1. ARIANE 5 FAILURE ► BACKGROUND:- ► European space agency’s re-useable launch vehicle. ► Ariane-4 was a major success ► Ariane -5 was developed for the larger payloads ► LAUNCHED:-on June 4 1996 ► MISSION was to delivered $500 million payloads to the orbit ► THE MAIDEN FLIGHT OF THE ARIANE 5 ENDED IN A FAILURE. ► ONLY AFTER 40 SECONDS THE FLIGHT VEERED OFF ITS PATH AND BROKE UP AND EXPLODED ► CAUSE: Unhandled floating point exception in code ► ENGINEERS FROM THE ARIANE PROJECT STARTED TO INVESTIGATE THE CAUSES OF LAUNCH FAILURE.

2. The failure ► On the basis of the investigation the following is the general description as follows: ► The weather at the site of the kourov was acceptable for launch and presented no obstacle. ► There was no risk of lightning since the strength of the electric field measured at the launch site was negligible. ► The time initially decided for the launch was at 08h 35mn.(local time) ► But due to some visibility conditions they waited until visibility improved as forecasted and launch was initiated at 09h 33 min 59 s. ► The flight performed the normal launch until 37 seconds, shortly after the time, its veered off it path. ► Failure of the backup inertial system

3. RECOVERY OF THE SYSTEM ► The destruction of the flight occurred at an altitude of 4000m, near to the launch pad so all debris fell back to the launch pad. ► Scattered over the area of app.. 12 km east of the site. ► Two IRS recovered, one had worked in active mode and stopped functioning last, and for which therefore certain information was not available in the telemetry data.

4. EVENTS ► ARIANE 5 ‘s flight control system was a standard design. ► SRI (INERTIAL REFERENCE SYSTEM) ► SRI Is used to measure the attitude of the launcher and its movement in the space, and the on this basis the angles and velocities are determined. ► The data from the SRI is transferred through the data bus to the on board computer (OBC). ► Two SRI were running in parallel to improve the reliability.

5. ► Two identical SRI were used with the identical software and hardware. ► One SRI is active and other is in the “hot standby”. ► If the OBC detects that one SRI has failed then it immediately switches to the other one. ► Like wise there were 2 OBC’s and other number of flight control system items were duplicate.

6. ► THE MAIN CAUSE OF THE FAILURE: ► The flight exploded after 40 seconds. ► The rocket was made after the development of a decade. ► A board investigated that it happened due to the software error in the inertial reference system. ► Specifically the 64 bit floating point number relating to the horizontal velocity was converted to the 16 bit signed integer.

7. ► The number was larger then 32,767 which was greater then the largest integer store able in the 16 bit signed integer and hence the conversion failed. ► A LOOK AT THE FINANCIAL ASPECTS OF THE LOSS:, the rocket cost over $7 billion.the destroyed rocket and its cargo were valued at $500 million.

8. Causes of the failure ► The loss of the ariane was due to the loss of guidance and attitude information 37 seconds after the 37 seconds main ignition. ► The loss of information was due to specification and design errors in the software of SRI. ► It was not considered wise to change the software that worker well on ariane -4. ► No trajectory data was provided, and the implementation assumption were not documented. ► They assumed that it could not happen??

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