Ariane Overview

     On June 4, 1996 a half billion dollars vanished in a brilliant explosion over French Guyana in South America. The loss was a heavy-lift rocket launcher designed to place into orbit satellites. This launcher self-destructed 40 seconds after liftoff. It was uninsured.

     The purpose of the Ariane launcher series was to make the European Space Agency more competitive on the commercial launch market. The Ariane 5 was considered to be an improvement over the Ariane 4 series because it could carry more cargo, was less expensive to operate, and was more reliable. This theory went up in a puff smoke when the launcher exploded. How did such an expensive failure occur? “The new launcher constitutes a significant step forward in terms of European industrial know-how,” trumpeted the space agency press release. No one denies the expertise and enthusiasm for the project were high and that there was competitive pressure to succeed.

The facts of the accident:
1. 7 minutes before liftoff the launch was put on hold because of poor visibility. Roughly an hour later, the launch resumed.
2. The software used in Ariane 5 was essentially the same as that used in Ariane 4 because the design was ‘practically’ the same.
3. However, if Ariane 4 had a liftoff delay, it could restart countdown without waiting for realignment. Small changes in the design made Ariane 5 unable to respond in this way.
4. When the launch was resumed, the alignment caused a computational exception (mathematical procedure error) which crashed the software and caused the launcher to self-destruct. The safety feature that caused the explosion was not necessary in the Ariane 5 because of design adaptations which weren’t updated in the software.
Accountability?

     Essentially, the problem was technical. Software engineers followed all standard procedures. Programmers understood the risk of failed computations and monitored 4 of the 7 variables according to the organization’s policy; the fault lay with one that was not monitored. Software management carefully organized and planned the process using industry standards. The European Space Agency decision to use the software from the Ariane 4 series was based on time pressures and cost. The technical glitch cost $500,000,000.