Luna-25 Vs. Luna-24: The evolution of the species

Almost exactly 47 years separate the launch of the last automatic station intended for the exploration of the lunar surface, Luna-25, from that of the previous mission in the series, Luna-24, which took place on August 9, 1976.

In recent years, the technical evolution, in the first place, and the different objectives of the mission, highlight substantial differences between the two automatic vehicles that have only one name in common: Luna.

Luna-24 – collect and ship

E8-5M: perhaps the initials will say little to most people.

This is the model of the probe, E8-5, which identifies the second series of automatic stations dedicated to the soft landing.

Also developed by what is now called NPO Lavochkin, from the E6 series onwards they allowed the Soviet Union to make a soft landing on our natural satellite. With Luna-9, on Dec. 3, 1966, an object built by Humanity landed softly on the lunar surface. Luna-24 was an automatic station intended to operate only one lunar day, 14 Earth days, on selenic soil.

However, its most important feature was the possibility of sending collected soil samples to Earth, as in the case of Luna-24, at equatorial latitudes: 12°45’N, Mare Crisium. The trajectory, direct as in Luna-25, brought Luna-24 to the moon landing only four days after the launch, which took place on Aug. 9, 1976, from the Baikonur Cosmodrome, using a Proton-K launcher.

I just have to dig…

Weight, 5,795 kg of which 514,8 for the reentry module towards the earth, it was devoid of solar panels. An RTG battery would have provided enough electricity to power the automatic station for its 14-day operational life.

Only 170 grams of soil were collected by the LB-09 lunar drill (from the Russian “Luny Bur” – lunar drill) in the Fahrenheit basin, not far from the place where the ill-fated Luna-23 mission crashed to the ground in 1974.

A few minutes after the moon landing, the LB-09 drill was positioned on the ground to begin its work. Like a domestic percussion drill, it drilled a dozen centimeters of soil by lifting a “carrot” which, conveyed in a spiral containment system, was positioned in the reentry module destined for the Earth.

On August 19, 1976, 22h 49′ after the moon landing, the KT reentry module departed for our planet where it arrived on Aug. 22, 1976, landing near the city of Surgut in Western Siberia.The soil sample showed a strong component of aluminum (19%) and iron (16%) with a modest amount of titanium (1%).

Luna-24 worked for all 14 scheduled days carrying out tests of the equipment and, in particular, carrying out further tests of the LB-09 in anticipation of a mission to Mars which, however, never took place.

Designed to last

Luna-25, 47 years later, has a radically different approach.

Only the name, which was attributed in recent years (previously the mission was cataloged as “Luna-Grunt” from the Russian “Grunt” – “terrain”) and the flight profile unite the old E8-5M with this automatic station, also built from NPO Lavochkin. Everything else is different; no longer a single lunar day, 14 Earth days, but an entire Earth year.

Moon landing at the southern polar latitudes of the visible hemisphere, in an area between 68 and 69°S. Solar panels are arranged vertically to be interested in our star’s radiation during the long phases in which, at those latitudes, our Sun is almost parallel to the ground and never at the Zenith. No re-entry module, which will be present in the future Luna-27 mission, and a sophisticated mining laboratory capable of collecting, using a robotic arm, and analyzing the underlying soil. All in anticipation of an imminent human settlement on the selenic surface from 2030 onwards.

The on-board instrumentation

35 kg of equipment, as well as solar panels and batteries capable of supporting the automatic station for 365 days, are part of Luna-25’s scientific equipment. Externally, the LMK (Lunny Manipuljatornij Komplex) robotic arm is the most evident element. A mechanical arm, remote controlled from the ground thanks to the vision offered by the LIS-TV-RPM camera, will take the soil samples subjected to the analysis of the onboard instruments.

The LIS-TV-RPM chamber will also be used for the infrared spectrographic analysis of the sample, and the LAZMA-LP laser analyzer will probe the same sample to provide isotopic examination. A radiation and neutron detector (ADRON-LP), a panoramic spectrometer for the detection of ionized particles (ARIES-L), and a dust monitoring device for measuring particle fluxes in the lunar terrain (PML). These complete the scientific equipment developed by the Academy of Sciences (IKI-RAS)

The moon landing live

Spectacular will be, thanks to the STS-L camera, the real-time shooting of the moon landing, scheduled for August 21, 2023.

According to the indications of Roscosmos, the shots, especially of the lunar dust raised by the braking engine, will serve to establish the consistency of the ground at those latitudes which are expected to be rather compact and bumpy.

The STS-L camera has already provided on August 13, 2023, the first spectacular images of the earth and the Moon taken during Luna-25’s last course correction before insertion into lunar polar orbit.

Get ready! It will be a show to witness this return to the Moon.