Commercial Lunar Propellant Architecture - A Collaborative Study of Lunar Communication and Navigation - o6 Introduction

Communication and Navigation - o6 Introduction

For decades, humans have fantasized about living on the moon, but we haven't sent anyone there since 1972. So, how close are we to a moon base?

To the Memory of Dr. Spudis

Dr. Spudis earned his master’s degree from Brown University and his Ph.D. from Arizona State University in Geology with a focus on the Moon. His career included work at the US Geological Survey, NASA, John Hopkins University Applied Physics Laboratory, and the Lunar and Planetary Institute advocating for the exploration and the utilization of lunar resources. His work will continue to inspire and guide us all on our journey to the Moon.

“By going to the Moon we can learn how to extract what we need in space from what we find in space. Fundamentally that is a skill that any spacefaring civilization has to master. If you can learn to do that, you’ve got a skill that will allow you to go to Mars and beyond.”

Unified Geologic Map of the Moon

"People have always been fascinated by the moon and when we might return," said current USGS Director and former NASA astronaut Jim Reilly. “So, it’s wonderful to see USGS create a resource that can help NASA with their planning for future missions.”

The lunar map, called the “Unified Geologic Map of the Moon,” will serve as the definitive blueprint of the moon’s surface geology for future human missions and will be invaluable for the international scientific community, educators and the public-at-large. The digital map is available online now and shows the moon’s geology in incredible detail (1:5,000,000 scale).

Orthographic projections of the "Unified Geologic Map of the Moon" showing the geology of the Moon’s near side (left) and far side (right) with shaded topography from the Lunar Orbiter Laser Altimeter (LOLA). This geologic map is a synthesis of six Apollo-era regional geologic maps, updated based on data from recent satellite missions. It will serve as a reference for lunar science and future human missions to the Moon. Credit:

NASA/GSFC/USGS

Overview Communication and Navigation

The Communication and Navigation (C&N) capability needed to support the lunar propellant production plant differs from the other systems in this paper in that much of the network infrastructure is already in operation or under development. A number of Earth ground stations owned by several national space agencies already provide service to lunar spacecraft. A growing number of Commercial Service Providers (CSP) have announced plans to provide service to future lunar spacecraft.

National space agencies with one or more operational Deep Space Antennas (DSA) include NASA, European Space Agency (ESA), Japanese Aerospace Exploration Agency (JAXA), Roskosmos, and Indian Space Research Organization (ISRO). Agencies developing a DSA include United Kingdom Space Agency (UKSA), Korean Aerospace Research Institute (KARI) and United Arab Emirates Space Agency (UAESA). Commercial ground station operators with lunar service ambitions are discussed in the From Earth section below.

These Earth-based capabilities only provide service to the nearside of the Moon. To provide coverage of the lunar far side and shadowed Polar Regions, lunar relays will be required. There is currently only one lunar relay in place, China’s Chang'e-4 Queqiao, which was launched on May 20, 2018 (Figure 43). Three other agencies plan to launch spacecraft with lunar relay capability.

Figure 43: Queqiao, the Chang'e 4 Relay

Chinese relay satellite to support the Chang'e 4 rover planned to land on the far site on the Moon in late 2018. The 425 kg relay satellite is three-axis stabilized with a 130 N hydrazine propulsion system and carries a deployable 4.2 m dish antenna for the relay. It provides four 256 kBps X-band links between itself and the lander/rover and one 2 MBps S-band link towards Earth.

In addition, an international organization is coordinating among the international space agencies to define a Lunar Communications Architecture (LCA). The Interagency Operations Advisory Group (IOAG) was founded in 1999 to act “as the international focal point for fostering and leading interoperable space communications and navigation matters for cross support of spaceflight missions.

A specific IOAG goal is the achievement of full interoperability among member space agencies.” 96 Members include Italian Space Agency (ASI) (Italy), French Space Agency (CNES) (France), CSA (Canada), German Aerospace Center(DLR) (Germany), ESA (Europe), JAXA (Japan), and NASA (US) with China National Space Administration (CNSA) (China), KARI (S. Korea), Roskosmos (Russia), South African National Space Agency (SANSA) (S. Africa), UKSA (United Kingdom), and UAESA (United Arab Emirates) as observer agencies.

The IOAG coordinates activities with the Consultative Committee for Space Data Systems (CCSDS) (develops international space C&N standards), the Space Frequency Coordination Group (SFCG) (coordinates spectrum allocation and usage), the International Space Exploration Coordination Group (ISECG) (performs a role similar to IOAG for other aspects of international space mission coordination), and the International Committee on Global Navigation Satellite Systems (ICG, GNSS) (is a UN committee that coordinates interoperability across the many national navigation and positioning systems)

The IOAG expects to reach agreement by late 2018 on the LCA, which addresses lunar spectrum, communication protocols, position, Navigation and Timing (PNT) protocols, and conventions on C&N operation. The LCA intended to be applicable to all international space agency lunar missions. Figure 44 describes the LCA that features three primary types of networks:

• Earth Networks representing the ground stations that support the lunar missions
• Lunar Relay Network(s) representing the lunar orbiting spacecraft that support the lunar missions in other lunar orbits and on the lunar surface
• Lunar Surface Network(s) representing the surface stations that provide wireless (RF or laser) communications to fixed and mobile surface systems.

Figure 44: IOAG Lunar Communications Architecture

Each of these types of networks represents a combination of capabilities provided by several international space agencies, all capable of interoperating much as terrestrial telecommunications companies provide seamless global telephone, television, and internet services.

Services shown in Table 7 are based on Delay/Disruption Tolerant Networking (DTN) for space internetworking which is similar to, and compatible with, Internet Protocol (IP) but capable of dealing with longer delays and the frequent loss of connectivity that occur with space links. DTN provides guaranteed data delivery by using store - and - forward capability built into the network service.

The architecture is based on modularity, layering, open international standards-based interfaces, and automation. Modularity dictates that the system be designed using a small number of reusable components that can provide increasing capacity merely by adding more components. Like terrestrial computer networks, the architecture can grow by flying additional relays and surface terminals.

Table 7: Data and PNT Services Provided in the Lunar Communications Architecture

An open question is the degree to which commercial lunar missions will be encouraged to contribute to the LCA or to comply with its provisions. The recommendation in this paper is for commercial lunar C&N providers to utilize the LCA, where possible, and work with the international space agencies to extend it, where necessary, to achieve the capabilities needed for the lunar propellant production plant.

Lunar Surface

Communications on the lunar surface rely on a combination of wired and wireless capabilities. As shown in Figure 45, the lunar surface network includes one or more Lunar Communications Terminals (LCT) (highlighted in yellow) that act as local multiplexers/demultiplexers/routers connecting many surface elements and then relays data to/from the overhead Lunar Relay Satellites (LRS) or directly to the Earth Network when it is visible.

The Local Area Network (LAN) can employ Ethernet or equivalent existing technology. Radiometric tracking continues to be provided by the relays supported by surface beacons. Surface users outside the range of the LCT continue to be supported by LRS.

Figure 45: Lunar Surface Comms Concept Featuring Wired LAN and Lunar Comms Terminal In Space.

In addition to China’s Chang'e-4 Queqiao, three other spacecraft with lunar relay capability are planned for launch between 2019 and the mid-2020s by the UK, India, and NASA.

Details are shown in Table 8. If these spacecraft are realized, the lunar propellant production plant should be designed to take advantage of their capabilities at the relatively low RC of commercial services.

Table 8: Current and Planned Lunar Relay Capabilities

If these spacecraft are not present, then the lunar propellant production plant cost will have to reflect the additional NRC of developing a LRS. A decision will be required to determine whether to design the LRS with just sufficient performance to meet the lunar propellant production plant’s needs or whether to establish a partnership with a CSP who can invest in the LRS as a commercial entity providing communications services to other customers as well as the lunar propellant production plant.

If new relays were required, the 12-hour frozen orbit recommended by the IOAG (and used by the Lunar Communications Pathfinder) would also work well for the lunar propellant production plant. Two LRS in this orbit, phased 180° apart, would provide continuous coverage of one lunar polar region. The two relays would provide redundancy and the ability to continue operations with reduced coverage if one relay fails.

NASA began testing lunar laser communications with the Lunar Laser Communications Demonstration (LLCD) flown on the Lunar Atmosphere and Dust Environment Explorer (LADEE) in 2013. It proved the ability to send 20 Mbps to the Moon and receive 622 Mbps from the Moon. The next step is to provide a second-generation payload on the Orion crew vehicle on Exploration Mission 2 (EM-2) in 2023 followed by a payload on the Gateway in 2025-26.

Both of these demonstrations will provide high rate Earth-to- Moon links at 20 Mbps and Moon-to-Earth links at ~1 Gbps requiring significantly less Size, Weight and Power (SWaP) than a comparable Ka-band system. NASA is in the process of commercializing the laser communications technology so that subsequent payloads will be available on the commercial market.

Figure 46 shows the design of the Optical to Orion (O2O) payload that will be installed on the Orion Adapter Module including its own vibration compensation module to achieve the extremely precise pointing needed by the laser.

Figure 46: Laser Communications Payload design for Orion crew vehicle on EM-2

From Earth

All operations are executed in a highly automated manner, thereby minimizing labor requirements and maximizing reliability. All ground interfaces are also expected to reflect well-established standards, thereby benefiting from ongoing industry developments.

Dividing the network into layers encapsulates network functions and separates implementation of each layer at standard interface boundaries allowing the evolution of each layer independently while minimizing the impact of changes on adjacent layers. The LRS and LCT are the only portions of the architecture that require entirely new systems to be developed.

These new systems will be “born flexible” by incorporating concepts from terrestrial telecommunications and the Internet. The capacity of the resulting architecture can be increased or decreased by adding or subtracting relays and other assets to meet individual and cumulative mission needs and available budget. Finally, layering and standardization provide a framework for incrementally inserting new technologies to meet evolving and expanding lunar exploration and science objectives.

Table 9 shows that there are several commercial networks under development that plan to be capable of providing communications services to lunar systems. NASA’s Deep Space Network (DSN) and Near Earth Network (NEN) are included for comparison purposes but the focus is on availability of commercial solutions.

NASA will begin testing lunar laser communications with a technology demonstration on the Orion crew vehicle on EM-2 in 2023 followed by a payload on the Gateway in 2025-26. Other international space agency capabilities include ESA's tracking station network (ESTRACK) which is a global system of ground stations providing links between satellites and the European Space Operations Centre (ESOC) in Darmstadt, Germany. ESTRACK has three 35 m-diameter DSA in New Norcia, Australia, Cebreros, Spain, and Malargüe, Argentina.

Table 9: Current and Planned Lunar C&N Networks

NASA’s initial Optical Ground Stations will be located at Table Mountain, CA (JPL facility) and Maui, HI. Figure 47 shows Optical Ground Station 2 (OGS-2) with an array of four telescopes being installed on the Air Force Maui Optical Station (AMOS). These stations will be tested first with the Laser Communications Relay Demonstration (LCRD), an experimental optical payload being flown on the Air Force’s Space Technology Program Satellite 6 (STPSat-6) in 2019. Optical ground technology uses modified commercially available telescopes and private utilization is producing very low cost ground terminals.

Figure 47: Optical Ground Station 2 installation on roof of Air Force Maui Optical Station

Moon Navigational Services

In addition to international government and private C&N systems for lunar and cislunar activities, Lunar Station Corporation (LSC) 102 is developing Moon navigational services for lunar activities. LSC is building their services for organizations pursuing scientific and business opportunities on the Moon. Solutions will provide surveying, navigating, and prospecting decision support from mission planning through mission execution with a constellation of remote sensing small satellites called MoonWatcher. Figure 48 shows the constellation deployed for maximum coverage of the Moon's surface.

Figure 48: Lunar Station Corporation’s MoonWatcher Constellation

The initial MoonWatcher Satellites will be remote sensing CubeSats (3U) payloads deployed in LEO. Each of the MoonWatchers will have slightly differing capabilities to create optimally spread spectrum coverage of the Moon. The benefit of CubeSat architectures is the ability to rapidly iterate and implement upgrades to the constellation for better performance and resolution.

Figure 49 is a 3D model of the MoonWatcher CubeSat scheduled to launch in 2019. Key technical specifications: 3U CubeSat architecture (10x10x30cm), dawn-dusk orbit, X-band communications, and estimated lunar spatial resolution: 1.15 miles. Current potential payloads: visible - 7200x7200 px, 0.55 um detector and infrared - 1- 1.7/2.4 um spectrometer. Future potential payloads: subsurface – microwave radiometer and subsurface - Ka-band radar package.

Figure 49: LSC’s Rendering of MoonWatcher CubeSat

The MoonWatcher constellation will continually send observations into LSC’s analytical platform called MoonHacker (Figure 50) for their machine learning algorithms to unlock new insights. This process specifically tailors the predictive analytics to meet the needs of customers and ensure the successful completion of their mission.

Commercial Moon navigational services such as this one can be used for site selections, hazard avoidance pathing, or maximum lunar day power availability during operations.

Figure 50: Lunar Station Corporation’s MoonHacker Data Analytics

MoonHacker will utilize innovative methodologies for customers to interact with the analytical platform. This innovative User Interface Experience (UIX) combines metadata layers overlaid on high definition 3D models of the Moon.

Customers will be able to select which metadata layers are critical for their mission planning and utilize the predictive algorithms to see environmental conditions during their planned mission execution windows. The example below of LSC’s MoonHacker UIX (Figure 51) shows 3D Model of the Moon with coordinates, human object locations and anticipated meteor strikes. Another example (Figure 52) shows the same information as above but now includes mineral deposits as well.

Figure 51: LSC’s MoonHacker 3D Model Showing Lunar Forecasted Meteor Storm - Also shown are human objects on the lunar surface. Source of meteorite storm forecast is from the lunar weather forecasting algorithms that LSC has already developed.

Figure 52: LSC’s MoonHacker 3D using mineral deposits metadata layer - Also shown is the forecast of meteorite storms and human objects on the lunar surface.