensor devices. We performed a
technical feasibility study of the Nano E-field Sensor stiffness by a non-contact stiffness
measurement method. The measurement is based on laser Doppler vibrometer measurement of
the thermal noise due to energy flunctuations in the devices. The experiment method provides a
novel approach to acquire data that is essential in analyzing the quantitative performance of the
E-field Nano Sensor. To carry out the non-contact stiffness measurement, we fabricated a new
Single-Walled Carbon Nanotube (SWCNT) E-field sensor with different SWCNTs suspension
conditions. The power spectra of the thermal induced displacement in the nano E-field sensor
were measured at the accuracy of picometer. The power spectra were then used to derive the
mechanical stiffness of the sensors. Effect of suspension conditions on stiffness and sensor
sensitivty was discussed. After combined deformation and resistivity measurement, we can
compare with our laboratory testing and field testing results. This new non-contact measurement
technology can also help to explore to other nano and MEMS devices in the future.
Carbon materials, including carbon nanotubes and nanostructured diamond, have been investigated for over a decade for
application to electron field emission devices. In particular, they have been investigated because of their low power
consumption, potential for miniaturization, and robustness as field emission materials, all properties that make
nanocarbon materials strong candidates for applications as long life electron sources for mass spectrometers for space
exploration, where electron sources are exposed to harsh environments, .A miniaturized mass spectrometer under
development for in situ chemical analysis on the moon and other planetary environments requires a robust, long-lived
electron source, to generate ions from gaseous sample using electron impact ionization. To this end, we have explored
the field emission properties and lifetime of nitrogen-incorporated ultrananocrystalline diamond films. We will present
recent results revealing that UNCD films with nitrogen incorporation during growth (N-UNCD) yield stable/high fieldinduced
electron emission in high vacuum for up to 1000 hours.
KEYWORDS: Electric field sensors, Sensors, Gold, Microelectromechanical systems, Silicon, Electrodes, Packaging, Single walled carbon nanotubes, Scanning electron microscopy, Calibration
A new nanoscale electric field sensor was developed for studying triboelectric charging in terrestrial and Martian dust
devils. The sensor was fabricated using MEMS techniques, integrated at the system level, and deployed during a dust
devil field campaign. The two-terminal piezoresistive sensor consists of a micron-scale network of suspended singlewalled
carbon nanotubes (SWCNTs) that are mechanically coupled to a free-standing electrically conductor.
Electrostatic coupling of the conductor to the electric field is expected to produce a deflection of the conductor and a
corresponding change in nanotube device resistance, based on the known piezoresistive properties of SWCNTs. The
projected device performance will allow measurement of the large electric fields for large dust devils without saturation.
With dimensions on the 100 μm scale and power consumption of only tens of nW, the sensor features dramatically
reduced mass, power, and footprint. Recent field testing of the sensor demonstrated the robustness of suspended
SWCNT devices to temperature fluctuations, mechanical shock, dust, and other environmental factors.
A carbon nanotube (CNT) field emission electron gun has been fabricated and assembled as an electron impact
ionization source for a miniaturized time-of-flight mass spectrometer (TOF-MS). The cathode consists of a patterned
array of CNT towers grown by catalyst-assisted thermal chemical vapor deposition. An extraction grid is precisely
integrated in close proximity to the emitter tips (20-35 μm spacing), and an anode is located at the output to monitor the
ionization beam current. Ultra-clean MEMS integration techniques were employed in an effort to achieve three
improvements, relative to previous embodiments: reduced extraction voltage during operation to be resonant with gas
ionization energies, enhanced current transmission through the grid, and a greater understanding of the fundamental
current fluctuations due to adsorbate-assisted tunneling. Performance of the CNT electron gun will be reported, and
implications for in situ mass spectrometry in planetary science will be discussed.
The lifetime of a patterned carbon nanotube film is evaluated for use as the cold cathode field emission ionization source
of a miniaturized mass spectrometer. Emitted current is measured as a function of time for varying partial pressures of
nitrogen gas to explore the robustness and lifetime of carbon nanotube cathodes near the expected operational voltages
(70-100 eV) for efficient ionization in mass spectrometry. As expected, cathode lifetime scales inversely with partial
pressure of nitrogen. Results are presented within the context of previous carbon nanotube investigations, and
implications for planetary science mass spectrometry applications are discussed.
We are implementing nano- and micro-technologies to develop a miniaturized electron impact ionization mass
spectrometer for planetary science. Microfabrication technology is used to fabricate the ion and electron optics, and a
carbon nanotube (CNT) cathode is used to generate the ionizing electron beam. Future NASA planetary science
missions demand miniaturized, low power mass spectrometers that exhibit high resolution and sensitivity to search for
evidence of past and present habitability on the surface and in the atmosphere of priority targets such as Mars, Titan,
Enceladus, Venus, Europa, and short-period comets. Toward this objective, we are developing a miniature, high
resolution reflectron time-of-flight mass spectrometer (Mini TOF-MS) that features a low-power CNT field emission
electron impact ionization source and microfabricated ion optics and reflectron mass analyzer in a parallel-plate
geometry that is scalable. Charged particle electrodynamic modeling (SIMION 8.0.4) is employed to guide the iterative
design of electron and ion optic components and to characterize the overall performance of the Mini TOF-MS device via
simulation. Miniature (< 1000 cm3) TOF-MS designs (ion source, mass analyzer, detector only) demonstrate simulated
mass resolutions > 600 at sensitivity levels on the order of 10-3 cps/molecule N2/cc while consuming 1.3 W of power and
are comparable to current spaceflight mass spectrometers. Higher performance designs have also been simulated and
indicate mass resolutions ~1000, though at the expense of sensitivity and instrument volume.
Solar system exploration and the anticipated discovery of biomarker molecules is driving the development of a new
miniature time-of-flight (TOF) mass spectrometer (MS). Space flight science investigations become more feasible
through instrument miniaturization, which reduces size, mass, and power consumption. However, miniaturization of
space flight mass spectrometers is increasingly difficult using current component technology. Micro electro mechanical
systems (MEMS) and nano electro mechanical systems (NEMS) technologies offer the potential of reducing size by
orders of magnitude, providing significant system requirement benefits as well. Historically, TOF mass spectrometry
has been limited to large separation distances as ion mass analysis depends upon the ion flight path. Increased TOF MS
system miniaturization may be realized employing newly available high speed computing electronics, coupled with
MEMS and NEMS components. Recent efforts at NASA Goddard Space Flight Center in the development of a
miniaturized TOF mass spectrometer with integral MEMS and NEMS components are presented. A systems overview,
design and prototype, MEMS silicon ion lenses, a carbon nanotube electron gun, ionization methods, as well as
performance data and relevant applications are discussed.
A cold cathode field emission electron gun (e-gun) based on a patterned carbon nanotube (CNT) film has been fabricated
for use in a miniaturized reflectron time-of-flight mass spectrometer (RTOF MS), with future applications in other
charged particle spectrometers, and performance of the CNT e-gun has been evaluated. A thermionic electron gun has
also been fabricated and evaluated in parallel and its performance is used as a benchmark in the evaluation of our CNT
e-gun. Implications for future improvements and integration into the RTOF MS are discussed.
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