What’s Orbiting Earth
I saw this image on CNN earlier today and went searching through the European Space Agency archives for it. It’s a great artist’s conception of the extent of material that humans have lofted into near-Earth space. Ever since we started sending up satellites in 1957, the number of objects — which includes satellites but also cameras and gloves and pieces of collided satellites and other oddments — has increased. Today there are about 12,500 things out there at various altitudes from the surface. This makes calculating safe launch times a complex matter. The objects in this depiction are not shown to scale — their sizes are exaggerated to make them visible.
Seeing this kind of begs an interesting question. With its ever-increasing supply of “stuff” orbiting around it, does this make Earth a ringed planet? The classical (canonical) definition of a planetary ring is a ring of cosmic dist and small particles in orbit around a planet in a flat, disc-shaped region. If that’s what we accept, then Earth’s “ring” could be termed an “artificial ring” (sort of the same way that we call Pluto a dwarf planet (it’s a planet, but a special case of a planet)). What do you think?
I’m sort of reminded of the early concepts of a Dyson shell, which was a very thin shell consisting of orbiting power satellites that would capture a star’s energy output and channel it for a civilization’s needs. Or, more correctly, perhaps this is Earth’s Dyson Shell and its Dyson Ring. Only instead of power, much of the structure is handling our communications needs (among other things).
Im guessing it would depend on the total density of the debris/objects that are in orbit? The image says its exaggerated, i wonder what the density per cubic meter this stuff actually is and what the rate of increase is per year or maybe decade? I wonder also if the inner rings rate of density increase is the same as the outer ring? It looks denser in the artist rendering. Just wondering……..
Yes, I was thinking about the density too… I would think that if it was a TRUE Dyson ring/sphere setup, we’d have extremely restricted flight potention from the surface. So, it’s an interesting thought experiment to consider it as a proto-sphere, perhaps.
The concept of the Dyson sphere was thought of first by Olaf Stapledon (as Dyson freely admits) in his “Starmaker” story (http://books.google.com/books?id=e2ah-AYb_MAC&printsec=frontcover&dq=Starmaker). Interestingly enough, in the story itself Stapledon writes about a ring of material to capture sunlight, not a sphere.
As far as the geostationary arc goes, if you work it out there’s on average of 1 satellite per degree of longitude, but the density is not uniform (higher over the US than over the Pacific ocean for example). Right now, I’m trying to increase the density of that ring .
Yes, you are right about Stapledon’s first concept of the sphere. I think that concept of the ring is what I first thought of when I saw the ESA image.
This article has been added to the Astronomy Link List.
What would be the details of a station that uses solar sails to hover above the sun at a distance to experience one g of suns gravity. How large would sails need to be per kg of station mass
Sounds like a homework question to me.