posted 06-02-2011 04:17 PM               

Anywho, the furthest out I've seen is a STS-91-T. STS-51-L was the 33rd mission (eight of which were canceled or postponed) and 61E would have been STS-34, so in three years to STS-91-T we would have gotten to STS-90 or 100. If the 20 flights a year for the three KSC orbiters combined could be sustained, it would take another 15 years post 1989 to reach STS-400.

posted 06-02-2011 04:25 PM            

It could have happened but the Columbia disaster was the beginning of the end. Looking with hindsight (as everyone does), perhaps the shuttle's career ended prematurely. Only time will tell.

Other than building, maintaining and supplying the International Space Station there's not much requirement for its versatility. Servicing the Hubble Space Telescope was also exceptional, but the last time a shuttle mission actually repaired/rescued a commercial satellite was STS-49 in May 1992. So it was neither cost-effective nor lived up to its original billing, as satellite deployments shifted to expendable vehicles after Challenger, further reducing those potential number of missions.

It's easy to get overly sentimental about the past three decades - am I the only one who followed those round-the-clock Spacelab missions religiously? And while I empathise with all those within NASA and its contractors who lost their livelihoods as a consequence, human spaceflight has to be about more than endless laps around the Earth. Though it makes perfect sense to do so on board a space station.

Ultimately, that's a management and political failing more than engineering. The shuttle could have continued to carry more Spacelabs if there was no ISS and may be a retrievable satellite every now-and-then, like SPAS or SPARTAN, till STS-200 or 300 or 400.

posted 06-02-2011 04:41 PM               

quote:

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Originally posted by issman1:
So it was neither cost-effective nor lived up to its original billing, as satellite deployments shifted to expendable vehicles after Challenger.

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posted 06-02-2011 05:03 PM               

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Originally posted by Hart Sastrowardoyo:
Expanding that role to bringing back or fixing satellites that failed, how many satellites did shuttle actually save, compared to the number of satellites that failed (whether due to satellite failure itself or launcher failure)?

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Typical spacecraft launches on ELVs have umbilicals that provide power, data and commanding prelaunch. The umbilicals connect to EGSE in the base of the pad which through various communication lines are linked to the spacecraft launch control center located at CCAFS, KSC or Astrotech.

Once liftoff occurs, the connection is severed and the spacecraft is quiet until separation when it wakes up and tries to communicate with its ground sites. On rare occasions, the launch vehicle can provide some discretes (commands), interleaved data (2k rate) and power (batteries added for the spacecraft which reduces the lift capability).

posted 06-02-2011 08:12 PM               

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Originally posted by Hart Sastrowardoyo:
I've always wondered how the 100 mission standard was created.

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posted 06-02-2011 09:12 PM               

quote:

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Originally posted by issman1:
am I the only one who followed those round-the-clock Spacelab missions religiously?

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We didn't have our first VHS tape recorder yet (I think my Dad was still on the fence between that and BetaMax) so I used to record the audio on my cassette recorder right from the TV speaker...I still have the tapes!

posted 06-02-2011 10:40 PM               

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Originally posted by BNorton:
It was a simple matter of structural fatigue analysis. The loads on the spacecraft during launch and entry, and the structure design, essentially established the 100 flight limit.

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Based on which spacecraft or in general? Don't have the reference (it may be Dennis Jenkins' book), but I recall reading that Enterprise was placarded not to exceed a certain load amount, Columbia was certified for a higher amount, and that subsequent orbiters for an even higher load factor (and Columbia was eventually certified for that amount as well.)

posted 06-03-2011 04:29 AM            

quote:

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Originally posted by Hart Sastrowardoyo:
The Vandenberg flights had their own numbering system, starting with STS-1V. Ironic that Discovery, now the fleet leader, had only been scheduled for four flights per year (the same sked with STS-91-T lists Vandenberg flights only up to STS-12V.)

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posted 06-03-2011 06:25 AM            

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Originally posted by 328KF:
I used to watch CNN's coverage of STS-9 for many more hours than I'd care to admit. I used to record the audio on my cassette recorder right from the TV speaker... I still have the tapes!

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Radio was the best form until discovering the internet in the mid-90s, especially as I was able to tune into American Forces Network Europe on AM and also the Voice Of America on SW.

posted 06-03-2011 08:30 AM               

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Originally posted by garymilgrom:
Does the entire world launch 50 satellites a year (or anything close to this number)?

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Of those 60 launches, 10 were by the United States (four Atlas, four Delta, two Minotaur).

posted 06-03-2011 08:37 AM               

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Originally posted by Henry Heatherbank:
I have never heard of the STS-1V etc designations. Can you tell us some more about that?

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(The designations are not to be further confused with missions STS-26R through 33R, which NASA used for the first eight missions post-Challenger. Even though there were 25 flights, there had been 33 scheduled missions. The "R" signified reflight, although it was actually a reuse of the number. STS-94 was originally known as STS-83R in some documentation.)

Bobko, according to Who's Who, was rumored to be tapped to fly the third Vandenberg mission. No crews had been formally named, aside from Kathy Roberts for 62-B.

Ironically, most of the crew for 62-A - Gardner, Ross and Mullane - wound up flying some of 62-B's payload.

Getting back to the topic at hand, it was believed that not only would the US be using shuttle, but so would international customers - hence the flying of foreign payload specialists in order to court their business.

Whether there was enough business to fly almost every other week (20 launches a year) is debatable. As time has seen, MDD's EOM was supplanted by other, cheaper methods. And countries like Indonesia, which launched satellites on shuttle and came close to having the first female, Muslim astronaut, have their own concerns other than a space program to deal with.

Engineering-wise, I think the shuttle could fly 12 to 14 missions a year. 1985 almost saw 10, and that was with three orbiters for the most part.

But the problem in flying the shuttle is that its utility is also what's limiting it. Every flight is mission specific.

Say you want to use shuttle just for launching comsats in order to make money. Do you use PAM-A, D, or D2? IUS or Centaur? One, two, or three satellites, or do you claim national security, stack four in an orbiter and hope you don't have to do an RTLS? And if you fly one or two satellites, what else do you carry in the payload bay?

posted 06-03-2011 10:59 AM               

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Originally posted by garymilgrom:
Maybe the planning rationale was to win all this business, but I don't know the actual launch rate.

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The world only launches a handful a satellites each year because it is prohibitively expensive. NASA's logic was that if they could lower the launch cost to $100/lb (or was it $10/lb?), everyone would be building satellites because they could afford to send them to space, thus the customer base would get huge and the shuttle would fly twice a week.

posted 06-03-2011 10:19 PM            

People in various citizen advocacy groups like the L5 Society and National Space Society had big hopes of NASA putting rows of passenger seats in glass-topped capsules that would fill a shuttle cargo bay. Limited space travel would finally become "affordable".

Of course, nothing like that ever came about and was probably never seriously discussed beyond water cooler conversations in places like Lockheed, Rockwell, and Martin Marietta.

posted 06-18-2011 11:14 PM            

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Originally posted by Jay Chladek:
You can't necessarily go by "half empty" though as the weight and mass of the payload tends to be more critical than the physical size of it...

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posted 06-20-2011 12:09 AM               

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Originally posted by Hart Sastrowardoyo:
Look at STS-93.

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If another shuttle not already configured for ISS flights had been available to fly Chandra, it probably would have been scheduled and likely would have had enough up-mass left over to take up a seven person crew (if there was a need for a seven person crew that is).