Launch News Luna 25 - Thursday, Aug. 10, 23:10 UTC
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Urwumpe
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The rumors in the German fediverse state, that the last burn was actually too long by the factor 1.6, but I can't find any evidence or at least reason for this hypothesis yet.
Boxx
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if the maneuver was to decrease the perilune, then it's bad...
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Regardless of what the burn was for, it's bad.
These types of missions tend have little to no propellant margin.
These types of missions tend have little to no propellant margin.
GLS
Well-known member
A few hours after the first official announcement about a problem aboard Luna-Glob, an unofficial Telegram channel, Zakryty Kosmos, reported that the spacecraft had broken communications with ground control during the orbit correction but Roskosmos continues its attempts to contact the spacecraft. Before the end of the day on August 19, Aleksandr Ivanov, First Deputy Director for the Development of Orbital Assets and Advanced Projects at Roskosmos, arrived at NPO Lavochkin, the prime contractor in the Luna-Glob project with its own mission control facility. Ivanov reportedly chaired a meeting on the status of the Luna-Glob mission.
Around the same time, another Telegram channel Yura Prosti claimed that a computational error led to the final engine firing to be 1.5 times longer than required and thus resulting in deorbiting and crash of the spacecraft on the Moon.
https://www.russianspaceweb.com/luna-glob-flight.html
I don't think these 2 scenarios are compatible with each other: if the LOS was during the burn, then it might have been caused by loss of control or engine kaput, while that overburn might/would only mean a LOS over 1 hour later.
Thunder Chicken
Fine Threads since 2008
Here come the Crimea Moon is Ukraine memes. 
Thunder Chicken
Fine Threads since 2008
Luna 25 was going to land near the south pole, was it not? If so, was the orbital inclination such that the perilune burn occurred near the north pole and then it had expected LOS as it passed behind the moon, or did it pass on the Earth-facing side? I'd guess that the latter would be preferred as it would allow telemetry to landing.
MaxBuzz
Well-known member
Official statement
"Today, in accordance with the Luna-25 flight program, at 14:10 an impulse was issued to transfer the station to the pre-landing orbit. During the operation, an emergency situation occurred on board the automatic station, which did not allow the maneuver to be performed with the specified parameters"
As specified in the state corporation, now the specialists of the management group are analyzing the situation.
"Today, in accordance with the Luna-25 flight program, at 14:10 an impulse was issued to transfer the station to the pre-landing orbit. During the operation, an emergency situation occurred on board the automatic station, which did not allow the maneuver to be performed with the specified parameters"
As specified in the state corporation, now the specialists of the management group are analyzing the situation.
TheShuttleExperience
Well-known member
So Col Brubaker was right with this comment in the shout box recently. It's not possible to land on the pole. Why the Russians should? 
BBC says it performed lithobraking on the moon.
www.bbc.com
Russia's Luna-25 spacecraft crashes into Moon
The unmanned craft spun out control before its planned landing on the Moon's south pole.
www.bbc.com
Boxx
Mars Addict
British cynical humor, :hum: Here is the news by Roscosmos / TelegramBBC says it performed lithobraking on the moon.
Russia's Luna-25 spacecraft crashes into Moon
The unmanned craft spun out control before its planned landing on the Moon's south pole.
On August 19, in accordance with the flight program of the Luna-25 spacecraft, it was planned to issue an impulse for the formation of its pre-launch elliptical orbit.
At about 14:57 Moscow time, communication with the Luna-25 spacecraft was interrupted.
Measures implemented on August 19 and 20 to search for the spacecraft and communicate with it did not yield any results.
According to the results of preliminary analysis, due to the deviation of actual pulse parameters from the calculated ones, the spacecraft moved to a non-calculated orbit and ceased to exist as a result of collision with the surface of the Moon.
A specially formed interdepartmental commission will investigate the reasons for the loss of the Luna.
GLS
Well-known member
They should have launched the orbiter probe first...
GLS
Well-known member
Putting the pieces back together, it does seem that it was an overburn. 
The burn was at 11:10 UTC, and LOS at 11:57 UTC, so 47 minutes from burn to surface. Firing up Orbiter and burning from 100x100 to 100x18, then burning again for half of the time of the first burn , the vessel hits the surface 46 minutes later, so IMO that scenario seems very plausable. The crash site was about 135º away from the burn, so it ended up a bit north of latitude 45º south.
(I didn't try to simulate the original orbit, so Orbiter can narrow down the crash site even further)
The burn was at 11:10 UTC, and LOS at 11:57 UTC, so 47 minutes from burn to surface. Firing up Orbiter and burning from 100x100 to 100x18, then burning again for half of the time of the first burn , the vessel hits the surface 46 minutes later, so IMO that scenario seems very plausable. The crash site was about 135º away from the burn, so it ended up a bit north of latitude 45º south.
(I didn't try to simulate the original orbit, so Orbiter can narrow down the crash site even further)
TheShuttleExperience
Well-known member
BBC says it performed lithobraking on the moon.
Russia's Luna-25 spacecraft crashes into Moon
The unmanned craft spun out control before its planned landing on the Moon's south pole.
"Russia was racing to the Moon's south pole against India, whose Chandrayaan-3 spacecraft is scheduled to land on there next week.
Once Chandrayaan-3 lands, it will take a few hours for the dust to settle before the six-wheeled rover crawls out and roams around the rocks and craters on the Moon's surface, gathering crucial data and images to be sent back to Earth for analysis."
Since when does the dust on the surface of the Moon take "a few hours" to settle with the absence of an atmosphere?
jedidia
shoemaker without legs
Dust got nothing to do with atmosphere or no atmosphere. The spacecrafts thrusters are going to blow up regolith dust when it lands, and in the low gravity it may indeed be advisable to wait a couple of hours to let it all fall back to the ground again. Lunar dust is really nasty stuff...
Also, congrats to Roscosmos for the successful "special landing operation".
GLS
Well-known member
You can see him in the (original) BBC series The Planets:
Venus (at 17:00)
TheShuttleExperience
Well-known member
Very small dust particles can "float" in an atmosphere for a while, especially on a windy day. Dust in the atmosphere even influences the climate. On the Moon, dust actually just falls back rather quickly (and simultaneously, no matter the size/mass of the grains). It goes up and falls down again straight. How does it float for "a few hours"?
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