3 comments

• Willi

  May 30, 2018 at 2:25 pm

  A more complete version of the image that accompanies the second segment can be found at:
  https://audioboom.com/posts/6876436-china-stakes-out-a-lunar-land-grab-bob-zimmerman-behindtheblack-com
  That image includes Astronaut Schmitt giving a better idea of the size of the rock.
• J Fincannon

  May 31, 2018 at 11:19 am

  So-called “Peaks of Eternal Light (PEL)” are what might be categorized as “Fake News (FNs)”. This term, much like the term “brown dwarf” (which is really magenta) or the concept that “the Earth is the Center of the Universe”, was speculation by ancient astronomers and repeated by others (up to today) with no basis in fact.

  Who were the first astronomers to speculate on them? Beer and Madler in 1837. Their book is here if you like German…
  https://archive.org/details/bub_gb_hO_mAAAAMAAJ

  It is entitled “Der Mond nach seinen kosmischen und individuellen Verhältissen oder allgemeine vergleichende Selenographie.” The relevant section on page 16 says, using Google Translate, “Areas where the Sun can describe a full circle without going up or down start there only 1.5 degrees from the poles, and the long night of the poles can be avoided on a 600 meter high mountain. Now that both the North and still the South Pole of the moon have much higher mountains in large numbers, whose illuminated peaks reflect the sunlight in the most different directions, the long night physically falls away completely for the Moon; yes, many of these mountain peaks (with the exception of the darkness caused by the Earth) have eternal sunshine).”

  An examination of the whole book shows that they do not make the statement based on observations from their telescopes. Essentially, they are “doing math” to speculate that this is so. Later, a French Astronomer Flammarion in 1879 published a popular book which repeated the Beer and Madler work, but again not based on observations.

  After that, up to the present day, it just became a repeated truism. Just speculation. Click bait. Fake News.

  If they had the time and energy and money to look for these so-called “Peaks of Eternal Light” through the year with their telescopes and validate they exist, would Beer or Madler or Flammarion have been able to? Just looking at the South Pole, the tallest peak is at 84.673 deg South latitude and 39.397 deg East longitude and 7.0 kilometers high. Analysis (using analytical tools and topographic models) show it is visible year round from Earth. So, they _could_ have observed the peak.

  Even so, the Sun is not always on the same side as the Earth. When the Sun is on the opposite side of Earth, the Sun may be illuminating the peak, but their telescopes could not see the illumination. So, they could _not_ observe a “Peak of Eternal Light”.

  In any event, recent illumination analyses shows that even this tall peak does not get 100% illumination.

  All recent spacecraft data show that there are no locations with 100% illumination throughout the year. Some spots have better illumination than others. A good paper is
  http://www-geodyn.mit.edu/mazarico_lunarillumination_icarus11.pdf.

  This paper shows that the best you can do is an average of 90% illumination for an entire year. The key point is that Summer lunations you can have 100% illumination, but Winter lunations have a lot more shadows, maybe as much as 30-50% of the lunation with shadow at the best spots! So much for eternal.

  Another thing suggested by some people is to have a tower or mast to “get the solar array into permanent sunlight”. At the best illuminated sites, you need a tower 2.1 km tall to clear all blockage of the Sun by terrain shadowing for the North pole and 3.5 km for the South pole. Good luck with that!

  In any event, as Beer and Madler themselves notes, there are eclipses of the Sun by the Earth that still must be contended with which no high tower can help avoid.

  One more thing to note, the proximity of highly illuminated sites to permanently shadowed regions is not necessarily the best deal. The highly illuminated sites must be high up, the permanently shadowed spots must be low down. So, you have quite drive between the two to contend with.

  So, the fears of people stealing the best spots on the Moon can be dismissed.
• Richard M

  May 31, 2018 at 11:28 am

  Actually, the commander of Apollo 12 was Pete Conrad, not Alan Shepard (who was commander of Apollo 14). Apollo 12’s crew was Pete Conrad (Commander), Dick Gordon (CMP) and Alan Bean (LMP).

  Great discussion on SLS, as always.