The Lunokhods Russias marvelous robotic rovers

By Ronald A. Creel

In the fall of 1971, Apollo Lunar Roving Vehicle (LRV) thermal control engineers were applying experiences from the successful use of the first LRV during the Apollo 15 mission, and preparing for the next Moon exploration mission. A very interesting document was delivered to me as one of the LRV thermal engineers. This document was an unexpected English translation describing the Russian "Lunokhod-1, Mobile Lunar Laboratory". Myself and others at NASA had been remotely following American space trade magazine reports about the parallel Russian exploits in Moon exploration, especially their highly successful first "extra-terrestrial" Lunokhod (Moonwalker) robotic rover in 1970.

Consideration had been given to converting the fourth LRV for robotic operation, after manned use, for the ultimately cancelled Apollo 18 mission. I was very interested in gaining more information about how the Russians had been able to develop their robotic rover, which survived the higher and then much lower temperatures during full temperature cycles on the Moon. In the translated document was a complete description of how the Russians had used a radioisotope heat source to maintain electronics temperatures in their remotely-operated rovers during the fifteen dormant eclipse days without solar heating and very cold lunar surface temperatures.

Many years later, E-mail discussions with my counterpart rover engineers in Russia led to an invitation for me to attend a robotic rover conference at the Lunokhod development facility in St. Petersburg, Russia, in October 2004. I shared the Apollo rover thermal control experiences and learned much about the Lunokhod experiences from the very informative and sharing Russian engineers. They related how special lubricants were used to allow external exposed motor and drive systems to survive, and how the nuclear heat source kept the electronics "alive". The Russian engineers showed me the smaller rover, with walking "skis" instead of wheels, which

294 Appendix 2: The Lunokhods - Russia's marvelous robotic rovers they had tried to land on Mars in 1971. I also accepted a medal from the Russian Cosmonautics Federation on behalf of all of the Apollo and LRV workers.

The Lunokhods were very successful and added greatly to the body of knowledge about lunar mobility and survival. Lunokhod-1 traversed more than 10.5 km during the almost eleven months it was operated on the Moon after its deployment on 17 November 1970. This was well beyond the planned four months of survival and exploration. The radioisotope heater system performed its temperature maintenance function quite well. The faster Lunokhod-2 then traversed more than 34 km on the Moon during a shorter four month period after its deployment on 15 January 1973. The reason for this reduced operating period had intrigued me, until I got a full explanation from one of the original Lunokhod drivers, General Dovgan.

There was a great desire to accumulate more and more daily mileage with Lunokhod-2. It was normally planned to keep the vehicle's protective top lid, with solar cells on the inside, open during the fairly slow (between 0.8 and 2.0 kph) daytime driving around on the Moon. A situation arose in which it was contemplated as to whether or not to proceed down into what looked to be a fairly steep crater. General Dovgan recommended that the lid be closed in order to protect the solar cells before proceeding. This was not the normal written procedure, and, with a recent new personnel shift change having occurred at Lunokhod Mission Control, the lid closing was not approved.

As Lunokhod-2 started down into that crater, it began to slide, and it was decided to immediately reverse its direction as soon as this could be accomplished. As the vehicle was being remotely driven back out of the crater, it hit the side of the crater and a large amount of lunar soil was dumped onto the exposed solar power collecting cells. The lunar soil deposited on the solar cells doomed Lunokhod-2, because it could not be removed, and therefore the needed energy to continue exploration could not be generated. This was similar to the problems which had been encountered with stirred up lunar soil and dust during the Apollo rover missions. Lunar dust was very resistant to being removed from surfaces, and resulted in overheating of several LRV and other components.

Being able to meet and share rover experiences with the Lunokhod engineers was very fulfilling and cathartic for me. After more than three decades, fellow rover designers and engineers could finally discuss challenges and ideas, which had previously been impossible due to political and geographical limitations. More than ever, I was convinced that mitigation of adverse lunar dust effects and nuclear energy sources like those used by the Russians on the Lunokhods (and also on past and future Mars rovers) will be required for future extended survival and operation on the Moon. Now, I anticipate further potential collaboration with my Russian friends on rover projects for the renewed vision for Moon exploration.

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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