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,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,382fcf8feeefdd50 X-Google-Attributes: gid103376,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news2.google.com!news1.google.com!Xl.tags.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!local02.nntp.dca.giganews.com!nntp.earthlink.com!news.earthlink.com.POSTED!not-for-mail NNTP-Posting-Date: Wed, 16 Jul 2008 16:57:07 -0500 From: "Brian" Newsgroups: comp.lang.ada References: <185ee7f9-9d4f-4f49-8dbe-6b623b8a8223@c58g2000hsc.googlegroups.com> <887fc0a7-0a5a-4d2e-a9ea-eb9e32d6a818@m36g2000hse.googlegroups.com> <807ef880-b2ac-4ac6-877c-21274e8ff4ab@d77g2000hsb.googlegroups.com> Subject: Re: computer language used to program Mars Lander Date: Wed, 16 Jul 2008 14:57:06 -0700 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-RFC2646: Format=Flowed; Original Message-ID: X-Usenet-Provider: http://www.giganews.com NNTP-Posting-Host: 71.92.210.194 X-Trace: sv3-aj1QcZmOBGvkcqHKPZDaueWWJZ10o0z4XCYQ6Xu8gI00fuL/6sI3Bf60nR+zDODrwYBHovQeS58OM/n!vmNIPrDigKFfOl5CIK5TZ2KtkNQVoA4JrOdlLDFm2ZMNZmf8ZxqkSUthATV4hRicjM6a7zKTBDKq!tzQr8h+oEk21Qt0sU51WFQLCTAMYtYLh2kQ= X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.39 Xref: g2news1.google.com comp.lang.ada:1181 Date: 2008-07-16T14:57:06-07:00 List-Id: wrote in message news:807ef880-b2ac-4ac6-877c-21274e8ff4ab@d77g2000hsb.googlegroups.com... > On Jul 14, 4:49 am, Nick Keighley > wrote: > >> contrary to popular expectations space probes are very >> conservative in their use of technolgy. > > I disagree. Actually, the space industry will try anything and stick > with it until stuff explodes (Ariane rocket) or crashes into the wrong > celestial body because of faulty software. They did use Ada widely > before, and they even programmed some of their probes in Lisp. Seems > like C is the new fad there. Wait until they get bitten by macros and > dangling pointers. And I disagree with your disagreement. The Ariane rocket disaster is a good example of trying to migrate existing software on a "known" platform in response to a business situation. Also, the crashes you refer to "because of faulty software" are examples of software that wasn't adequately tested before implementation in order to comply with non-changing, and non-changeable, mission requirements. Celestial mechanics won't let you slip your ship date! JPL, along with the rest of NASA has an extraordinary success record with their software. It would be stunning in any kind of endeavor, but is especially so when you consider the kinds of missions, and the kinds of things that happen with their funding and manpower on a yearly basis. Then, just to make the engineering problem a bit more interesting please remember that there isn't a lot of hardware that functions in that environment, and it's a few million miles from anybody who might be able to hit CTRL-ALT-DEL. With all this in mind, I think that these guys deserve a lot of respect. So, why did they choose C for this application? I wasn't there when the decision was made, but I'd suspect that it was the language that their coders were most familiar with, the language that had the right libraries for their application, and the language that they felt was most appropriate for this application. In other words, good engineering judgment. Give 'em their "props", okay? Brian