{
 "v": 1,
 "fetched": "2026-10-04",
 "items": [
  {
   "id": "messenger-md3-color",
   "name": "Mercury MESSENGER MDIS Basemap MD3 Color Global Mosaic, 665 m/px",
   "url": "https://planetarymaps.usgs.gov/mosaic/Mercury_MESSENGER_MDIS_Basemap_MD3Color_Mosaic_Global_665m.tif",
   "credit": "USGS Astrogeology Science Center / NASA MESSENGER MDIS team",
   "licence": "Public domain (US Government work, NASA / USGS)",
   "fetched": "2026-10-04",
   "transform": "GeoTIFF 23040x11520 RGB uint8, equirectangular, PositiveEast, domain -180..180 (x=0 is lon -180, no roll). Chosen as the default over the Global Color Mosaic v3 because it has no patchy holes, keeps the low-sun relief shading and has a near-grey, slightly warm look (v3 is blue-tinted and softer). No-data (value 0, with 1 and 255 edge pixels, about 3 percent: the polar caps above about 83.5 N and below about 85 S plus a few small patches) was masked with a 9x9 erosion. The mosaic was area-reduced to 8192x4096 with coverage weighting, then holes were filled from a smooth local-mean colour (300 Jacobi passes at 2048 wide, bicubic upsample) multiplied by DEM hillshade, with a feathered blend. Tone: luminance (channel mean) remapped to a 30..252 range with gamma 0.88; then the per-pixel chroma (RGB minus its mean) has the global mean chroma subtracted and is scaled to 40 percent, and the result is multiplied by (1.045, 1.0, 0.945) for a warm grey balance, so low-reflectance material reads only as slightly darker, cooler grey. 4K and 2K are Lanczos reductions. Encoded WebP q60 (8K) and q66-74 (4K) and JPEG to meet the CONTRACT size budgets. The polar caps are invented fill, not data.",
   "used": [
    "assets/tex/color-2k.jpg",
    "assets/tex/color-4k.webp",
    "assets/tex/color-4k.jpg",
    "assets/tex/color-8k.webp",
    "assets/tex/color-8k.jpg",
    "assets/fallback/poster.jpg",
    "assets/fallback/map-2k.jpg",
    "assets/og.jpg"
   ]
  },
  {
   "id": "messenger-enhanced-color",
   "name": "Mercury MESSENGER MDIS Basemap Enhanced Color Global Mosaic, 665 m/px",
   "url": "https://planetarymaps.usgs.gov/mosaic/Mercury_MESSENGER_MDIS_Basemap_EnhancedColor_Mosaic_Global_665m.tif",
   "credit": "USGS Astrogeology Science Center / NASA MESSENGER MDIS team",
   "licence": "Public domain (US Government work, NASA / USGS)",
   "fetched": "2026-10-04",
   "transform": "GeoTIFF 23040x11520 RGB uint8, same grid and longitude convention as the MD3 mosaic. Same no-data mask and hole fill as the default colour, no tone change (the product is already exaggerated: blue for low-reflectance material, orange for smooth plains). Area-reduced to 8192, then Lanczos to 4096x2048, WebP q62.",
   "used": [
    "assets/tex/enh-4k.webp"
   ]
  },
  {
   "id": "messenger-dem-v2",
   "name": "Mercury MESSENGER Global DEM 665 m (64 ppd) v2",
   "url": "https://planetarymaps.usgs.gov/mosaic/Mercury_Messenger_USGS_DEM_Global_665m_v2.tif",
   "credit": "USGS Astrogeology Science Center / Becker et al. 2016 (MLA + stereo)",
   "licence": "Public domain (US Government work, NASA / USGS)",
   "fetched": "2026-10-04",
   "transform": "int16 23040x11520, 0.5 m per DN (label Multiplier 0.5, band MedianRadius), values are metres relative to the 2439.4 km sphere (label radius 2439400 m), no nodata pixels. LongitudeDomain 360 centred on 180, so x=0 is lon 0: rolled by half the width so x=0 is lon -180. Elevation range -5382 to +4497 m. The DEM is interpolated where MLA and stereo coverage are thin (mainly the southern hemisphere). Area-reduced to 8192x4096, then box-reduced to 4096x2048 (normal map, 1x exaggeration, R=2439.4 km) and 2048x1024 (elev-2k.png, h_m=(R*256+G)-9000) and 1024x512 (elev-1k.png, exact 2x2 integer mean). The 2K box reduction has min -5357 m (Rachmaninoff floor, 27.7 N 57.4 E) and max about +4435 m.",
   "used": [
    "assets/tex/elev-2k.png",
    "assets/tex/elev-1k.png",
    "assets/tex/normal-4k.webp",
    "assets/fallback/map-2k.jpg"
   ]
  },
  {
   "id": "iau-mercury-nomenclature",
   "name": "IAU Gazetteer of Planetary Nomenclature, Mercury center points (WGPSN)",
   "url": "https://asc-planetarynames-data.s3.us-west-2.amazonaws.com/MERCURY_nomenclature_center_pts.zip",
   "credit": "IAU Working Group for Planetary System Nomenclature / USGS Astrogeology",
   "licence": "Public domain / IAU nomenclature, free to use with credit",
   "fetched": "2026-10-04",
   "transform": "Shapefile attributes read from the DBF. Albedo features (historical Mariner 10 names) and exact duplicate rows were dropped. Longitudes converted from 0..360 east to -180..180. Kept every Planitia and Planum, the landmark list in tools/landmarks.json, and every feature with diameter >= 20 km. Origin text trimmed to 140 characters and folded to ASCII.",
   "used": [
    "data/features.json"
   ]
  },
  {
   "id": "mission-facts",
   "name": "Mission dates, altitudes and impact data",
   "url": "https://messenger.jhuapl.edu/Resources/Flyby-Information.html",
   "credit": "JHU/APL MESSENGER flyby pages; Wikipedia articles for Mariner 10, MESSENGER and BepiColombo; ESA BepiColombo news pages",
   "licence": "Facts; citations only",
   "fetched": "2026-10-04",
   "transform": "Hand-curated. MESSENGER flyby sub-spacecraft points (4.521 S 37.730 E; 3.419 S 228.945 E; 0.329 S 211.653 E) are from the JHU/APL pages. The impact site (54.4 N, 149.9 W = 210.1 E; 14,080 km/h = 3.91 km/s; crater about 16 m) is from the MESSENGER article. BepiColombo launch 2018-10-20, MPO orbit insertion 2026-11-21, Mio 2026-12-10 (separation 9/10 Dec). No sub-spacecraft point was found for the Mariner 10 or BepiColombo flybys, so none is stored.",
   "used": [
    "data/missions.json",
    "data/orbits.json"
   ]
  }
 ]
}