Roscosmos Planetary Exploration Missions

RTN wrote:
These low IQ, corrupt, street shitting, impoverished and miserable Indians were able to land their rover on the Moon

Accelerometer Malfunction Prompted Luna-25 Module to Crash Into Moon - Roscosmos

BAIKONUR (Sputnik) - Russia's Luna-25 automatic landing module crashed due to a malfunction of the accelerometer that failed to transmit the information needed for the engine to turn off, Yuri Borisov, the head of Russian state space corporation Roscosmos, said on Friday.

On August 20, Roscosmos said that Luna-25 module crashed into the moon's surface after going into an unplanned orbit. Communication with the spacecraft was lost at around 2:57 p.m. Moscow time (11:57 GMT) on August 19.

"The correction engine has not stopped working according to the information from the accelerometer, this is the device that shows the change in speed. The reason is that the accelerometers did not turn on. Why they did not turn on, we are looking into it in detail now," Borisov said at a news conference.
Currently, there are 16 preliminary causes for the crash, 11 of which have already been checked, and the examination into the causes of the Luna-25 crash is planned to be completed by the end of September, the official added.

The first person to convey words of support in connection with the accident was NASA Administrator Bill Nelson, Borisov said.

Roscosmos earlier detailed that the landing module crashed because the engine failed to turn off as program, having worked 127 seconds instead of 84 seconds during a transition to pre-landing orbit.
However, despite the unsuccessful landing, Russian authorities have underscored that the mission has provided invaluable information to the assignment.

Luna-Glob failure scenario emerges

Speaking at a press-conference in Baikonur after the launch of the Soyuz MS-24 mission on Sept. 15, 2023, Head of Roskosmos Yuri Borisov said that the orbit correction engine of the Luna-Glob (Luna-25) lander had failed to cut off as planned due to (lack of) data from an accelerometer that measures velocity changes (critical for the accuracy of orbit correction). According to Borisov, the accelerometers had failed to activate (during the maneuver, preventing the on-time engine shutdown).

Borisov also said that Roskosmos specialists had evaluated 11 out of 16 possible failure scenarios and planned to complete the investigation by the end of September. However, by that time, Borisov's disclosure combined with various rumors and details surfaced on the Internet during the mission and in the subsequent weeks made it possible to ascertain an overall picture of the accident.

During the trans-lunar cruise phase of the flight, when the Luna-Glob lander had to perform some corrections of its path from the Earth to the Moon, ground controllers noticed unexplained switches from the primary to the secondary set of the BIUS-L instrument, which measures angular velocity and linear acceleration for the lander's flight control computers (INSIDER CONTENT). Upon the second attempt to activate BIUS (and with growing acceleration induced by the maneuver), the primary instrument would return to action. However, ahead of the fateful lunar orbit correction on August 19, both accelerometers worked correctly, but once the maneuver started, one set failed again, while the flight control system never switched to data from the second set. As a result, onboard computers were not receiving data about critical parameters required for properly completing the orbit correction, such as orientation of the spacecraft in space, velocity and altitude.

If confirmed, this crash scenario would likely implicate deficiencies in the development or testing of the flight control system and its software rather than any mechanical problem of the propulsion system, which was implied in the initial statement about the incident.

Big_Gazza wrote:

T-47 wrote:

Big_Gazza wrote:Build another Luna-25 and fly it.  Get it done, and stop wasting time.  Post-mortem can be performed in parallel to the required procurements.

Get it done without finding the previous mistake properly just to face the same issue again and crash. Very very easy to type get it done.

Not suggesting that.  Its not a sequential process.  You don't need to hold up the procurement process while diagnosing the fault.  Once identified, you issue variations to contract to fix the hardware/software required.

Flying a replacement probe will take years.  Plenty of time to conduct post-mortems and make the necessary fixes (ie fix the accelerometer hardware issues, and fix the error-handling routines in the flight control software).