{
  "id": "muos",
  "name": "Mobile User Objective System (MUOS)",
  "aliases": [],
  "domain": "space",
  "country": "USA",
  "category": "Narrowband military communications constellation",
  "status": "in-service",
  "fielded": 2012,
  "operators": [
    "USA",
    "CAN"
  ],
  "summary": "UHF narrowband satellite system giving mobile forces cellular-like voice, chat and data; replaces UFO.",
  "specs": [
    {
      "k": "orbit_regime",
      "v": "GEO",
      "src": [
        "asf-mobile-user-objective-system"
      ],
      "conf": "high"
    },
    {
      "k": "sats_count",
      "v": 5,
      "src": [
        "asf-mobile-user-objective-system"
      ],
      "conf": "medium",
      "note": "Four operational plus one on-orbit spare"
    },
    {
      "k": "first_launch",
      "v": 2012,
      "src": [
        "asf-mobile-user-objective-system"
      ],
      "conf": "medium"
    },
    {
      "k": "design_life_yr",
      "v": 14,
      "src": [
        "asf-mobile-user-objective-system"
      ],
      "conf": "medium"
    },
    {
      "k": "mass_kg",
      "v": 3813,
      "src": [
        "asf-mobile-user-objective-system"
      ],
      "conf": "medium",
      "note": "8,405 lb including 6,450 lb of fuel"
    },
    {
      "k": "mission",
      "v": "UHF narrowband BLOS voice, chat and data, 89.5°N to 65°S",
      "src": [
        "asf-mobile-user-objective-system"
      ],
      "conf": "medium"
    },
    {
      "k": "contractor",
      "v": "Lockheed Martin",
      "src": [
        "asf-mobile-user-objective-system"
      ],
      "conf": "medium"
    },
    {
      "k": "program",
      "v": "Two more satellites targeted by 2030 (Boeing, $2 billion); Canada first allied user (IOC June 2024)",
      "src": [
        "asf-mobile-user-objective-system"
      ],
      "conf": "medium"
    },
    {
      "k": "on_orbit",
      "v": 5,
      "src": [
        "celestrak-gp"
      ],
      "conf": "high",
      "note": "Payloads with current element sets in the public catalog, active or not."
    },
    {
      "k": "active_sats",
      "v": 5,
      "src": [
        "celestrak-gp"
      ],
      "conf": "medium",
      "note": "Count in the CelesTrak active satellites list, which estimates operational status."
    },
    {
      "k": "perigee_km",
      "v": [
        34924,
        35573
      ],
      "src": [
        "celestrak-gp"
      ],
      "conf": "high",
      "note": "Active satellites per CelesTrak, element epoch about 2026-11-08."
    },
    {
      "k": "apogee_km",
      "v": [
        36000,
        36649
      ],
      "src": [
        "celestrak-gp"
      ],
      "conf": "high",
      "note": "Active satellites per CelesTrak, element epoch about 2026-11-08."
    },
    {
      "k": "period_min",
      "v": 1436.1,
      "src": [
        "celestrak-gp"
      ],
      "conf": "high",
      "note": "Active satellites per CelesTrak, element epoch about 2026-11-08."
    },
    {
      "k": "inclination_deg",
      "v": [
        1.91,
        5.77
      ],
      "src": [
        "celestrak-gp"
      ],
      "conf": "high",
      "note": "Active satellites per CelesTrak, element epoch about 2026-11-08."
    }
  ],
  "payloads": [],
  "variants": [],
  "art": "satellite",
  "image": {
    "file": "muos.jpg",
    "thumb": "muos-thumb.jpg",
    "credit": "Courtesy photo, U.S. Government / DVIDS",
    "license": "Public domain",
    "url": "https://www.dvidshub.net/image/976415",
    "title": "Atlas V rocket",
    "source": "DVIDS",
    "dvids_id": 976415,
    "unit": "U.S. Navy"
  },
  "verified": null,
  "changelog": [
    {
      "date": "2026-11-08",
      "change": "Entry created from cited open sources"
    },
    {
      "date": "2026-11-08",
      "change": "Orbital elements from CelesTrak GP data (epoch about 2026-11-08): 5 catalogued, 5 active."
    }
  ],
  "satellites": [
    {
      "name": "MUOS-1",
      "norad": 38093,
      "cospar": "2012-009A",
      "perigee_km": 35573,
      "apogee_km": 36000,
      "inclination_deg": 5.77,
      "period_min": 1436.1,
      "epoch": "2026-11-08",
      "active": true,
      "owner": "US",
      "launch": "2012-02-24"
    },
    {
      "name": "MUOS-2",
      "norad": 39206,
      "cospar": "2013-036A",
      "perigee_km": 35540,
      "apogee_km": 36035,
      "inclination_deg": 5.28,
      "period_min": 1436.1,
      "epoch": "2026-11-08",
      "active": true,
      "owner": "US",
      "launch": "2013-07-19"
    },
    {
      "name": "MUOS-3",
      "norad": 40374,
      "cospar": "2015-002A",
      "perigee_km": 35535,
      "apogee_km": 36039,
      "inclination_deg": 4.8,
      "period_min": 1436.1,
      "epoch": "2026-11-08",
      "active": true,
      "owner": "US",
      "launch": "2015-01-21"
    },
    {
      "name": "MUOS-4",
      "norad": 40887,
      "cospar": "2015-044A",
      "perigee_km": 35568,
      "apogee_km": 36005,
      "inclination_deg": 4.6,
      "period_min": 1436.1,
      "epoch": "2026-11-07",
      "active": true,
      "owner": "US",
      "launch": "2015-09-02"
    },
    {
      "name": "MUOS-5",
      "norad": 41622,
      "cospar": "2016-041A",
      "perigee_km": 34924,
      "apogee_km": 36649,
      "inclination_deg": 1.91,
      "period_min": 1436.1,
      "epoch": "2026-11-08",
      "active": true,
      "owner": "US",
      "launch": "2016-06-24"
    }
  ],
  "url": "https://www.defensepedia.com/systems/muos.html",
  "sources": {
    "asf-mobile-user-objective-system": {
      "title": "Mobile User Objective System (weapons and platforms entry)",
      "publisher": "Air & Space Forces Magazine",
      "url": "https://www.airandspaceforces.com/weapons/mobile-user-objective-system/",
      "published": null,
      "tier": 3,
      "checked": "2026-11-08"
    },
    "celestrak-gp": {
      "title": "NORAD GP element sets (current data)",
      "publisher": "CelesTrak (data from the U.S. Space Force 18th/19th Space Defense Squadron catalog)",
      "url": "https://celestrak.org/NORAD/elements/",
      "published": "2026-11-08",
      "tier": 1,
      "checked": "2026-11-08"
    }
  }
}