IEEE - Aerospace and Electronic Systems - March 2020 - 3

LUNAR FLASHLIGHT: ILLUMINATING THE LUNAR SOUTH POLE
Lunar Flashlight is an innovative small NASA mission to be launched as a secondary payload on the
first Space Launch System, Artemis-1. This highly mass- and volume-constrained satellite will
demonstrate several technologies for NASA, including the use of "green" propellant, the ability for
a CubeSat-sized satellite to perform science measurements beyond low Earth orbit, and the first planetary mission to use multiband active reflectometry from orbit. Lunar Flashlight will detect and map
water ice in permanently shadowed regions of the lunar south pole by measuring surface reflectance at
multiple wavelengths. Mapping and quantifying lunar water ice addresses one of NASA's Strategic
Knowledge Gaps to understand the lunar resource potential for future human exploration of the Moon.

THE LUNAR POLAR HYDROGEN MAPPER CUBESAT MISSION
The Lunar Polar Hydrogen Mapper (LunaH-Map) mission will map the distribution of hydrogen
around the lunar South Pole using a miniature neutron spectrometer. The mission builds on a decade
of lunar science, which has revealed both regional and more localized enrichments of water ice near
the lunar poles. Localized enrichments are primarily within permanently shadowed regions (PSRs)
and craters throughout the South Pole. The spatial extent of these regions is often below the resolution
of previous neutron instruments that have flown on lunar missions. The neutron leakage spectrum
from planetary surfaces is primarily sensitive to hydrogen abundance in the top meter of regolith,
however, for neutron spectrometers with omnidirectional sensitivity, the spatial resolution is limited
by the spacecraft orbital altitude above the surface. A low altitude measurement from a distance on
the same scale of the PSRs could spatially isolate and constrain the hydrogen enrichments both within
and around within those regions. A small spacecraft mission is ideally suited to acquire the low-altitude measurements required to localize hydrogen enrichments using neutron spectroscopy at the lunar
South Pole. LunaH-Map will use a solid iodine ion propulsion system, X-Band radio communications
through the NASA Deep Space Network, star tracker, Command & Data Handling System, and
EPS from Blue Canyon Technologies, solar arrays from MMA Designs, LLC, and mission design
and navigation by KinetX. Spacecraft systems design, integration, qualification, test, and mission
operations are performed by Arizona State University, AZ Space Technologies, and Qwaltec.

IMPROVED SIGNALS FOR DIFFERENTIAL ONE-WAY RANGE
This article describes the current limiting error source for Delta Differential One-way Range (DOR),
provides a means to reduce this error, and lists the benefits to deep space navigation. Particular
advantages for Small Satellite class missions are addressed. The key idea is spreading the spacecraft
DOR signal with a pseudonoise (PN) code to make the spacecraft signal spectrum closely resemble
the spectrum of natural radio sources used for instrument calibration. How spectral differences affect
the measurement are discussed. This article describes the general formulation for PN DOR signal
design, and the specific X-band implementation of PN DOR on a software defined radio at JPL.
Finally, a prototype implementation at -band, providing even better performance, is presented.

MARCH 2020

IEEE A&E SYSTEMS MAGAZINE

IEEE - Aerospace and Electronic Systems - March 2020

Table of Contents for the Digital Edition of IEEE - Aerospace and Electronic Systems - March 2020