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  • Demonstrate benefits of in-flight IVHM to the operation of a Reusable Launch Vehicle
  • Advance Technology Readiness Level of this IVHM technology within a flight environment
  • Operate IVHM software on the Vehicle Management Computer

About the X-37 Spacecraft

  • Unpiloted
  • Reusable
  • 27.5 feet long
  • Mission
    • launch from Space Shuttle’s cargo bay
    • orbit Earth up to 21 days
    • land autonomously on runway
    • designed to allow future derivatives of the design (such as the Air Force's Space Maneuver Vehicle) to be launched atop an expendable launch vehicles as well as from inside the shuttle bay
  • First flight was originally scheduled for 2002
  • Being built by Boeing for NASA Marshall Space Flight Center

Experiment used Livingstone

  • Performs diagnosis using qualitative, Model-based Reasoning
  • Searches system-wide interactions to detect and isolate failures.
  • Reasons about complex system interactions within a real-time monitoring and control loop, rather than requiring an engineer to reason through all possible interactions and ‘hardwire’ the appropriate response to a pre-defined set of failures.
  • Updating and verifying the model is straightforward and less labor intensive than the task of identifying changes required in explicit procedural code.
  • Streamlines the software development process and maximizes code reusability across vehicles.
  • Facilitates the generation of an explanation or justification of the diagnosis, allowing the human operator to decide whether the diagnosis is reasonable before selecting or confirming the appropriate recovery action.
  • Was previously used in the Remote Agent Experiment on board Deep Space 1

Overview of the hardware and software

software chart The IVHM software was intended to run as a task on the Vehicle Management Computer (VMC). The Vehicle Management System (VMS) will be another task running on the VMC (and written by Boeing). The VMS will be responsible for telemetry and power management. The IVHM task will communicate with the VMS task in order to obtain sensor data and vehicle commands, and to send telemetry to the ground. The VMC will use PowerPC microprocessors and will run the VxWorks operating system. The IVHM software will be written in C++.

Scope of the Experiment

  • Monitor and diagnose Electro-mechanical Actuators and associated Electrical Power System components
  • Real-time fault detection and isolation
  • Diagnosis, not prognosis
  • Shadow mode only (no reconfiguration commands)
  • Generate advisory recommendations for ground ops


  • Limited resources (CPU, memory, telemetry bandwidth)
  • Rigorous software safety standards


NASA's Computational Sciences Division
Mark Schwabacher, Software Lead
Scott Poll, X-37 Models & Monitors
Jeremy Ou, integration, ground station, and monitors
Lee Brownston, Livingstone support

NASA's Aerospace Directorate
Jeff Samuels, Technical Lead
Mina Cappuccio, Task Manager
Scott Christa, Software Integration and Test

Boeing Reusable Space Systems - Seal Beach
Erv Baumann


The experiment was canceled in 2001.


M. Schwabacher, J. Samuels, and L. Brownston. The NASA Integrated Vehicle Health Management Technology Experiment for X-37. SPIE AeroSense 2002.
Full paper (pdf, 150 KB)

Page maintained by Mark Schwabacher. Last updated Dec 19, 2008

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