The lunar environment is known to be characterized by complex interactions between plasma, the exosphere, dust, and the surface. However, our understanding of the environment is limited due to the lack of experimental evidence. Here, we propose a small, low-cost mission to characterize the dust and exosphere environment of the Moon. Named the Limb Pathfinder (LimPa), this is a proof-of-concept mission aimed toward understanding the coupling between plasma, dust, and tenuous neutral atmosphere. The LimPa mission was proposed to a call for the Small Mission to the Moon issued by European Space Agency in 2023. LimPa is designed to examine the dust exosphere above the lunar polar regions by using an utterly novel remote-sensing technique to measure the solar wind hydrogen atoms-the solar wind protons that are neutralized to hydrogen atoms. Its goals are (1) to detect for the first time the neutralized solar wind hydrogen produced by exospheric gas and levitated dust; (2) to measure the height profiles of the levitated dust and exospheric gas densities; and (3) to determine the emission mechanism of the horizon glow. Our baseline design of the LimPa mission is a 12U CubeSat. Three highly matured instruments are used: an energetic neutral atom camera, a proton sensor, and a camera system. The LimPa CubeSat is proposed to be inserted into a circular lunar polar orbit, with an altitude of 100 km as a baseline. The Sun-pointing attitude will allow measurements of neutralized solar wind that are produced by the exosphere and dust grains above the polar regions. The nominal lifetime is for 3 months as a pathfinder mission. The LimPa mission will open a new window to remote characterization of the lunar dust exosphere environment above the poles, and will demonstrate that this monitoring can be achieved with a simple and low-cost instrument system and spacecraft operation. The concept to be proven by the LimPa mission will enable long-term monitoring of the fragile dust exosphere environment, which substantially impacts on lunar exploration and will be significantly altered by human activities.

Determining the abundance, origin, movement, and storage of water on the Moon with far greater certainty is an ongoing primary goal of lunar exploration. Essential constraints would come from measuring water absorption features repeatedly over the same swaths as a function of time of day from a nearly polar orbit with equatorial periapsis, the goal proposed for BIRCHES (Broadband InfraRed Compact High Resolution Exploration Spectrometer) on the original Lunar Ice Cube mission. Establishing these constraints would be the goal of CLEW, Compact Lunar Explorer for Water, the instrument described in this paper. CLEW has mass, volume, and power requirements comparable but performance, including imaging capability, greatly improved relative to BIRCHES. High heritage CLEW would utilize the NASA GSFC Compact Thermal Imager (CTI), state of the art self-calibrating focal plane array combined with SIDECAR ASIC instrument electronics, combined with an active cooling system and optics similar to CLuHME (Compact Lunar Hydration and Mineralogy Experiment). The platform would likely be significantly more robust and 'roomy', due to availability of high-performance thermal protection components and a larger 12U platform. Planned addition of a compact context camera would enhance image interpretation.

We investigated the ability of a three-band lidar instrument (with wavelengths of 532, 1064, and 1560 nm) to detect and quantify different types of regolith +/- water ice mixtures for both mare and highlands regions. A variety of samples were spectrally characterized, focusing on variables such as type of lunar regolith (simulant, lunar meteorite, highland vs mare), grain size (<45 mu m, 45-1000 mu m, <1 mm), water ice surface coverage and porosity of regolith (discontinuous, continuous, packed), and water ice percentages in intimate mixtures vs areal mixtures. Spectral metrics included absolute reflectance (532, 1064, 1560 nm) and reflectance ratios (1560/532, 1064/532, 1560/1064 nm). The ability to detect water ice in the presence of different types of regolith is critically dependent on the optical properties of end members, the selected wavelength, and the physical nature of the samples, such as grain size and areal vs intimate mixtures. Given the differences in the spectroscopic properties of the end members, both absolute reflectance and reflectance ratios have different predictive powers and both are required for robust analysis. The 1560 nm region is the most sensitive of the three wavelength regions to water ice content, as it falls well within a major water ice absorption band. Spectral contrast affects the ability to detect water ice. It is most sensitive for characterizing water ice + highland materials because the latter are brighter than water ice in this wavelength region. Powdered lunar materials are red-sloped across the 532 to 1064 to 1560 nm regions. By contrast, water ice shows a large downturn in reflectance between 1064 and 1560 nm. Detection limits for water ice in many situations can be as low as 2% and are lower for areal vs intimate mixtures. We found that porosity and angle of incidence with the surface have only minor effects on spectral reflectance properties of regolith. Further confirmation of water ice could be realized by comparing lidar data acquired by transects across permanently-shadowed regions and seeing how absolute reflectance and reflectance ratios vary between sunlit and adjacent shadowed regions. If it is known or assumed that regolith properties do not change as one enters a PSR, with the exception of the presence of surficial water ice, changes in reflectivity and reflectance ratios could provide compelling evidence for the presence of water ice.

Technological advancements have revolutionized the space industry, facilitating deep space exploration using CubeSats. One objective is to locate potential life-support elements, such as water, on extraterrestrial planets. Water possesses a distinct spectral signature at 183 GHz, useful in remote sensing and environmental monitoring applications. Detecting this signature provides crucial information about water and ice presence and distribution on celestial bodies, aiding future exploration and colonization efforts. Mostly in space remote sensing uses corrugated horn antennae due to high gain and radiation patterns but fabrication of corrugated antenna is very challenging or even impossible in some cases. To ease this challenge, in our research we propose ideas to transform a corrugated horn antenna into a smooth-walled design by using MATLAB Cubic smoothing Splines algorithms. We compare simulation results between smooth-walled and corrugated antennas, and we can see some improvements in insertion losses, Voltage Standing Wave ratio (VSWR), and gain. We also manufactured this 183 GHz antenna using a commercially available 3D printer by utilizing Acrylonitrile Butadiene Styrene (ABS) material. The antenna surface was then coated with a thin layer of copper using conductive paint. In the end, we practically evaluate smooth-walled antenna functionality and compare it with the theriacal results. Validating the antenna's functionality proposes a cost-effective and accessible production method to be used in a CubeSat engineering model or university students' project.

Recently, there is a renewed interest in Earth Observation (EO) of the cryosphere as a proxy of global warming, soil moisture for agriculture and desertification studies, and biomass for carbon storage. Global Navigation Satellite System-Reflectometry (GNSS-R) and L-band microwave Radiometry have been used to perform these measurements. However, it is expected that the combination of both can largely improve current observations. (3)Cat-4 mission aims at addressing this technology challenge by integrating a combined GNSS-R and Microwave Radiometer payload into a 1-Unit CubeSat. One of the greatest challenges is the design of an antenna that respects the envelope and stowage requirements of 1-Unit CubeSat, being able to work in the different frequency bands: Global Positioning System (GPS) L1-band (1575 MHz), GPS L2-band (1227 MHz), and microwave radiometry at 1400-1427 MHz. After a trade-off analysis, a helix antenna was found to be the most suitable option. This antenna has 11 turns equally distributed with 68.1 mm of diameter. This design generates an antenna with 506 mm of axial length, providing the maximum radiation gain in the endfire direction. Additionally, a counterweight is added at the tip of the antenna to enhance the directivity, and it is used as gravity gradient technique. The deployment of this antenna in vacuum and extreme temperature conditions is the greatest mechanical challenge that needs to be addressed for the success of the mission. This work presents a mechanical solution that enables to deploy the helix antenna from 25.5 mm (stowed configuration) to the final 506 mm (deployed configuration). By sequentially deploying different parts of the antenna, the final configuration is reached without impacting the attitude pointing of the CubeSat. This is accomplished using dyneema lines that are melted sequentially by commands. In addition, the deployment velocity, acceleration, and waving are presented as part of its characterization. The current test results in a Thermal Vacuum Chamber indicate also that the deployment can be achieved in -35 degrees C. The (3)Cat-4 CubeSat, with the L-band helix antenna, will be launched in Q4 2020 as part of the ''Fly Your Satellite!'' program of the European Space Agency (ESA).

The Lunar Volatile and Mineralogy Mapping Orbiter (VMMO) comprises a low-cost 12U Cubesat with deployable solar arrays, X-Band/UHF communications, option of electric or chemical propulsion, the Lunar Volatiles and Mineralogy Mapper (LVMM) payload, and an optional GPS receiver technology demonstrator. The LVMM facilitates three operational modes: Active mode using illumination of the lunar surface at 532nm, 1064nm and 1560nm to enable volatiles mapping during the lunar night and within Permanently Shadowed Regions (PSRs); Passive mode during the lunar day with spectral channels at 300nm, 532nm, 690nm, 1064nm and 1560nm for mapping lunar surficial ilmenite (FeTiO3); and a Communications mode for an optical data downlink demonstration at 1560nm. Previous lunar missions have detected the presence of water-ice in the lunar South Pole region. However, there is considerable uncertainty with regards to its distribution within and across the lunar surface. A number of planned future missions will further map water ice deposits, but the spatial resolution of these observations is expected to be on the order of kilometers. The LVMM using single-mode fiber lasers can improve the special resolution of the mapping to 10s of meters. VMMO has completed the Phase A study with ESA. This paper discusses the baseline LVMM payload design and its dual-use applications for both the stand-off mapping of lunar volatiles and a high-speed optical data link demonstration. In particular, the supporting fiber-laser technology readiness was advanced through ground qualification.

JPL is developing the Lunar Flashlight (LF) CubeSat mission, a 6U 14 kg spacecraft whose objective is to demonstrate new technology and measure potential surface water ice deposits in the permanently shadowed region (PSR) of the moon in preparation of future possible human lunar exploration. This mission will become the first interplanetary CubeSat to orbit the Moon. It uses a new green propulsion system as well as an instrument with spectrally tuned IR laser technology to search for volatiles in a specific region of the moon. The Guidance, Navigation and Control (GNC) system is crucial for delivering the spacecraft from Earth into Lunar orbit and supporting scientific measurements. Due to the challenging lunar orbit insertion and high tip off rate out of launch vehicle's dispenser, the initial design concept using solar sail propulsion accompanied with small commercial-on-the-shelf (COTS) reaction wheels was abandoned mid-course and replaced by a green propulsion system along with larger reaction wheels, both newly developed for LF. However, using thrusters for the small CubeSat created an additional challenge of controlling the spacecraft attitude. The story of the GNC system development, qualifications, technical challenges encountered, and lessons learned are discussed in this paper.

Lunar Ice Cube, scheduled to be launched on ARTEMIS I in late 2021, is a deep space cubesat mission with the goals of demonstrating 1) a cubesat-scale instrument (BIRCHES) capable of addressing NASA HEOMD Strategic Knowledge Gaps related to lunar volatile distribution (abundance, location, and transportation physics of water ice), and 2) cubesat propulsion, via the Busek BIT 3 RF Ion engine. The mission will also demonstrate the AIM/IRIS microcryocooler for the first time in deep space. BIRCHES integration is nearly complete, with several changes made to the thermal design to improve detector performance. Final preflight instrument testing and calibration, our ongoing concern to be emphasized here, have been delayed due to the mandated closure rules of NASA facilities. Lunar Ice Cube, along with two other cubesats deployed from ARTEMIS I, Lunar Flashlight and LunaH-Map, will be the first deep cubesat missions to deliver science data to the Planetary Data System.

Lunar Flashlight (LF) is an innovative National Aeronautics and Space Administration (NASA) CubeSat mission that is dedicated to quantifying and mapping the water ice harbored in the permanently shadowed craters of the lunar South Pole. The primary goal is to understand the lunar resource potential for future human exploration of the Moon. To this end, the LF spacecraft will carry an active multi-band reflectometer, based on an optical receiver aligned with four high-power diode lasers emitting in the 1 to 2-m shortwave infrared band, to measure the reflectance of the lunar surface from orbit near water ice absorption peaks. We present the detailed optical, mechanical, and thermal design of the receiver, which is required to fabricate this instrument within very demanding CubeSat resource allocations. The receiver has been optimized for solar stray light rejection from outside its field of view, and utilizes a 70 x 70-mm, aluminum, off-axis paraboloidal mirror with a focal length of 70 mm, which collects the reflected light from the Moon surface onto a single-pixel InGaAs detector with a 2-mm diameter, hence providing a 20-mrad field of view. The characterization of the flight receiver is also presented, and the results are in agreement with the expected performance obtained from simulations. Planned to be launched by NASA on the first Space Launch System (SLS) test flight, this highly mass-constrained and volume-constrained instrument payload will demonstrate several firsts, including being one of the first instruments onboard a CubeSat performing science measurements beyond low Earth orbit, and the first planetary mission to use multi-band active reflectometry from orbit.

Lunar Ice Cube (LIC) is one of 13 6U cubesats that will be deployed by EM1 in cislunar space. LIC along with Lunar Flashlight and LunaH-Map, all focused on the search for volatiles but with very different payloads, will be the first deep space cubesats designed to address goals for both demonstrating new technologies and collecting scientific data. Effectively, as their developments are occurring in parallel, they are acting as prototypes for future deep space cubesats missions. One useful outcome of this `experiment' is to evolve a working paradigm for the development and operation of compact, cost-capped, standardized (supporting subsystems) spacecraft to serve the needs of diverse user communities. The lunar ice cube mission was developed as the test case in a GSFC R&D study to determine whether the cubesat paradigm could be applied to deep space, science requirements driven missions, and BIRCHES was its payload. Here, we present the design and describe the ongoing development, and testing, in the context of the challenges of using the cubesat paradigm to fly a broadband IR spectrometer in a 6U platform, including a very harsh environment, minimal funding and extensive need for leveraging existing assets and relationships on development, and minimum command and telemetry bandwidth translating into simplified or canned operation and the collection of only essential data.