Common Space Vehicle Mechanisms

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Actuators at a Glance

Northrop Grumman has been delivering space mechanisms for stowing and articulating spacecraft payloads and solar arrays for 40+ years with 100% mission success and our modular actuators are represented on over 50 missions.

Our designs specialize in:

  • Long-life or high-use missions
  • Low disturbance (induced vibrations reduced for simultaneous operation of payloads)
  • Precision pointing (higher altitude missions)
Data Sheet: Common Space Vehicle Mechanisms

Heritage Products

Deployment Actuators (TRL 9)

Mechanisms to deploy structure or to spool cables. High torque output with current limit drive, or stepper motor (or micro-stepping for low disturbance).

  • Continuous rotation
  • Cable winder mechanisms have two assemblies:
    • Cable Drive Module (CDM)
    • Current Limiter Assembly (CLA)

Solar Array Drive Assembly (TRL 9)

Provides transmission of solar power and electronic signals between solar array and spacecraft; custom or modular slip ring designs for full 360-degree rotation or cable wrap design for limited angle rotations; EMI shielding; Electrically redundant

  • SADA with limited travel (cable management system)
    • Provides bi-directional rotation to maintain limited angle positioning of the solar array
    • Provides absolute angular position knowledge
  • SADA with continuous rotation (slip ring)
    • Provides continual 360-degree rotation of the solar array to maintain solar orientation
    • Provides null position information (via switch ring 1X/Rev)
  • Configurable items:
    • Modular Slip ring - scalable power with 20 or 30 ring modules; Up to four modules (max 120 circuits)
    • Position Feedback: Switch Ring/Poten
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Precision Pointing Mechanisms:

Single and multiple axes rotary mechanisms with cable management systems (RF and DC data/power transmission), zero cogging motors (optional jitter compensation algorithms), zero backlash gearing, highly accurate position feedback, and micro-stepping capability yielding arc-second magnitude pointing

Stop Assembly Options:

  • Deployable/Stowage stops
  • Large travel range (up to 510 degrees)

Large Rotary Actuators (TRL 9)

High Torque & Large Range of Travel

  • Large payload (antenna or boom assembly) articulation

Medium Rotary Actuators (TRL 9)

High Torque & Medium Size Payload

  • Higher speed capability with dual actuator configuration
  • Higher torque options with larger motor

Biaxial Actuators (TRL 9)

Orthogonal Axes of Rotation/”Cone” Coverage

  • Commonly used to host medium sized antennas in different orbits (e.g. 1-2 meter diameter)
  • RF/DC/waveguide for payload signal/power transmission
  • Used for JWST, AEHF and STSS antennas

Extra Large Rotary Actuators (TRL 9)

High Stiffness/Torque Applications

  • Extended boom steering mechanisms with beryllium structural parts
  • 10.5" diameter Zero-Cogging Motor
  • Dual chamber, counter rotating cable wrap with RF and DC data and power transmission
  • High strength external stop assembly to handle large inertial loads
Custom Mechanisms

Custom Mechanisms

Optical pointing, high-speed scanning (terrestrial or space applications), flip mechanisms, tracking and launching mechanisms


  • 4 axis deployable boom assembly
  • High torque latch actuator with bevel gears
  • Linear actuator utilizing ball screw with photo-resistor position feedback
spacecraft part

Modular Actuator Product Line

The Customizable Actuator for Space Precision Rotation (CASPR) product line offers accurateand smooth rotation of spacecraft payloads. It can be used for antenna pointing mechanisms (single axis or biaxial) on communications satellites, or coupled with a slip ring for solar array driving applications. Its long-life design can be adapted for shorter-life missions.

Design Highlights
The actuator comes in two sizes for small (CASPR 10) and medium (CASPR 20) payloads.

  • Optional position feedback
  • Low torque disturbance
  • Two-phase or three phase motors
  • Zero backlash (harmonic drive gears)
  • High stiffness
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  • 5.5" dia. x 6" long
  • 516 in-lbs torque @28V
  • Articulate 1-3 meter antenna


  • LEO, HEO, MEO, and GEO orbits
  • Flight heritage
  • Class A-D versions available
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  • 3.6" dia. x 4" long
  • 78 in-lbs torque @ 28V
  • Articulate <1 meter antenna

For More Information, Contact

Space Vehicle & Payload Products