Roskosmos explains this with additional tests
The launch of the Luna-25 spacecraft, which was planned for July, has been postponed again. Now for August. According to the official Roscosmos, this was done «in order to achieve the required reliability of the mission.»
Recall that the original sending of our device to the Moon (it should be a continuation of the Soviet lunar program, which was interrupted in 1976 after the launch of Luna-24) was planned for the end of 2019. Then Roskosmos postponed launches: first to July-October 2021, then – on August 2022, for July 2023…Now, the fourth time, – as of August 2023
Last year, the transfer was associated with the need to complete fire tests of the propulsion system, with which problems had previously arisen. They also talked about «certain technical difficulties in terms of the device of an external manufacturer.» As it turned out, it was about the developed at the JSC «Concern» Vega » Doppler speed and range meter (DISD-LR). So that he confidently and gently landed the device on the moon, they decided to finalize it. This revision took almost a year.
Today, several industry experts answered the question "MK" about the new reasons for the transfer, they say about the same thing: additional tests are required in order for us to land Luna-25 safely; to an earth satellite. This is most likely about testing again & nbsp; DISD-LR, – after all, this is a key part of the apparatus, on which the success of both Luna-25 and all subsequent Lunas depends.
Launch «astronomical window» 2023 will be open from July to August. According to Roskosmos, the spacecraft is currently undergoing the final cycle of ground tests at the test bench for the onboard control system. Specialists are completing statistical modeling of a soft landing on the lunar surface. For the first time in the history of astronautics, it will be produced in the vicinity of the South Pole of the Moon.