First steps of the Lunokhod-1 lunar rover

On November 17, 1970, at 7:20 a.m. Moscow time, the Soviet self-propelled lunar rover Lunokhod-1, controlled from Earth, covered the first few meters in the area of Moon’s Mare Imbrium. From this moment a new era of research on the Earth's satellite has begun.

The triumph of the lunar rover was the occasion for a national jubilation!

The development of heat and electricity sources based on isotope nuclear power units (NPU) was one of the factors that made it possible to implement the Soviet lunar rover program. Work on these units commenced in 1962. The advantage of isotopic NPUs is their relative simplicity and the possibility of using them in space flights of various complexity and duration.

To create such installations, it was necessary to create special heat-generating materials, and heat and electricity generators based on them. The polonium-210 isotope was studied as the first radioactive energy source.

Initially, the polonium-210 radionuclide was used to make polonium-beryllium sources of neutrons placed within nuclear charges. Under the scientific guidance of Zinaida Ershova, a sustainable, environmentally friendly production of polonium was established in the country. Industrial reactors were built to produce plutonium and tritium nuclear materials for nuclear weapons. However, VNIINM specialists found an original technical solution to reduce the cost of fissionable materials production. Uranium graphite commercial nuclear reactor were developed to produce heat and electricity.

The phase of conversion of isotope production began in 1962. Scientists and specialists were tasked with finding civilian applications for polonium. And it was found.

The problem of operation of spacecraft that consume significant amounts of electricity to power onboard equipment was solved. Traditionally, for this purpose chemical batteries recharged from solar panels were used. In those cases, where the use of solar panels is inefficient, for example, in deep space or on planets, it is advisable to use isotope-based sources of heat and electricity. Although, the efficiency of such systems is low (no more than 5%), their use has proved to be justified.

The first experimental model of the l-106 thermoelectric generator with a heat source based on Po-210 was developed, manufactured and presented in 1962. A year later, the collaboration of Avangard Electromechanical Works, the Sukhumi Institute of Physics and Technology and the Obninsk Institute of Physics and Energy, solved the main technical problems, and proposed the concept for the design of an capsule containing Po-210 isotope fuel was proposed. The requirements specifications were demanding. Suffice it to say that the capsule containing the isotope fuel must remain tight after hitting granite or soil at a speed of up to 100 m/s and temperatures of 1,000 to 1,300 °C.

In 1965 two polonium-based isotope power generators were successfully operating on the Kosmos-84 and Kosmos-90 satellites.

In 1969, the problem of using an isotope as a heat source for a space station launched to the Moon was resolved. The heat source designed specifically for this purpose met all the requirements of the specification and radiation safety demands. Its intended use was a heat source to maintain a normal temperature in the instrument compartment during the lunar night.

In 1970, isotope power generators were used as power supply of the Lunokhod-1 rover, and in 1973 -- for Lunokhod-2.

There were so many challenges. Never forget that the duration of the "lunar day" and "lunar night" is about 15 days. The absence of an atmosphere and the slow rotation of the Earth's natural satellite around its axis entails a huge temperature drop of 300 °C (from +130 °C during the day to - 170 °C at night). The optimal temperature for some systems, however, should not exceed terrestrial room temperature. The design of the heating block provided these "home" conditions.

Thanks to the isotope source, Lunokhod-1 roved the Moon for 322 days, and Lunokhod-2 -- for 220 days, which significantly exceeded the specified requirements.

The crew of Lunokhod-1

For a long time, it has been officially stated that "the Lunokhod-1 is controlled from the Deep-Space Communications Center using information about the position of the unit and the nature of the relief of the surrounding lunar surface sent by a camera...". Despite the entirely civilian designation of the lunar rover, its crew members were kept anonymous for many years.

The lunar rover driver crew was created in 1967.

The difficulty of controlling Lunokhod-1 rover was that the signal delay caused by the distance reached up to 24 seconds. It turned out that by the time of th availability of the new image, the lunar rover would move several meters.

To train the crew to drive the lunar rover, a test range 70 by 120 m was created with terrain similar to that on the Moon. The test range had depressions, craters, fissures, and scattered stones of various sizes.