ARIANE 5 FAILURE

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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