Luna 25 lander mission, Russian lander following on from the Soviet-era lunar program Options

[Ron Hobbs]

I found a post on twitter (or X) that has what looks like a release from Roscosmos that says that TLI has been performed and Luna 25 has separated from the Fregat stage.

https://twitter.com/TitaniumSV5/status/1689...9728000/photo/1

It says the landing is now scheduled for August 21.

[Phil Stooke]

https://iki.cosmos.ru/news/ot-zemli-uleteli-letim-k-lune

IKI (Institute for Cosmic Research) news page for Luna 25 with some early images.

This is the mission website:

https://iki.cosmos.ru/missions/luna-25

Phil

[Toma B]

There is this quite detailed site about Luna-25 and its instruments.
It is written in Russian so you should open it in some browser that enables translation like Google Chrome. It works just fine for me. Takes some time to load.

Luna-25 site

[Hungry4info]

From Anatoly Zak - possible LOI success.

According to unofficial reports, the Luna-25 (Luna-Glob) spacecraft was expected to enter an initial orbit around the Moon at noon Moscow Time (5 a.m. EDT) on Aug. 16, 2023. According to an unofficial report on the Novosti Kosmonavtiki web forum, posted around 1.5 hour after the expected lunar orbit insertion maneuver and citing available telemetry, the probe's engine fired as scheduled and the spacecraft maintained correct attitude during the maneuver.

[Hungry4info]

And it's official. From the Roscosmos Telegram post:

This was ensured by two switching on of the propulsion system of the automatic station. The first activation was performed at 11:57 Moscow time by a corrective braking engine and lasted 243 seconds, the second - by soft landing engines and lasted 76 seconds.

For the first time in the modern history of Russia, at 12:03 Moscow time, an automatic station was launched into the orbit of an artificial satellite of the Moon!

All Luna-25 systems are functioning normally, communication with it is stable. Sessions are being taken to measure the current navigational parameters.

[Phil Stooke]

https://iki.cosmos.ru/news/kosmicheskiy-app...-sputnikom-luny

update with a colour version of the spacecraft image seen earlier in monochrome.

Phil

[Hungry4info]

Zeeman crater from Luna 25.
(source)

Attached thumbnail(s)

 

[kenny]

The text issued with above picture.

Luna-25" took the first picture of the lunar surface

An automatic station flying in a circular orbit of an artificial satellite of the Moon took pictures of the lunar surface with television cameras of the STS-L complex.
The picture shows the south polar crater Zeeman on the far side of the Moon. The coordinates of the center of the crater correspond to 75 degrees south latitude and 135 degrees west longitude.
Invisible from Earth, the Zeeman crater is a unique object on the lunar surface and is of great interest to researchers - the height of the shaft surrounding it reaches 8 kilometers above the surface of a relatively flat bottom.
The resulting images significantly complement the currently available information about this crater. The world's first image of the far side of the moon was obtained in October 1959 by the Soviet automatic station "Luna-3".
"Luna-25" carried out observations with the help of ADRON-LR and PmL, ARIES-L instruments. Fluxes of gamma rays and neutrons from the lunar surface are measured, and the parameters of the circumlunar space plasma and gas and dust exosphere in the circumlunar orbit are also obtained.

[Hungry4info]

The manoeuvre to lower to a pre-landing orbit failed.

Today at 11:10 UTC, an impulse was given to transfer the spacecraft to a pre-landing orbit. During the operation, an emergency situation occurred, which didn't allow the maneuver to be performed as planned. Currently, the specialists are analyzing the situation.

[Phil Stooke]

We don't have anything official as I write this but the suggestion floating around various Russian online forums (Astroforum, Novosti Kosmonavtiki) is that a braking burn lasted about 60% longer than intended, causing excessive braking and an impact on the surface. Mare Tranquillitatis has been suggested as an impact area. This is NOT official.

Phil

[abalone]

Russian spacecraft has crashed into the Moon after it spun into an uncontrolled orbit, Russia's national space agency Roskosmos says.
https://www.abc.net.au/news/2023-08-20/russ...-moon/102753294

[rlorenz]

Space is hard. Landings especially so.

I put this table together a few years ago for a paper on evaluating risk and payoff of planetary missions (in part to show the advantage of mobility, and of reconnaissance, to note that without at least the latter, a single, fixed Europa lander would be unlikely to realize the claims being made for it...)

It shows that the empirical historical record for landings is something like 25-83% reliable (which is in stark contrast to the 99% reliability sought, and used in e.g. landing ellipse specification). I havent run the numbers, but I suspect the Chandrayaan2-Beresheet-Hakuto-Luna25 set of losses is consistent with the lower end of that. We'll see what happens later in the week....

The paper is at https://www.sciencedirect.com/science/artic...273117719303539 (may be paywalled, tho. email me if you need it and cant get it)

Attached thumbnail(s)

 

[stevesliva]

Always tell us the odds, Ralph.

[fredk]

And presumably the "expected success probability" for something like ESA Mars landings needs to be taken with a healthy grain of salt, since there have been no successes...

[kenny]

And the Soviet moon landings had a lot more than 1 failure, and a lot more than 5 attempts (if that is what "trials" means).