Path: utzoo!attcan!uunet!husc6!mailrus!uflorida!gatech!ncsuvx!ncspm!jay From: jay@ncspm.ncsu.edu (Jay C. Smith) Newsgroups: sci.space.shuttle Subject: Re: Built-in delays & 51-L meaning Keywords: countdown delays, mission designations Message-ID: <1310@ncspm.ncsu.edu> Date: 1 Oct 88 18:43:40 GMT References: <852@scubed.UUCP> Reply-To: jay@ncspm.ncsu.EDU (Jay C. Smith) Organization: Crop Science Dept., North Carolina State University Lines: 43 In article <852@scubed.UUCP> rankin@scubed.arpa (Tom Rankin) writes: >What is the purpose of built-in delays in the countdown? It is my understanding that the countdown represents progress toward the launch. Before the launch there are times when there is progress made (and the countdown clock is running), and there are times when everything stops and checks and doublechecks on the progression so far and the upcoming progression are made (that's the hold). It may seem silly, but it's really not. It's analogous to an expedition to the top of Mt. Everest -- one doesn't just go all the way up from the base without stopping. >I know that "STS" stands for "Space Transportation >System" or some such and that "26" designates the count of missions, >but what do "51" and "L" stand for? STS-51L was actually the 25th mission. It works like this: 5 The year, as in 198*5*. Yeah, that's right, it went up in '86, but it was originally planned for '85. In fact, some previous flights got out of order in this respect (was the mission before 51L a 6?). 1 The launch site number, in this case Kennedy Space Center. The only other launch site was 2, Vandenberg AFB in California, but it was never used, and probably never will be now. L The particular mission. Originally alphabetized in the initial planning, these could easily rearranged or even dropped as schedules were shuffled. L could have the same meaning that 12 might have, see? Of course, I think NASA only went to this obscure mission designation system to avoid the dreaded STS-13. Since that mission has passed, because there was a major break in mission continuity (great understatement, huh?), and the need to give a launch site designation is gone, NASA has gone back to the old consecutive number system. My question now is: does their internal mission numbering correspond to this, or do they still use another system so that STS-30 won't fly before STS-29? -- "I don't suppose you have any idea what the damn thing is, huh?" --------------------------------------------------------------------- Jay C. Smith uucp: ...!mcnc!ncsuvx!ncspm!jay Domain: jay@ncspm.ncsu.edu internet: jay%ncspm@ncsuvx.ncsu.edu