June 5, 2020

Astro-Challenge: The Stars of Apollo 1.

Apollo 1 & the mission patch that never flew. (Credit: NASA).

What’s in a name? When it comes to stars in astronomy, a curious and often confusing system has arisen over the years; many stars are known by multiple designations from numerous surveys and catalogs done over the centuries, while many of the brighter stars have familiar designations handed down from Arab astronomers that remain fixed in our cultural lexicon. Say the name “Alpha Virginis” and you many get quizzical stares at the next star party, but everyone knows good ‘ole Spica as the brightest star in the constellation Virgo, even if few of us recall its obscure translation as the “ear of wheat”. Interestingly, even murkier stellar names seem to be making a comeback as various GOTO telescopes know exhort us to slew to “Cursa” or center “Thuban”…

This week, I’d like to draw your attention to three stellar names honoring a crew of brave pioneers that have made their way into the modern lexicon and even publication on some star maps. 45 years ago this week on January 27th, 1967, astronauts Roger Chaffee, Edward White, and Virgil “Gus” Grissom perished in a fire that engulfed the cabin of their Apollo 1 spacecraft during a training simulation. The tragedy was the worst that NASA had experienced up until that time. In fact, the argument has been made that the resolve and safety overhaul that resulted from the fire was what allowed NASA to step back, reassess, and make that ultimate drive towards the Moon. The final week of January into early February has also marks two other tragedies in the history of NASA, with the loss of Space Shuttle Challenger and her crew during launch on January 28th, 1986 and the destruction of Columbia and her gallant crew upon re-entry on February 1st, 2003. Space travel is a hazardous business, and the very fact that we as a nation and a species were able to pick up and press on marks the resolve embodied by these brave men and women.

Over the years, these astronauts have been memorialized by the naming of schools, landmarks, and more. In the case of the Apollo 1 astronauts, craters on the Moon and hills on Mars are named in their honor, as well as a plaque entitled the “Fallen Astronaut” containing their names along with those of Russian cosmonauts that perished in Soyuz 1, 11, and training accidents that was placed at Hadley Rille by Apollo 15 astronauts. But another quiet tribute rests in the springtime sky, one with a fascinating tale…

The Fallen Astronaut Memorial on the Moon (Credit: NASA/Apollo 15).

Astronauts used stellar targets to find their way during their missions to the Moon, much like ancient seafaring mariners. This enabled them to get an accurate fix on their position in time and space. This method also gave astronauts the autonomy to navigate without the help of ground control and  would have been crucial in an emergency situation if communications had been damaged. Much of this celestial training was conducted at the Morehead Planetarium in Chapel Hill, North Carolina in 1966. The story goes that Command Pilot Gus Grissom conspired to have the crew of Apollo 1′s names inserted for 3 of the more obscure 36 target stars in the flight navigation manual. A November 1966 checklist later surfaced depicting the ‘revisions’ and backing up the story!

A common mis-conception is that these three stars were named in honor of the Apollo astronauts, but in fact, they themselves placed their reversed monikers among the stars, which then came into common use after the Apollo 1 fire. Astronauts can even be heard on later mission tapes referring to the Apollo 1 “stars” by their names, and they have also found their way into various star charts. The good news is that late northern hemisphere winter into early spring is a fine time to find these three modern wonders of astronomical lore; all three shine at easy naked eye visiblibility threshold in the evening skies;

Navi, a finder chart. (Graphics created by the Author using Starry Night).

Right Ascension: 00 Hours 56’ 43”

Declination: +60° 43’ 00”

The northernmost Apollo star is “Navi,” backwards for “Ivan” as in Virgil “Ivan” Grissom. Located in the central “pivot” of the “W” asterism in the constellation Cassiopeia, this star is also referred to as Gamma Cassiopeia or “Tish” in Chinese, meaning “The Whip”. Navi is an eruptive variable star with a close spectroscopic white dwarf or neutron star companion. Earlier in the 20th century Navi attained a peak brightness of magnitude +1.6 in 1936, outshining the other stars of Cassiopeia. Navi rides high in February skies immediately after sunset.

Dnoces rising!

Right Ascension: 08 Hours 59’ 12”

Declination: +48° 02’ 30”

Dnoces” as in “Second” backwards for Edward White “The Second,” is located in the constellation Ursa Major and is also referred to as Iota Ursa Majoris or Talitha, meaning “The third leap” in Arabic. Dnoces is an interesting close multiple star system first noticed by John Herschel in 1820. The  magnitude +3.12 A component has a 9th magnitude B component that was at 10” arc seconds of separation on discovery that closed down to 4.4” and closing as of 1969. The B component in turn has a faint 10 magnitude companion on a 39.7 year orbit that will reach a maximum separation from the primary of 0.9” (tiny but perhaps just spilt-able with a large scope under excellent seeing!) in 2020. The entire system is about 48 light years distant. Dnoces rises around 10 PM for middle northern latitudes in February and earlier during the following months.

Suhail… or do you say Regor?

Right Ascension: 08 Hours 09’ 32”

Declination: -47° 20’ 12”

Regor” The southernmost of the three Apollo 1 stars, is also known as Gamma Velorum in the constellation Vela. This star also has the obscure name of Suhail and is one of the brighter stars in the southern sky shining at +1.7th magnitude. Regor is a Wolf-Rayet variable star and one of the most massive known at 10 times the mass of our own Sun. The system is also a complex one comprising no less than 6 stars, tying Castor for the title of most stars in one system. Gamma Velorum is a binocular double, with a blue-white +4.2 magnitude sub-giant companion about 41” arc seconds distant. A telescope will tease out further companions C (+8 magnitude, sep 62”) and D and E (magnitudes +9 & +13 respectively) 2” apart and 94” from the primary. The entire complex system is about 800 light years distant along the galactic plane.  From our 28° degree north latitude vantage point here at Astroguyz HQ in Hudson, Florida, Regor has a maximum elevation of about 16° degrees on the meridian at midnite local on February 1st, then progressively earlier in the evening as spring arrives.

Apollo 1 astronauts during a test checkout of the spacecraft. (Credit: NASA).

What I really love about the Apollo 1 stars is the wry thought put into naming them that the astronauts obviously gave; “Regor, Dnoces, and Navi” all sound suitably cryptic and simply sound “stellar”… one could image a pedantic astronomy professor utilizing them, or a sci-fi flick entitled “Invaders from Regor!!!” As we mark the anniversary of the fire that marred the Apollo program and shaped NASA, make a point to get out and spot these stars that pay tribute to these fine brave men and the legacy that they gave us!