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DN-002 L: Comprehensive, high-fidelity digital elevation map (DEM) coverage of lunar south pole exploration zones and sites

Complete South Pole elevation maps (84°S–90°S) gridded finer than 1 m/pixel with under 0.1 m height error, for hazard avoidance, illumination modeling, landing ellipses and traverse planning. Today's maps come mainly from LRO's laser altimeter (LOLA) and image-based models at about 1–2 m/pixel. As with DN-001 L, more data is "not required" to land a nominal mission but is wanted for design margins, especially winter power. It is named in the Moon Base Users Guide (near-term), under two challenges (Data gaps spreadsheet, DN-002 L; Users Guide, p. 12).

Quotations below are from row DN-002 L of the data gaps spreadsheet unless marked otherwise. ADD Rev C's Appendix E prints the same record as a table, and it matches the row field for field (ADD Rev C, p. 266).

Description

"Provide complete, higher resolution ( <1m/pixel, <0.1 vertical error) DEM coverage of lunar south pole regions (84°S-90°S), with sufficient spatial and temporal resolution to support hazard avoidance, illumination modeling, landing ellipse definition, and traverse planning."

Data utility (white paper, Table Two): "To better enable characterization of lunar landing sites and increase confidence in landing accuracy and mobility system navigation." The table titles the gap "Comprehensive, high-fidelity elevation map coverage …", without "digital" and "(DEM)" (ACR25 data-gaps white paper, p. 3).

Need driver and data type

  • Need driver: Lunar Exploration Surface Site Characterization
  • Data type: Remote Sensing

Target measurement parameters

"The topographic products should be gridded at < 1m/pixel with less than 0.1 m height error."

Current state of data

"Lunar topographic data comes predominantly from LRO's Lunar Orbiter Laser Altimeter (LOLA). LOLA DEMs have been generated at multiple resolutions and have been used in the development of Terrain Referenced Navigation (TRN) algorithms. LOLA-derived DEMs are limited to some extent by the frequency of individual altimeter measurements, which when gridded require interpolation, and contain a level of uncertainty. For mission planning purposes at select locations, higher resolution LOLA DEMs are supplemented by other topographic products such as Stereo and Shape from Shading models which range from ~1 – 2 m/pixel in spatial resolution. Such image-based topographic products generally have denser coverage than the LOLA products. However, such products may contain interpolation in shadowed areas when there isn't a corresponding altimeter observation. As LRO's orbit altitude continues to increase and its inclination decreases, additional NAC imagery of polar sites will be increasingly difficult. Topographic products from KPLO ShadowCam images are expected to be released publicly in the near-future and will provide independent topographic data in permanently shadowed regions."

Impact if data is unavailable

"Additional elevation map coverage is not required to land and conduct a nominal surface mission at the lunar south pole. High resolution data collected by LRO over the last 15 years is the primary data set being used to plan missions in the HLR and initial FE segment. However, additional elevation map coverage is desirable to inform surface element design, such as power systems, energy storage and user operating power especially for winter hibernation. Lack of accurate data could lead to Element loss due to power failure in winter, unsafe landings, or mission-ending mobility hazards. Overcompensating for uncertainty adds prohibitive mass, while underestimating risks threatens survival and operational success. While south pole new crater impacts are not a concern, continued altimeter measurements to guarantee no changes that could impact safe landing and traverse planning. The concern increases as go equatorial."

Benefits if data is available

"With the desired DEM resolutions, Artemis missions will gain significant situational awareness, reduce risk by enabling navigation and hazard avoidance with respect to known DEMs, can plan more optimal landing and EVA scenarios, and increase confidence in ability to meet mission objectives. A prior acquisition of high resolution, low height error surface elevation data enables the ability to predict the illumination over challenging winter periods of the year which will put the Element energy storage to its limit. Underestimating the energy storage required duration could result in Element loss."

Traceability

  • Objectives: SE-05 LM, LI-03 L, TH-03 L (codes as printed; the sheet gives no titles)
  • Segment: Human Lunar Return (HLR): "The M2M segment during which the data is needed, but not necessarily when it is collected" (Data gaps spreadsheet, Key sheet). A segment is not a Moon Base phase.

Priority

None. The spreadsheet has no priority field, and the Users Guide calls the data-gap list "not comprehensive or prioritized" (Users Guide, p. 11).

Moon Base relevance

The Users Guide names DN-002 L for two challenges (Users Guide, p. 12):

  • "Landing Safely and Accurately on the Lunar Surface" (headline challenge). Its knowledge challenge has two sentences: "Observe the lunar surface to identify surface blocks, such as rocks and craters; map surface topology; and characterize variance in gravitational fields to enable precise and safe landings." and "Characterize and predict the properties of a plume-surface interaction (PSI) event, including ejecta trajectory, particle size distribution, and resulting surface site alterations to evaluate impact risk to mission and nearby assets." The guide lists DN-001 L, DN-014 L, DN-002 L, DN-017 L and DN-018 L under both sentences together and does not say which sentence each serves. The challenge's technology half cites tech gap #1101.
  • "Securing sites": "Identifying, selecting, and landing at individual sites requires more data about the lunar surface, including regolith properties, high-resolution imagery, mapping, and resource locations." Also cited: DN-001 L, DN-003 L to DN-010 L, DN-013 L and DN-014 L. No tech gap.

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.

Phase 1 mission on the same subject (the wiki's link; no source pairs them): MoonFall's drones will create "terrain maps of potential landing sites" (Moon Base Phases, "MoonFall"). See the data gaps index.

Sources

Data gaps spreadsheet, DN-002 L · ACR25 data-gaps white paper, p. 3 · Users Guide, pp. 11–12 · Moon Base Phases, "MoonFall" · ADD Rev C, p. 266