Re: ARIANE-5 Failure

["Theodore E. Dennison" <dennison@escmail.orl.mmc.com>]

John McCabe wrote:
> 
> I have heard that the failure of the Ariane 5 rocket's first launch on
> Tuesday was caused by a software fault in the attitude control system.
> 
> Does anyone know whether Ada was used on that system, and if so, who
> designed and built the software, and which compiler and target were
> used.

I was wondering the same thing.

They said that the crash was caused by the rocket recieving
an "false computer command", which caused it to make a hard left
at full thrust (a BAD thing). They don't know the source of the
command yet, other than it happened somewhere on-board the rocket.
So its a bit early to try and blame any individual component, much 
less the compiler used for the software on any individual component.

Here's the full story as I read it:

 False computer command blamed in Ariane V failure

      A spurious computer command sent the first Ariane V booster heeling
 over sideways only 37 seconds into its inaugural flight, wrecking what
 had been shaping up to be a textbook flight and throwing Europe's civil
 and commercial space program into uncertainty over the long-term.
      But loss of the $500 million vehicle Tuesday should not impact the
 lucrative commercial launch program managed by Arianespace in the near
 term. The European launch services consortium has enough Ariane IV
 boosters in stock or on order to keep up its pace through 1998, and
 could order more of the veteran launch vehicles if necessary.
      European space officials told reporters at the Ariane V launch
 complex in Kourou, French Guiana, yesterday that the main task of the
 inquiry board probing the failure will be to learn the source of the
 command, which sent all three of the huge rocket's nozzles swiveling as
 far to the side as they would go.
      The abrupt pitchover sheared off the vehicle's upper stage and
 short- version fairing with the European Space Agency's four Cluster
 scientific satellites inside, triggering an automatic on-board
 self-destruct command that was quickly followed with a command-destruct
 signal from controllers on the ground. The flight that was to have
 placed the Cluster satellites in elliptical orbits as far as 125,000
 kilometers from Earth ended at an altitude of about four kilometers
 (DAILY, June 5).
      Jean-Marie Luton, head of the European Space Agency, said in Kourou
 that the inquiry board will be established by the end of this week, with
 orders to issue at least an interim report by July 15. Although even
 before the launch failure European press reports were questioning the
 high cost of the program - 20% over budget at $8 billion to date - Luton
 said ESA member nations remained committed to the program after the
 explosion.
      Daniel Mugnier, launch operations director for the French Space
 Agency (CNES), which manages the Ariane V program for ESA, told
 reporters in Kourou that the false signal from the On-Board Computer
 caused hydraulic nozzle actuators for the twin solid rocket boosters
 that provide 95% of the rocket's power on ascent to hit their hard
 stops, flipping the vehicle on its side. The nozzle on the Vulcain main
 engine also swivelled, Mugnier said, even though it normally is
 activated only if the solid booster nozzles are unable to make a course
 correction.
                       Pre-flight testing found no problems
      The source of the false command was unclear based on preliminary
 analysis of telemetry tapes, Mugnier said. Both the primary and backup
 on- board inertial reference systems were producing the same readings,
 he said, allaying suspicion that they were the source of the error.
 Guidance software and hardware all checked out on the ground, and Luton
 said the inquiry board will try to determine why the testing did not
 detect the fatal problem.
      ESA had planned a second Ariane V qualification flight in October
 or November, but that schedule will slip until the cause of the failure
 is pinpointed and fixed. Although the primary payload on that flight is
 ESA's Atmospheric Reentry Demonstrator, Arianespace is trying to market
 3.5 tons in unused geostationary transfer payload capability at a
 $20-$25 million discount, according to Doug Heydon, president of
 Arianespace Inc., the U.S. subsidiary of the European consortium.
      Heydon said the payload for the third Ariane V flight, originally
 targeted for March 1997, is also unclear. PanAmSat, the original
 customer, was already looking for a different launcher for scheduling
 reasons, he said, while officials in Kourou said there is a remote
 chance ESA will want to dedicate the third flight qualification rather
 than commercial purposes. Arianespace will continue to offer a free
 reflight to early Ariane V customers in the event of another launch
 failure, Heydon said.
      Charles Bigot, the Arianespace chairman, said from Kourou that the
 consortium will have enough Ariane IVs to maintain its launch rate of
 17.5 satellites a year through 1998, and could continue beyond that with
 another Ariane IV order. That decision is at least a year in the future,
 and will depend on the outcome of the inquiry board investigation and
 future Ariane V developments, he said.

  Copyright 1996 The McGraw-Hill Companies, Inc.


-- 
T.E.D.          
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