Our group designs, builds and flies nuclear instruments to map hydration, elemental compositions, and decode planetary geology.
Our group builds and operates neutron & gamma-ray spectrometers for planetary exploration and terrestrial applications. We lead instrument development, calibration, Monte Carlo modeling, and science analysis for missions including LunaH-Map, Lunar-VISE, MSL Curiosity (DAN), and Mars 2020 Mastcam-Z. We collaborate with national labs and industry on active neutron techniques, including Associated Particle Imaging (API). Planetary geologists by training, we bring a geology-driven lens to nuclear-instrument design and implementation. Our group uses this scientific expertise to lead the US science data analysis of neutron data from the Mars Science Laboratory Curiosity rover.
Selected instruments we’ve developed or are developing. Images below are placeholders—click through for papers and technical details.
NASA PICASSO (2015). Developed and demonstrated in partnership with NASA Goddard Space Flight Center. Single-scintillator active neutron instrument concept for coincident neutron/gamma detection and compact planetary payloads. SINGR can be used with a pulsed neutron generator (PNG) to quantify hydration and burial depth. More details can be found Dr. Heffern's publication.
Built for the Lunar Polar Hydrogen Mapper (LunaH-Map) mission. Launched on SLS (Nov 2022); the Mini-NS acquired hours of lunar neutron & gamma-ray data during a lunar flyby. See the IEEE paper for technical details.
The Lunar-VISE GRNS uses LunaH-Map heritage with expanded capability to enable precise gamma-ray spectroscopy; optimized for K, Th, Fe measurements on the Lunar-VISE rover (launching 2028). Designed for improved elemental quantification and science traceability across the rover traverse.
Portable terrestrial system for soil moisture/hydration measurements to ~1 m depth in analog environments. Supports field campaigns and calibration datasets for planetary missions; hydration and soil moisture measurements deployable with lightweight power and logging.
Joint development for potential accommodation on a future Mars helicopter mission. JPL leads electronics; ASU leads sensor head and science. A miniaturized gamma-ray/neutron package targeted for measuring hydration on a low-mass aerial platforms with constrained power/thermal envelopes.
We are leading the design and qualification of the Lunar-VISE Gamma-Ray and Neutron Spectrometer (GRNS) that will map hydrogen and key elements (K, Th, Fe) at the Moon's Gruithuisen Domes. The instrument uses LunaH-Map–derived heritage and the Lunar-VISE GRNS science team leads the calibration/Monte Carlo modeling, as well as science operations planning. Launch targeted for 2028.
DAN measures subsurface hydrogen along Curiosity’s traverse. We analyze DAN active/passive neutron data to quantify hydration and bulk neutron absorption, relate them to topography and geology, and integrate with orbital datasets (thermal inertia, spectroscopy) to constrain surface–subsurface processes at Gale Crater.
We take neutron spectroscopy into the field to test retrievals of soil moisture/hydration and to validate models. Recent and planned campaigns span diverse terrains—including an international season at the Gobabeb dunes (Namibia)— to assess geometry, roughness, and layering effects and to inform future missions (e.g., Dragonfly-relevant sensing).
Our new Alpha-Particle-coincidence Pulsed Neutron Generator (API PNG) lab will support active neutron imaging, scattering, and capture-gamma experiments. We develop measurement techniques and calibrations for planetary, environmental, and materials applications, using CLYC/EJ-309 detectors and GEANT4/MCNP modeling to tie data to physics.
We contribute to ESA’s BepiColombo science, continue instrument and data roles with Mastcam-Z and Curiosity, and co-develop applied neutron sensing with partners. Current work includes hydrogen quantification for LHANS— Canada’s first planetary microrover—collaborating with the Canadian Space Agency, Bubble Technologies, and Canadensys, with design and ops practices adapted from LunaH-Map/Lunar-VISE.
LunaH-Map is a CubeSat mission that launched in November 2022, carrying a pioneering miniaturized neutron and gamma-ray spectrometer. The spacecraft successfully collected several hours of flyby data at the Moon, demonstrating a new class of planetary nuclear instrumentation. Our group leads the analysis of these data, focusing on hydration and elemental mapping of the lunar surface and polar regions.
PI, LunaH-Map · Co-I & Instrument Scientist, Lunar-VISE · Participating Scientist, MSL Curiosity
PhD student, ASU
Active neutron die-away modeling in complex geometries (walls, multi-walls, cave-like). Using MCNP6, shows that local relief shifts peak timing/magnitude and can produce late-time secondary peaks—implications for retrievals and for sensing surfaces beyond the nominal footprint.
PhD student, ASU
Research focuses on onboard estimation for active neutron spectroscopy—deriving physical parameters directly on the spacecraft to speed downlink decisions and enable autonomy. Recent work presented at the 2025 IEEE Aerospace Conference (Big Sky) demonstrates real-time estimation approaches tailored to pulsed-neutron instruments and planetary field scenarios.
PhD student, ASU
MSL/DAN analysis across the Clay–Sulfate Transition Zone: hydration (WEH) and bulk neutron absorption (BNACs) co-vary; links trends to CheMin mineralogy. Results point to excess water in amorphous phases or pore water; methods include elevation/site-drive correlations and SNR-filtered datasets.
PhD student, ASU
Investigates lunar hydrogen anomalies around Mons Mouton using LOLA/WAC/Diviner, NAC/ShadowCam, and LP/LRO neutron datasets. Maps micro-PSRs and crater depth–diameter to test whether Nobile’s PSRs supply volatile-rich materials—relevant to Artemis III science and ISRU targeting.
Researcher (UiO-CENSSS / EIDEL / ASU collaborator)
Active neutron imaging technologies for in-situ hydrogen detection and geochemical mapping at centimeter scales. API-based fast-neutron imaging with D–T generators and dual neutron/gamma detectors such as CLYC, combined with GEANT4 modeling, to achieve depth-resolved 3D regolith imaging and identification of hydrogen-rich regions. Lunar-VISE analog studies.
THERE ARE NO CURRENT OPENINGS Check back soon. Our group typically welcomes PhD students, postdocs, and undergrads interested in neutron/gamma spectroscopy, instrument calibration, with Mars, lunar & terrestrial applications.
How to apply: Email a 1-page statement + CV to chardgro@asu.edu.
Email: chardgro@asu.edu
Phone: (480) 727-2170
Address: ISTB4, Arizona State University, Tempe, AZ
Follow: LunaH-Map
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