August 08, 2005

A Space Story., both 20050731 and 20050805

Steven DenBeste is one of the best writers out there. His USS Clueless was one of the few multiple-times-daily reads I had, until he stopped blogging (Fortunately, he's shifted to writing about Anime, with the occasional foray into other topics). Agree with him or not, he always made you think on USS Clueless, and his eye for anime is excellent (even despite disliking Azumanga Daioh).

Recently, though, he's had two posts taking swipes at the Space Shuttle. While I agree that the Shuttle's sun is setting, he believes that the program should have been shut down right after the Columbia Disaster, noting that there have been two fatal flights out of 113: "A 2% failure rate is unacceptably high. It's time to end it."

A 2% failure rate is unacceptably high for airliners. A 2% failure rate is unacceptably high for ships. A 2% failure rate is unacceptably high for cars, plates, rubber ducks, and washing machines.

For manned space missions though, 2 in 113 is actually a little better than the past track records, believe it or not.

Consider: Mercury had 6 manned flights. Gemini had 10, and Apollo had 11. No fatalities, right? A perfect record.

Except for what was retroactively called Apollo 1, the Apollo systems test that resulted in the deaths of three astronauts, caused by an atmosphere of (amazingly) pure oxygen in the capsule, and a spark. It's fair to include this in the Apollo record, I suggest.

Adding one to Apollo's record gives it 12, Gemini 10, Mercury 6, for a total of 27. One fatal mission of 27 gives a rough percentage of 4%, twice as bad as the Shuttle. Throw in the Apollo 13 miracle, where a lot of sweat and luck got the crew back alive, and the number jumps to nigh on 8%.

Yet nobody called for an end to the missions on grounds of safety... Apollo was killed for bugetary reasons. I suggest that two fatal shuttle accidents in four times as many missions is, historically, a good rate. Only that they have been spectacular disasters and widely televised is different.

If you throw in Soviet manned space flight, the Space Shuttle's numbers get even better. I'll refer the reader to this Wikipedia article for details.

In his second post, he criticises NASA for sending 7 astronauts on what he calls a "garbage flight.": "Why risk that many people to operate a space-going garbage truck? If the damned thing had to fly at all, prudence would dictate that it carry the minimum crew capable of performing the mission."

To quote NASA's website, the mission objectives for this flight were to: "test and evaluate new safety procedures and conduct assembly and maintenance tasks on the (International Space) Station. A late addition to the timeline tasked the crew with first ever on-orbit repair of the Shuttle heat shield."

The Shuttle is vital to the continued existence of the ISS, as only it can carry the parts and such to perform maintainance to the station, as well as being able to carry broken parts back to be repaired and reused. If the Shuttle program was killed, the ISS would be written off. This would result in future exploration of space being limited to unmanned missions until the distant future, since the ISS will be used to stage manned flights out of (eventually).

Lets look at the crew assignment for this flight. You have the mission commander, a pilot, and two spacewalkers (for repairs to the ISS. They were also there for repairs to the shuttle, if needed). That's four of the seven right there. Throw in a Manipulator Arm Operator, an expert in that task, to support the spacewalks, and you're up to five crew as your minimum. The other two are expert extras, master redundancies (though, obviously, they're sharing duties with the others). Considering what was being done on this mission, seven crew doesn't seem excessive at all.

As far as DenBeste's gripe that the Shuttle is 'only' returning with 5000 pounds of trash, it's a little more complicated than that. I suggest James Oberg's views on the matter, found here.

But if you're looking for reasons to trash the Shuttle program, there are plenty of better ones than these listed above.

Posted by: Wonderduck at 03:49 PM | Comments (3) | Add Comment
Post contains 719 words, total size 4 kb.

1 Mercury/Gemini/Apollo was a program which ran on what amounted to engineering prototypes. It was fully understood that they had a higher chance of operational failure, and that's part of why we all thought that the astronauts were heroes. (And by the way, there were two major failures, if you count Apollo 13.)

The Shuttle was supposed to be an end-product. The original design spec for failure for the shuttle program was less than 1 catastrophic failure per thousand flights.

2 in 113 is almost than 20 times the design specification. (And lets hope that tomorrow morning we don't discover that it was 3 in 114.)

The Shuttle didn't meet any of its important operational design specifications. Turnaround time and cost per launch were also drastically higher than they were supposed to be.

And now the orbiters are getting old. Old equipment has an increasing rate of failure; that's just how things are. Maintaining old aircraft and keeping them flying involves increasingly large amounts of money and effort.

It's time to end it, and to design something new. (In fact, design of a replacement should have started 15 years ago.)

Posted by: Steven Den Beste at August 08, 2005 05:05 PM (CJBEv)

2 Just in passing, the last Mercury flight (Mercury 9) had a near-catastrophic failure when there was a major failure in the electrical power supply, leaving "automatic stabilization and control system without electric power."

As a result, Gordon Cooper had to make a dead-stick reentry to keep the capsule balanced. Had he screwed it up, the capsule would have tumbled and been destroyed.

It's true that the Shuttle has had a much better operational safety record than Mercury/Gemini/Apollo. It's also true that it's had a better record than the Russians, or the Ariane program. But that isn't saying anything. It didn't come close to meeting the programs operational safety specification, and that's the real point.

For 1970 it was quite an achievement. For 2005 we can do better, and we should.

Posted by: Steven Den Beste at August 08, 2005 05:13 PM (CJBEv)

3 For the record, I agree that the Shuttle should be put out to pasture, or at best used for exceedingly rare emergencies (i.e., the ISS will die if a left-handed widget isn't brought up, and the Shuttle is the only thing that can carry it).

I also agree that a replacement should have been designed by now, or at least be close to being finished.

If NASA seriously thought that the Shuttle would have an operational failure rate of 1:1000, then they had a screw loose. If you look back at the Shuttle's flight history the same way you look at any modern aircraft, 114 flights isn't even out of the flight test stage, and there's usually more than two crashes during those... and even a F-15 is orders of magnitude less complex than the Shuttle.

But then, we now know that NASA had problems at the upper levels, don't we?

Posted by: Wonderduck at August 08, 2005 07:28 PM (M7kiy)

Hide Comments | Add Comment

Comments are disabled. Post is locked.
30kb generated in CPU 0.0147, elapsed 0.0808 seconds.
47 queries taking 0.0718 seconds, 278 records returned.
Powered by Minx 1.1.6c-pink.