For what it’s worth, control chart sensitivity rules are selected based on economic considerations. So the decision to use five points is influenced by both statics and how affordable it is to investigate why the control chart alerted. Sensitivity rules can be adjusted, applied, or ignored based on the specific situation and the analysts tolerance for false positives/negatives.
A single data point doesn't establish any direction or trend at all.
With two data points you can establish a trend and make a prediction about the next data point. However, any two data points form a line, so any two results can be used to make a trend, however wrong it may be.
Only when more points are used can you confirm the trend and reduce the probability of being (un)lucky.
If the worry is about the manufacturer rather than the design, then we have more than two data points. The Soyuz-2 launch vehicle, which is replacing Soyuz-FG, has about a 10% failure rate (including an ISS resupply mission in 2015). This was as far as I know the second-to-last -FG flight planned, as manufacturing has been discontinued and the -2 is the main production line now.
This reminds me of the fact that if you give most people the output of a true random number generator, they'll think it's rigged because there appears to be more clustering than is intuitive.
I recommend making a playlist and making a self-blind study which feels more random: your native music player shuffling it or a true random shuffling of the list.
That's because most people don't really want a "random" playlist. They want a random shuffle: A set of songs played in random order with no repeats until all have been played. That's not the same as making independent random picks from a list, but that's what most people want when they "randomize" their playlist.
I was more thinking about taking a list and shuffling it instead of picking songs at random.
In both cases, people complain because, for example, the same artist might be picked twice in a row. Most shuffle functions aren't random but try to make distance between similar songs.
"Once is happenstance, twice is coincidence, three times is enemy action." Maybe it's a coincidence, maybe it's not. I think it's very reasonable to want alternatives in any case.
Russia at this point is largely deindustrialized and rapidly losing its tech know-how. The recent string of failures in space programme is only one (but certainly high profile) manifestation of it.
Even with three failures I would not consider it a trend unless they are related in nature. For the current trend of "basically no failures" to go to "some failures" you'd need a couple dozen failures at minimum.
I don't think that's particularly much news. I would expect any space agency to ground every single part of a rocket until they are 100% ruled out as source of a failure.
That Soyuz rockets have been grounded pending investigation is also a fact, and a natural course of action for any responsible space agency. Other rockets have also been grounded after accidents. The implications for the ISS crew if future Soyuz flights do not resume on schedule are a question that many are asking, so it's hardly unusual to address it.
Given that everyone knew the astronauts were safe and nobody died, the idea that people shouldn't discuss the causes and consequences of an incident when it's still fresh in people's minds makes even less sense than usual.
The article went up in less than an hour after the accident. At that time it was only known that the crew landed and not much else. They updated the story later on with details on the crew condition, but the title you see is the original one.
The article was published 1 hour 46 minutes after the failed launch, not "less than an hour", and as reported the crew's survival was confirmed 20 minutes after the incident:
> After about 20 minutes of uncertainty, Russian officials confirmed the crew were OK, and had landed about 20km east of Dzhezkazgan, a city in central Kazakhstan. As rescue crews arrived, Hague and Ovchinin were reported in "good condition" and found out of the capsule.
The launch took place at 8:40 UTC. The article's timestamp indicates it was published at 10:26 UTC (3:26 AM PDT). That lines up with the cached copy above from 10:45 UTC, and a snapshot of Ars Technica's homepage at 10:05 UTC in which the Soyuz story had not yet appeared (with the next snapshot at 11:02 UTC showing the article, as expected): https://web.archive.org/web/20181011100529/https://arstechni...
The fact that the headline says the crew made an "emergency landing" and not a "crash" should have been a tip-off.
I saw some articles that were blaming someone on the station for making the hole. Basically blaming an American in an attempted sabotage.
I don't know if it was just sensationalist headlines or an official government stance.
While that sounds wild, there is really an article in an Russian newspaper that tells, that allegedly Roskosmos was investigating whether an American astronaut could drill the hole to return home his ill collegue sooner.
US's and Russian's modules are separate, their life systems are separate. So an emergency in one module will not impact the other.
I highly doubt it happened because for sure they have camera surveillance, it's just frustratingly dumb to accuse the others in your own shortcomings.
You're playing some weird games with numbers here. "100% if we subtract the failures" isn't 100%, and something that hasn't been tested yet doesn't really have a 0% success rate, it just doesn't have a success rate at all.
I'm not saying that Commercial Crew is "better" than the Soyuz program, but I am definitely saying that after two high profile incidents within a few weeks, I am concerned about the long term viability of relying on it for human access to space.
We continued to fly the shuttle even after it killed 14 astronauts. By measure of total astronauts killed, it was the worst spacecraft design in history. Though not sure how it ranks in deaths per flight.
Even in rocketry, you just need to keep even more distance to the top and bottom of any ratings on any part than in normal engineering and put in a few redundancies in case it does fail.
We've already done ground testing, launch abort tests, etc on the commercial crew vehicles plus a reference class of space vehicle first launches. So there's no cause to fall back on the Laplacian prior.
