{
  "id": "nasa-viking-lander",
  "title": "Viking lander",
  "maker": "NASA",
  "maker_type": "Space agency",
  "kind": "mission",
  "category": "rovers",
  "page": "https://spacemushroom.com/space-products/nasa-viking-lander/",
  "website": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
  "summary": "NASA Mars lander (Viking 1 and 2, 1975-76); sources describe an aluminium base, titanium propellant tanks, an aluminium aeroshell with an ablative heat shield, and plutonium-238 RTGs.",
  "application": "NASA's pair of Mars landers that carried the first successful surface science to Mars. Each rode inside an aeroshell with an ablative heat shield, then descended on engines fed from titanium tanks and was powered by plutonium RTGs.",
  "story": {
    "headline": "The Viking landers were the NASA craft that carried out the first successful science on the surface of Mars.",
    "intro": [
      "The Viking landers came from NASA's 1975-76 Viking missions. Each rode to Mars inside an aeroshell with an ablative heat shield, a coating that wears away as it heats. It then descended on engines fed from titanium tanks and drew its power from two generators fuelled by plutonium-238.",
      "A six-sided aluminium base formed the body of the lander, with two spherical titanium tanks on opposite sides. The 3.5 m aeroshell around it was aluminium too, coated with an ablator about 0.86 cm thick that slowed the craft during entry."
    ],
    "built": [
      {
        "title": "The base",
        "text": "The base was a six-sided aluminium structure, with sides that alternate between 1.09 m and 0.56 m long. The footpads formed an equilateral triangle with sides of 2.21 m. After landing, the lander had a mass of about 600 kg.",
        "parts": [
          "Base"
        ]
      },
      {
        "title": "The propellant tanks",
        "text": "Two spherical titanium tanks were mounted on opposite sides of the lander. They fed the engines used for the descent to the surface.",
        "parts": [
          "Propellant tanks (2)"
        ]
      },
      {
        "title": "The aeroshell",
        "text": "The shell skin, its rings and the base ring structure were all aluminium. The base cover of the outer cone was aluminium alloy sheet 0.0254 cm thick, while the inner cone's was fibreglass 0.0406 cm thick.",
        "parts": [
          "Shell skin, Z-rings and base ring structure",
          "Outer cone base cover",
          "Inner cone base cover"
        ]
      },
      {
        "title": "The heat shield",
        "text": "The forebody carried SLA-561, a super-lightweight ablator developed by Martin Marietta. The coating on the aeroshell skin was about 0.86 cm thick. With this heat shield, the aeroshell slowed the craft for entry.",
        "parts": [
          "Forebody heat shield",
          "Aeroshell outer skin ablation coating (thickness)"
        ]
      },
      {
        "title": "Power and bioshield",
        "text": "Two radioisotope thermal generators, which turn the heat of decaying plutonium-238 into electricity, gave 30 W each of continuous power. At launch the lander was encased in a bioshield to prevent contamination.",
        "parts": [
          "RTG fuel (2 units)",
          "Bioshield"
        ]
      }
    ],
    "materials": [
      {
        "name": "Aluminium",
        "mid": "aluminium",
        "where": "The six-sided base of the lander, and the aeroshell skin, rings and outer cone cover."
      },
      {
        "name": "Titanium",
        "mid": "titanium",
        "where": "The two spherical propellant tanks."
      },
      {
        "name": "Fibreglass with phenolic resin",
        "mid": "fiberglass-phenolic-laminate",
        "where": "Glass fabric laminated with phenolic resin, used for the inner cone base cover of the aeroshell, 0.0406 cm thick."
      },
      {
        "name": "SLA-561 ablator",
        "mid": "sla-561v",
        "where": "A super-lightweight ablator on the forebody heat shield."
      },
      {
        "name": "Plutonium-238",
        "mid": "plutonium-238",
        "where": "The fuel in the two radioisotope generators, which gave 30 W each."
      }
    ],
    "connections": "Viking sent two separate spacecraft to Mars. Viking 1 launched on 20 August 1975 and touched down on 20 July 1976 on Chryse Planitia. The lander carried two plutonium-238 radioisotope generators and descended on engines fed from its titanium tanks. Martin Marietta developed the SLA-561 ablator on its heat shield.",
    "unknown": "The materials of the bioshield, legs, footpads, instrument bay and instruments are not stated. Nor are the generator housings, the thermoelectric materials inside them and the alloys of the aluminium and titanium parts.",
    "facts": [
      {
        "label": "Landed mass",
        "value": "about 600 kg"
      },
      {
        "label": "Aeroshell diameter",
        "value": "3.5 m"
      },
      {
        "label": "Footprint",
        "value": "Footpads on an equilateral triangle, 2.21 m sides"
      },
      {
        "label": "Power",
        "value": "Two RTGs, 30 W each"
      },
      {
        "label": "Viking 1 launch",
        "value": "20 August 1975"
      },
      {
        "label": "Viking 1 landing",
        "value": "20 July 1976, Chryse Planitia"
      }
    ]
  },
  "specifications": [
    {
      "label": "Landed mass",
      "value": "about 600 kg",
      "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
      "quote": "After separation and landing, the lander had a mass of about 600 kg"
    },
    {
      "label": "Footprint",
      "value": "Footpads on an equilateral triangle, 2.21 m sides",
      "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
      "quote": "formed the vertices of an equilateral triangle with 2.21 m sides"
    },
    {
      "label": "Power",
      "value": "Two RTGs, 30 W each",
      "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
      "quote": "provided 30 W continuous power at 4.4 volts"
    },
    {
      "label": "Aeroshell diameter",
      "value": "3.5 m",
      "source_url": "https://ntrs.nasa.gov/citations/20060017066",
      "quote": "The entry vehicle was a 3.5-meter diameter 70-deg sphere-cone forebody",
      "quote_check": "not matched on the source page"
    },
    {
      "label": "Viking 1 launch",
      "value": "20 August 1975",
      "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
      "quote": "Viking 1, launched on 20 August 1975"
    },
    {
      "label": "Viking 1 landing",
      "value": "20 July 1976, Chryse Planitia",
      "source_url": "https://nssdc.gsfc.nasa.gov/planetary/viking.html",
      "quote": "touched down on July 20, 1976",
      "quote_check": "not matched on the source page"
    },
    {
      "label": "Destination",
      "value": "Mars",
      "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
      "quote": "launches of two separate spacecraft to Mars"
    }
  ],
  "features": [
    {
      "text": "Aeroshell with ablative heat shield slowed the craft for entry",
      "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
      "quote": "The aeroshell with its ablatable heat shield slowed the craft"
    },
    {
      "text": "Encased in a bioshield at launch to prevent contamination",
      "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
      "quote": "The lander was encased in a bioshield at launch to prevent contamination"
    },
    {
      "text": "Powered by radioisotope thermal generators using plutonium 238",
      "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
      "quote": "Power was provided by two radioisotope thermal generator (RTG) units containing plutonium 238"
    }
  ],
  "parts": [
    {
      "assembly": "Lander body",
      "parts": [
        {
          "part": "Base",
          "material": "aluminium (alloy not stated)",
          "form": "six-sided base",
          "finish": null,
          "standard": null,
          "hardware_ref": null,
          "quote": "six-sided aluminum base with alternate 1.09 m and .56 m long sides",
          "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
          "profile": "aluminium",
          "mid": "aluminium"
        }
      ]
    },
    {
      "assembly": "Propulsion",
      "parts": [
        {
          "part": "Propellant tanks (2)",
          "material": "titanium (alloy not stated)",
          "form": "spherical tanks",
          "finish": null,
          "standard": null,
          "hardware_ref": null,
          "quote": "two spherical titanium tanks mounted on opposite sides of the lander",
          "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
          "profile": "titanium",
          "mid": "titanium"
        }
      ]
    },
    {
      "assembly": "Aeroshell",
      "parts": [
        {
          "part": "Shell skin, Z-rings and base ring structure",
          "material": "aluminium (alloy not stated)",
          "form": "chem-milled conical segments with Z-rings",
          "finish": null,
          "standard": null,
          "hardware_ref": "NASA TN D-8300, Langley",
          "quote": "A l l of these components are constructed of aluminum.",
          "source_url": "https://ntrs.nasa.gov/citations/19770005493",
          "profile": "aluminium",
          "mid": "aluminium"
        },
        {
          "part": "Outer cone base cover",
          "material": "aluminium alloy (grade not stated)",
          "form": "0.0254 cm sheet",
          "finish": null,
          "standard": null,
          "hardware_ref": null,
          "quote": "0.0254 cm of aluminum alloy for the outer cone",
          "source_url": "https://ntrs.nasa.gov/citations/20060017066",
          "profile": "aluminium",
          "mid": "aluminium"
        },
        {
          "part": "Inner cone base cover",
          "material": "laminated glass fabric and phenolic resin (fiberglass)",
          "form": "0.0406 cm laminate",
          "finish": null,
          "standard": null,
          "hardware_ref": null,
          "quote": "laminated glass fabric and phenolic resin (fiberglass) for the inner cone",
          "source_url": "https://ntrs.nasa.gov/citations/20060017066",
          "profile": null,
          "mid": "fiberglass-phenolic-laminate"
        }
      ]
    },
    {
      "assembly": "Thermal protection",
      "parts": [
        {
          "part": "Forebody heat shield",
          "material": "SLA-561 super-lightweight ablator",
          "form": "ablative layer, about 0.86 cm on the aeroshell skin",
          "finish": null,
          "standard": null,
          "hardware_ref": "Developed by Martin Marietta per same source",
          "quote": "Super-Lightweight Ablator - SLA-561",
          "source_url": "https://ntrs.nasa.gov/citations/20190032239",
          "profile": null,
          "mid": "sla-561v"
        },
        {
          "part": "Aeroshell outer skin ablation coating (thickness)",
          "material": "ablation material (type not named in this report)",
          "form": "about 0.86 cm thick",
          "finish": null,
          "standard": null,
          "hardware_ref": null,
          "quote": "coated with an ablation material approximately 0.86 c m thick",
          "source_url": "https://ntrs.nasa.gov/citations/19770005493",
          "profile": null,
          "mid": null
        }
      ]
    },
    {
      "assembly": "Power",
      "parts": [
        {
          "part": "RTG fuel (2 units)",
          "material": "plutonium-238",
          "form": "radioisotope heat source",
          "finish": null,
          "standard": null,
          "hardware_ref": null,
          "quote": "two radioisotope thermal generator (RTG) units containing plutonium 238",
          "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
          "profile": null,
          "mid": "plutonium-238"
        }
      ]
    },
    {
      "assembly": "Bioshield",
      "parts": [
        {
          "part": "Bioshield",
          "material": null,
          "form": null,
          "finish": null,
          "standard": null,
          "hardware_ref": null,
          "quote": "The lander was encased in a bioshield at launch to prevent contamination",
          "source_url": "https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1975-075C",
          "profile": null,
          "mid": null
        }
      ]
    }
  ],
  "materials": [
    {
      "id": "aluminium",
      "name": "aluminium alloy (grade not stated)",
      "material_page": "https://spacemushroom.com/profiles/aluminium/"
    },
    {
      "id": "titanium",
      "name": "titanium (alloy not stated)",
      "material_page": "https://spacemushroom.com/profiles/titanium/"
    },
    {
      "id": "fiberglass-phenolic-laminate",
      "name": "laminated glass fabric and phenolic resin (fiberglass)",
      "material_page": null
    },
    {
      "id": "sla-561v",
      "name": "SLA-561 super-lightweight ablator",
      "material_page": null
    },
    {
      "id": "plutonium-238",
      "name": "plutonium-238",
      "material_page": null
    }
  ],
  "standards": [],
  "relations": [],
  "not_published": "Bioshield material, RTG housing/thermoelectric materials, legs, footpads, lander bay and instrument materials not found in NASA sources reached. Propellant tank alloy not stated. The TN D-8300 report does not name the ablator; SLA-561 is linked to Viking in a separate NASA Ames slide deck. SLA-561V was used on the heat shield, the aluminium skin of the aeroshell is not confirmed to be honeycomb.",
  "depth": "partial",
  "photos": [
    {
      "file": "products/context/nasa-viking-lander-1.jpg",
      "alt": "Viking lander replica on display at the Smithsonian National Air and Space Museum with dish antenna, sampling arm and legs",
      "long": "Viking lander replica on display at the Smithsonian National Air and Space Museum with dish antenna, sampling arm and legs",
      "kind": "product",
      "credit": "Vintage Fan 5678, CC BY 4.0, via Wikimedia Commons",
      "license": "CC BY 4.0",
      "page_url": "https://commons.wikimedia.org/wiki/File:Viking_Mars_Lander_replica_on_display_in_the_Smithsonian%27s_Air_and_Space_museum_in_August_2015.jpg"
    },
    {
      "file": "products/context/nasa-viking-lander-2.jpg",
      "alt": "Viking spacecraft in flight configuration: orbiter with the lander aeroshell capsule on a black background (NASA photo of",
      "long": "Viking spacecraft in flight configuration: orbiter with the lander aeroshell capsule on a black background (NASA photo of model/hardware)",
      "kind": "context",
      "context": "Viking in flight configuration",
      "credit": "NASA (public domain, via Wikimedia Commons)",
      "license": "Public domain",
      "page_url": "https://commons.wikimedia.org/wiki/File:Viking_spacecraft.jpg"
    },
    {
      "file": "products/context/nasa-viking-lander-3.jpg",
      "alt": "Painting by Don Davis of a Viking orbiter releasing the lander aeroshell above Mars",
      "long": "Painting by Don Davis of a Viking orbiter releasing the lander aeroshell above Mars",
      "kind": "artwork",
      "context": "Painting by Don Davis",
      "credit": "Don Davis / NASA (public domain, via Wikimedia Commons)",
      "license": "Public domain",
      "page_url": "https://commons.wikimedia.org/wiki/File:Viking_Orbiter_releasing_the_lander.jpg"
    }
  ],
  "context": {
    "size": [],
    "mass": [],
    "orbit": [
      "Deep space"
    ]
  },
  "licence": "Product data CC BY 4.0, cite Space Mushroom. Photos keep their own licences, given per photo.",
  "mcp": "https://spacemushroom.com/mcp"
}