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=3.8 required=5.0 tests=BAYES_00,INVALID_MSGID, RATWARE_MS_HASH,RATWARE_OUTLOOK_NONAME autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,485ea727233a52ce X-Google-Attributes: gid103376,public From: "Nick Roberts" Subject: Re: Will Boeing Use Ada To Build $9 Bln Network For Teledesic? Date: 1997/05/02 Message-ID: <01bc5750$1a57e7a0$d5fd82c1@xhv46.dial.pipex.com>#1/1 X-Deja-AN: 238975807 References: <3368134a.21286600@news.mindspring.com><5kb77u$89@bcrkh13.bnr.ca> <5kcmkd$f3q$1@mdnews.btv.ibm.com> Organization: UUNet PIPEX server (post doesn't reflect views of UUNet PIPEX) Newsgroups: comp.lang.ada Date: 1997-05-02T00:00:00+00:00 List-Id: Dale Pontius wrote in article <5kcmkd$f3q$1@mdnews.btv.ibm.com>... [...] > Is it possible to use a hard drive on a small satellite, or will > the rotating platters foul things up. I'd expect that the shuttle > is so big that the effect is insignificant. A single hard disk drive on a satellite would tend to cause the satellite to rotate significantly, unless it was spun up once and never spun down during operation. Two identical drives mounted back-to-back would solve this problem. However, they would have to be rigged so that if one failed and spun down, the other would be spun down also. Conventional hard disk drives would be unsuitable for a satellite, because they are not sufficiently immune to the vibrations caused during the launch into orbit. They would also be prone to failure in space, if kept continuously spun up. Hardened versions exist, but are expensive. I suspect that FLASH RAM (or similar) would pose a better solution. The software controlling the satellite's ability to contact its base control station would have to be highly reliable. Ada would be less suitable than an 'artificial intelligence' language, such as Prolog, LISP, or other, for this section of the software, since it would be best to endow the software with some rudimentary 'intelligence', so it could use rules-based induction to solve certain problems for itself. The remainder of the software would not necessarily have to be very reliable (depending on what sort of communications it was being used for). I would suggest that the reuse of existing software (such as all that TCP/IP and related stuff) would be very important (most of which is written in 'legacy' languages). But, for some of the software, Ada is likely to be a good choice. Nick.