Close-up on the lonely trail of Lunokhod-2

Long and winding road of the last rover deployed on the Moon, Lunokhod-2. Image cropped from a diagonal slice through the rover trail swept up in an extreme close-up of Le Monnier crater August 14, 2012. LROC Narrow Angle Camera (NAC) frame M168000478R, LRO orbit 9892; resolution 41 cm per pixel, angle of incidence 47.65° from 22.11 kilometers [NASA/GSFC/Arizona State University].

The Soviet Union's Lunokhod-2, riding to the lunar surface on the Luna-21 lander, arrived on the Moon January 15, 1973. The 84 kg. rover Lunakhod-2 was afterward deployed and, with the benefit of a robust radioisotope thermoelectric generator to warm itself through the long lunar nights, was teleoperated a total of 37 km, across the southern floor of le Monnier crater, until the following June.

It's not quite as easy to distinguish the twin ruts of the Lunakhod trail in the mosaic of both the right and left-hand frames of LROC NAC observation M168000478. The unusual close-up, from less than half the nominal 50 km altitude, was caught as flight directors prepared to raise LRO's orbit to above 100 km at the end of 2011. Because the camera was considerably closer to the surface, the field of view is quite a bit more narrow, in compliance with the Inverse Square Law, slightly less than one-half kilometer across. LRO was slewed a full 25° off nadir, which resulted in the right-hand frame being very slightly more distorted than the left [NASA/GSFC/Arizona State University].

LROC principal investigator Mark Robinson discussed the Lunokhod-2 mission in detail on March 13, HERE. Also, there are spacecraft panoramas and close-ups of both Luna-21 and Lunokhod-2 at the following links:

Lunokhod-2 revisited (March 13, 2012)
Luna 21 (March 20, 2010)
Lunokhod-1 and Lunokhod-2 (March 17, 2010)

Phil Stooke's familiar survey of the Lunokhod-2 traverse is seen here graced with the scaled mosaic of LROC NAC M168000047, at lower left. The small white box shows the field of view seen at 41 cm resolution in the opening image, above [Google Earth].

ILIADS application perspective of le Monnier, LROC Wide Angle Camera 100 meter global monochrome mosaic draped over LOLA 128 ppd digital elevation model (v.2) [NASA/GSFC/Arizona State University].

LROC: Lunokhod 2 revisited

The tele-operated Soviet Lunokhod 2 rover, the last lunar rover deployed on the Moon, parked facing southeast with the lid still open 39 years later. Rover tracks extend north to this final parking place. The inset is a zoomed in view, the main body is labeled B and open lid labeled L, with the instrument suite (including its French-built laser-ranging retro-reflector array, still in use) on the front labeled I. LROC Narrow Angle Camera (NAC) observation M175070494, orbit 10934, November 4, 201; resolution 30 cm per pixel [NASA/GSFC/Arizona State University].

Mark Robinson

Principal Investigator

Lunar Reconnaissance Orbiter Camera

Arizona State University

The Lunokhod 2 rover is still parked on the floor of the crater Le Monnier (25.830°N, 30.914°E). This NAC image was taken when the spacecraft was only 24 km above the surface, zipping along at about 1.6 km/sec (about 3600 mph). The spacecraft had to turn on its axis 27° to view the rover. The resolution is about two times higher than usual!

The Lunokhod 2 rover was carried to the surface on board the Luna 21 spacecraft. Lunokhod is the English translation of the Russian word “Луноход”, meaning Moon Walker. The ensemble was launched on 11 January 1973 and the landing occurred on 15 January in Le Monnier crater on the eastern margin of Mare Serenitatis. The coordinates of the landing site are 26.005°N, 30.406°E (on the basis of nine observations) at an elevation of -2769 m (1734630.9 m radius).

Le Monnier crater lies on the eastern wall of the Serenitatis basin. Lavas that compose Mare Serenitatis also flooded the floor of this 61 kilometer diameter ancient crater. The two red crosses indicate the locations of the Luna 21 lander (L21) and the ultimate  parking spot of the Lunokhod 2 rover (L2) after enduring three full lunar nights. View the original full resolution context image HERE [NASA/GSFC/Arizona State University/USGS/JAXA/Phil Stooke/Google].

Lunokhod 2 is about 170 cm (5’ 7”) long x 160 cm (5’ 3”) wide x 135 cm (4’ 5”) tall, and it is almost circular when viewed from above. The vehicle had eight wheels and could travel at either 1 km/hr or 2 km/hr (0.6 and 1.2 mph). The lid on the top of the rover served to provide solar power and to keep the vehicle warm at night. When the lid was opened, the solar cells collected energy to operate the rover. At night, the lid was closed and a fluid heated by the decay of Polonium-210 kept the rover warm. The rover was controlled remotely by a team of Soviet controllers on Earth.

Lunokhod rover in publicity still. Note the mesh wheel design and LRRR on the extended instrument suite housing [Russian Space Academy].

During its 37 km traverse, Lunokhod 2 headed south from the landing site and into the highlands from the southern rim of Le Monnier crater. Lunokhod 2 had difficulty on the slopes of the southern rim so it was turned northward and commanded to backtrack to the flat mare basalts that form the floor of Le Monnier. It then continued eastward across the crater floor eventually encountering a 250 wide north-northeast trending rille named Fossa Recta (Straight Rille).

The Luna 21 lander with ramps deployed on both sides,
to the northwest and to the southeast. LROC NAC
M122007650L [NASA/GSFC/Arizona State University].

Lunokhod 2 drove off the lander to the northwest and circled around to the east. Several turns were made as the rover photographed the lander. It then departed and headed south.

The rover had to work its way down the rille wall and across the floor before finally climbing out on the east side. Lunokhod 2 continued north before reaching its final position. The mission officially ended on 4 June 1973 due to a failure of the rover. Apparently on 9 May, the rover’s lid touched a crater wall and become covered with fine-grained lunar regolith. That regolith was dumped onto the radiators when the lid closed. Subsequently, when the lid opened, the rover overheated and failed.

The scientific payload on the rover included three television cameras for navigation, four panoramic cameras, a cone penetrometer to test the lunar regolith, a solar X-ray experiment, a magnetometer, radiometer, and laser ranging retroreflector.

Luna 21 lander as seen from the Lunokhod 2 rover. This view as taken from south of the lander looking to the northwest. The tracks around the east side of the lander are quite apparent, note the small berms of regolith that were pushed up as the rover turned. Lunation 1, Session 4, Panorama 12 [RSA]..

Examine the regional geology that Lunokhod 2 was exploring, HERE (hint: sample 4493, line 15645; look to the south for some spectacular rover tracks).

First LROC Featured Image of the Lunokhod rovers.

And another LROC Featured Image of Lunokod 2