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How did astronauts using rovers tell direction without compasses on the Moon? [duplicate]

How did astronauts navigate the Lunar Roving Vehicle (LRV) over the surface of the Moon?During its final descent, how will the InSight lander know cardinal directions in order to land with proper orientation?What is a gyrocompass and how might one be used by a planetary rover?Why do the Mars rovers move so cautiously?How did the Apollo astronauts train for the 1/6G lunar landing?How will the Falcon 9 carry the lunar xprize rovers to the moon?Why did NASA send two astronauts to the moon instead of one?The types of motors used on the Martian rovers?How did astronauts navigate the Lunar Roving Vehicle (LRV) over the surface of the Moon?When Chang'e-3 landed on the moon, did LADEE notice?How might the Lunar X Prize contestant spacecraft have navigated their descent from orbit, to landing?What was learned from study of Surveyor-3's components, retrieved and returned to Earth by Apollo-12?How can electronics on board JWST survive the low operating temperature while it's difficult to survive lunar nights?

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23

6

$begingroup$

This question already has an answer here:

• 
  How did astronauts navigate the Lunar Roving Vehicle (LRV) over the surface of the Moon?
  
  3 answers
  
  

I read that the astronauts who used Lunar rovers used heading indicators, which typically use compasses, for direction. How, on the Moon, did their equipment tell the direction of travel, presuming a compass made for earth would not work on the Moon?

rovers lunar-landing navigation

share|improve this question

edited Jul 30 at 15:09

peterh

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asked Jul 30 at 14:42

john doejohn doe

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marked as duplicate by Ingolifs, Mark Omo, DrSheldon, Manu H, peterh Aug 2 at 6:37

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  See the answer to this question
  $endgroup$
  – Uwe
  Jul 30 at 14:51
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  See What is a gyrocompass and how might one be used by a planetary rover? as well as During its final descent, how will the InSight lander know cardinal directions in order to land with proper orientation? and also Uwe's link How did astronauts navigate the Lunar Roving Vehicle (LRV) over the surface of the Moon?
  $endgroup$
  – uhoh
  Jul 30 at 21:44
  

  
  
  
  


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  You might explain why you think they'd need a compass for navigation. They have the sun and the Earth as references, perhaps also the stars - though I don't know how visible the were through the faceplates of their suits. They also have the terrain, which I would assume they'd have studied extensively in preparation for the mission.
  $endgroup$
  – jamesqf
  Jul 31 at 5:04
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Heading indicators (in aircraft) typically use gyroscopes, not compasses. At least in light aircraft, we have to reset them from our magnetic compass each time we start the plane.
  $endgroup$
  – reirab
  Jul 31 at 21:18
  

  
  
  
  

add a comment | 

23

6

$begingroup$

This question already has an answer here:

• 
  How did astronauts navigate the Lunar Roving Vehicle (LRV) over the surface of the Moon?
  
  3 answers
  
  

I read that the astronauts who used Lunar rovers used heading indicators, which typically use compasses, for direction. How, on the Moon, did their equipment tell the direction of travel, presuming a compass made for earth would not work on the Moon?

rovers lunar-landing navigation

share|improve this question

edited Jul 30 at 15:09

peterh

2,12133 gold badges1717 silver badges3535 bronze badges

asked Jul 30 at 14:42

john doejohn doe

21811 silver badge66 bronze badges

$endgroup$

marked as duplicate by Ingolifs, Mark Omo, DrSheldon, Manu H, peterh Aug 2 at 6:37

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  See the answer to this question
  $endgroup$
  – Uwe
  Jul 30 at 14:51
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  See What is a gyrocompass and how might one be used by a planetary rover? as well as During its final descent, how will the InSight lander know cardinal directions in order to land with proper orientation? and also Uwe's link How did astronauts navigate the Lunar Roving Vehicle (LRV) over the surface of the Moon?
  $endgroup$
  – uhoh
  Jul 30 at 21:44
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  You might explain why you think they'd need a compass for navigation. They have the sun and the Earth as references, perhaps also the stars - though I don't know how visible the were through the faceplates of their suits. They also have the terrain, which I would assume they'd have studied extensively in preparation for the mission.
  $endgroup$
  – jamesqf
  Jul 31 at 5:04
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Heading indicators (in aircraft) typically use gyroscopes, not compasses. At least in light aircraft, we have to reset them from our magnetic compass each time we start the plane.
  $endgroup$
  – reirab
  Jul 31 at 21:18
  

  
  
  
  

add a comment | 

$begingroup$

This question already has an answer here:

• 
  How did astronauts navigate the Lunar Roving Vehicle (LRV) over the surface of the Moon?
  
  3 answers
  
  

I read that the astronauts who used Lunar rovers used heading indicators, which typically use compasses, for direction. How, on the Moon, did their equipment tell the direction of travel, presuming a compass made for earth would not work on the Moon?

rovers lunar-landing navigation

share|improve this question

edited Jul 30 at 15:09

peterh

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asked Jul 30 at 14:42

john doejohn doe

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$endgroup$

share|improve this question

edited Jul 30 at 15:09

peterh

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asked Jul 30 at 14:42

john doejohn doe

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share|improve this question

edited Jul 30 at 15:09

peterh

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asked Jul 30 at 14:42

john doejohn doe

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edited Jul 30 at 15:09

peterh

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edited Jul 30 at 15:09

peterh

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asked Jul 30 at 14:42

john doejohn doe

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asked Jul 30 at 14:42

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2 Answers
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33

$begingroup$

The Lunar Roving Vehicle did have a (form of) compass. It was gyroscopic rather than magnetic, thus it needed calibration when first powered up using the sun angle as a reference. It's in the upper left of the console here:

According to Wikipedia:

Navigation was based on continuously recording direction and distance through use of a directional gyro and odometer and feeding this data to a computer that would keep track of the overall direction and distance back to the LM. There was also a Sun-shadow device that could give a manual heading based on the direction of the Sun, using the fact that the Sun moved very slowly in the sky.

I presume the "bearing" display in the middle of the compass is the direction to travel back to the LM. Sun-shadow navigation was helped by the fact that the sun was low in the East during all the lunar EVAs.

share|improve this answer

edited Jul 31 at 21:29

answered Jul 30 at 14:47

Russell BorogoveRussell Borogove

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$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  In aviation it says that pilots use the Directional Gyroscope in-flight, but occasionally re-calibrate it (when flying without acceleration at a flat altitude or before/after take-off) to what the compass says (as the compass is prone to errors if not flat/constant velocity). How did they initially calibrate it in the absence of a compass? Just pointed the vehicle towards the LM and used the LM's location as polar North?
  $endgroup$
  – Magic Octopus Urn
  Jul 30 at 17:40
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  $begingroup$
  I'd guess either the sun-shadow indicator, or the inertial platform of the LM, would be the reference. Pointing at the LM would not be a good choice, because the direction toward the LM changes wildly as you move around near it. Any arbitrary direction you chose would work for navigation, but it would be annoying to correlate your arbitrary direction reference to e.g. lunar orbiter maps later.
  $endgroup$
  – Russell Borogove
  Jul 30 at 17:59
  

  
  
  
  


• 
  
  
  

  
  9
  

  
  
  
  
  
  

  
  $begingroup$
  Per the document linked in my answer"Gyro heading initialization was accomplished by means of an extremely simple sun shadow device and vehicle attitude indicators"
  $endgroup$
  – Organic Marble
  Jul 30 at 18:01
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  "The Lunar Roving Vehicle did have a compass." I think that's usually called a "Heading Indicator," not a compass. From the picture, it appears to be a standard aircraft Heading Indicator, which is gyroscopic in operation, not magnetic. When we fly an airplane (at least the light GA ones; I can't speak for larger ones with fancier avionics,) we have to reset the HI using the magnetic compass each time before flight. It's part of the Before Takeoff checklist.
  $endgroup$
  – reirab
  Jul 31 at 21:25
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I'll change the wording to "a form of compass", which Wikipedia backs up.
  $endgroup$
  – Russell Borogove
  Aug 1 at 23:18
  

  
  
  
  

add a comment | 

16

$begingroup$

The rovers used a gyroscope-based navigation system.

The Lunar Roving Vehicle (LRV) navigation system consists of a
directional gyro, a set of incremental odometers, and a hybrid
analog-digital signal processor plus appropriate controls and
readouts.

Info from Lunar Roving Vehicle Navigation System Performance Review, (NASA Tech Note D-7469)

share|improve this answer

edited Jul 30 at 19:28

DrSheldon

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answered Jul 30 at 14:50

Organic MarbleOrganic Marble

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$endgroup$

add a comment | 

33

$begingroup$

The Lunar Roving Vehicle did have a (form of) compass. It was gyroscopic rather than magnetic, thus it needed calibration when first powered up using the sun angle as a reference. It's in the upper left of the console here:

According to Wikipedia:

Navigation was based on continuously recording direction and distance through use of a directional gyro and odometer and feeding this data to a computer that would keep track of the overall direction and distance back to the LM. There was also a Sun-shadow device that could give a manual heading based on the direction of the Sun, using the fact that the Sun moved very slowly in the sky.

I presume the "bearing" display in the middle of the compass is the direction to travel back to the LM. Sun-shadow navigation was helped by the fact that the sun was low in the East during all the lunar EVAs.

share|improve this answer

edited Jul 31 at 21:29

answered Jul 30 at 14:47

Russell BorogoveRussell Borogove

101k44 gold badges358358 silver badges440440 bronze badges

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  In aviation it says that pilots use the Directional Gyroscope in-flight, but occasionally re-calibrate it (when flying without acceleration at a flat altitude or before/after take-off) to what the compass says (as the compass is prone to errors if not flat/constant velocity). How did they initially calibrate it in the absence of a compass? Just pointed the vehicle towards the LM and used the LM's location as polar North?
  $endgroup$
  – Magic Octopus Urn
  Jul 30 at 17:40
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  $begingroup$
  I'd guess either the sun-shadow indicator, or the inertial platform of the LM, would be the reference. Pointing at the LM would not be a good choice, because the direction toward the LM changes wildly as you move around near it. Any arbitrary direction you chose would work for navigation, but it would be annoying to correlate your arbitrary direction reference to e.g. lunar orbiter maps later.
  $endgroup$
  – Russell Borogove
  Jul 30 at 17:59
  

  
  
  
  


• 
  
  
  

  
  9
  

  
  
  
  
  
  

  
  $begingroup$
  Per the document linked in my answer"Gyro heading initialization was accomplished by means of an extremely simple sun shadow device and vehicle attitude indicators"
  $endgroup$
  – Organic Marble
  Jul 30 at 18:01
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  "The Lunar Roving Vehicle did have a compass." I think that's usually called a "Heading Indicator," not a compass. From the picture, it appears to be a standard aircraft Heading Indicator, which is gyroscopic in operation, not magnetic. When we fly an airplane (at least the light GA ones; I can't speak for larger ones with fancier avionics,) we have to reset the HI using the magnetic compass each time before flight. It's part of the Before Takeoff checklist.
  $endgroup$
  – reirab
  Jul 31 at 21:25
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I'll change the wording to "a form of compass", which Wikipedia backs up.
  $endgroup$
  – Russell Borogove
  Aug 1 at 23:18
  

  
  
  
  

add a comment | 

33

$begingroup$

The Lunar Roving Vehicle did have a (form of) compass. It was gyroscopic rather than magnetic, thus it needed calibration when first powered up using the sun angle as a reference. It's in the upper left of the console here:

According to Wikipedia:

Navigation was based on continuously recording direction and distance through use of a directional gyro and odometer and feeding this data to a computer that would keep track of the overall direction and distance back to the LM. There was also a Sun-shadow device that could give a manual heading based on the direction of the Sun, using the fact that the Sun moved very slowly in the sky.

I presume the "bearing" display in the middle of the compass is the direction to travel back to the LM. Sun-shadow navigation was helped by the fact that the sun was low in the East during all the lunar EVAs.

share|improve this answer

edited Jul 31 at 21:29

answered Jul 30 at 14:47

Russell BorogoveRussell Borogove

101k44 gold badges358358 silver badges440440 bronze badges

$endgroup$

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  In aviation it says that pilots use the Directional Gyroscope in-flight, but occasionally re-calibrate it (when flying without acceleration at a flat altitude or before/after take-off) to what the compass says (as the compass is prone to errors if not flat/constant velocity). How did they initially calibrate it in the absence of a compass? Just pointed the vehicle towards the LM and used the LM's location as polar North?
  $endgroup$
  – Magic Octopus Urn
  Jul 30 at 17:40
  
  

  
  
  
  


• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  $begingroup$
  I'd guess either the sun-shadow indicator, or the inertial platform of the LM, would be the reference. Pointing at the LM would not be a good choice, because the direction toward the LM changes wildly as you move around near it. Any arbitrary direction you chose would work for navigation, but it would be annoying to correlate your arbitrary direction reference to e.g. lunar orbiter maps later.
  $endgroup$
  – Russell Borogove
  Jul 30 at 17:59
  

  
  
  
  


• 
  
  
  

  
  9
  

  
  
  
  
  
  

  
  $begingroup$
  Per the document linked in my answer"Gyro heading initialization was accomplished by means of an extremely simple sun shadow device and vehicle attitude indicators"
  $endgroup$
  – Organic Marble
  Jul 30 at 18:01
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  "The Lunar Roving Vehicle did have a compass." I think that's usually called a "Heading Indicator," not a compass. From the picture, it appears to be a standard aircraft Heading Indicator, which is gyroscopic in operation, not magnetic. When we fly an airplane (at least the light GA ones; I can't speak for larger ones with fancier avionics,) we have to reset the HI using the magnetic compass each time before flight. It's part of the Before Takeoff checklist.
  $endgroup$
  – reirab
  Jul 31 at 21:25
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  I'll change the wording to "a form of compass", which Wikipedia backs up.
  $endgroup$
  – Russell Borogove
  Aug 1 at 23:18
  

  
  
  
  

add a comment | 

$begingroup$

The Lunar Roving Vehicle did have a (form of) compass. It was gyroscopic rather than magnetic, thus it needed calibration when first powered up using the sun angle as a reference. It's in the upper left of the console here:

According to Wikipedia:

Navigation was based on continuously recording direction and distance through use of a directional gyro and odometer and feeding this data to a computer that would keep track of the overall direction and distance back to the LM. There was also a Sun-shadow device that could give a manual heading based on the direction of the Sun, using the fact that the Sun moved very slowly in the sky.

I presume the "bearing" display in the middle of the compass is the direction to travel back to the LM. Sun-shadow navigation was helped by the fact that the sun was low in the East during all the lunar EVAs.

share|improve this answer

edited Jul 31 at 21:29

answered Jul 30 at 14:47

Russell BorogoveRussell Borogove

101k44 gold badges358358 silver badges440440 bronze badges

$endgroup$

share|improve this answer

edited Jul 31 at 21:29

answered Jul 30 at 14:47

Russell BorogoveRussell Borogove

101k44 gold badges358358 silver badges440440 bronze badges

answered Jul 30 at 14:47

Russell BorogoveRussell Borogove

101k44 gold badges358358 silver badges440440 bronze badges

answered Jul 30 at 14:47

Russell BorogoveRussell Borogove

101k44 gold badges358358 silver badges440440 bronze badges

16

$begingroup$

The rovers used a gyroscope-based navigation system.

The Lunar Roving Vehicle (LRV) navigation system consists of a
directional gyro, a set of incremental odometers, and a hybrid
analog-digital signal processor plus appropriate controls and
readouts.

Info from Lunar Roving Vehicle Navigation System Performance Review, (NASA Tech Note D-7469)

share|improve this answer

edited Jul 30 at 19:28

DrSheldon

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answered Jul 30 at 14:50

Organic MarbleOrganic Marble

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$endgroup$

add a comment | 

16

$begingroup$

The rovers used a gyroscope-based navigation system.

The Lunar Roving Vehicle (LRV) navigation system consists of a
directional gyro, a set of incremental odometers, and a hybrid
analog-digital signal processor plus appropriate controls and
readouts.

Info from Lunar Roving Vehicle Navigation System Performance Review, (NASA Tech Note D-7469)

share|improve this answer

edited Jul 30 at 19:28

DrSheldon

13.2k44 gold badges5151 silver badges116116 bronze badges

answered Jul 30 at 14:50

Organic MarbleOrganic Marble

73.6k44 gold badges214214 silver badges316316 bronze badges

$endgroup$

add a comment | 

$begingroup$

The rovers used a gyroscope-based navigation system.

The Lunar Roving Vehicle (LRV) navigation system consists of a
directional gyro, a set of incremental odometers, and a hybrid
analog-digital signal processor plus appropriate controls and
readouts.

Info from Lunar Roving Vehicle Navigation System Performance Review, (NASA Tech Note D-7469)

share|improve this answer

edited Jul 30 at 19:28

DrSheldon

13.2k44 gold badges5151 silver badges116116 bronze badges

answered Jul 30 at 14:50

Organic MarbleOrganic Marble

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$endgroup$

share|improve this answer

edited Jul 30 at 19:28

DrSheldon

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answered Jul 30 at 14:50

Organic MarbleOrganic Marble

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edited Jul 30 at 19:28

DrSheldon

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edited Jul 30 at 19:28

DrSheldon

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answered Jul 30 at 14:50

Organic MarbleOrganic Marble

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answered Jul 30 at 14:50

Organic MarbleOrganic Marble

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