NASA Office of Logic Design

NASA Office of Logic Design

A scientific study of the problems of digital engineering for space flight systems,
with a view to their practical solution.

2003 MAPLD International Conference

Ronald Reagan Building and International Trade Center
Washington, D.C.

September 9-11, 2003


Panel Session

Wednesday Evening, September 10, 2003

Last year we discussed "Why is Mars So Hard?"
and a question that arose was ...

Why Is Software So Hard?

A Discussion of the Technical, Programmatic, and Political Factors

That Have Lead To Failures Over the Last 40 Years and Its Impact for Future Systems

Some Examples ...

Panel Moderator: Dr. Rod Barto (Bio)
Spacecraft Digital Electronics 

Dr. James Tomayko,
Carnegie Mellon University (bio)
Dr. Paul Cerruzi, Smithsonian National Air and Space Museum (bio)

Opening Case Studies: Magellan and Mars Pathfinder
Tony Spear, Jet Propulsion Laboratory (bio)

Panel Member Organization
Dr. Nancy Leveson (bio)

Professor of Aeronautics and Astronautics
Massachusetts Institute of Technology

Jack Garman (bio) Lockheed-Martin (NASA, retired)
Fred Martin (bio) Averstar/Intermetrics
Steven S. Scott (bio) Chief Engineer, NASA Goddard Space Flight Center
John P. Dimtroff (bio) Federal Aviation Administration
Aircraft Certification Engineer - Avionics Systems
Jim Lewis (bio) SynthWorks Design Inc.

Note: All panel members at this time are tentative, as the Panel is in the process of formation.

Two Examples of One Failure Type: Garbage In, Garbage Out

Program A Anomaly

IMU parameters had to be entered just prior to launch

  • Could not be verified in a test bed

  • Procedure required a second operator to verify manual entries against factory printout

A supervising engineer copied data from the factory printout and gave it to operators, saying that it was suitable.

Flight was degraded because the engineer wrote down the wrong sign!

Program B Anomaly

A roll rate filter constant, manually entered into the upper stage’s avionics database missed an exponent - in effect misplaced a decimal point.

Error was not spotted due to data format complication

Flight tape not checked against software test bed – thought test bed could only be used for default values

IV&V only used default constants, not the flight database

  • Independent simulations deemed not fully capable
  • Would have caught the gross error

Highlights from the 2002 MAPLD International Conference Panel

"Why Is Mars So Hard?"

A Discussion of the Technical, Programmatic, and Political Factors
That Have Lead To Failures at Mars over the Last 40 Years

Panel Moderator
Dr. Rod Barto (Bio)
Spacecraft Digital Electronics

Dr. Roger Launius (Bio)
Chair, Dept. of Space History, National Air and Space Museum
"A Historical Perspective"
Dr. Ed Euler
Lockheed Martin Astronautics Operations
Dr. James Garvin
NASA Headquarters, Mars Exploration Program Office
Dr. Stamatios M. (Tom) Krimigis (bio)
Head, Space Department
Johns Hopkins University/Applied Physics Lab
Anthony Spear (bio)
JPL; Chair, NASA Faster, Better, Cheaper (FBC) Task Force;
Mars Pathfinder Project Manager, Magellan Project Manager
James Oberg (bio)
Soaring Hawk Productions, Inc. (Consultant and Author)
Ken Ledbetter (bio)
Executive Director for Programs in the Office of Space Science (OSS) at NASA Headquarters

Some reference material:


We invite your participation in our Panel Session.


Richard B. Katz
NASA Goddard Space Flight Center

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Last Revised: February 03, 2010
Digital Engineering Institute
Web Grunt: Richard Katz