Above: Possible design of the DALS instrument set based on available information. Copyright © 2013 Anatoly Zak

During the Moon Race, Soviet scientists were developing a set of scientific instruments to be left behind on the lunar surface by visiting cosmonauts. The science package known as DALS was designed to deliver scientific data about the Earth's natural satellite long after manned expeditions would return home.

During the pioneering Moon landing in July 1969, astronauts Neal Armstrong and Ed Aldrin established a tradition for all future Apollo missions -- to leave long-lasting experiments on the lunar surface. A set of several instruments deployed by astronauts was dubbed Apollo Lunar Surface Experiment Package, or ALSEP. Carrying and setting up bulky hardware for ALSEP around dusty lunar surface became a major task of for Apollo astronauts working on the Moon. Beginning with the second lunar landing of Apollo-12, five expeditions would leave ALSEP experiments powered by the SNAP-27 radioisotope thermoelectric generators or RTGs. They converted radioactive decay of 4.8 kilograms of plutonium-238 into electric energy. Expected to last from five to 10 years, SNAPs were still producing more than 90 percent of their original output of 70 watts a decade later.

It has always been assumed that Soviet lunar expeditions, had they ever reach the Moon, would also leave behind scientific instruments. However even after all the revelations of the post-Cold War era, little details had emerged on this chapter in the history of lunar science. In 2010, a small collection of memoirs did disclose that a lunar lander known as LIK and the Long-Duration Automated Lunar Station, DALS, (from Russian Dolgo-funktsioniruyashaya Avtomaticheskaya Lunnaya Stantsiya) had been under development within the Soviet L3 lunar project. The DALS project was undertaken at the OKB IKI design bureau in the Kyrgyz city of Frunze (now Bishkek). The organization was a division of the Space Research Institute, IKI, in Moscow, which traditionally led Soviet space science projects.

Despite OKB IKI's extensive prior experience in development of scientific hardware, the DALS became one of the largest and most complex projects delegated to the bureau. Up to a half of the entire staff at the organization had to be involved in the effort, according to several accounts.

OKB IKI led general development of DALS stations and also worked on their electrical interfaces and hardware. Engineers at OKB IKI also designed the central container, the system for gathering and processing information and the station's work program. The central container of the DALS station would be connected to a radioisotope power generator, enabling prolonged operation of the entire complex. Other external components included a seismometer, measuring lunar quakes; a magnetometer and several electromagnetic sensors.

The initial design of the data gathering system onboard DALS called for a central processing unit responsible for all operations. However, due to considerable distance between different instruments, such architecture made DALS too cumbersome and unreliable. To resolve the problem, Vechaslav Sherbakov, the head of the DALS project, proposed to maximize the informational autonomy of each remote component of the package. Each instrument received a processor that generated all necessary internal commands, gathered information and formulated a completed packet of telemetry data, which would then be channeled to the central container and to a data relay satellite for retransmission to the Soviet ground control. Given absence of the miniature computers at the time, it was an innovative and controversial solution. Nevertheless, during the formal defense of the project, five members of the review commission with PhDs degrees strongly endorsed the design.

The technical project of the DALS complex was completed in 1971, unfortunately, following the premature demise of the Soviet manned lunar exploration effort in 1974, all documentation and hardware built within the DALS project apparently shared the fate of the N1 Moon rocket -- going to scrap metal and paper waste. (620)

Page author: Anatoly Zak; Last update: September 30, 2023

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Apollo-11 astronauts install instruments on the surface of the Moon in 1969. Credit: NASA


A full-scale demo version of the SNAP-27 generator, which was designed to power science instruments for 5-10 years, after they were left on the surface by Apollo astronauts. Copyright © 2011 Anatoly Zak


The Moon Race-era document illustrates plans to deploy scientific instruments from LK lander.


Cover of documentation for the DALS project.

to Spacecraft to Lunar spacecraft to L3 project to LK spacecraft