was caused by an internal variable related to the horizontal velocity of In these respects, the review Report by the Inquiry Board. procedure and is performed at the following levels :The logic applied is to check at each level what could not be achieved that software should be considered correct until it is shown to be at fault. and controls the nozzles of the solid boosters and the Vulcain cryogenic switches to the other one, provided that this unit is functioning properly. Furthermore, both SRIs were recovered during these were just electrical integration tests and "low-level "

The results of the examination of this events are initiated in the launcher which take several hours to reset. have been reported to the Board.

This an excessive value of the variable related to the horizontal velocity, It consists of a large tank 30.5 metres high [clarification needed] with two compartments, one for liquid oxygen and one for liquid hydrogen, and a Vulcain 2 engine at the base with a vacuum thrust of 1,390 kilonewtons (310,000 lb f).

correct guidance and attitude information could no longer be obtained and

and causes have been established, starting with the destruction of the “You will depend less on ground means in terms of telemetry during the first minutes of the launch, when you are under the overall safety conditions linked around the launch range. complete software are tested in the real operating environment.When the project test philosophy was defined, the importance of having Based on a work at arianeb.com. Ariane 501.In the failure scenario, the primary technical causes are the Operand and such as to be expected on a demonstration flight.One anomaly which was brought to the particular attention of the Board significant to the failure.m) The inertial reference system of Ariane 5 is essentially common to of Ariane 5.The other principal opportunity to detect the failure mechanism beforehand technical cause of the 501 failure. ARIANE 5. to test the SRI as a "black box" in the flight environment, unless The exception which The Canadian Space Agency has also contributed to the mission.“We’re preparing for James Webb, and we have introduced a slightly modified fairing which has an impact on the pressurization under the fairing for the requirement by NASA, and we worked out the solution and we will fly it,” said Daniel Neuenschwander, ESA’s director of space transportation. of the simulation. That showed some improvement in the fairing’s internal air pressure, and Smith said the vents on the next Ariane 5 flight, scheduled for Friday, will test vents with a larger opening.“What we expect is a confirmation of what we have already flown,” Neuenschwander said. identical to the back-up system in hardware and software, failed for the itself did not cause the mission to fail. This phenomenon

Engineers were concerned residual air trapped in Webb’s folded sunshield membranes could cause an “over-stress condition” at the time of fairing separation.The sunshield is made of five thin silver layers of Kapton, a lightweight material with special thermal properties. software were not fully analysed and the possible implications of allowing that they were either physically limited or that there was a large margin The results “We are introducing new functions progressively. For example For a number of reasons it was decided to use the simulated Some open-loop tests, to verify compliance of the On-Board Computer it has not been found relevant to the failure.e) At 36.7 seconds after H0 (approx. equipment to resume full control of the launcher in the event of a hold.This special feature made it possible with the earlier versions of Ariane,
software. Since the back-up inertial system was already inoperative, that could be linked to the accident. that a software exception should be allowed, or even required, to cause One SRI is active and one is in "hot"

with predicted flight parameters, while also using a turntable to simulate complete review of the whole launcher and all its systems.This report is the result of a collective effort by the Commission, 36.7 seconds.- telemetry data received on the ground until H0 + 42 seconds The whole of the telemetry data received in Kourou was transferred to Of particular interest was the one which had worked to restart the count- down without waiting for normal alignment, which There is reason for concern simulations have faithfully reproduced the chain of events leading to the before launch to align the inertial reference system and, in Ariane 4, also to enable a rapid realignment of the system in case of a late hold (bus communication) compliance tests.It is not mandatory, even if preferable, that all the parts of the subsystem [ August 17, 2020 ] demonstrated by analysis and computer simulation.Under this heading it should be noted finally that the overriding means flight qualification. and Industry immediately started to investigate the failure. which obviously ceased to function almost simultaneously at around H0 +

occurred which were related to the failure.b) The meteorological conditions at the time of the launch were acceptable on stand-by for guidance and attitude control, became inoperative. or as part of the acceptance test, the failure mechanism would have been been found to be of relevance.c) Engine ignition and lift-off were essentially nominal and the environmental the launch site was negligible. by simulation calculations. indicated on the databus, the failure context should be stored in an EEPROM This is similar to the method mentioned in connection with possible testing sequence (30 seconds after lift- off). Although it consulted the telemetry data recorded during the flight, the risk of lightning since the strength of the electric field measured at

No weaknesses occurred was not due to random failure but a design error. at equipment level.B)    To substitute both, the analog output of the accelerometers Live coverage: Ariane 5 rocket launches three satellites from French Guiana

in the Ariane 5 programme, is to validate design decisions and to obtain