
Radar reveals two moons orbiting asteroid Florence - japaget
https://astronomynow.com/2017/09/05/radar-reveals-two-moons-orbiting-asteroid-florence/
======
jaquers
Is the 'light' reflecting off the asteroid emitted from the sun? I had never
seen or even knew radar could distinguish value like what is shown here.

I suppose terrestrial radar looks at much smaller objects and what it sees is
emitted from the tower and bounced back in a straight line so that sort of
makes sense.

More info on the observatory:
[https://en.wikipedia.org/wiki/Goldstone_Solar_System_Radar](https://en.wikipedia.org/wiki/Goldstone_Solar_System_Radar)

~~~
benjoffe
> Is the 'light' reflecting off the asteroid emitted from the sun? I had never
> seen or even knew radar could distinguish value like what is shown here.

Yes it's emitted from the sun, it's clear given that the time-lapse shows
"Inner moon eclipsed" when passing behind the site of the asteroid that is not
lit.

~~~
Lordsandwhich
I was always under the assumption that with Radar images that it didn't rely
on a light source as technically the radar is the source. So that the
impression that there is a light an dark side was based purely on the motion
towards and away from the receiver.

But, you have pointed out something interesting and that would appear to
indicate other wise. The clear rotation independent of source already shows
that I am wrong on that.

Apparently I don't understand this very well.

~~~
radicalbyte
This thread is very confused.

There are two things: the radar images are created with radio waves emitted by
the radar installation. The second thing is that the visualisation shows a
light source. They are unrelated to each other. I assume that the light source
was added during rendering of the film and that it approximates the sun.

~~~
TorKlingberg
I don't think the visualisation shows any light source. The radar reflection
from the asteroid just looks like it is "lit up"

------
mukundmr
How about we have satellites orbiting asteroids for a piggy back ride and then
getting off the orbit when they are near a point of interest? My guess is the
gravity would be too feeble.

~~~
krastanov
You would need to first match the asteroid's velocity, and by then you do not
really need the asteroid. But something very similar to your idea is used
constantly for interplanetary travel - gravity assist which uses other bodies'
gravity to accelerate and change direction.

------
bediger4000
How do the orbits of the moons, and the asteroid's axis of rotation match up
to the ecliptic? Do both moons orbit in the same direction? How eccentric are
the orbits of the moons?

What's the going theory on how such a small body can capture moons? It must
not be too difficult, otherwise 3122 Florence wouldn't be the 3rd triplet
spotted.

------
hyperpallium
What's the surface gravity?
[https://en.wikipedia.org/wiki/3122_Florence](https://en.wikipedia.org/wiki/3122_Florence)

Mass isn't given, but could estimate from volume, and typical asteroid
density?

~~~
lmm
A quick wolfram alpha suggests about 0.002 ms^-2, i.e. about 1/500 Earth
gravity.

~~~
mturmon
9.8 / 0.002 = 4900, so was that about 1/5000 Earth gravity?

~~~
lmm
Yes, sorry.

------
SCAQTony
Imagine hijacking a 100-meter moon made of rare earth metals like gold,
platinum, rhodium, ruthenium, iridium, etc. etc. More than enough to under
write the mission and pay for a moon base.

~~~
arihant
If we go grab a moon sized ball of gold, gold will lose most of its value.
It'll be the next Aluminium.

~~~
labster
That much gold would still be worth it for electronic and spaceflight
applications. Gold's like a better copper or silver there. And let's not
forget the most important application, stereo plug connectors.

For platinum or iridium, making it cheaper there would enable all sorts of
catalytic chemical processes that are prohibitively expensive now. If abundant
enough, new demand will keep the bottom of the market from falling out.

~~~
russdill
They actually just plate connectors typically, I think with around 7µm of
gold. And no, gold is not a better copper or silver. Both silver and copper
are more conductive than gold (then followed by aluminum).

Gold is excellent for contact points though as it does not tarnish.

Silver conducts heat and electricity the best of the three, but tarnishes the
most easily, so it can have issues with high frequency signals as most of the
signal travels on the outer surface.

If both silver and copper were the same price as copper, it'd probably be
silver that would see the most increase in use in electrical applications.
During the Manhattan project, there was a shortage of copper and cost was not
an option. 430 million troy ounces of silver from the West Point Bullion
Depository was melted down and used to make magnetic coils. At the end of the
project, it was all returned, minus 120 oz.

[https://en.wikipedia.org/wiki/Calutron](https://en.wikipedia.org/wiki/Calutron)

~~~
labster
The stereo plug thing was a joke, but thanks for educating me on the Calutron.
Very cool.

