3
$\begingroup$

Is it possible, due to asteroid mining activities, for a space-fairing civilization to produce a dust ring around a very large asteroid (Ceres)?

In my world, there is a lot of ore processing being carried out in low Ceres orbit. Mining equipment is smashing rocks to gravel, and a lot of dust is escaping into the equatorial orbit.

What amount of work and mass would be required to produce a thin, yet naked-eye visible ring? I'm assuming the ring is composed of tiny dust particles which have little to no negative effects on ships which pass through the ring.

Improve this question
$\endgroup$
5
  • 2
    $\begingroup$ "little to no negative effects" This really, really depends on the speed the ships are moving. Even a fleck of dust could punch a hole throw a ship when they're moving at orbital velocities $\endgroup$
    – Cygnus X-1
    Jul 16, 2019 at 20:03
  • 1
    $\begingroup$ Also, you should take a look at Kessler Syndrome. Over hundreds or thousands of years, the debris caused by this would condense into a ring $\endgroup$
    – Cygnus X-1
    Jul 16, 2019 at 20:08
  • 1
    $\begingroup$ @CygnusX-1 be careful to define "orbital velocity". For Ceres, escape velocity is about 500m/s, and we already have small arms that can fire projectiles substantially faster than that and armour that can protect against them. $\endgroup$
    – Starfish Prime
    Jul 17, 2019 at 9:43
  • $\begingroup$ Lets just say the ships are tough mining rigs with thick hulls so impacts with the dust can be ignored. I'm more interested in whether the amount of dust to build a ring is practical in the first place. Is it hundreds of tons, thousands? And what size of an activity would be needed, hundreds of ships eating away at thousands of tons of rock? That kind of thing. Would scattered dust create a ring at all, or would it form a shell? $\endgroup$
    – Innovine
    Jul 17, 2019 at 9:54
  • $\begingroup$ Orbital velocity is 150m/s up to 500m/s. In my world it's pretty easy for the ships to achieve this $\endgroup$
    – Innovine
    Jul 17, 2019 at 9:55

1 Answer 1

Reset to default
3
$\begingroup$

Dust rings: Not possible during mining.

There are 2 theories of how the dust rings around Saturn and Uranus were formed:

  1. Millions of years ago the planet had a large moon orbiting around it. It got destroyed and the remains are now the dust and larger particles in the rings

  2. They date back to the formation of the planet, when a heap of dust particles started to coalesce in one location and started rotating. Stuff rotated fast enough that not everything got pulled into the emerging planet and instead stayed as a disk around it.

The only reason there are rings instead of a dust shell is that either there was something orbiting the planet, or that the planet's rotation during creation is responsible for it. Since you've got a lone asteroid, neither of these cases can be fulfilled. After all, I very much doubt that all your mining stations keep to the same equatorial orbit. Especially if they are trailing debris behind them in their orbit - it'd get much too dangerous much too quickly.

(why have the processing station in orbit? What do they do with the unwanted rocks after they got all the ores? Dump down to Ceres? That would be very energy efficient - it's much cheaper to have the processing station on planet due to the fuel requirements to carry all the raw materials up to orbit)

(where is the equatorial orbit on an object with no rotation? Or does Ceres rotate?)

Yes, the Kessler Syndrome as mentioned in a comment, will eventually force debris to condense around an equatorial ring, but for that you would need a lot of debris at the same height. On Earth, that would be geosynchronous or low earth orbit, because we deliberately shoot stuff up there. On your asteroid, mining would not be as precise - as a result your debris will be distributed much more evenly and thus take a lot longer for the Kessler Syndrome to take effect.

(Not all rock and dust thrown up by your mining operation gets exactly the velocity and -vector needed to settle in an orbit. Only a tiny fraction of it does that, the rest either escapes to space or falls down to the asteroid.).

Dust shell: Maybe.

A dust shell is more in the realms of the possible. Compare it to the space debris around earth - it is orbiting in more or less stable circles, but those circles are angled in every direction at any height.

In case your asteroid is part of an asteroid field, however, it is very likely that your dust shell will be depleted by other asteroids passing closeby and catching some of the debris in their own gravitational field. Depending on how dense your field is, it might prevent a dust shell from forming entirely.

Size of the dust shell

With the Orbital Velocity Calculator, it means that if your ships can manage 500m/s you'd have your Low Ceres Orbit at around 270km. Slower orbital speeds means a higher orbit, larger orbital speeds means a lower orbit. That gives you a shell around Ceres starting at around 270km radius (most particles) and stretching out to several 10000km radius (those that barely manage escape velocity).

Visibility of dust shell

A shell starting at 270km height should be visible (Ceres' diameter is only about 900km, and it has no atmosphere to block visibility). However, you will probably not see a lot.

If you take the entire mass that you need for visible dust rings and spread it out to a sphere, not much will be left.

Maybe, if you view Ceres against a bright object, you might detect some distortion around Ceres. Or, if the debris is highly reflective, you might notice it when sunlight reflects of stuff where Ceres' dark side is supposed to be.

Easy Visibility? no.

Visibility of dust rings

If you just can't live without dust rings, you could do comparisons to Saturn.

The mass of Saturn's rings is estimated at 1.5*10^19kg. Saturn's mass at 5.7*10^26kg is about 7 orders of magnitude bigger. For Ceres (9 * 10^20kg) the mass of similarly visible rings would be 2.5*10^13kg (ignoring potential square-cube laws between ring mass and planet mass).

Assume that only 1 in 1000 debris particles from your mining operation receives a stable orbit vector (it's probably a lot lower still), and you will need to produce 2.5*10^16kg debris to get your Saturn-like rings. That is a measurable fraction of the planet's entire weight! (1/40000).

Not to mention that it's turned absolutely lethal for all orbiting processing stations a long time before that. Earth has 'only' a couple million objects larger than 10cm in orbit, and it's already considered crowded in LEO and GEO.

Improve this answer
$\endgroup$
3
  • $\begingroup$ If it wasnt clear, my ships are processing ore in orbit already, so any dust they discard is already in orbit.. $\endgroup$
    – Innovine
    Jul 17, 2019 at 18:53
  • $\begingroup$ "t means that if your ships can manage 500m/s " uhh, at that speed, they will depart Ceres.. My orbital heights are anything from 5 to 20km $\endgroup$
    – Innovine
    Jul 17, 2019 at 18:54
  • $\begingroup$ Ceres rotates around its axis once every nine hours. Asteroids do not "pass close by", and Ceres is by far the largest anyway. My mining operation does involve bringing raw asteroids into Ceres orbit for processing, as well as resource extraction below the surface, which can also get processed in orbit, for storys sake. So other gravitational influences are pretty much zero, but I can have a lot of orbiting mass in the equatorial plane, if that'd help the dust coalesce to a ring? You might want to incorporate this extra info into the answer. $\endgroup$
    – Innovine
    Jul 17, 2019 at 18:57

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .