Helium-3 is a trendy new possibility for clean and efficient fusion power, but most of the Earth's supply has long since floated away like a party balloon. To get enough helium-3 to power an interstellar spacecraft (and the rest of the planet for the forseeable future), Project Icarus wants to send floating robotic gas mines to Uranus.
You remember Project Icarus, right? They're the people who are working on a realistic interstellar probe. To make that happen, they need a really big and powerful engine, that engine needs a bunch of fuel, and that fuel is looking more and more like helium-3, which can be fused with deuterium (an isotope of hydrogen) to produce energy and thrust.
Helium-3 isn't easy to find on Earth anymore, but there's scads of it just floating out there in space in the form of the outer planets. Of these, Jupiter is big and nasty, Saturn has those problematic rings, and Neptune is really freakin' far away, but Uranus could fit the bill perfectly. Nuclear rockets could get there in 70 days and use robotic hot-air balloons to harvest 500 tons of helium-3 at a time and cart it all the way back to Earth. And beyond starship fuel, it would only take about 14,000 tons of deuterium/helium-3 mix (28 round trips) to supply the energy needs of our entire planet for a year, and Uranus wouldn't even notice we'd stolen it.
We have no idea when this kind of thing might happen, but Project Icarus is suggesting that an interstellar probe could hypothetically be fueled and ready by 2100. All I can say is, we'd better hurry it up, lest our mining operations get the attention of The Empire who could force us to make a deal that gets worse all the time.