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posted 05-24-2018 12:43 AM               

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From 1988 to 1989, seven space shuttle missions were numbered as follows and flew in the following order -

• STS-26R
  
• STS-27R
  
• STS-29R
  
• STS-30R
  
• STS-28R
  
• STS-34R
  
• STS-33R

In this flight sequence, apparently, the STS-28R and STS-33R missions were delayed and were flown out of the numerical sequence of the missions.

But what does the "R" signify in these missions?

It appears that these were the first seven missions to be flown after the Challenger accident. So I am guessing that the first seven missions were considered shuttle "requalification" flights. Is this correct? And if so, did these flights have any specific requalification duties?

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posted 05-24-2018 06:52 AM               

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To fully understand this, it is important to know that the STS numbers up to 33 had already been used internally for the shuttle missions prior to Challenger. In fact, STS-51L was the original STS-33. (STS-51B was STS-26; STS-51I was STS-27; STS-51J was STS-28; STS-61A (STS-51K in earlier schedules) was STS-30; STS-61B was STS-31 and STS-61C was STS-32 — I believe the missing STS-29 was Vance Brand's cancelled/delayed STS-51H/EOM).

On the same subject: when STS-41D (STS-14) and STS-41F (STS-16) were combined in the summer of 1984, the mission was officially known as STS-41DR (Remanifested) — it remained STS-41D for the public.

Also, in March 1985, when STS-51E was cancelled and the Bobko crew was assigned to Brandenstein's STS-51D slot, the mission became STS-51DR (but STS-51D to the public).

To complicate things a little and also throw in the word "Reflight": STS-51E was listed in the schedules around Autumn 1983 as "Reflight Opportunity." At first, this was meant as a possible reflight of Spacelab-1 (in case it was hampered too much by the TDRS-1 problems and launch delays).

With STS-9/Spacelab-1 completed successfully, this "Reflight Opportunity" mission ended up with some other leftovers from rescheduled missions: TDRS-B (not flown on STS-8 and the cancelled STS-12 due to IUS-problems) and Telesat (removed from the original STS-41D/STS-14 because of the PAM-problems).

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posted 05-24-2018 07:58 PM               

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I once had one of those ground tracking maps with the designation of "STS-16 (41F)." And post-Challenger, I have some FDF Crew Activity Plans and Flight Requirement Documents where the alphanumeric was listed on the cover, and if you look at the typewritten label, you can figure out the STS number; STS-61H has a label ending in 37 (or STS-37); STS-61G one ending in 36 (or STS-36).

To really understand this, the alphanumeric was the payload code, while the STS was the flight sequence — even if missions were canceled, postponed, or combined. Thus, 51D was the LDEF retreival (initially), whether that was flown by Brandenstein as CDR, then by Bobko as CDR.

Interestingly, Spacelab 4/61D seems not have to received an STS number when it was canceled — because 51L was STS-33, and 61E, the next up, would have been STS-34 (because 61F was STS-35).

41D was originally STS-12 (count the stars on the patch). Count the stars on 41B and 41G's emblem and you'll find their STS numbers.

(To complicate things, Hoffman will write his first mission number as STS-16, which isn't entirely true; it was the 16th shuttle mission flown.)

As well, before it received its final STS number, the reflight of STS-83 was known internally as STS-83R.

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posted 05-25-2018 08:55 AM               

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It's convoluted, but it's also quite simple. In the ramp up of shuttle missions, is it (say) STS-22 or 23 or 25 we're flying this week? But if you can say, "It's the LDEF retrieval," then the reply is, "Oh, that's 51D we're processing for launch this week" and everyone knows what you're talking about - whether that's the 22nd, 23rd, or 25th shuttle flight owing to delays and such.

And in looking at your initial post, there was no STS-34R. It would have just been STS-34, because only STS-1 through 33 were flown or scheduled but canceled/postponed (even though pre-Challenger STS-34 through at least 41 were in various stages of planning.)

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posted 05-25-2018 05:41 PM               

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quote:

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Originally posted by Hart Sastrowardoyo:
Interestingly, Spacelab 4/61D seems not have to received an STS number...

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Spacelab-4 held a variety of STS numbers. It was STS-33 in early 1982, STS-35 at the end of 1982, in April 1983 it was STS-34, in August 1983 it was STS-32. Then, with the new numbering system in November 1983, it had become STS-61D.

If the schedule had held, it would have eventually ended up on STS-33. However, in May 1984, the launch date for STS-61D was already under review and by the time of the Challenger accident, 61D had been postponed well into 1987.

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posted 05-25-2018 06:51 PM               

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Contrary to my earlier post: the EOM-1/51H mission was not STS-29, but STS-31 when it was deleted. The reason why it was STS-29 that disappeared from the schedule, must have been the late delivery of Columbia for 61A/Spacelab-D1.

61A moved from the STS-29/Columbia slot/flow/stack into the STS-30/Challenger slot (was 61B) and 61B moved into the STS-31/Atlantis slot (was 51H). 61C was already on STS-32/Columbia and 51L was already on STS-33/Challenger, so these two combinations of shuttle stacks and mission numbers remained unchained.