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Author
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Topic: Compass use during Apollo surface ops
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Max Q
Member Posts: 399
From: Whyalla South Australia
Registered: Mar 2007
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posted 08-24-2007 10:24 PM
   
I am reading "A Man on the Moon" and the section about Apollo 15 where Dave Scott removed the top hatch of Falcon and stood on the ascent stage cover and had a look around. Now the book mentions several features and their directions given as compass like from the lunar module: Immediately, he spotted familiar features. To the northeast, a slender crescent of sunlight delineated the ridge crest of Mount Hadley, almost 3 miles high, the bulk of the great mountain still cloaked in shadow. Due east, beneath the sun's obliterating glare stood the hills he and Irwin had christened Swann Ridge. M understanding is that compasses don't function properly on the moon given that the moon has a very weak and patchy magnetic field. Were these directions given as artistic license by the author, or was a direction designated north on Falcon for ease of explanation? |
Jay Chladek
Member Posts: 2272
From: Bellevue, NE, USA
Registered: Aug 2007
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posted 08-24-2007 11:56 PM
I would say that given the photos of the region prior to the flight and the orientation of Falcon after touchdown that Dave would have had a very good idea what direction "North" was on the moon since they were in a spot between a canyon area and a set of mountains. A compass might not work, but the lunar module used other navigation equipment which didn't need it. And the astronauts needed to have a good idea of where they were so that they wouldn't go off in the wrong direction on the first day of EVA activities. |
Obviousman
Member Posts: 438
From: NSW, Australia
Registered: May 2005
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posted 08-25-2007 05:58 AM
A compass wouldn't work. The directions quoted were based on known directions upon landing. They always faced east on approach, with the sun behind them, so the LM shadow would help with movement and depth perception. |
Max Q
Member Posts: 399
From: Whyalla South Australia
Registered: Mar 2007
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posted 08-25-2007 06:24 AM
But east would still be a relative Earth term I guess. |
Blackarrow
Member Posts: 3393
From: Belfast, United Kingdom
Registered: Feb 2002
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posted 08-25-2007 01:23 PM
Actually, they always faced west on the landing approach. |
Michael Davis
Member Posts: 545
From: Houston, Texas
Registered: Aug 2002
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posted 08-25-2007 04:37 PM
In the lunar rover, I recall that there was a compass of sorts. It was not magnetic of course, but rather used the know sun angle to give an indication of direction. I don't believe that this system was used for the initial EVA to survey the landscape. Since the LM always faced west shortly after lunar sunrise, and the crews had trained for months on the details of the landing site, and they typically landed within a few hundred meters of their intended target, determining directions would have been easy. |
Obviousman
Member Posts: 438
From: NSW, Australia
Registered: May 2005
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posted 08-27-2007 04:29 AM
Ooops - that why I should check my facts. I thought that north was to the left of the lunar module ladder.Yes, the terms east, west, etc., are or earthly origin. In navigation terms, east is defined as the direction in which the Earth rotates. We tidy it up for geographic north, etc. |
BMckay
Member Posts: 3719
From: MA, USA
Registered: Sep 2002
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posted 01-11-2022 01:07 PM
On Apollo 17, did they not use a sun compass?  
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