On Aug. 19, at 11:10 UTC, the Russian spacecraft Luna 25 performed a planned orbit maneuver. After an eight-day flight and two orbit corrections, it was parked in a circumlunar 90 by 113-kilometer orbit. It was time to transfer to the pre-landing orbit with the parameters of 18 by 100 kilometers. But something went wrong, and at 11:57 UTC, the connection with the spacecraft was lost and it crashed into the Moon.
At 12:01 UTC, the first Russian lunar lander performed a rapid unscheduled landing, and a few hours later, Roscosmos informed that problems occurred during the maneuver. On Aug. 20, after a few hours of attempting to communicate with the spacecraft, Roscosmos considered it lost, and moreover, it said that Luna 25 crashed on the lunar surface.
Usually, Roscosmos doesn’t confirm its problems unless it must. If there is a small chance to connect with the spacecraft, it will never deem it a loss. This means teams were totally aware that Luna 25 is not in the wrong orbit or in the wrong orientation, but it crashed, and the crash site will be visible to orbiters.
Unofficial, but reliable, sources note the transfer impulse somehow turned out to be 1.5 times higher than expected. It means according to the calculations of Jonathan McDowell that Luna 25 was transferred to the orbit of -15 by 100 kilometers and therefore crashed into the Moon with a speed of 1.68 kilometers per second.
If it started at 91 x 113 km and was heading for 18 x 100, a 50% overburn would put it at -15 x 100 km (oops). But if it was already halfway down, say starting at 50 x 100 km heading for 18 x 100, then 50% extra gets to 2 x 110 km and it's skimming the mountaintops…
— Jonathan McDowell (@planet4589) August 19, 2023
What exactly caused the crash is currently unknown. There are two possible scenarios: a software error (a programmer’s mistake) and a hardware error (the engine failure), with both teams blaming the other.
What’s next for space exploration in Russia?
It was planned that after Luna 25, an orbiter named Luna 26 will be sent to the Moon, followed by another, more powerful lander Luna 27, and a lunar soil return mission Luna 28.
All these missions were also part of the Russian-Chinese lunar base project (Roscosmos had nothing else to offer, even on paper). And now there are three possibilities for Roscosmos.
In Soviet times, many missions were built in pairs. If the first spacecraft was lost for some reason after reaching orbit, it received a “Cosmos-XXXХ” name, and the second one was ready for launch. It was especially important for Venus missions, where the launch window opened not every year.
If the first mission launched successfully, its twin was either launched too or served as a test object to test the commands and scientific instruments. Unfortunately, Luna 25 has no twin and no second chance.
The first possibility is to collect all the test models and backup instruments and try to create Luna 25B, a spacecraft very similar to the lost one, to perform its program.
The second way is to continue with Luna 26, as if there was no Luna 25 at all. The orbiter is easier, it may perform precise cartography of the possible landing regions for Luna-27. However, none of the current directors will be on duty in the 2030s or later. If so, Luna 26 launch can be expected as planned, in 2027 or (with possible delays) in 2028-2030.
Surprisingly, the fate of the Russian lunar program will depend on Chandrayaan-3. If the Indian lander succeeds, it will not bring Russia credit of the “first country to land on the south pole of the Moon”. That means it will be harder for Roscosmos to receive funding for the new spacecraft. However, if Chandrayaan-3 fails, there will still be an achievement to win, and the Russian government may be more willing to invest.
And the third scenario is that the whole Russian lunar program will be canceled, which is unlikely due to Russia’s reputation.
(Lead image: Soyuz 2.1a launching from Vostochny Cosmodrome. Credit: Roscosmos)