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ESDMD #0101: Positioning, Navigation, and Timing for Lunar Surface Extreme Environments

Absolute and relative positioning, navigation and timing (PNT) for crew and surface assets that tolerates radiation, extreme temperatures and dust (bin 3, rating 20 of 57). Today's systems give relative position only. The target is real-time absolute localization to within 10 m (3 sigma), using a navigation infrastructure such as an orbital constellation. It is named in the Moon Base Users Guide (near-term), for long-duration operations and timing systems (Tech gaps spreadsheet, ESDMD #0101; Users Guide, pp. 12–13).

Quotations below are from row ESDMD #0101 of the tech gaps spreadsheet unless marked otherwise. ADD Rev C's Appendix D prints the same table for this gap, and it matches the row field for field (ADD Rev C, p. 204).

Description

"Current positioning, navigation, and timing (PNT) systems for exploration assets and crew provide relative position but lack the ability to precisely determine their absolute location. The state of the art is insufficient for long traverses across the lunar surface that will require absolute localization to facilitate path planning and execution. The state of the art is also insufficient for the expected extreme environments at the lunar surface over the mission durations. There is a need for absolute and relative PNT systems and technologies that accurately track crew and mobile surface assets and that are tolerant to radiation, extreme temperatures, and dust. For example, solar wind plasma and ultraviolet radiation can electrically charge lunar regolith to increase the electrostatic properties and amplify the regolith on the lunar surface. These charged particles introduce an electric field on the surface that can impact navigation and timing systems and science instruments."

Impacts and benefits: "Without gap closure, the impacts may include reduced positioning, navigation, and timing systems accuracy. Additionally, due to the environment, there is a risk of PNT systems being compromised and unable to operate and perform at expected levels."

Current state of the art

"Current Mars rovers possess state-of-the-art PNT capabilities for mobile assets on another planetary surface, primarily utilizing onboard sensors for relative navigation with minimal onboarding processing. However, lunar rovers will have an increased pace of exploration and operational range, which as a result will require technology advancement for absolute navigation, real-time accuracy, and increased onboard processing of sensor data, especially for crew manual control. Additionally, Mars rovers differ from lunar rovers due to variations in the environmental conditions, lighting, and signal latency. The VIPER project developed high fidelity navigation tools for future use on an exploration rover at the lunar South Pole region."

Performance target

Moon:

  • "Achieve absolute real-time localization of crew, mobile, and in-place assets to within 10m, 3 sigma enabled by a navigation infrastructure (such as an orbital constellation) defined by a geometric dilution of precision (GDOP) of less than six with at least four broadcast PNT signals. Given the line-of-sight and current infrastructure coverage requirements, systems on the lunar surface can determine their location within a short period of time. Once initialized, the systems can maintain this level of accuracy given a combination of navigation infrastructure signals, local sensors and onboard processing."
  • "Initial navigation infrastructure capability for the FE segment is planned for 40% of 24 hours for the lunar South Pole region with slightly degraded performance during the remainder of the day. The navigation infrastructure for the SLE segment can include expanded coverage and availability both in terms of surface area and percent time available. In addition to absolute localization, mobile assets may need to leverage relative measurements to meet a minimum close approach to distance."
  • Degraded performance: "When C&PNT infrastructure is not available or inadequate, Artemis navigation systems can determine absolute location (within 3 sigma of targeted accuracy) for crew within 150m and vehicles within 100m, both 3-sigma."
  • Future performance: "Surface capabilities utilizing multiple fixed and mobile assets will require greater local and relative navigation accuracy, especially during coordinated operations in close proximity."

The ACR25 C&PNT white paper's figures. "At the 2025 Architecture Concept Review, NASA presented findings on real-time absolute navigation accuracy for the Foundational Exploration segment … the C&PNT sub-architecture needs to offer a real-time absolute accuracy of 25-50 meters. While NASA needs 25-50-meter accuracy early in the Foundational Exploration segment, NASA has procured systems to realize 10-meter or better accuracy, which offers margin for future missions" (C&PNT white paper, p. 4). So the paper's early-segment need (25–50 m) is a larger figure than this gap's target (10 m, 3 sigma), and the procured capability is stated as "10-meter or better". The paper gives no sigma level, doesn't name the procured systems, and doesn't cite this gap. It does name a gap from the 2024 list, "Position, Navigation, and Timing (PNT) for In-Orbit and Surface Applications" (p. 6); that this is #0101 is the wiki's reading.

Child gaps

  • 0101-01: Positioning and navigation systems for lunar surface applications
  • 0101-02: Accurate and stable timing systems for surface exploration assets on the lunar surface
  • 0101-03: Robust positioning, navigation, and timing systems for the extreme lunar surface environment

Traceability

  • Use cases and functions: UC-M-601 L -- FN-C-201 L; UC-C-202 L -- FN-C-201 L; UC-C-203 L -- FN-C-201 L
  • Definition tasks: none listed
  • Cross-reference: FN-C-201 L, "Provide position, navigation, and timing services at the south pole region on the lunar surface", is also one of the Users Guide's Phase 1 functional gaps. Its Phase 1 capability target includes "Deployment of orbital navigation and timing assets" (Users Guide, p. 8; see Phase 1 functional gaps). This link joins the two sources; neither makes it.

Segments and sub-architectures

Priority

Priority bin 3, overall prioritization rating 20 of 57. The rating is "the gap's location in the prioritized list of gaps", so 1 is the highest priority, and bins group gaps of similar priority, bin 1 highest. Criticality, urgency, breadth and depth set the order; cost is not considered (ADD Rev C, pp. 78, 199; method on the gaps index).

Moon Base relevance

For the long-duration challenge, the guide lists #0101, #0201, #0301, #0801 and #0804 together against its three technology bullets, without assigning gaps to bullets. The bullet quoted below is the one closest to this gap's subject.

The Users Guide names #0101 in two places (Users Guide, pp. 12–13):

  • the headline challenge "Operating on the lunar surface for long durations", whose technology challenge includes "Develop navigation and timing systems that account for the lunar surface electromagnetic radiation environment, which can impact their accuracy";
  • the associated challenge "Timing systems": "Timing systems must be capable of providing precise real time synchronization between assets on the lunar surface with low latency and drift."

The guide ties its challenges to "near-term Moon Base development efforts": missions in phase one "offer opportunities to collect data and mature technologies to enable essential phase two and phase three capabilities" (p. 11). See Technology and knowledge challenges.

Same subject in the Ignition material (the pairing is the wiki's; the deck names no gap). The Moon Base Program's Ignition deck plans, phase by phase, the kind of navigation infrastructure this gap's target assumes ("such as an orbital constellation") and clocks, the subject of the guide's "Timing systems" challenge. Phase 1's "Orbital comm & PNT relay" is to "Deploy initial 5-satellite constellation" and "Add second provider constellation". Phase 2's "Navigation infrastructure" is a "Clock technology demonstration", and the render labels "Phase 2 Lunar PNT" and a "Phase 2 Clock Demo". Phase 3's is "Clock ensembles – persistent time broadcast" (slides 50–51) (Ignition deck 2, slides 50–51). The deck gives no accuracy, coverage or drift figure to set beside this gap's "within 10m, 3 sigma" or the guide's "low latency and drift". Child gap 0101-02, timing systems for surface assets, is the nearest to the clock items. See SCaN Networks.

In the 2024 executive overview

The 2024 executive overview prints this gap as its "Example Tech Gap" (PDF p. 13, read from the PDF), laid out like an ADD Appendix D table. It is older than Rev C, and the overview doesn't say which revision the table comes from. As printed:

  • Title: "Lunar Surface Positioning, Navigation, and Timing Systems for Extreme Temperature, Radiation, and Dust".
  • Description: "Current positioning, navigation, and timing (PNT) systems for exploration assets and crew provide relative position but lack the ability to determine their absolute location. Long traverses across the lunar surface will require absolute localization to facilitate path planning and execution. There is a need for improvements to current absolute and relative PNT systems and technologies to accurately track crew and mobile surface assets. Additionally, PNT systems should be operable for expected durations and protected from lunar debris, dust, temperature variations, and exposure to radiation or any other space weather/lunar phenomena."
  • Current state of the art: "There are no current NASA or ESA rovers on the moon. Current Mars rovers possess state-of-the-art PNT capabilities for mobile assets on another planetary surface."
  • Performance target: "Achieve absolute localization of crew, mobile, and in-place assets on the order of TBD meters."
  • The same as today: the impacts and benefits, the three child gaps, the three use case–function pairs, the C&PNT sub-architecture and the two segments (Foundational Exploration and Sustained Lunar Evolution, drawn as icons).
  • Blank or unnumbered: the "Key Decision" field is empty, and the "Priority" column is a shaded scale marked "Higher Priority", with no rating.

What changed by Rev C (the wiki's comparison): a new title; a number where "TBD" stood ("within 10m, 3 sigma"), with the coverage, degraded-performance and future-performance targets added (above); a longer description, adding "precisely", the two "state of the art is insufficient" sentences and the electrostatic example (above); and a rewritten state of the art that drops the "no current NASA or ESA rovers" line and adds VIPER. The 2024 title isn't the C&PNT paper's name either (above; open question 35).

Sources

Tech gaps spreadsheet, ESDMD #0101 · ADD Rev C, pp. 78, 199, 204 · Users Guide, pp. 8, 12–13 · C&PNT white paper, pp. 1, 4, 6 · Lunar Reference Frames white paper, p. 2 · 2024 executive overview, PDF p. 13 · Ignition deck 2, slides 50–51