Lunar roving vehicle
The Lunar Roving Vehicle ( LRV ) is an electric vehicle type with high off-road capability , of which three copies in the years 1971 and 1972 as part of the US manned lunar missions of NASA as a rover on the moon drove. One such four-wheeled , two-seater automobile was carried during the last three of the so-called J-class Apollo missions (Apollo 15, 16 and 17) in order to increase the mobility of the astronauts and to transport payloads on the moon.
Development began in 1969 under the direction of Hungarian engineer Ferenc Pavlics at the General Motors Research Institute in Santa Barbara on behalf of Boeing Aerospace Corporation and lasted only 17 months. It was thanks to the wheels designed by Pavlics that the LRV - all three of which were left on the moon - was able to move easily under the adverse conditions. Another key developer was Georg von Tiesenhausen .
construction
The LRV is 3.1 m long and has a wheelbase of 2.3 m. It consists mainly of aluminum and has a mass of 210 kg. A maximum of 490 kg could be loaded onto the moon , of which 353 kg were accounted for by the astronauts and their life support systems, 45.4 kg for communication equipment, 54.5 kg for scientific payloads and 27.2 kg for rock samples . When fully loaded, the ground clearance was 36 cm. The chassis was designed to be foldable so that it could be transported with a pack size of 0.90 m × 1.50 m × 1.70 m on the outside of the Quad 1 of the descent stage of the lunar module ( LM for Lunar Module ). Quadrant 1 was located between the front and left landing leg of the descent stage (in the ferry's reference system between the + X and −Y legs). The construction took about 20 minutes and was controlled by the astronauts using cables, the actual unfolding was done by spring force.
The LRV was driven by a 180 W electric motor per wheel, which was connected to it via a harmonic drive gear with a reduction of 80: 1 . The steering was controlled by a 72 W electric motor per axle; the driver controlled the LRV using a joystick , which was positioned in the middle and could therefore be reached from both seats. For the power supply of two were Varta developed, non-rechargeable 36- volt - silver oxide-zinc batteries with a capacity of charge of 121 Ah; this allowed a top speed of 13 km / h and a maximum distance of 92 km. A gyroscope and an odometer were used to navigate . The computer calculated the current position relative to the landing module from their data. The communication equipment and two cameras, including a remote-controlled television camera, were attached to the front of the LRV, while the devices for exploring the moon were placed in a small rack at the rear. The umbrella-shaped directional antenna for TV image transmission in the S-band had to be manually aligned with the earth by the astronauts using an optical sighting device, so that there was only one data and radio connection during the journey.
The LRV had three steering modes : front, rear and synchronized steering.
Calls
It was already clear in advance that each of the planned missions would have to bring its own vehicle, as the distance between the landing sites was much greater than the range of the rover.
Operational principles
The excursions with the Lunar Roving Vehicle were subject to various restrictions. The astronauts always had to stay within the so-called walk back limit . H. they had to be able to walk to the lunar module at all times in the event of a rover failure before their life support systems ran out of oxygen . The possible failure of a life support system was also taken into account. In this case, the astronauts would have connected the cooling water circuits in their spacesuits with hoses. The astronaut with the failed system could have used his emergency oxygen system and, if necessary, that of his colleague and thus had oxygen available for about two hours. This would have been sufficient for the return journey and the re-entry into the lunar module.
In the run-up to the missions, it was also discussed whether the simultaneous failure of the rover and a life support system should be taken into account. However, this would have meant that the radius of action would have been so far restricted that the planners accepted the risk in view of the extremely low probability of such an event occurring.
Apollo 15
- Distance covered: 27.9 km
- Greatest distance from the LM: 5 km
Drivers: David Scott and James Irwin
After the assembly of the LRV took longer than planned and the control of the front axle did not work, the new vehicle was extensively tested during the first drive to the Hadley Rille . The navigation system in particular turned out to be very precise. During two further EVAs , one visited the Mons Hadley and one more time the Hadley Rille and collected a total of 76.8 kg of rock samples.
Apollo 16
- Distance covered: 26.7 km
- Greatest distance from the LM: 4.5 km
Drivers: John Young and Charles Duke
During three EVAs, Stone Mountain and the North Ray Crater were explored in addition to small craters . On the return flight, an attempt was made for the first time to record the starting ascent of the lunar module with the camera attached to the LRV. The rear axle control of the LRV failed on this mission. The front axle control worked this time.
Apollo 17
- Distance covered: 35.9 km
- Greatest distance from the LM: 7.6 km
Drivers: Eugene Cernan and Harrison Schmitt .
The north and south massifs near the Littrow crater were visited . On the second day, a torn fender had to be repaired in a makeshift manner. There were only resources available on board the lunar module, such as adhesive strips, folded lunar maps and clips. To date, it is the only repair of a vehicle that has been carried out outside of the earth. The Apollo 17 LRV is also responsible for the legendary take-off from the moon. The previous mission had already tested whether it was possible to record the return start with the television camera mounted on the LRV. In Apollo 17, mission control operator Ed Fendell steered the camera from Earth and, despite the delay in control commands of around 2.5 s (signal transit time) caused by the distance of the moon from Earth, kept the starting spaceship in the picture, which he did later was awarded the Golden Camera by the German television magazine HÖRZU .
LRV from Apollo 17
Instruments of the LRV
The repaired fender of the Apollo 17 LRV
See also
literature
- Anthony H. Young: Lunar and Planetary Rovers. The Wheels of Apollo and the Quest for Mars. Springer, Berlin 2006, ISBN 0-387-30774-5 (English).
- Kenneth S. Thomas, Harold J. McMann: The Lunar Roving Vehicle (1963-72). In: Kenneth S. Thomas, Harold J. McMann: US spacesuits. Springer, Berlin 2006, ISBN 0-387-27919-9 , pp. 99-101, 114-115, 143 (English; online at Google Books ).
- Scott P. Sullivan: Virtual LM Apogee Books Space Series, Ontario, Canada 2004, ISBN 1-894595-14-0 .
Web links
- NASA: The Apollo Lunar Roving Vehicle (English)
- NASA: A Brief History Of The Lunar Roving Vehicle (English; PDF; 4.0 MB)
- NASA: The complete LRV User Guide (English)
- Apollo LRV in the Encyclopedia Astronautica (English)
Videos
- Restart of Apollo17, recorded with the LRV camera (MPG, 36 s, 4.8 MB)
- Charlie Duke during the Apollo 16 mission ( WMV ; 1.2 MB)
Individual evidence
- ↑ Andrew Chaikin: A Man on the Moon , Penguin Books, 2009, ISBN 978-0-141-04183-4 , pp. 426f.