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DN-014 L: High resolution lunar rock size distribution and morphology at the lunar south pole

The sizes, shapes and numbers of rocks and particles from 10 μm to 1 m at the South Pole, below what orbital images can resolve, measured continuously rather than in sieve bins, and how they change with depth and place. Orbital instruments "can unambiguously detect rocks of 1m or greater". The sub-meter rocks below that are a tip-over hazard for landers and rovers. It is named in the Moon Base Users Guide (near-term), under two challenges, landing and "Securing sites" (Data gaps spreadsheet, DN-014 L; Users Guide, p. 12).

Quotations below are from row DN-014 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. 278).

Description

"Constrain the size-frequency distribution and shape of lunar rocks/regolith that exist below the resolution of existing imagery (sub-meter scale) at the south pole to better understand the lunar surface environment as it pertains to lunar surface activities. Activities could include survey instruments/cameras of surrounding terrain to capture areal rock distributions as well as sampling instruments of the regolith."

Need driver and data type

  • Need driver: Lunar Surface Natural Environment Characterization
  • Data type: In Situ Measurement

Target measurement parameters

"Measurements of particle sizes and frequencies from length scales > 10 um to 1 m not via discrete bins or sieve sizes, but measurements capable of detecting all unique sizes, shapes, and aspect ratios in this range. Understand how these distributions change with depth/spatially."

Current state of data

"Surface images from Surveyor, Apollo, Lunokhod, and Chang'e missions have been used to derive quantitative estimates of rock abundance on the surface of the Moon at multiple locations. Orbital instruments can unambiguously detect rocks of 1m or greater; depending on the height of the feature in question, submeter detection may be possible."

Impact if data is unavailable

"The population of sub-meter scale rocks poses a hazard to landers and rovers, especially during landing phases which require precise navigational inputs to prevent tip-over. Incomplete datasets about morphology and size of regolith/rocks poses a risk to understanding how and where to safely operate surface assets."

Benefits if data is available

"In-situ surveys of surface regolith/rocks would provide valuable data on the distribution and abundance of sub-meter scale rocks that would allow for refined size-frequency models. Improved models could impact landing site selection and traverse paths."

Traceability

  • Objectives: SE-05 LM, LI-06 L, TH-03 L, OP-05 LM (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-014 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 to DN-010 L and DN-013 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.

Sources

Data gaps spreadsheet, DN-014 L · Users Guide, pp. 11–12 · ADD Rev C, p. 278