The Lunar Polar Hydrogen Mapper (LunaH-Map) Mission

The Lunar Polar Hydrogen Mapper (LunaH-Map) mission will map hydrogen enrichments within permanently shadowed regions at the lunar south pole using a miniature neutron spectrometer. While hydrogen enrichments have been identified regionally from previous orbital missions, the spatial extent of these regions are often below the resolution of the neutron instruments that have flown on lunar missions. LunaH-Map will enter into an elliptical, low altitude perseline orbit which will enable the mission to spatially isolate and constrain the hydrogen enrichments within permanently shadowed regions. LunaH-Map will use a solid iodine ion propulsion system, X-Band radio communications through the NASA Deep Space Network, star tracker, C&DH and EPS systems from Blue Canyon Technologies, solar arrays from MMA Designs, LLC, mission design and navigation by KinetX. Spacecraft systems design, integration, qualification, test and mission operations are performed by Arizona State University

LunaH-Map: Revealing Lunar Water with a New Radiation Sensor Array

A new type of neutron and gamma-ray spectrometer called the Miniature Neutron Spectrometer (Mini-NS) has been developed, assembled, qualified and delivered as part of the Lunar Polar Hydrogen Mapper (LunaH-Map) cubesat mission. The LunaH-Map spacecraft is currently manifested as a secondary payload on the Space Launch System (SLS) Artemis-1 rocket. LunaH-Map will deploy from Artemis-1 and enter a low altitude perilune elliptical orbit around the Moon. The Mini-NS will measure the lunar epithermal neutron albedo, and measurements around perilune will be used to produce maps of hydrogen enrichments and depletions across the lunar South Pole region including both within and outside of permanently shadowed regions (PSRs). The Min-NS was designed to achieve twice the epithermal neutron count rate of the Lunar Prospector Neutron Spectrometer (LP-NS). The instrument response was characterized through the collection of pre-flight neutron counting data with a Cf-252 neutron source at Arizona State University across hundreds of power cycles, as well as across the expected temperature range. The instrument spatial response was characterized at the Los Alamos National Laboratories (LANL) Neutron Free In-Air Facility. The LunaH-Map Mini-NS was designed to fit within the cubesat form-factor and uses two detectors with eight sensor heads that can be operated independently. For future missions with different science goals that can be achieved with epithermal neutron detection, the number of Mini-NS sensor heads can easily be modified without requiring a complete re-design and re-qualification

Flight Development of Iodine BIT-3 RF Ion Propulsion System for SLS EM-1 CubeSats

Busek previously developed a 3cm RF ion thruster known as BIT-3 that was the world\u27s first iodinefueled gridded ion thruster. The 60W prototype thruster completed a 500-hour endurance test on iodine and was shown capable of delivering 1.3mN thrust and 3200sec Isp nominally, excluding neutralizer flow. This exceptional performance, combined with the many benefits of iodine propellant, has led to a number of CubeSat flight opportunities on NASA\u27s SLS EM-1 mission. The first confirmed EM-1 mission for the thruster is onboard the 6U Lunar IceCube spacecraft that is being developed by Morehead State University and its partners. This paper will describe the technological advances made to date on the BIT-3 system and the remaining development to flight readiness. Specifically it will include updates on the thruster design and power optimization, measured thruster and Isp performance with an innovative RF cathode neutralizer, and details regarding the flight iodine feed system and power electronics module. In addition, it will include an overview of the BIT-3 system\u27s digital command/control structure and mechanical interfaces in the context of the Lunar IceCube bus. The BIT-3 ion thruster\u27s ability to use iodine as propellant is a huge game-changer for CubeSats, as iodine is stored in high-density solid form (4.9g/cc vs. xenon\u27s 1.95g/cc at 2000psi) devoid of bulky pressure vessels. The solid storage property makes iodine-fueled propulsion systems safe and facilitates compliance with range safety requirements, which is especially important for secondary payloads. The sub-Torr storage vapor pressure also allows for thin-walled, lightweight and conformal tanks that could further reduce the overall volume and mass budget impact without compromising performance. For example, Lunar IceCube\u27s tightly packaged 2U iodine BIT-3 system can provide more than 2km/s delta-V to a 6U/14kg CubeSat for lunar or other deep-space missions. Such unprecedented capability can help increase the practicality and appeal of CubeSats alike, ultimately gaining acceptance within the science community as a viable platform for future robotic exploration missions to destinations currently unachievable with small satellites

Deep UV photon-counting detectors and applications

Photon counting detectors are used in many diverse applications and are well-suited to situations in which a weak signal is present in a relatively benign background. Examples of successful system applications of photon-counting detectors include ladar, bio-aerosol detection, communication, and low-light imaging. A variety of practical photon-counting detectors have been developed employing materials and technologies that cover the waveband from deep ultraviolet (UV) to the near-infrared. However, until recently, photoemissive detectors (photomultiplier tubes (PMTs) and their variants) were the only viable technology for photon-counting in the deep UV region of the spectrum. While PMTs exhibit extremely low dark count rates and large active area, they have other characteristics which make them unsuitable for certain applications. The characteristics and performance limitations of PMTs that prevent their use in some applications include bandwidth limitations, high bias voltages, sensitivity to magnetic fields, low quantum efficiency, large volume and high cost. Recently, DARPA has initiated a program called Deep UV Avalanche Photodiode (DUVAP) to develop semiconductor alternatives to PMTs for use in the deep UV. The higher quantum efficiency of Geiger-mode avalanche photodiode (GM-APD) detectors and the ability to fabricate arrays of individually-addressable detectors will open up new applications in the deep UV. In this paper, we discuss the system design trades that must be considered in order to successfully replace low-dark count, large-area PMTs with high-dark count, small-area GM-APD detectors. We also discuss applications that will be enabled by the successful development of deep UV GM-APD arrays, and we present preliminary performance data for recently fabricated silicon carbide GM-APD arrays.Defence Advanced Research Projects Agency (contract FA8721-05-C-0002