I didn't know asteroids could have a moon!

[BUTCH1]

Kinda neat!, the little ah heck is about 1 mile wide and orbits 243Ida, here's the pic..

and the link to it's description..https://en.wikipedia.org/wiki/243_Ida

 

[lxskllr]

It would be cool to walk on a sphere with a ~2000' radius.

 

[OutHouse]

It would be cool to walk on a sphere with a ~2000' radius.

yea that would be epic.

 

[GagHalfrunt]

Anything with enough mass can have a moon. <insert random Kardashian ass comment here>

 

[Paratus]

You pretty much wouldn't be walking as a 2000ft radius asteroid with a density similar to the moon would exert a force of about 0.02N on you. As opposed to around 800N on the Earth.

So taking a step would launch you off the surface.

 

[Dr. Zaus]

You pretty much wouldn't be walking as a 2000ft radius asteroid with a density similar to the moon would exert a force of about 0.02N on you. As opposed to around 800N on the Earth.

So taking a step would launch you off the surface.

I wonder what density the material would have to be to be something that could keep you planted.

 

[BUTCH1]

You pretty much wouldn't be walking as a 2000ft radius asteroid with a density similar to the moon would exert a force of about 0.02N on you. As opposed to around 800N on the Earth.

So taking a step would launch you off the surface.

Yea, you better shuffle your feet across or else momentum will take you floating away.

 

[Red Squirrel]

That's pretty cool, but makes sense. I would imagine that a moon could even have a moon. And that moon could possibly have it's own. But then it gets pretty unstable and will probably correct itself ex the smaller moon gets sucked out of orbit by the bigger one etc.

There's a saying with asteroids though because of their weak gravity, you don't land on them, you dock with them.

 

[Paratus]

I wonder what density the material would have to be to be something that could keep you planted.

It's not too hard to get an approximate idea.

We know astronauts in lunar 1/6th g can hop around. Let's just assume you could shuffle along at 1/20th of a G.

So our theoretical asteroid would need it's acceleration due to gravity to be about ~

Ga = 1/20 x 9.8m/s^2
Ga~ 0.5m/s^2

Force on a 300lbs astronaut + gear =

F = mass of astronaut and suit x Ga
F ~ 70N

Newtons laws of Gravitation gives the force between two masses as

F= G(m1xma)/r^2
r = 2000ft ( distance from the center of mass of our asteroid to the center of our astronaut - we'll ignore the extra 3 ft to his center)
m1 = 300lbs
ma = mass of the asteroid
G = the gravitational constant (6.674×10−11 N · (m/kg)2)
F= 70N

ma = 2.86x10^15 kg

Now we divide by the volume of the asteroid. We'll assume a sphere with a 2000ft radius.

Va = 4/3 Pi r^2
Va ~.95km^3

Density of our asteroid = ma/va
Density = 3.0x10^6 kg/m^3

Osmium is the densest element at 22,600 (2.26x10^4) kg/m^3

So our asteroid would need to be 100x denser than that.

Wolfram Alpha puts it at

• 20x denser than the a solar core
• 3% as dense as white dwarf.

 

[BUTCH1]

That's pretty cool, but makes sense. I would imagine that a moon could even have a moon. And that moon could possibly have it's own. But then it gets pretty unstable and will probably correct itself ex the smaller moon gets sucked out of orbit by the bigger one etc.

There's a saying with asteroids though because of their weak gravity, you don't land on them, you dock with them.

IIRC someone did land a probe on one after it's mission was finished.

 

[John Connor]

How the fuck did they grab a snap?

 

[Ken g6]

That's no moon! It's a...oh wait yes it is a moon.

The picture was taken from a space probe.

 

[John Connor]

Space...probe? I never heard of this.

LOL

 

[John Connor]

I mean it must be moving like 30,000 MPH or more right? And then the strange orbit and all. Pretty crazy they managed to grab a snap.

 

[Red Squirrel]

I imagine it would not be any different than doing a rendez vous with something. The bigger it is, the more gravity it will have so that huge one they landed on a few years back was big enough that it had significant gravity. But still small enough that the sphere of influence is pretty small.

 

[DrPizza]

Escape velocity, if I didn't screw up pushing a button on the online calculator was around 2.7 m/s. So, yep, you'd probably launch yourself into space. But, my wife just suggested the solution: Heavy boots. I'm not sure how we never thought of that!

 

[DrPizza]

(Of course, those boots would be very large and likely made of lead.)

 

[Red Squirrel]

And a heavy backpack. You can probably fit a couple lead ingots in a standard size backpack. Good to go!

 

[JTsyo]

Escape velocity, if I didn't screw up pushing a button on the online calculator was around 2.7 m/s. So, yep, you'd probably launch yourself into space. But, my wife just suggested the solution: Heavy boots. I'm not sure how we never thought of that!

I know you're joking but while there's not much weight, the mass is still there. You will still need to exert energy to start and stop moving. Stopping could be real tricky if you managed to get up to any speed.

 

[dave_the_nerd]

I know you're joking but while there's not much weight, the mass is still there. You will still need to exert energy to start and stop moving. Stopping could be real tricky if you managed to get up to any speed.

If you built up any speed, you'd just fly off the moon anyway, so... don't do that.

 

[Squisher]

Tread lightly my friend.

 

[John Connor]

I seen the moon play the piano in the 80's.

 

[rumpleforeskin]

That's no moon....

 

[lxskllr]

<insert random Kardashian ass comment here>

Those are flies, not moons.

 

[zinfamous]

doesn't Pluto have a moon, Io?