Russia’s next attempt to leave Low Earth Orbit is currently scheduled to liftoff at the end of next year. However, it may be delayed by two years because of a technical issue combined with ballistic and political problems.
The Luna-Glob probe will land near the Moon’s South Pole, in the Boguslawsky crater, and is also dubbed Luna-25 to mark the continuity with Luna-24, the last Soviet mission to the Moon, which brought back ground samples to Earth in August 1976.
Its launch was originally scheduled for 2016 but was postponed to 2019 mainly because of lack of funding. Roscosmos allocated a budget of 4.5 billion rubles to NPO Lavochkin, Luna-Glob’s builder, as recently as October 2016.
Since then, almost everything has gone according to the plan, except with a crucial instrument called BIB, the probe’s inertial measurement unit.
Provided by the Russian company NPO IT – located in the city of Korolyov, not far from ISS Mission Control – the BIB should provide the onboard computer with the necessary information to ensure guidance on the path from the Earth to the Moon.
However, BIB testing at NPO IT showed unexpected results, clearly indicating it was not working properly.
The designers of this system noted it won’t be ready for the 2019 launch window, which resulted in NPO Lavochkin trying to replace it with a European equivalent called ASTRIX, designed by Airbus Defence & Space.
However, the ITAR regulatory regime strictly forbids such a deal, because the ASTRIX has several US components inside.
Scheme of Luna-Glob showing the BIB inertial measurement system. Credit : Space Research Institute (IKI).
The only other solution is a system called BIUS-L, developed by Moscow’s NPTs AP. This is equivalent to BIB. However, this system would not be ready for flight before February 2020.
The delay consecutive to this technical challenge brings into play additional consequences. During its course to the Moon, Luna-Glob will have to make trajectory corrections using its main engine, giving itself a speed increase, classed as Delta-V.
The value of Delta-V cannot be greater than 0.846 km/s, because this is the maximum speed that main engine will be able to nullify when it arrives in the vicinity of the Moon.
Delta-V value (blue line) compared to the maximum acceptable value (red line). Credit : Russian Academy of Science.
Since the Moon’s orbit is not a perfect circle, the Delta-V needed to reach it depends on the date of the launch. There are only a few windows during which the Delta-V is below 0.846 km/s. The next window opens in October 2019 and closes in January 2020. This was the targeted window to launch Luna-Glob.
Another window will open from June to September 2020, but Delta-V will be very close to the limit. The next window with comfortable margin only opens in May 2021.
Last May, Russian Academy of Science’s Council for Space recommended Roscosmos to postpone the launch to this 2021 window. However, Mikhail Khailov, Roscosmos’ deputy director for unmanned satellites, noted his opposition to such a delay. Discussions are still underway and to date no decision has been taken.
However, some people involved in Luna-Glob mission can’t wait much longer for a decision. That applies to the Swedish Institute of Space Physics (IRF), which was to provide one of the mission’s key scientific payloads.
Luna-Glob test model. Credit : Nicolas PILLET.
LINA-XSAN (eXtra Small Analyzer for Neutrals) goal is to study the space plasma interaction with the lunar surface, which could be at the origin of the water already observed on the Moon. ARIES-L, another payload of Luna-Glob built by Russia, has the same objective.
Some of the components of LINA-XSAN were built in 2012, nearing their maximum lifetime, and cannot wait three more years on the ground. Building new items is not possible since IRF teams are fully involved in JUICE, a European mission to Jupiter for which they are providing a payload called Particle Environment Package (PEP).
Last year, IRF received a proposal from the Chinese, who offered to fly LINA-XSAN on their Chang’e 4 lunar probe. The Swedish decided to accept this opportunity and informed their Russian colleagues that the payload would not fly on their probe but instead on the Chinese spacecraft.
Although it is now clear that Luna-Glob will fly without the Swedish payload, Roscosmos decision regarding the date of the launch is still pending.