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NASA NTRSDate not supplied

Ground-testing of One-way Ranging from a Lunar Beacon Demonstrator Payload (Lunar Node -1)

Similar to lighthouses providing navigation aids and awareness to ships sailing along the coast, in-situ navigation beacons can be used to provide redundancy, awareness, and improved onboard position knowledge for vehicles operating in and around the lunar sphere of influence. Lunar Node - 1 is a radio frequency navigation beacon that is manifested on Intuitive Machines' NOVA-C lunar lander flight in 2022 for operation during cruise and from a mid-latitude landing location. This payload utilizes commercial components developed for Low Earth Orbit applications and packages them into an integrated package to provide a navigation reference signal as part of a large lunar-centric navigation network. As part of its operations, Deep Space Network ground stations will operate as the notional "user" of this service, allowing for performance characterization, calibration, and operation of the beacon payload. This paper provides an overview of the payload, how its fits into a large concept of operations, and ground testing results. A specific focus is on ground testing of the payload with DSN ground receivers as part of RF Compatibility Testing. A primary goal of this testing was to characterize a pseudo-noise ranging code sequence generated by the payload. The results in this paper define the testing sequence, unique operational constraints with two-way ranging ground equipment, and applications of the ground-derived error model to predicted in-flight performance of the ranging code.

Evan Anzalone↗

NASA NTRSDate not supplied

Ground-Testing of One-Way Ranging from a Lunar Beacon Demonstrator Payload (Lunar Node -1)

Similar to lighthouses providing navigation aids and awareness to ships sailing along the coast, in-situ navigation beacons can be used to provide redundancy, awareness, and improved onboard position knowledge for vehicles operating in and around the lunar sphere of influence. Lunar Node - 1 is a radio frequency navigation beacon that is manifested on Intuitive Machines' NOVA-C lunar lander flight in 2022 for operation during cruise and from a mid-latitude landing location. This payload utilizes commercial components developed for Low Earth Orbit applications and packages them into an integrated package to provide a navigation reference signal as part of a large lunar-centric navigation network. As part of its operations, Deep Space Network ground stations will operate as the notional "user" of this service, allowing for performance characterization, calibration, and operation of the beacon payload. This paper provides an overview of the payload, how its fits into a large concept of operations, and ground testing results. A specific focus is on ground testing of the payload with DSN ground receivers as part of Radio Frequency (RF) Compatibility Testing. A primary goal of this testing was to characterize a pseudo-noise ranging code sequence generated by the payload. The results in this paper define the testing sequence, unique operational constraints with two-way ranging ground equipment, and applications of the ground-derived error model to predicted in-flight performance of the ranging code.

Evan J Anzalone↗

NASA NTRS2007

Dilution-of-Precision-Based Lunar Surface Navigation System Analysis Utilizing Earth-Based Assets

The NASA Vision for Space Exploration is focused on the return of astronauts to the Moon. Although navigation systems have already been proven in the Apollo missions to the Moon, the current exploration campaign will involve more extensive and extended missions requiring new concepts for lunar navigation. In contrast to Apollo missions, which were limited to the near-side equatorial region of the Moon, those under the Exploration Systems Initiative will require navigation on the Moon's limb and far side. These regions are known to have poor Earth visibility, but unknown is the extent to which a navigation system comprised solely of Earth-based tracking stations will provide adequate navigation solutions in these areas. This report presents a dilution-of-precision (DoP)-based analysis of the performance of a network of Earth-based assets. This analysis extends a previous analysis of a lunar network (LN) of navigation satellites by providing an assessment of the capability associated with a variety of assumptions. These assumptions pertain to the minimum provider elevation angle, nadir and zenith beam widths, and a total single failure in one of the Earth-based assets. The assessment is accomplished by making appropriately formed estimates of DoP. Different adaptations of DoP, such as geometrical DoP and positional DoP (GDoP and PDoP), are associated with a different set of assumptions regarding augmentations to the navigation receiver or transceiver.

Welch, Bryan W.↗

NASA NTRS2022

Preliminary Approach to Assess the Seismic Hazard on a Lunar Site

The passive seismic network deployed on the Moon during the Apollo missions operated for eight years and allowed the observation of seismic activity. More than 12500 seismic events were registered, where 28 were classified as shallow moonquakes with moment magnitudes up to 4.1. Seismic events of this nature pose a significant risk to future long-term lunar habitats; thus, these events must be carefully studied and considered in the seismic design of these structures. This paper proposes a preliminary seismic hazard assessment imposed by shallow moonquakes. The hazard assessment is performed using the Probabilistic Seismic Hazard Analysis (PSHA) methodology, considering previous studies and theories regarding the seismic environment of the Moon. The study zone covers ~860 km2 of the Taurus-Littrow Valley, containing the Apollo 17 landing site and the Lee-Lincoln lobate scarp as the considered seismic source. The seismic hazard is quantified in terms of peak ground acceleration (PGA) and spectral acceleration (5% damped pseudo-acceleration, PSA). Seismic hazard deaggregation scenarios, Uniform Hazard Spectra (UHS) for different hazard levels, and a Conditional Mean Spectrum (CMS) for a target period of 0.2 s are obtained to quantify the seismic hazard on a specific site on the Moon. The developed seismic hazard assessment provides a preliminary approach for realistic scenarios to conduct structural designs that ensure the seismic performance of fully operational long-term lunar structures.

Moonquake↗

NASA NTRS1973

Moonquakes, meteoroids, and the state of the lunar interior

Analysis of data returned from the four stations of the Apollo Seismic Network has revealed that the lunar interior can be divided into two major zones: a rigid, dynamically inactive outer shell, about 1000 km thick (the lunar lithosphere); and a relatively weak central zone (the lunar asthenosphere) in which partial melting is probable. The transition between these two zones is gradual. Seismic activity within the moon is far below that of the earth. The small moonquakes that do occur originate near the base of the lithosphere, and appear to fall within two major belts. Tidal energy appears to be an important, if not the dominant, source of energy released as moonquakes. A secular component of moonquake energy release may result from slight thermal expansion or contraction of the moon, weak convection in the asthenosphere, or secular recession of the moon from the earth. Lack of shallow moonquake activity implies that the moon is neither expanding nor contracting at an appreciable rate at present.

Latham, G.↗

NASA NTRSDate not supplied

3GPP Telecommunications Technology on the Moon

Under NASA’s Artemis program, NASA is planning to send astronauts back to the Moon in the next couple of years. Near term missions will be analogous but much more sophisticated versions of the last couple of Apollo missions. However, unlike Apollo, this time NASA intends to put the infrastructure in place to support long term human presence and eventual industrialization of the Moon. To make this vision a reality, NASA plans to collaborate with commercial and international partners as much as possible as opposed to developing, building, and operating equipment on its own. Lunar infrastructure will eventually be built over time by many organizations, public and private, to support sustained human exploration, science, and industrial activities. Obviously, this vision for the future will be impossible without a robust lunar communications and navigation system that can support many users with varying degrees of services. On Earth, most people are very familiar with the 3rd Generation Partnership Project (3GPP) 5G mobile telecommunications technology. NASA’s Space Technology Mission Directorate and NASA’s Space Communications and Navigation office would like to see a lunar communications and navigation network with similar capabilities to the cellular communication networks most of us enjoy today. Building such a network will require participation by many organizations. This paper will provide an overview of NASA’s interest in using 5G and beyond on the lunar surface; it will also describe current work based on 3GPP standards within NASA or funded by NASA, such as Nokia’s upcoming Tipping Point demonstration of 4G / LTE on the lunar surface.

Bernard Edwards↗

NASA NTRS1972

Lunar surface magnetometer experiment

The Apollo 16 lunar surface magnetometer (LSM) activation completed the network installation of magnetic observatories on the lunar surface and initiated simultaneous measurements of the global response of the moon to large-scale solar and terrestrial magnetic fields. Fossil remanent magnetic fields have been measured at nine locations on the lunar surface, including the Apollo 16 LSM site in the Descartes highlands area. This fossil record indicates the possible existence of an ancient lunar dynamo or a solar or terrestrial field much stronger than exists at present. The experimental technique and operation of the LSM are described and the results obtained are discussed.

Dyal, P.↗

NASA NTRS2005

Integrated network architecture for sustained human and robotic exploration

The National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate is planning a series of human and robotic missions to the Earth's moon and to Mars. These missions will require telecommunication and navigation services. This paper sets forth presumed requirements for such services and presents strawman lunar and Mars telecommunications network architectures to satisfy the presumed requirements.

network architecture human robotic sustained explo↗

NASA NTRSDate not supplied

LunaNet Governance: Organizing and Planning for LunaNet Operations

LunaNet is proposed to be the lunar internet, providing services for communications, networking, position, navigation, and timing for missions in transit to and from the moon, in orbit around the moon, in transit to and from the surface, and on the surface. It is envisioned to be an open, international architecture with contributions from multiple organizations including international civil space agencies, commercial service providers, academic institutions, and other organizations. Using a combination of conventional and emerging technologies, LunaNet will create a lunar-centric network-of-networks that inherits some features of the terrestrial internet but has unique characteristics that will drive substantially different operations. Government acquisition efforts have already begun to procure commercial lunar communications and navigation services. A multi-stakeholder approach to developing the community-wide concepts of operation has been initiated by the Interagency Operations Advisory Group (IOAG), which is formed of international government space agencies, that includes other international organizations such as the Internet Society, Internet Engineering Task Force, International Committee on Global Navigation Satellite Systems, and Space Frequency Coordination Group as well as industry and academic participants. Products of the Interim Committee on LunaNet Governance will include the recommendation and definition of an initial international organizational governance structure; associated roles, responsibilities, and processes; and recommended steps to implement the governance approach. This paper will describe the progress made in developing these concepts and coordinating them among the participating organizations.

LunaNet↗

NASA NTRS2015

Nighttime Aerosol Optical Depth Measurements Using a Ground-based Lunar Photometer

In recent years it was proposed to combine AERONET network photometer capabilities with a high precision lunar model used for satellite calibration to retrieve columnar nighttime AODs. The USGS lunar model can continuously provide pre-atmosphere high precision lunar irradiance determinations for multiple wavelengths at ground sensor locations. When combined with measured irradiances from a ground-based AERONET photometer, atmospheric column transmissions can determined yielding nighttime column aerosol AOD and Angstrom coefficients. Additional demonstrations have utilized this approach to further develop calibration methods and to obtain data in polar regions where extended periods of darkness occur. This new capability enables more complete studies of the diurnal behavior of aerosols, and feedback for models and satellite retrievals for the nighttime behavior of aerosols. It is anticipated that the nighttime capability of these sensors will be useful for comparisons with satellite lidars such as CALIOP and CATS in additional to ground-based lidars in MPLNET at night, when the signal-to-noise ratio is higher than daytime and more precise AOD comparisons can be made.

Berkoff, Tim↗

NASA NTRS2022

Research Campaign: Lunar Gravitational-wave Antenna

The Lunar Gravitational-wave Antenna (LGWA) is a mission conceived as a network of stations to measure the vibrations of the Moon caused by gravitational waves (GWs). The long-term vision is to accomplish ground-breaking, paradigm shifting science in the coming decades on the Moon. LGWA will lead to the first observation of GW signals in the decihertz band greatly expanding our understanding of the universe and laying out a path to eventually probe the moment of its creation. LGWA stations will also be unique contributions to a lunar geophysical network shedding light on the Moon’s formation history. LGWA is a project of inclusion and international collaboration, where space-faring and space-aspiring nations can contribute to the LGWA network with their own stations whose cost depends on the targeted station lifetime and deployment location. With respect to the baseline concept proposed here, different sensor technologies can be implemented over time with the goal to continually increase the performance of the LGWA network. The broader context of lunar GW detection and its long-term vision are outlined in an accompanying topical white paper.

Lorella Angelini↗

NASA NTRSDate not supplied

NASA’s Interest in 3GPP Mobile Telecommunications Protocols for Near Earth Space and the Lunar Surface

In the next several years, NASA intends to return astronauts to the Moon through the Artemis Program. Under Artemis, NASA plans to collaborate with commercial and international partners to establish a long-term presence on the Moon. Near-term Artemis missions will be analogous but much more sophisticated versions of the last couple of Apollo missions. For example, the first area expected to be explored by an Artemis mission is near the south pole as opposed to the mid-latitudes visited by the Apollo astronauts, which makes direct communications with Earth more complicated. Lunar infrastructure will eventually be built over time by many organizations, public and private, to support sustained human exploration, science, and industrial activities on the Moon. A robust lunar communications and navigation infrastructure will be essential to realizing this long-term vision. Meanwhile, on Earth, major advances are being made as5G mobile telecommunications rollout across the globe. Furthermore, the 3rdGeneration Partnership Project (3GPP) is beginning to define future 6G capabilities. NASA envisions a lunar communications and navigation network with capabilities similar to those of communication networks we enjoy here on Earth. Building such a network will require participation by many organizations. NASA’s Tipping Point program seeks industry-developed space technologies that can both foster commercial space capabilities and benefit future NASA missions. This paper provides an overview of NASA’s interest in 3GPPanddescribescurrent work based on 3GPP standards within NASA or funded by NASA, such as Nokia’s upcoming Tipping Point demonstration of 4G/LTE on the lunar surface in early 2023.

Bernard L Edwards↗

NASA NTRS2013

GRAIL Refinements to Lunar Seismic Structure

Weber, Renee C.↗

NASA NTRS2014

GRAIL Refinements to Lunar Seismic Structure

Joint interpretation of disparate geophysical datasets helps reduce drawbacks that can result from analyzing them individually. The Apollo seismic network was situated on the lunar nearside surface in a roughly equilateral triangle having sides approximately 1000 km long, with stations 12/14 nearly co-located at one corner. Due to this limited geographical extent, near-surface ray coverage from moonquakes is low, but increases with depth. In comparison, gravity surveys and their resulting gravity anomaly maps have traditionally offered optimal resolution at crustal depths. Gravimetric maps and seismic data sets are therefore well suited to joint inversion, since the complementary information reduces inherent model ambiguity. Previous joint inversions of the Apollo seismic data (seismic phase arrival times) and Clementine- or Lunar Prospector-derived gravity data (mass and moment of inertia) attempted to recover the subsurface structure of the Moon by focusing on hypothetical lunar compositions that explored the density/velocity relationship. These efforts typically searched for the best fitting thermodynamically calculated velocity/density model, and allowed variables like core size, velocity, and/or composition to vary freely. Seismic velocity profiles derived from the Apollo seismic data through travel time inversion vary both in the depth of the crust and mantle layers, and the seismic velocities and densities assigned to those layers. The lunar mass and moment of inertia likewise only constrain gross variations in the density profile beyond that of a uniform density sphere. As a result, composition and structure models previously obtained by jointly inverting these data retain the original uncertainties inherent in the input data sets. We perform a joint inversion of Apollo seismic delay times and gravity data collected by the GRAIL lunar gravity mission, in order to recover seismic velocity and density as a function of latitude, longitude, and depth within the Moon. We relate density (p) to seismic velocity (v) using a depth-dependent linear relationship. The corresponding coefficient (B) can reflect a variety of material properties, including temperature and composition. The inversion seeks to recover the set of p, v, and B perturbations that minimize (in a least-squares sense) the difference between the observed and calculated data.

Weber, Renee C.↗

NASA NTRSDate not supplied

NASA's Efforts to Pursue Commercial Communications Services for Missions in Near Space

The National Aeronautics and Space Administration (NASA) Space Communications and Navigation (SCaN) Program enables high speed, robust, secure and cost-effective space communications and navigation services to current and future science and exploration missions. Consistent with National Space Policy, NASA is seeking commercial services for all its future near Earth requirements by incorporating additional direct to Earth (DTE) providers and introducing commercial satellite communications (SATCOM) vendors as NASA’s Tracking and Data Relay Satellites (TDRS) begin to decline. Through the progression of these efforts, SCaN is also integrating commercial services in the cislunar domain. The overarching objective is to satisfy the demands from the mission community – both in terms of capacity and capability – in a robust and cost-effective way, leveraging the strong and growing commercial space sector. For near earth space relay, six SATCOM vendors were awarded Funded Space Act Agreements in June of 2022 to demonstrate the ability to serve near-Earth missions, and are working through their committed milestones. The failure of TDRS Flight-9 (F9) in late 2022 prompted an increased tempo of mission engagement to identify driving user needs that commercial SATCOM can meet in the near-term. NASA has set a course to accelerate a decision to terminate commitments for TDRS services to new missions and has developed a plan to execute validation and risk reduction efforts with early adopter “pathfinder” missions to pave the way to earlier operational services. As the Artemis Program matures and builds on the successful Artemis I flight in November/December of 2022, the definition of the supporting communications and navigation architecture has further been refined. Although NASA government assets will continue to play a key role in provision of services, such as through the Deep Space Network, SCaN is pursuing commercial services offerings to expand ground network capability and implement lunar relay services. In February of 2023, SCaN released solicitation for services that include DTE services to missions near-Earth and in cislunar space, as well as lunar relay services. Further, SCaN is seeking opportunities to integrate commercial capability into lunar surface communications infrastructure. NASA is also advocating for standards that promote interoperability and strategic technology investments in the commercial sector. This paper addresses the recent progress and future plans in the near-Earth space and lunar regimes, discusses the unified approach for industry engagement, and highlights both the common and unique challenges of commercialization efforts in the two regimes.

commercialization↗

NASA NTRS2013

GRAIL Refinements to Lunar Seismic Structure

Joint interpretation of disparate geophysical datasets helps to reduce drawbacks that can result from analyzing them individually. The Apollo seismic network was situated on the lunar nearside surface in a roughly equilateral triangle having sides approximately 1000 km long, with stations 12/14 nearly co‐located at one corner. Due to this limited geographical extent, near‐surface ray coverage from moonquakes is low, but increases with depth. In comparison, gravity surveys and their resulting gravity anomaly maps have traditionally offered optimal resolution at crustal depths. Gravimetric maps and seismic data sets are therefore well suited to joint inversion, since the complementary information reduces inherent model ambiguity. Previous joint inversions of the Apollo seismic data (seismic phase arrival times) and Clementine‐ or Lunar Prospector‐derived gravity data (mass and moment of inertia) attempted to recover the subsurface structure of the Moon by focusing on hypothetical lunar compositions that explore the density/velocity relationship. These efforts typically search for the best fitting thermodynamically calculated velocity/density model, allowing variables like core size, velocity, and/or composition to vary freely. Seismic velocity profiles previously derived from the Apollo seismic data through inversion of travel times vary both in the depth of the crust and mantle layers, and the seismic velocities and densities assigned to those layers. The lunar mass and moment of inertia likewise only constrain gross variations in the density profile beyond that of a uniform density sphere. As a result, composition and structure models previously obtained by jointly inverting these data retain the original uncertainties inherent in the input data sets. We will perform a joint inversion of Apollo seismic delay times and gravity data collected by the GRAIL lunar gravity mission, in order to recover seismic velocities and density as a function of latitude, longitude, and depth within the Moon. We will relate density to seismic velocity using a linear relationship that is allowed to be depth‐dependent. The corresponding coefficient (B) can reflect a variety of material properties that vary with depth, including temperature and composition. The inversion seeks to recover the set of density, velocity, and B‐coefficient perturbations that minimize (in a least‐squares sense) the difference between the observed and calculated data.

Weber, Renee C.↗

NASA NTRS2008

Architecting Communication Network of Networks for Space System of Systems

The National Aeronautics and Space Administration (NASA) and the Department of Defense (DoD) are planning Space System of Systems (SoS) to address the new challenges of space exploration, defense, communications, navigation, Earth observation, and science. In addition, these complex systems must provide interoperability, enhanced reliability, common interfaces, dynamic operations, and autonomy in system management. Both NASA and the DoD have chosen to meet the new demands with high data rate communication systems and space Internet technologies that bring Internet Protocols (IP), routers, servers, software, and interfaces to space networks to enable as much autonomous operation of those networks as possible. These technologies reduce the cost of operations and, with higher bandwidths, support the expected voice, video, and data needed to coordinate activities at each stage of an exploration mission. In this paper, we discuss, in a generic fashion, how the architectural approaches and processes are being developed and used for defining a hypothetical communication and navigation networks infrastructure to support lunar exploration. Examples are given of the products generated by the architecture development process.

Bhasin, Kul B.↗

NASA NTRSDate not supplied

Fine pointing of Laser Beams by using Laser Arrays for Applications to CubeSats

A method of fine pointing of laser beams by using laser arrays has been developed. The telescope system combines a lens system and a VCSEL/Photodetector Array. It does not use moving parts. In computer simulations, it is applied to CubeSats that use body pointing. Body pointing was used by the Aerospace Corporation for CubeSats in LEO in NASA’s Optical Communications and Sensors Demonstration (OCSD) program. Computer simulations of this fine pointing capability have been applied previously to CubeSats in the OCSD program. In this paper, computer simulations of laser pointing using this telescope design are applied to CubeSats in LLO, at 100 km. These CubeSats could form part of the LunaNet, the lunar communications and navigation network, part of the NASA ARTEMIS Program. With more accurate pointing, a laser beam with smaller divergence can be used. For the case of the AeroCube-7B vehicle that was used in the OCSD program, computer simulations will show, for example, that the divergence of the output beam can be reduced from approximately 0.06° FWHM to 0.014°. For the proposed electro-optical system, reaction times to pointing changes and vibrations are on a nanosecond time scale, much faster than those for fine pointing systems that use moving parts such as fast steering mirrors, including MEMS, or that use quad-cell photodetectors to improve the body pointing of the CubeSat. Other possible applications are to Optical Multiple Access (OMA)for simultaneously communicating with ground stations at different locations and to Wavelength-Division Multiplexing (WDM)for increasing data rate transmission.

SMD↗