Sand and Stars

Apollo Navigation Stars

“Menkent. Menkent. God, what a star.” DSS2 image

20 July 2017

I can’t ever glance up at Menkent (Theta Centauri) without thinking what Michael Collins said when using the sextant onboard Apollo 11 and looking at the star, “Menkent. Menkent. God, what a star.”

Here is the NASA transcript:

Collins: “Okay, again, looking through the telescope. Okay, proceed to Menkent. There she goes. Menkent. Menkent. God, what a star.”

Buzz Aldrin cuts in: “Nobody in their right —”

Collins, speaking at the same time: “Menkent’s good.”

Aldrin again: “Nobody in their right mind would pick that one.” A moment later, “Hey, I sure wish you’d get out that — that star chart.”

Armstrong says: “Can’t see a thing, huh?”

Collins can see, but not too well. They plot Menkent, Nunki (Sigma Sagittarii) – at least Collins is pretty sure it’s Nunki (!) – and Atria (Alpha Trianguli Australis) for good measure.

Collins ends by saying: “God, I’ll tell you, the visibility through that telescope is a big disappointment.”

Astronomy is the oldest of the sciences, and quite possibly the oldest use of astronomy is navigating by the stars. The ancient Minoans, who lived on the Mediterranean island of Crete from 3000 to 1100 BC left records of using the stars to navigate and they surely weren’t the first to employ celestial navigation. How appropriate that the astronauts and engineers of the Apollo programme used celestial navigation to chart their way to the moon and back.  

The Apollo Guidance Computer (of which two were flown on each mission, one in the Command Module and one in the LEM) each had a list of 37 stars and various other bodies coded into the computer’s rope memory. The reference points were evenly distributed across the sky so as to maximise their utility during missions.

The three Apollo navigation stars, Navi, Dnoces, and Regor, were named in the spring of 1967 during an astronomy training session among the original Apollo 1 backup crew and Dr. Clarence Cleminshaw, Director of the Griffith Planetarium. This was in admiration, respect, and memory of three wonderful teammates who contributed all they had to the human exploration of the Moon.  The new names were simply parts of an Apollo 1 astronaut’s name spelled backwards: Gamma Cassiopeia became Navi for Virgil ‘Ivan’ Grissom; Suhail (Gamma Velorum) became Regor for ‘Roger’ Chaffee; and Talitha (Iota Ursa Majoris) became Dnoces for Ed White II (‘Second’)

The Apollo navigation stars:

01 Alpheratz – Alpha Andromedae
02 Diphda – Beta Ceti
03 Navi – Gamma Cassiopeiae
04 Achernar – Alpha Eridani
05 Polaris – Alpha Ursae Minoris
06 Acamar – Theta Eridani
07 Menkar – Alpha Ceti

10 Mirfak – Alpha Pegasi
11 – Aldebaran – Alpha Tauri
12 Rigel – Beta Orionis
13 Capella – Alpha Aurigae
14 Canopus – Alpha Carinae
15 Sirius – Alpha Canis Majoris
16 Procyon – Alpha Canis Minoris
17 Regor – Sigma Puppis
20 Dnoces – Iota Ursae Majoris
21 Alphard – Alpha Hydrae
22 Regulus – Alpha Leonis
23 Denebola – Beta Leonis
24 Gienah – Gamma Corvus
25 Acrux – Alpha Crucis
26 Spica – Alpha Virginis
27 Alkaid – Eta Ursae Majoris
30 Menkent – Theta Centauri
31 Arcturus – Alpha Boötes
32 Alphecca – Alpha Coronae Borealis
33 Antares – Alpha Scorpii
34 Atria – Alpha Trianguli Australis
35 Rasalhague – Alpha Ophiuchi
36 Vega – Alpha Lyrae
37 Nunki – Sigma Sagittari
40 Altair – Alpha Aquilae
41 Dabih – Beta Capricorni
42 Peacock – Alpha Pavonis
43 Deneb – Alpha Cygni
44 Enif – Epsilon Pegasi
45 Fomalhaut – Alpha Piscis Austrini
46 Sun
47 Earth
50 Moon

Copyright © Susan Young 2017