Which M type asteroid provides the maximum iron ?

Question

Which of these asteroids is easily accesible from an orbit around ceres for the purpose of mining?

Answer 1

253 Mathilde (a C-type asteroid) has already been visited by a spacecraft. It was visited by the NEAR Shoemaker spacecraft on its way to asteroid 433 Eros.

The first M-type asteroid to be so visited will be 21 Lutetia, an anomalous, probably nometallic body, due to be imaged by the Rosetta space on July 10, 2010.

It seems it would be wrong to equate M-type asteroids with necessarily having a metallic content. Wikipedia states:

"22 Kalliope has an accurately known density that is far too low for a solid metallic object or even a metal rubble pile: a rubble pile of iron-nickel metal would need about 70% porosity which is inconsistent with packing considerations. Kalliope and 21 Lutetia have features in their spectra which appear to indicate the presence of hydrated minerals and silicates, anomalously low radar albedos inconsistent with a metallic surface, as well as characteristics more in common with C-type asteroids. A variety of other M-type asteroids do not fit well into a metallic body picture."

However 16 Psyche is the largest M-type asteroid (280×230×190 kilometres), and does appear to be metallic. It is estimated to contain 0.6 percent of the mass of the entire asteroid belt.

Wikipedia reports as regards possible mining on Psyche:

"Even a relatively small asteroid with a diameter of 1 km can contain billions of metric tons of raw materials.

In 2004, the world production of iron ore exceeded 1,000 million metric tons. In comparison, a comparatively small M-type asteroid with a mean diameter of 1 km could contain more than 2,000 million metric tons of iron-nickel ore, or two to three times the annual production for 2004. The asteroid 16 Psyche is believed to contain 1.7×10^19 kg of iron-nickel, which could supply the 2004 world production requirement for several million years."

So it is not inconceivable that a permanent mining facility could be set up on Psyche, Distance is one logistical problem, though:

Perihelion: 2.513 AU
Aphelion; 3.328 AU
Orbital period; 1823.115 days (4.99 years)

The further a cargo has to be transported, the more it will add to the cost, If Ceres is being thought of as a base from which to operate, it is in the same region of the asteroid belt as Psyche:

Perihelion: 2.544 AU
Aphelion: 2.987 AU
Orbital period: 1679.819 d (4.599 years)

but the 10% difference in their orbital periods could make for problems when they are on opposite sides of the sun from one another and it could take a further 22.5 years for them to realign themselves in close proximity again (10 Ceres orbits = approx 9 Psyche orbits = 45 years),

So there are many practical problems to solve before we see a Gold Rush of 49ers heading out on the next space shuttle to Psyche.

Answer 2

No idea but why spend a few billion to dig out a ton of ore that you can get for few hundred bucks on earth ?