Because NASA's running low on Plutonium and congress didn't approve the funds for NASA to make new Plutonium. It might be cheaper to retrieve this plutonium than to restart the whole plutonium production program.

NASA needs this plutonium for deep space missions. If we wanted to send a mission to a place like Europa, we'd need plutonium.

In fact the SNAP at the bottom of the ocean contains about as much plutonium as the RTG on the Curiosity rover.

While the initial 'cost' of a lithium battery is higher than the initial 'cost' of an internal combustion engine, the overall or "lifecycle" cost of a lithium battery is lower than that of an internal combustion engine.

That's pretty much the process that's been proposed by the USC contour crafting group proposed for doing rebar. Print a shell layer, drop in some modular rebar sections,then you fill up the shell with concrete so that your rebar connectors sticks out, and then repeat for the next layer. Another way to do reinforcement is to put a metal coil on your top layer and to print over it, so the coil gets embedded in the concrete. They've actually demonstrated this.

So why stop at just printing in colors? The contour crafting group has proposed putting in tiling, plumbing, electrical wiring, heaters, and strain gauges.

See this paper for more:
http://craft.usc.edu/CC/Welcome_files/resources/AIC2004-Paper.pdf

One approach to energy harvesting is to increase the efficiency of human walking and capture the energy the human would have expended walking. This has actually been demonstrated with an energy harvesting backpack. The amount of power the human should consume carrying the backpack and doing work on the generator was found to be more than the amount of power the human actually consumes.

So in other words, you still have to pay for your lunch, but you get more for your money.

see "Harvesting Energy by Improving the Economy of Human Walking," for more
http://www.sciencemag.org/content/309/5741/1686.short

Instead of throwing all that potentially valuable material into the pacific ocean, why not coral it all into one big "trash heap" and recycle it? After, it takes a lot more energy to put something into orbit than it does to move something to another orbit. At the very least, the trash heap could serve as a testing ground for space manufacturing processes.

So what happens when some wiseguy decides to mine asteroids for gold? The gold market could crash into the ground from the amount of gold flowing into the market.

As it is, gold is already more expensive per unit kilogram than the cost of launching a kilogram into space.

Cost of gold as of now: $26970.70
Cost of launching a kilogram into space:
Using the space shuttle: ~$22,000
Using a falcon 9: ~$2800

The moon's gravity well is much shallower than Earth's How much shallower you might ask? Well to get a pretty good idea, take a look at the Saturn V compared to the Apollo Lunar Module. If you want to get more technical, the mass ratio, or initial mass of rocket(w/ propellant)/final mass of rocket minus propellant of a rocket increases exponentially with the amount of delta V you need. So in other words you need 37* times "more rocket" to launch the same amount of mass to LEO from the Earth than it does from the Moon all other things being equal. * mass ratio =e^ (Delta V/ Exhaust velocity) Delta V from Lunar surface to LEO 6.4 Delta V from Earth surface to LEO 10 e^10/e^6.4= 36.5982344

According to "Sustainable Energy--- without the hot air," it's pretty much impossible to get anything but small gains in energy efficiency in aircraft.

So according to this article it takes 40 people wearing these to purify 2 cubic meters of air in a minute. Each of which needs to be in direct sunlight as this probably relies on a photocatalyst. At this rate it'd probably be far more effective for these 40 people to bike or bus instead of commuting by car.(Of course, one could put the photocatalyst in the pavement, but that's already been done) And not to mention, given that these dresses likely use a photocatalytic mechanism, they do nothing about particulate pollution.

One reason the researchers might be suggesting a device that plugs into the phone, is that the microfluidic chip might require power. The detection process might require a PCR step(and yes, PCR can be done in 'CSI plot device' timeframes) this takes power. Bodily fluids are often quite viscous and might need to be pumped through the device. This would be especially necessary if part of the detection process involved mixing the bodily fluids with reagents as on small size scales(low Re, unless the fluid's going at the speed of sound) fluids don't mix, at least over reasonable time scales. This necessitates pumping your fluids to be mixed through micromixers, this takes power. Also, at the very least a UV LED would be needed to show fluorescent markers.