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AlarmingConsequence t1_je13j92 wrote

I read about another coolant leak on a second Soyuz capsule and that Russia claimed this second one was also a micrometeorite.

What is consensus on these back-to-back leaks outside of the Russian state media?

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pmMeAllofIt t1_je1z78b wrote

It's possible. Soyuz and other crafts arent shielded nearly as well as the rest of the ISS, which is heavily shielded. And they're constantly being bombarded with objects.

To put into perspective, the LDEF was put into orbit in 1984 and recovered in 1990. They found over 5000 large impacts and 30,000 small ones.

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TRKlausss t1_je4u24h wrote

Let’s not forget that the incidence of MMOD has been increased because of human activity. Due to the increased launch frequency and some orbital collisions, there are way more bolts and nuts loose in orbit than 50 years ago. It’s a big topic nowadays in the space community.

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za419 t1_je2z1hb wrote

It's possible. Impacts happen, Soyuz isn't especially well shielded, and Soyuz docks to the "front" of the ISS (the side that faces prograde, into the direction of travel and therefore into the direction where you expect to find high energy stuff to hit)

... Butttt... While the ISS is much better protected and it's entirely plausible that it's not damaged by hits that hurt Soyuz, someone should still notice impact scarring even if the impact has no effect inside the station, and the Soyuz is a small part of the profile of the station - If Soyuz and Progress (same form factor) each take one hit, you'd expect the station to take.... At least five or six, maybe? Just a guess, not a measured statistic... But you see where I'm going with it.

Russian spacecraft getting hit makes sense, only Russian spacecraft and not the station they're attached to is kinda suspicious.

That said, in the interest of perhaps undue (the Ukrainian half of my family would definitely agree it's undue, but that's not how math works) fairness to Russia - Two is not a very large sample. Just because it's unlikely doesn't mean it's out of the question - After all, people have won at roulette before, and likely will continue to.

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AlarmingConsequence t1_je35lja wrote

Besides these two back-to-backs, I have not heard of other micrometeorite damage to soyez coolant systems - I am sure others know more than me.

Given that this has been in the news, including testing of the empty descent, this seems novel, and not at all routine. So we are not looking at a sample size of 2, but of ALL Soyuz -- which have been in service for decades, no?

Good observation that the station should provide context on strikes (if not damage).

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pmMeAllofIt t1_je58jdk wrote

They don't often notice the strikes inside, the station takes MMOD hits daily.

Just looking at some data- SpaceX dragon 1, missions CRS-1 - CRS-17 spent a total of 410 days exposed at ISS. In those days it collected a total of 246 MMOD impacts. That's an impact on average every 40hrs.Or even worse, the MPLMs in 10 missions with almost 70 exposed days collected 398 impacts. Some of which completely penetrated the hull.

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robotical712 t1_je3jb3m wrote

Micrometeorites hitting in the same spot is incredibly unlikely.

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bigcitydreaming t1_je7pyp8 wrote

Two isn't too large a sample size though so it's difficult to say. Unlikely but firmly within the realm of possibility. We'll see how it continues, 3 or 4 occurances would be incredibly suspicious and damning

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robotical712 t1_je7vc2b wrote

If they hadn’t had so many other incidents in recent years, I might give them the benefit of the doubt. In light of everything else, serious quality issues are more likely.

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