Russia seems to have lost contact with its first lunar probe in half a century

"The management team is currently analyzing the situation."

See full article...

 

[Wickwick]

Not wanting to jinx it by saying it loud, but I am still hoping for a nice and very energetic lithobraking manoeuvre from Luna 25. Just losing comms with it still being in the pre‑landing orbit would be kinda anti‑climatic!

That would serve them right, IMO. Although I am pretty sure TASS would still try to twist a high‑speed lithobraking crash event into a "very successful landing" somehow...

I'm pretty sure that if the probe was in a low lunar orbit, it will find a way to impact the surface soon enough. Orbits around the moon aren't particularly stable. What would be awesome is if other countries' probes could find the Russian lander and track it to the very end. Perhaps we can get some spectroscopy of the ejecta and get useful information out of the event.

 

[Wickwick]

Seems like Russia has successfully delivered their signature outcome - destruction and chaos.

Can they be sanctioned for littering the moon with old probe parts ?

Much of the debris will have turned to vapor if not plasma and whatever's left would have been pulverized and atomized pretty well. I doubt you'd be able to find much that's identifiable as the lander other than the hole and ejecta it left behind.

 

[Wickwick]

Pulverized, sure, but atomized, vaporized, turned to plasma? … Impact velocity is only going to be ~2km/s.

Not turned to plasma. That would be the case from TLI entry I suspect. In LLO, you're only getting the other outcomes.

2 km/s is 2 MJ/kg kinetic energy. The heat of fusion of aluminum is only 321 J/kg and the latent heat of vaporization is 0.7 MJ/kg. Some of the kinetic energy will go into accelerating the regolith. So some of the aluminum won't turn to gas. But essentially all of it will turn to liquid - and hot liquid at that (never mind the propellant). So yeah, hot liquid with a high pressure stagnation point will lead to an expanding pressure wave that will atomize the aluminum.

 

[Wickwick]

That figure for heat of fusion is too low by more than a factor of 1000.

The heat of vaporization of Al is 293.4 kJ/mol, or 10.8 MJ/kg.

I happened to grab this link as the first one I found. Others do suggest it's closer to 5x the specific kinetic energy.
So no vaporization. The aluminum is still going to turn to liquid and be atomized over hundreds of meters.

Edit: newp, I just misread the table at the bottom wrong. So that's on me. But liquid aluminum is all I was expecting regardless.

 

[Wickwick]

It's ~600kJ/kg to heat to boiling, depending on temperature, and another 400kJ/kg to melt it. That's half the energy just to melt, before you consider energy that goes to the regolith. Boiling is another 1.6MJ/kg to heat, and 10.5MJ/kg to vaporize, so that's not going to happen. You're a full third under the speed of sound, so you will get structural deformation slowing the rear of the satellite, so you likely won't even get full melt. The portion that does melt is now molten aluminum, with a surface tension ~10x that of water, and you're not going to have the mechanical energy left over to "atomize" it.

Molten aluminum and water have about the same kinematic viscosity so they end up atomizing about the same (I'm speaking from experience here). If you drop a cup of water it will atomize (splash) so yeah, molten aluminum accelerating from 2 km/s to zero in a few meters will too. I'm not suggesting the metal droplets will be 50 microns. They might be several millimeters across. That's still an atomized fluid. And from where I started: pulverized and atomized, I still feel my initial description was right. Ok, nothing not near propellant will vaporize. Fine.

 

[Wickwick]

Colonialism is people using technology to beat those with less technology. We have often conflated higher technology with higher morality, when often the opposite is the case. Possibly because those with more tech have better printing presses...

Is there an absolute scale of morality? Isn't that an internal judgement only? Two moral codes could be different and yet each finds the other to be morally inferior. What's the objective test?

 

[Wickwick]

I'm mistaking the term "atomized" for something more literal, as opposed to just making a fine spray.

Not my field so I never gave it much thought. Atomized just means finely divided. It's not like the spray coming out of an atomizer is invisible. Makes sense, learnt something new today.

No worries. Not everyone can be an expert in sprays. I won't hold it against you. Much

 

[Wickwick]

The head of Roscosmos Borisov gave an interview on the accident Luna-25.
Briefly
1. Uncalculated operation of the propulsion system. 127 seconds instead of 84. The device entered an open orbit and crashed on the surface.
2. There was a stable connection throughout the correction period. The entire set of telemetry was received.
3. All operations were simulated on a ground layout before execution. The causes of the accident are being investigated.
4. The main objective of the mission is not fulfilled.
5. The reason is the lack of flight experience for 50 years. He did not say the reason for the small financing.
6. Russia will participate in the lunar race.
7. The preparation of new Miss and 1 - Luna-26 and Luna-27 will go in a forced mode.
8. The NGO Lavochkina (manufacturer) has a working team. They believe her.

I wonder if a burn time of 127 seconds was enough to deplete the propellant tanks and they didn't actually manage to ever command the thruster to stop firing. That's basically a repeat of what Nauka did recently.

 

[Wickwick]

127 could also indicate an issue with the variable size used. 127 is the largest integer of a signed byte. But that is almost certainly not the case here.

I would be very surprised if one-second was the shortest interval that could be commanded for a burn. That's an eternity and less than 1% of the intended burn time.

Edit: is less accurate than 1% of the intended burn time or is more than 1%. Take your pick on which edit makes more sense because my original statement is crap.

 

[Wickwick]

FFS, why does seem the usually cognisant Ars commentariat tend to totally mix up "ethics" and "morals"?

Ethics is a branch of philosophy, concerned with the search for what is right and wrong. A search, like all philosophy – as ontology might not definitely answer the nature of being, so ethics might not answer all the trolley problems and others, even as it strives to.

Morals are more or less a moral code, specific to some society. It could be totally moral to kill firstborns in a certain (shitty) society. It could be totally immoral to help the homeless in a certain (equally shitty) society. @llanitedave is right on that one, IMHO (though I might have missed the earlier posts that actually started this tangent).

Perhaps there might be a language barrier causing all the confusion? In my primary language (not English) and philosophy lessons, the distinction between ethics and morals was always pretty clear.

The entire branch of discussion started from a statement about the "higher" morality of one code vs. another. Kind of, by definition, each morality is superior to all others from within the society that subscribes to either moral code. That was the point of my original objection. There is no objective higher morality.