Author Topic: Kordylewski clouds may affect plans for future space exploration  (Read 1417 times)

Offline Star One

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Earth’s moon may not be alone. After more than half a century of speculation and controversy, Hungarian astronomers and physicists say they have finally confirmed the existence of two Earth-orbiting “moons” entirely made of dust.

As they describe in the Monthly Notices of the Royal Astronomical Society, the team managed to capture snapshots of the mysterious clouds lurking just 250,000 miles away, roughly the same distance as the moon.

This is the key section.

Quote
These dusty hazards are a bit like cosmic tumbleweeds and may end up having quite a bit of relevance for future space exploration.

For instance, certain space missions involve parking satellites at the Lagrange points, where they consume minimal fuel to stay in orbit. That includes the upcoming James Webb Space Telescope, which is due to unfurl at the Lagrange point L2 sometime in the 2020s. Space agencies have also come up with plans to use Lagrange points as transfer stations on a so-called interplanetary superhighway for missions to Mars, Horváth says.

“The investigation of the dynamics of Kordylewski clouds may very well end up being most important from the point of view of space navigation safety,” he adds.

And if Horváth amd Slíz-Balogh’s hypotheses are right, there may be more of these roving clouds of dust chasing Earth, just waiting to be discovered in neighboring Lagrange points.

https://www.nationalgeographic.com/science/2018/11/news-earth-moon-dust-clouds-satellites-planets-space/

Offline flyright

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Interesting article.
It would be even more interesting to know what the estimated mass of these clouds are. I think refering to them as "moons" is a bit of a stretch.

I think, based on references in Wikipedia, the clouds were imaged around the L5 point:
https://en.wikipedia.org/wiki/Kordylewski_cloud

The Japanese Hiten probe investigated dust in the L4 and L5 Lagrange Points and found no increase over background levels: https://en.wikipedia.org/wiki/Hiten

Offline Star One

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Interesting article.
It would be even more interesting to know what the estimated mass of these clouds are. I think refering to them as "moons" is a bit of a stretch.

I think, based on references in Wikipedia, the clouds were imaged around the L5 point:
https://en.wikipedia.org/wiki/Kordylewski_cloud

The Japanese Hiten probe investigated dust in the L4 and L5 Lagrange Points and found no increase over background levels: https://en.wikipedia.org/wiki/Hiten

Does that mean there was some issue with the Hiten probe?

Offline ChrisWilson68

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Interesting article.
It would be even more interesting to know what the estimated mass of these clouds are. I think refering to them as "moons" is a bit of a stretch.

I think, based on references in Wikipedia, the clouds were imaged around the L5 point:
https://en.wikipedia.org/wiki/Kordylewski_cloud

The Japanese Hiten probe investigated dust in the L4 and L5 Lagrange Points and found no increase over background levels: https://en.wikipedia.org/wiki/Hiten

Does that mean there was some issue with the Hiten probe?

Or with this new study.  Or maybe the thresholds were just different -- the dust level might be below the threshold Hiten was looking for but above that this new study found.

Still, even if there is some elevated level of dust there, it's likely less than the amount in LEO.  It's also far less dangerous than dust in LEO because the orbits around the Lagrange points are much slower than those in LEO.  So, if it's gravitationally bound to one of the Lagrange points, it's likely not moving fast relative to the point, and likely neither is any spacecraft in the area.  It would still be better not to encounter any, but the problem is likely less sever if it is encountered there then in LEO.

Offline Phil Stooke

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Right!  The amount of dust is very small.  I'm sure it was well below Hiten's ability to measure it, not an indication of a problem with Hiten.  The other comments about JWST don't apply because that is not at an Earth-Moon Lagrange point anyway, and the idea that there may be dust at other EM points is suspect because L4 and L5 are by far the most stable points. 

It is significant that the dust exists (assuming the observation holds up) and it might be interesting to sample it, to assess if it has a lunar rather than asteroidal source, for instance, but the likelihood that it will interfere with anything at all is pretty small.

Offline Star One

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Thanks both. Sounds that like the article has added together two and two and got five over this issue then?

Offline as58

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I'm surprised how much publicity this claim has received. After reading the original pair of papers I'm far from convinced. And that illustration in the National Geographic is one of the worst that I've seen in a long time...

Offline sanman

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Right!  The amount of dust is very small.  I'm sure it was well below Hiten's ability to measure it, not an indication of a problem with Hiten.  The other comments about JWST don't apply because that is not at an Earth-Moon Lagrange point anyway, and the idea that there may be dust at other EM points is suspect because L4 and L5 are by far the most stable points. 

It is significant that the dust exists (assuming the observation holds up) and it might be interesting to sample it, to assess if it has a lunar rather than asteroidal source, for instance, but the likelihood that it will interfere with anything at all is pretty small.

Not even a Solar Sail? So it makes me wonder how many other such dust clouds exist inside our solar system? New alternative explanation for Dark Matter?

I wonder why these things inhabit the Lagrange zones in particular?

Offline plutogno

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I wonder why these things inhabit the Lagrange zones in particular?

because in any other position they would have already been de-orbited or expelled in solar orbit by the combined gravity of the Earth and Moon. this is what Lagrange points mean

Offline sanman

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because in any other position they would have already been de-orbited or expelled in solar orbit by the combined gravity of the Earth and Moon. this is what Lagrange points mean

So you mean that outside a Lagrange point, the dynamic combination of gravitational forces would have broken up the clouds, whereas inside the Lagrange point conditions are more stagnant.

But can that make Lagrange zones a particular hazard for any kind of debris accumulation, never mind just dust? Never considered that before.

Offline eeergo

because in any other position they would have already been de-orbited or expelled in solar orbit by the combined gravity of the Earth and Moon. this is what Lagrange points mean

So you mean that outside a Lagrange point, the dynamic combination of gravitational forces would have broken up the clouds, whereas inside the Lagrange point conditions are more stagnant.

But can that make Lagrange zones a particular hazard for any kind of debris accumulation, never mind just dust? Never considered that before.

Never heard of Trojans?

There are stable (local potential minimum) and unstable (gravitational pulls cancel out at the precise point but small perturbations increase them) Lagrange points, mind you, so the attractor concept is only valid in the former case.
« Last Edit: 11/08/2018 10:27 AM by eeergo »
-DaviD-

Offline ugordan

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because in any other position they would have already been de-orbited or expelled in solar orbit by the combined gravity of the Earth and Moon. this is what Lagrange points mean

So you mean that outside a Lagrange point, the dynamic combination of gravitational forces would have broken up the clouds, whereas inside the Lagrange point conditions are more stagnant.

But can that make Lagrange zones a particular hazard for any kind of debris accumulation, never mind just dust? Never considered that before.

Never heard of Trojans?

A good example is the Saturnian system: https://en.wikipedia.org/wiki/Moons_of_Saturn#Trojan_moons

Also, Jupiter has two largish families of asteroids shepherded into its Sun-Jupiter L4 and L5 points (well, point is a bit of a misnomer as the dynamically stable area is quite vast). Neptune IIRC also has a couple known ones, etc.
« Last Edit: 11/08/2018 10:44 AM by ugordan »

Offline Star One

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I am bit surprised the Earth keeps hold of this even at the Lagrange points being as it doesn’t seem to hold onto its mini moons.

Offline sanman

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Never heard of Trojans?

There are stable (local potential minimum) and unstable (gravitational pulls cancel out at the precise point but small perturbations increase them) Lagrange points, mind you, so the attractor concept is only valid in the former case.

But I thought the Trojans were actual asteroids, and not clouds, or swarms of pebbles.

Offline as58

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I am bit surprised the Earth keeps hold of this even at the Lagrange points being as it doesn’t seem to hold onto its mini moons.

The simulation paper doesn't really do anything to show that the dust clouds would be stable. The simulation setup was very simple, the test particles were followed for only ten years and looking at the figures in the paper, the clouds still seemed to be dispersing at the end of the simulation. Also the reasoning for ignoring non-gravitational forces is very strange; just because radiation forces are smaller in magnitude than gravitational doesn't mean that they can be completely ignored when studying the stability.

To be honest, I don't understand how the paper was accepted to MNRAS in its current state. Even the language would have benefitted from some polishing.


Offline ugordan

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Never heard of Trojans?

There are stable (local potential minimum) and unstable (gravitational pulls cancel out at the precise point but small perturbations increase them) Lagrange points, mind you, so the attractor concept is only valid in the former case.

But I thought the Trojans were actual asteroids, and not clouds, or swarms of pebbles.

Dynamically, what's the difference?

Offline plutogno

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From a dynamic point of view, I suspect that dust clouds would be subject to non-negligible Poynting-Robertson radiation pressure effects https://en.wikipedia.org/wiki/Poynting%E2%80%93Robertson_effect
Which is why even at the stable Lagrangian points dust clouds may not be long-lived.

Offline eeergo

Never heard of Trojans?

There are stable (local potential minimum) and unstable (gravitational pulls cancel out at the precise point but small perturbations increase them) Lagrange points, mind you, so the attractor concept is only valid in the former case.

But I thought the Trojans were actual asteroids, and not clouds, or swarms of pebbles.

As ugordan pointed out, it doesn't really matter which type of object is trapped, the fact is they can be trapped. Obviously, with a much more massive object such as Jupiter or Saturn, more massive objects can be trapped in a stable enough fashion, but even Earth has one such (discovered) object in L4: https://it.wikipedia.org/wiki/2010_TK7 , and Mars has several. In fact, Wiki states that even Ceres and Vesta have temporary ones too, as one might expect.

If large objects can be trapped, small bodies with less inertia should be even more likely to stay in the stable points, although their dynamics can be on the other hand more easily influenced by solar wind or photon pressure.
-DaviD-

Offline Star One

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I am bit surprised the Earth keeps hold of this even at the Lagrange points being as it doesn’t seem to hold onto its mini moons.

The simulation paper doesn't really do anything to show that the dust clouds would be stable. The simulation setup was very simple, the test particles were followed for only ten years and looking at the figures in the paper, the clouds still seemed to be dispersing at the end of the simulation. Also the reasoning for ignoring non-gravitational forces is very strange; just because radiation forces are smaller in magnitude than gravitational doesn't mean that they can be completely ignored when studying the stability.

To be honest, I don't understand how the paper was accepted to MNRAS in its current state. Even the language would have benefitted from some polishing.

So you disagree with its conclusions?

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