MOLA Analysis Definitions

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  • Acceptance Level
    (see Qualification Level) Once a design has been qualified, any other components built using the same design only need to be tested to lower acceptance levels to ensure the workmanship is good.
  • Instrument
    MOLA is itself an instrument; i.e., a component on a spacecraft that collects scientific data.
  • Launch Vehicle
    The rocket that puts the spacecraft into space. For MOLA, this will be a Delta II expendable launch vehicle.
  • Protoflight
    A protoflight component is one that designed, built, tested to qualification levels, and then flown. Generally, we like to use engineering prototype models for testing, just in case something goes wrong. But often, to save money, we will build only one protoflight component. The word comes from combining "prototype" and "flight hardware." See also, Qualification Level.
  • Qualification Level
    Before a new component design can ever fly, it must be analyzed and tested to a qualification level, so the design can be qualified. This level is usually 1.4 times the highest load the component should ever experience in operation. Protoflight test levels are the same as qualification levels.
  • Shaker Point
    This term refers to the point on a finite element model to which a random vibration or sine vibration input is applied; i.e., the model is shaken at this point. The shaker point corresponds to the shaker table used during vibration testing.
  • Spacecraft
    The Mars Global Surveyor is the spacecraft; i.e., the craft that actually makes the voyage from Earth to Mars. The spacecraft contains the instruments, the communications equipment, the power supply (batteries and solar shields), and the navigation and propulsion systems.
  • T1, T2, and T3
    Translational directions generally corresponding to X, Y, and Z. This nomenclature is often used to avoid confusion with the three rotational directions R1, R2, and R3.

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    Goddard Meatball This page is maintained by Ryan Simmons, at
    This page was last updated on December 20, 1995.