Stepping Stone 
It’ll be a long time before we can send even a robotic probe to another star. The challenges of time, distance, and energy are just too tough to overcome with present-day technology — or even foreseeable technology.
Yet some scientists and engineers are pondering a small step toward the stars: a probe that would travel farther than any has yet journeyed.
The initial goal is to get a ship out to 250 times the distance from Earth to the Sun — more than 20 billion miles — within 20 years of launch. By comparison, the farthest object yet launched is only half that far, and it took 35 years to get there.
After that, the ship would keep going, perhaps reaching close to a hundred billion miles before losing contact with Earth.
One concept calls for the mission to be propelled by solar sails — giant sheets that would be pushed by the pressure of sunlight. Another, devised about a decade ago, calls for a smaller sail that would be propelled by nuclear reactions triggered by antimatter. The study found the mission could reach the goal of 250 times the Earth-Sun distance in a decade, using just 30 milligrams of antimatter. One small problem, though — it would take decades to produce that much antimatter.
As such a craft sailed out of the solar system, it could measure the particles and magnetic fields of interstellar space. So even though it wouldn’t reach another star, it could give us a taste of what our stellar neighborhood is like.
Script by Damond Benningfield, Copyright 2014