Quote from: Richy_T on Today at 07:04:13 PM

Quote from: Phil_S on Today at 06:14:36 PM

Quote from: Richy_T on Today at 05:22:21 PM

Energy is pretty cheap in space. You also don't need a whole lot of power as even quite low thrusts will eventually get you where you want to go.

It's not as simple as going from point A to point B.

'Points of interest' in space (like asteroids) are not stationery, but flying as incredible speed.

For example, when NASA sent a spacecraft to Pluto, it took 9 years to get there, but they only had 1 day to actually study Pluto.

Only 1 day because the spacecraft couldn't just 'stop' once it arrived.

Relative speed during Pluto flyby was 13.78 km/s (49,600 km/h; 30,800 mph) so it would requite extraordinary amount of energy to 'stop'.

No, you're right, it's not point A to point B. Most things of interest are orbiting the sun so it is a case of matching orbit. This means speeding up or slowing down at strategic points. Typically, one would accelerate for approximately half the journey then decelerate for the other half. Depending on many factors, you might have a long time to do this. Even with quite modest (sub 1G) accelerations, it it possible to travel long distances in quite short times (particularly if one is not having to worry about human cargo). This can be achieved with a photon drive which means you can obtain power from the sun or, for some parts of the journey, a solar sail arrangement (which we are not at yet but given time)...

The Pluto flyby being so fast was because it was designed as a flyby, because that better suited the mission parameters rather than a matched orbit. Apples and oranges really. Also bear in mind that the sun is quite weak out in the vicinity of pluto (30-49 AU) vs the asteroid belt (~2.5AU) - inverse-square law. So plenty of energy available for maneuvering.

Energy is everything. As already noted, with free energy we would be able to create elements instead of mining it.
For space mining we would need to reach orbit with an heavy payload, go to the the asteroid, land, use a lot of energy to probe and mine materials, escape the gravity of the asteroid and come back to earth. I cannot extrapolate any good number but the cost of orbit seems to exponentially grow for biggest ships, and this is a huge ship. Maybe you can do it cheaper with nuclear explosions project-orion-style, but meh.
I suppose that at the current energy costs this is not convenient even if you do not consider the billions in hardware and research.