{
  "termsOfUse": "https://cdn.earthdata.nasa.gov/conduit/upload/5182/KeywordsCommunityGuide_Baseline_v1_SIGNED_FINAL.pdf",
  "keywordVersion": "draft",
  "schemeVersion": "2025-07-25",
  "viewer": "https://gcmd.earthdata.nasa.gov/KeywordViewer/scheme/instruments/efaebf9a-57ad-4f9a-873f-b5846b51bf49",
  "lastModifiedDate": "2026-07-21T18:52:09.969Z",
  "uuid": "efaebf9a-57ad-4f9a-873f-b5846b51bf49",
  "prefLabel": "Arcstone",
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  "definitions": [
    {
      "text": "Arcstone is a mission concept that provides a solution to this challenge. An orbiting spectrometer flying on a small satellite in low Earth orbit (LEO) will provide lunar spectral reflectance with accuracy sufficient to establish an SI-traceable absolute lunar calibration standard for past, current, and future Earth viewing sensors and constellation systems.",
      "reference": "https://science.nasa.gov/mission/arcstone/"
    }
  ],
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}