Simon Calcutt

Abstract:

Selected in 2019 as a NASA SIMPLEx mission, Lunar Trailblazer is in implementation for flight system delivery at the end of 2022. The mission's goal is to understand the form, abundance, and distribution of water on the Moon and the lunar water cycle. Lunar Trailblazer also collects data of candidate landing sites to inform planning for future human and robotic exploration of the Moon and evaluate the potential for in situ resource utilization. Lunar Trailblazer's two science instruments, the High-resolution Volatiles and Minerals Moon Mapper (HVM3) and the Lunar Thermal Mapper (LTM) provide simultaneous high-resolution spectral imaging data to map OH/water, crustal composition, and thermophysical properties from a 100pm 30 km lunar polar orbit. The ∼210-kg flight system deploys from an ESPA Grande and utilizes a ∼1000 m/s Deltamathrm{V} hydrazine chemical propulsion system, similar to that employed by GRAIL. Trailblazing elements include the novel state-of-the-art dataset collected at substantially reduced price point, fully geographically co-registered data products delivered to the Planetary Data System, planetary mission team demographics, Caltech campus mission operations, and student staffing of select mission ops roles. Lunar Trailblazer's pioneering development is providing key lessons learned for future planetary small spacecraft.

Abstract:

Seismometers deployed on the Moon by the Apollo astronauts from 1969 to 1972 detected moonquakes and impacts, and added to our understanding of the lunar interior. Several lunar missions are currently being planned, including the Commercial Lunar Payload Services (CLPS), the Lunar Geophysical Network, and the astronaut program Artemis. We propose a microseismometer for the Moon: the Silicon Seismic Package (SSP). The SSP’s sensors are etched in silicon, and are predicted to have a noise floor below 2 ´ 10-10 (m s-2) Hz between 0.3 and 3 Hz (similar to the Apollo instruments between 0.3 and 0.5 Hz, and better than Apollo above 0.5 Hz). The SSP will measure horizontal and vertical motion with the three sensors in a triaxial configuration. The instrument is robust to high shock and vibration and has an operational range from -80°C to +60°C, allowing deployment under harsh conditions. The first-generation version of this sensor, the SEIS-SP, was deployed on Mars in 2018 as part of the InSight mission’s seismic package. We will reconfigure the seismometer for the lower gravity of the Moon. We estimate that a single SSP instrument operating for one year would detect around 74 events above a signal-to-noise ratio of 2.5, as well as an additional 500+ above the noise floor. A mission lasting from lunar dawn until dusk, carried on a CLPS lander, could test the instrument in situ, and provide invaluable information for an extensive future network.

Abstract:

We describe the capabilities, radiometric stability, and calibration of a custom vacuum environment chamber capable of simulating the near-surface conditions of airless bodies. Here we demonstrate the collection of spectral measurements of a suite of fine particulate asteroid analogs made using the Planetary Analogue Surface Chamber for Asteroid and Lunar Environments (PASCALE) under conditions like those found on Earth and on airless bodies. The sample suite includes anhydrous and hydrated physical mixtures, and chondritic meteorites (CM, CI, CV, CR, and L5) previously characterized under Earth- and asteroid-like conditions. And for the first time, we measure the terrestrial and extra-terrestrial mineral end members used in the olivine- and phyllosilicate-dominated physical mixtures under the same conditions as the mixtures and meteorites allowing us better understand how minerals combine spectrally when mixed intimately. Our measurements highlight the sensitivity of thermal infrared emissivity spectra to small amounts of low albedo materials and the composition of the sample materials. As the albedo of the sample decreases, we observe smaller differences between Earth- and asteroid-like spectra, which results from a reduced thermal gradient in the upper hundreds of microns in the sample. These spectral measurements can be compared to thermal infrared emissivity spectra of asteroid (101955) Bennu's surface in regions where similarly fine particulate materials may be observed to infer surface compositions.

Abstract:

Launched onboard the BepiColombo Mercury Planetary Orbiter (MPO) in October 2018, the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) is on its way to planet Mercury. MERTIS consists of a push-broom IR-spectrometer (TIS) and a radiometer (TIR), which operate in the wavelength regions of 7-14 μm and 7-40 μm, respectively. This wavelength region is characterized by several diagnostic spectral signatures: the Christiansen feature (CF), Reststrahlen bands (RB), and the Transparency feature (TF), which will allow us to identify and map rock-forming silicates, sulfides as well as other minerals. Thus, the instrument is particularly well-suited to study the mineralogy and composition of the hermean surface at a spatial resolution of about 500 m globally and better than 500 m for approximately 5-10% of the surface. The instrument is fully functional onboard the BepiColombo spacecraft and exceeds all requirements (e.g., mass, power, performance). To prepare for the science phase at Mercury, the team developed an innovative operations plan to maximize the scientific output while at the same time saving spacecraft resources (e.g., data downlink). The upcoming fly-bys will be excellent opportunities to further test and adapt our software and operational procedures. In summary, the team is undertaking action at multiple levels, including performing a comprehensive suite of spectroscopic measurements in our laboratories on relevant analog materials, performing extensive spectral modeling, examining space weathering effects, and modeling the thermal behavior of the hermean surface.