Satnav for the Moon could benefit from Fibonacci’s expertise

Future satellite navigation systems intended for Earth's Moon may be aided by a model of it developed with methods that go back to mathematician Fibonacci, who lived 800 years ago. With increasing interest in missions to return people to the Moon and even establish some sort of permanent outpost on Earth’s satellite, it seems …

[Greybearded old scrote]

I think you'll find it's more complicated than that.

The moon doesn't have anything near a uniform density, the mares having measurably greater mass than the lighter coloured rocks. These mascons (mass concentrations) put the Eagle's landing spot well downrange of the planned location.

Now the later flights were programmed to take the variation into account, even on those tiny Apollo Guidance Computers, but it's still more than just the shape that matters.

[A Non e-mouse]

Re: I think you'll find it's more complicated than that.

Burried monoliths distort the gravity field too.

[Korev]

Re: I think you'll find it's more complicated than that.

Clangers too

[Francis Boyle]

Are you sure?

I thought the effect was purely magnetic.

[John Robson]

Re: I think you'll find it's more complicated than that.

If you're plotting a map then it's the shape that matters, but the inconsistent density is not helpful for calculation of orbital positions.

[Greybearded old scrote]

Re: I think you'll find it's more complicated than that.

If you're measuring your position based on the satellites, then you'll need to account for the varying orbital speeds.

[Paul Kinsler]

Re: you'll need to account for the varying orbital spee

Earth orbit GNSS satellites broadcast their orbital parameters [1] at regular intervals as a matter of course; so it is reasonable to assume lunar ones would do likewise; so doing most of the hard work for your navigation device. Although perhaps lunar ones might need more frequent nav broadcasts, the constellation might need more ongoing orbit-management, and perhaps there might be a different scheme for orbit description, ... but the navigation device would not have to guess or estimate orbit-like trajectories; just compute them from what is provided.

[1] GPS, Gallileo, and BeiDou broadcast orbital parameter as an axis length, angles, eccentricities, and all that sort of thing; but Glonass broadcast positions, velocities, and accelerations, which you then have to integrate. See e.g. https://gssc.esa.int/navipedia/GNSS_Book/ESA_GNSS-Book_TM-23_Vol_I.pdf

[Gene Cash]

Re: I think you'll find it's more complicated than that.

No, a large boulder field put Eagle well downrange of the planned location. Armstrong had to hand-fly it over that, and put them down with just a whiff of fuel left.

[Benegesserict Cumbersomberbatch]

Re: I think you'll find it's more complicated than that.

Armstrong knew Eagle was going to be long well before he could even see the boulders. The boulder field was west of West Crater (the boundary of their planned landing ellipse) and it was the last in a series of events that added up to put them west of their planned landing site, which included mascons and failing to fully depressurise the link between LM and CSM before separation.

They sorted it out for Apollo 12, though. They landed so close to Surveyor 3 that the blast from the DPS sandblasted the surface of the old lunar lander, inadvertently destroying some of the evidence they came to collect.

[Terry 6]

Re: I think you'll find it's more complicated than that.

Even worse is the different types of cheese.

[werdsmith]

David Braben and Ian Bell already harnessed the fibonacci sequence in space to great effect.

[Uncle Slacky]

Right on Commander!

[The Oncoming Scorn]

Alan Carter flying again?

[J.G.Harston]

Their results *MATCHED* the existing model closely.

[Howard Sway]

Satnav for the Moon

"Proceed 200 metres until you reach the crater. Turn left and drive 50 metres to the next crater. Turn right and drive between the 2 craters until you reach the next crater.........."

"Oh shit, we've just rolled into a crater, why didn't we hear about that one?"

"Map updating. Meteor storm detected 12 hours ago.."

[Graham Cobb]

Re: Satnav for the Moon

"I've been telling you for the last 3 hours... let's just stop and ask one of those nice Clangers. Why won't you stop and ask for directions?"

[munnoch]

Tidal Lock

I always thought the moon had a bulge towards the earth which is what keeps its rotation in sync with its orbit around the earth. Maybe that just affects its density rather than its shape.

[Spherical Cow]

Re: Tidal Lock

Yes there is a bulge towards Earth (and a corresponding one on the other side).

https://www.space.com/26246-lunar-tide-seen-from-space.html