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Gliding on starlight: Celestial Navigation for Martian Explorers

On January 1, 2016, the Southern Fried Science central server began uploading blog posts apparently circa 2041. Due to a related corruption of the contemporary database, we are, at this time, unable to remove these Field Notes from the Future or prevent the uploading of additional posts. Please enjoy this glimpse into the ocean future while we attempt to rectify the situation.


Thousands of years ago, merchants on the Arabian Peninsula would cross vast, featureless desert as they traveled from settlement to settlement, selling their goods. They had no roads, no maps, no GPS, yet still they managed to find their mark. They accomplished this tremendous feat of navigation with the help of the stars and a tiny instrument called a kamal.

The kamal was a piece of wood, bone, or ivory, with a piece of string threaded through it at a precise point and measured out to a precise distance. By sighting the kamal against the horizon and the north star, these merchants could maintain a constant latitude as they marchd across the desert, and find their way home. For millennia, this basic principal–that the celestial pole could, with the right instrument, reveal latitude–was the driving force for exploration, trade, and travel. Polynesian sailors used latitude hooks to mark their journey. Portuguese explorers used quadrants to find their way across the Atlantic and around Africa. The age of discovery was already entering its twilight by the time we had figured out longitude–the great scientific puzzle of an generation. For most, simply knowing latitude and cardinal direction was enough to circle the world and return home.

The Martian Circumtropical Expedition kicks off net month, with teams from 17 nations racing to see who will be first to circumnavigate the red planet. Their sandgliders will be outfitted with the most sophisticated expedition gear that their sponsors can afford, costing, at the low end, hundreds of millions of dollars. The budget for China’s team surpasses the GDP of most countries. These will be the best outfitted and most connected explorers in history.

What happens if things go wrong?

Right now, the MCE relies on 5 geospatial satellites to feed GPS data to the teams. Three of those satellites have been experiencing significant irregularities over the last month and one is in danger of de-orbiting. If the GPS network goes down, will these teams still be able to finish the race? Or will they just roam in hopeless circles until someone finds them.

In order to find latitude, you need to know three things. You need a celestial pole (the point in the sky above the axis upon which your planet rotates), you need a way to measure length (the length of your arm, for example), and math.  Latitude equals the angle between Polaris, an observer, and the horizon. If you hold a rule out at arms length, line it up against the horizon, and measure the height to the celestial pole, with a little bit of trigonometry, you can find your latitude to withing about 1 degree (or 59 kilometers). That’s not bad, and certainly good enough to get close enough to a known base station to make radio contact.

Of course, the old navigators didn’t have the math. They just knew that if you set a kamal at a particular spot, it would lead you back to that spot. Ever with nothing more than a straight piece of metal, a lost Martian explorer could, at the very least, hold a line. And that’s enough to keep you from going in circles (except, of course, for the one big circle).

The greatest challenge for Martian navigators will be finding the celestial poles. In the southern hemisphere, Kappa velorum hangs just 3 degrees of from the celestial south pole. This is good enough for emergency navigation. A careful navigator would make sure to sight at the same time every night and attempt to compensate for the 3 degree list. They won’t be using their measurement to launch rockets, but for a few days of sandgliding, it should be serviceable.

There is a north star for the northern hemisphere. HD 201834 is even more precise than our own Polaris. But it is faint, so faint that the first colonists named it Pale Lady. On a good day, you would be just barely able to see it. Fortunately, you can approximate the position on the north celestial pole base on the position of Alderamin and Zeta Cephei on one side, and Deneb on the other. Much like the Southern Cross in our own southern hemisphere, these three stars rotate around the Martian celestial north pole, making it easy to locate.

Finding latitude is a huge deal if your lost, either at sea or drifting across the sands of Mars. By nailing down latitude in the event of an equipment failure, these explorers will be able to guide themselves home, or, for the particularly courageous, finish the race, and be forever known as the toughest Mariners on the planet.


On January 1, 2016, the Southern Fried Science central server began uploading blog posts apparently circa 2041. Due to a related corruption of the contemporary database, we are, at this time, unable to remove these Field Notes from the Future or prevent the uploading of additional posts. Please enjoy this glimpse into the ocean future while we attempt to rectify the situation.


Deep-sea biologist, population/conservation geneticist, backyard farm advocate. The deep sea is Earth's last great wilderness.


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