The bill in Congress is moot. The Space Treaty boils down to requiring international approval for any activities of any kind on celestial bodies, whether the moon, an asteroid or a planet. With robotic mining ships using ion propulsion after conventional rocket boost to orbit, it is currently technically feasible to cobble together a functional attempt at space mining. Financially viable is another question entirely, as Art pointed out. If a way to "run ahead" a mining bot ship along the calculated trajectory of a "near miss" comet or asteroid, perhaps the ship could get up enough speed to land on it. If the calculated orbit of the asteroid or comet is such that the mining bot can harvest a payload and then sling-shot back to Earth, all within the "time is money" feasibility window, then yeah, I guess these space mining start-ups must have something up their sleeves.
