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Viking lander replica on display at the Smithsonian National Air and Space Museum with dish antenna, sampling arm and legs
NASA

Viking lander

The Viking landers were the NASA craft that carried out the first successful science on the surface of Mars.

Landers and rovers
Product IDnasa-viking-lander
Visit NASA
Landed mass
about 600 kg
Aeroshell diameter
3.5 m
Footprint
Footpads on an equilateral triangle, 2.21 m sides
Power
Two RTGs, 30 W each
Viking 1 launch
20 August 1975
Viking 1 landing
20 July 1976, Chryse Planitia

In short

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.

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.

How it is built

The base

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.

  • Base

The propellant tanks

Two spherical titanium tanks were mounted on opposite sides of the lander. They fed the engines used for the descent to the surface.

  • Propellant tanks (2)

The aeroshell

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.

  • Shell skin, Z-rings and base ring structure
  • Outer cone base cover
  • Inner cone base cover

The heat shield

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.

  • Forebody heat shield
  • Aeroshell outer skin ablation coating (thickness)

Power and bioshield

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.

  • RTG fuel (2 units)
  • Bioshield
Where the parts areNumber of parts we have listed in each group
  • Aeroshell3
  • Thermal protection2
  • Lander body1
  • Propulsion1
  • Power1
  • Bioshield1

What it is made of

  • Aluminium

    The six-sided base of the lander, and the aeroshell skin, rings and outer cone cover.

  • Titanium

    The two spherical propellant tanks.

  • Fibreglass with phenolic resin

    Glass fabric laminated with phenolic resin, used for the inner cone base cover of the aeroshell, 0.0406 cm thick.

  • SLA-561 ablator

    A super-lightweight ablator on the forebody heat shield.

  • Plutonium-238

    The fuel in the two radioisotope generators, which gave 30 W each.

The materials by familyHow many of the parts that name a material use each one
  • Aluminium3
  • Other3
  • Titanium1
  • Glass fibre1

How it connects to other things

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.

Products that use the same materials

  • Curiosity

    NASA / JPL

    AluminiumSLA-561 super-lightweight ablatorTitanium
    Where each one is used

    Aluminium. Here: Base; Shell skin, Z-rings and base ring structure and more. There: Wheel (6); Wheel shell thickness.

    SLA-561 super-lightweight ablator. Here: Forebody heat shield. There: Backshell ablator.

    Titanium. Here: Propellant tanks (2). There: Suspension tubes and arms to wheels.

  • Perseverance

    NASA / JPL

    AluminiumSLA-561 super-lightweight ablatorTitanium
    Where each one is used

    Aluminium. Here: Base; Shell skin, Z-rings and base ring structure and more. There: Wheel body (6).

    SLA-561 super-lightweight ablator. Here: Forebody heat shield. There: Backshell ablator.

    Titanium. Here: Propellant tanks (2). There: Wheel spokes; Legs / suspension tubing and more.

  • Proba-V

    ESA

    AluminiumTitanium
    Where each one is used

    Aluminium. Here: Base; Shell skin, Z-rings and base ring structure and more. There: Telescope (structure and mirrors, 3 telescopes).

    Titanium. Here: Propellant tanks (2). There: Focal plane interconnecting structure; Instrument mounting feet / flexures and more.

  • Proba-3 Coronagraph spacecraft

    ESA / Airbus

    AluminiumTitanium
    Where each one is used

    Aluminium. Here: Base; Shell skin, Z-rings and base ring structure and more. There: Main structure tube; Equipment box (EQB) and more.

    Titanium. Here: Propellant tanks (2). There: OBA unit attachment fittings; Instrument support bipods (3).

  • Apollo Lunar Roving Vehicle

    Boeing

    AluminiumTitanium
    Where each one is used

    Aluminium. Here: Base; Shell skin, Z-rings and base ring structure and more. There: Hub and wheel disc (MESH-1 prototype wheel).

    Titanium. Here: Propellant tanks (2). There: Tread chevrons; Inner frame (MESH-1 prototype wheel; flight material not stated).

  • Apollo Lunar Module (LM)

    Grumman / NASA

    AluminiumTitanium
    Where each one is used

    Aluminium. Here: Base; Shell skin, Z-rings and base ring structure and more. There: Cabin front-face, RCS cluster trusses, decks and bulkheads; Micrometeoroid shield and more.

    Titanium. Here: Propellant tanks (2). There: Some brackets and fasteners (lunar module); Descent-stage hot-area structure and more.

What we do not know

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.

The detailed data

What is written above is built from these numbers and quotes. Each row links to the page it was taken from. Get all of it as JSON, or ask our MCP server.

Features

  • Aeroshell with ablative heat shield slowed the craft for entry
  • Encased in a bioshield at launch to prevent contamination
  • Powered by radioisotope thermal generators using plutonium 238

Specifications

WhatValue
Landed massabout 600 kg
FootprintFootpads on an equilateral triangle, 2.21 m sides
PowerTwo RTGs, 30 W each
Aeroshell diameter3.5 m
Viking 1 launch20 August 1975
Viking 1 landing20 July 1976, Chryse Planitia
DestinationMars

Materials in detail

Each material named in the sources: where it is used here, which other products use it, and its key numbers when its material page exists.

  • Aluminium

    Used in 3 partsBase · Shell skin, Z-rings and base ring structure · Outer cone base cover

    Weight
    2.7 g/cm3
    Electrical conduction
    2.6458 µΩ·cm
    Heat conduction
    220 W/(m·K)
    Also in 33 other products
    Pumpkin CubeSat Kit structureProba-2Proba-V+30 more
    Open material page

  • laminated glass fabric and phenolic resin (fiberglass)

    fiberglass-phenolic-laminate

    Used in 1 partInner cone base cover

    Material page coming soon

  • plutonium-238

    plutonium-238

    Used in 1 partRTG fuel (2 units)

    Material page coming soon

  • SLA-561 super-lightweight ablator

    sla-561v

    Used in 1 partForebody heat shield

    Also in 2 other products
    CuriosityPerseverance
    Material page coming soon

  • Titanium (commercially pure, grades 1 to 4)

    Used in 1 partPropellant tanks (2)

    Density, CP grade 1
    4.51 g/cm³
    Density, CP grade 2 (bar and billet)
    4.51 g/cm³
    Density, CP grade 3
    4.51 g/cm³
    Also in 17 other products
    Proba-VProba-3 Coronagraph spacecraftCHEOPS+14 more
    Open material page

Every part we have

Structure, tanks, aeroshell and ablator have stated materials; bioshield and RTG hardware do not.

Material IDs

aluminiumtitaniumfiberglass-phenolic-laminatesla-561vplutonium-238
Lander body1
PartMaterialFinish and standardMade by
Base“six-sided aluminum base with alternate 1.09 m and .56 m long sides” aluminium (alloy not stated)aluminium — —
Propulsion1
PartMaterialFinish and standardMade by
Propellant tanks (2)“two spherical titanium tanks mounted on opposite sides of the lander” titanium (alloy not stated)titanium — —
Aeroshell3
PartMaterialFinish and standardMade by
Shell skin, Z-rings and base ring structure“A l l of these components are constructed of aluminum.” aluminium (alloy not stated)aluminium — NASA TN D-8300, Langley
Outer cone base cover“0.0254 cm of aluminum alloy for the outer cone” aluminium alloy (grade not stated)aluminium — —
Inner cone base cover“laminated glass fabric and phenolic resin (fiberglass) for the inner cone” laminated glass fabric and phenolic resin (fiberglass)fiberglass-phenolic-laminate — —
Thermal protection2
PartMaterialFinish and standardMade by
Forebody heat shield“Super-Lightweight Ablator - SLA-561” SLA-561 super-lightweight ablatorsla-561v — Developed by Martin Marietta per same source
Aeroshell outer skin ablation coating (thickness)“coated with an ablation material approximately 0.86 c m thick” ablation material (type not named in this report) — —
Power1
PartMaterialFinish and standardMade by
RTG fuel (2 units)“two radioisotope thermal generator (RTG) units containing plutonium 238” plutonium-238plutonium-238 — —
Bioshield1
PartMaterialFinish and standardMade by
Bioshield“The lander was encased in a bioshield at launch to prevent contamination” Not said — —

What the sources leave out

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.

Where this comes from

5 pages from 2 websites

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Collected from public pages and documents, checked 4 Nov 2026.

Published · Updated