Highlight of Lockheed’s Shuttle Software Group

Mission Critical Software Controls every aspect of the space shuttles flight. Controls every aspect of the space shuttles flight. Some Tasks Some Tasks Gives orders to gimbal the main engines. Gives orders to gimbal the main engines. Belly roll the shuttle after it clears the towers. Belly roll the shuttle after it clears the towers. Throttles the engines. Throttles the engines. Keeps Track of where the shuttle is. Keeps Track of where the shuttle is. Makes course corrections. Makes course corrections.

Continued Orders the solid rocket boosters to fall away. Orders the solid rocket boosters to fall away. Directs the shuttle into orbit. Directs the shuttle into orbit. Orders the main engines to shut down. Orders the main engines to shut down.

Architecture Four computers Four computers Each run identical software and check with each other continuously. Each run identical software and check with each other continuously. They take information from thousands of sensors and vote on every decision. They take information from thousands of sensors and vote on every decision. A fifth computer stands by just in case. A fifth computer stands by just in case.

The Software 420,000 lines of code. 420,000 lines of code. Only 17 errors in the last 11 versions Only 17 errors in the last 11 versions

The Organization 260 Men/Women. 260 Men/Women. Software Shuttle Group is just one of four outfits in the world to achieve level 5 ranking by the Software Engineering Institute (1996) Software Shuttle Group is just one of four outfits in the world to achieve level 5 ranking by the Software Engineering Institute (1996) 70% of software organizations are stuck at level one or two. 70% of software organizations are stuck at level one or two.

The Process Careful design process Careful design process 2500 Page spec for the GPS module (6.5K LOC) 40,000 pages total for the entire software Page spec for the GPS module (6.5K LOC) 40,000 pages total for the entire software. No “cowboy” coders or late night heroics. No “cowboy” coders or late night heroics. Extensive database of the software. Extensive database of the software. History of every line of code. History of every line of code. Errors history: When, What, Why, Where and How dating back 20 plus years. Errors history: When, What, Why, Where and How dating back 20 plus years.

Continued Fix the mistakes, but also whatever permitted the mistake. Fix the mistakes, but also whatever permitted the mistake. Senior technical manager must fly to Florida before every launch and sign a document certifying that the software will not endanger the shuttle. Senior technical manager must fly to Florida before every launch and sign a document certifying that the software will not endanger the shuttle.

Conclusion “Perfect” software because it has to be. “Perfect” software because it has to be.