NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Dolkas
Date: 2019 May 1, 04:32 +0000
Frank-
I think all Apollo crews used the sextant system regularly to correct for gyroscopic drift in the same way most current spacecraft use automated star trackers.
That is of course, not really celestial navigation per se. I think you are correct that Lovell was the only astronaut who actually used the system in its full capability.
The story I remember is that he actually ended up doing more than he wanted: at the end of his practice session he inadvertently erased the ship’s navigation
settings by pushing the wrong buttons on the keyboard. (Considering how primitive the keyboard was, it’s a wonder it only happened this once.) So he had to manually reset everything, which I suppose proved that the system could in fact be used to navigate
autonomously from earth based help.
Paul Dolkas
From: NavList@fer3.com [mailto:NavList@fer3.com]
On Behalf Of Frank Reed
Sent: Tuesday, April 30, 2019 11:02 AM
To: Paul Dolkas
Subject: [NavList] Re: Earthrise.
I didn't cheat! When you posted this, I knew the names of the more famous of the two immediately. The name of the third astronaut popped into my head late last night. The Apollo 8 earthrise photo was taken by Bill Anders on
Christmas Eve, 1968. There are details and useful links here: https://en.wikipedia.org/wiki/Earthrise. The astronauts who were alone in lunar orbit, as you note so well, Francis, completely isolated from
the rest of the billions of the human population, were Frank Borman, Jim Lovell, and Bill Anders.
Borman, oddly enough, I remember best from television commercials in the late 1970s. After he left NASA, he became CEO of Eastern Airlines (following in the steps of World War One ace Eddie Rickenbacher). His astronautical
expertise could not save Eastern from the period of airline deregulation, and that airline was dissolved five years after Borman left (here's an image from an
alternate timeline for Eastern). After NASA, Bill Anders was US ambassador to Norway for a few years. Neither Borman nor Anders flew in space again after Apollo 8.
Jim Lovell, of course, was the only real deep-space navigator in history. He got great personal satisfaction from using the sextant and analyzing his sights with the computer. After Apollo 8, the sextant sights were mostly
ignored apart from some initial practice on each flight. The sextant was, nevertheless, employed as an astrocompass on all the Apollo missions, and in that role sights were taken almost daily to ensure proper alignment of the inertial navigation system (INS).
Lovell, of course, had the privilege of flying to the Moon again on Apollo 13. Alas, the team at NASA studied tea leaves and astrology only and paid far too little attention to numerology when planning the mission, so unlucky 13 did not include a moon landing.
Of all the Apollo lunar mission crews, this one has a last unique distinction: all three of them are still alive. Lovell and Borman are both 91 years old. Anders is 85. More than half, 14 of the 24 astronauts who flew to the
Moon, have died. All three members of the crews of both Apollo 12 and Apollo 14 have already passed away.
There is one bit of celestial navigation data that we can apply to this photo. We can determine the angular diameter of the Earth as seen by the astronauts with relative ease. The SD of the Earth as seen from the Moon is essentially
identical to the Moon's HP as seen from Earth. At 16:00 UT when the photo was taken, the
Moon's HP was 58.0'. So the angular diameter of the Earth (twice HP) was 1°56' as seen by the astronauts. That's about the same as a US quarter (coin) held at arm's length.
Frank Reed
