From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,f039470e8f537101 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-07-27 19:39:55 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!wn14feed!worldnet.att.net!204.127.198.203!attbi_feed3!attbi.com!sccrnsc02.POSTED!not-for-mail Message-ID: <3F248CEE.5050709@attbi.com> From: "Robert I. Eachus" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.0.2) Gecko/20021120 Netscape/7.01 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Ariane5 FAQ References: <1058968422.225561@master.nyc.kbcfp.com> <3F200AD0.94F79098@adaworks.com> <7u9Ua.13412$634.10307@nwrdny03.gnilink.net> <3F215120.1040706@attbi.com> <1059151910.357790@master.nyc.kbcfp.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit NNTP-Posting-Host: 66.31.71.243 X-Complaints-To: abuse@comcast.net X-Trace: sccrnsc02 1059359995 66.31.71.243 (Mon, 28 Jul 2003 02:39:55 GMT) NNTP-Posting-Date: Mon, 28 Jul 2003 02:39:55 GMT Organization: Comcast Online Date: Mon, 28 Jul 2003 02:39:55 GMT Xref: archiver1.google.com comp.lang.ada:40885 Date: 2003-07-28T02:39:55+00:00 List-Id: Berend de Boer wrote: > Except requirements it seems. And I think you should have a look at > Design By Contract and in particular Eiffel. No. And that is what all the sound and fury has been about. The mapping from requirements to actual code was perfectly done. The problem was that the requirements which were perfectly filled were for the Ariane 4, not the Ariane 5. The nature of the political/management problem at Arianespace was such that no one ever saw both the Ariane 5 requirements and the SRI documentation until after the disaster. The red herring dragged about of documenting requirements in the source code is just that, a red herring. The programmers simulating the SRI for the flight guidance simulator did not see the alignment function code--because simulating it was not part of their contract. Of course, if anyone involved in letting that contract had known that the alignment function on the Ariane 4 was required to run for 40 seconds after engine start, simulation of it might have been included in the simulator. Or something else might have happened that resulted in an engineer learing of this requirements mismatch. But as we know, no one was ever in a position to do a diff between the Ariane 4 and Ariane 5 requirements, and then apply that to reused subsystems. Did everyone miss the point of the SECOND Ariane 5 failure investigation? Diffferent launch, different subsystem, very different failure mode. But the thing both failures had in common was systems reused from Ariane 4 without checking that they met the new requirements. If you missed it, here it is again. The failure didn't get nearly the press that the first one did, but the result was the same, a launch failure: http://spaceflightnow.com/ariane/v142/010713followup.html and http://www.arianespace.com/site/news/03_06_19_release_index.html There was also a FOURTH Ariane 5 failure (out of 14 tries) on flight 157: http://www.esa.int/export/esaCP/ESA7198708D_index_0.html This was due to failure of the cooling of the Vulcain 2 engine, new to the Ariane 5 ECA. Although this failue had nothing to do with Ariane 4 reuse, or Ada, what do we find under contributing factors? "non-exhaustive definition of the loads to which the Vulcain 2 engine is subjected during flight" Translation, ANOTHER requirements definition failure. The first three launch failures were all due to the failure of change mananagement and requirements tracking during the original Ariane 5 development. But this latest failure involves a design subsequent to the first two Ariane 5 failures. You have to wonder... In any case, focusing on the particular details of the first failure and not the overall programmatic issues is a mistake. In Arianespace's case, so far a multi-billion Euro mistake. -- "As far as I'm concerned, war always means failure." -- Jacques Chirac, President of France "As far as France is concerned, you're right." -- Rush Limbaugh