BOX 3.1 Lunokhod

The Soviet Luna 17 and 21 missions (launched in 1970 and 1973, respectively) each delivered to the Moon's surface an eight-wheeled, roving vehicle called Lunokhod (Figure 3.1.1). Weighing 756 and 840 kg, respectively, Lunokhods 1 and 2 each carried several instruments, including stereocameras, a survey camera, a laser reflector (for laser ranging), a magnetometer, a cosmic ray detector, an x-ray spectrometer, and a penetrometer.1 Lunokhod 1 returned data for more than 10 months and traversed 10.54 km, while its successor operated for only 3 months but ranged 37 km over the surface of the Moon.2

Lunokhod resembled a teapot, complete with an openable lid that was hinged along one side of the kettle top. Solar panels covered the underside of the lid; during the day, the lid remained open, collecting energy for operation and storage. At night, the lid closed to conserve heat inside the instrument housing. Lunokhod's chassis supported eight independently suspended and powered wheels. Each wheel was constructed of three wire rims, each of which was attached to the hub by sixteen spokes. A wire mesh and lugs covered and connected the wheel rims.3 Additional characteristics of the Lunokhod vehicles are listed in Table 3.1.1.

The Lunokhods fulfilled both scientific and engineering objectives. Combined, they returned more than 500,000 images and 500 panoramas, performed some 1000 soil property tests and 50 soil chemical analyses, and returned astronomical observations from the surface of the Moon.4 Despite its shorter life span, Lunokhod 2 took proportionally more measurements than did its predecessor, consistent with the distance it traversed. The Lunokhods successfully negotiated the lunar mare, a surface that is relatively free of large obstacles and for which they were specifically designed. Lunokhod 1 traversed the western section of Mare Imbrium, and Lunokhod 2 traveled over Mare Serenitatis.

The rovers could operate only under the direction of a team of five (including a vehicle commander, a driver, a navigator, and engineers) who controlled the vehicle remotely based on input from the rover

TABLE 3.1.1 Lunokhod Characteristics

Characteristic

Both Rovers

Lunokhod 1

Lunokhod 2

Rover mass

 

756 kg

840 kg

Rover length

2.13 m

 

 

Wheel basea

1.70 m

 

 

Number of driving wheelsa

8

 

 

Wheel diameter/widtha

0.51 m/0.2 m

 

 

Wheel dynamic rangea

0.1 m

 

 

Maximum surmountable vertical obstaclea

0.4 m

 

 

Range traversedb

 

10.54 km

37 km

Length of operations

 

10 mo

4 mo

a A.P. Vinogradov, Lunokhod 1—Mobile Lunar Laboratory, translated by Joint Publications Research Service, JPRS#54525, distributed by National Technical Information Service, U.S. Department of Commerce, 1971, p. 73.

b Marcia S. Smith, Space Activities of the United States, ClS, and Other Launching Countries/Organizations: 1957–1994, Congressional Research Service 95–873 SPR, Library of Congress, Washington, D.C., 1995, p. 90.



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