Once habitable planets are discovered and chemically fingerprinted around nearby stars, there will be a lot of interest in dispatching interstellar probes to check out the best candidates for life.
But dreams of star travel present an awfully steep slope when one calculates the energy needed to make the journey. Though exotic "massless" drives, somehow tapping the "vacuum energy" of space may eventually be realized, let's assume for this discussion only simple action/reaction engines based on good ol' Newtonian physics can be used.
ANALYSIS: Harnessing Solar Energy to Sail to the Stars?
Whatever the drive -- nuclear fusion, matter-antimatter, and even black hole -- enormous reservoirs of fuel are needed to be transported along with the starship. And, that requires even more energy to accelerate and decelerate a fuel-laden massive vessel.
The way around this dilemma is to generate enormous amounts of energy close to home and just beam energy across space to an interstellar probe. Think of propelling a leaf with the power of a garden hose. The leaf is a bare fraction the mass of the hose and water supply.
"It is the only method of interstellar flight that has no physics issues," writes James Benford of the R&D firm Microwave Sciences.
This proposal is still woefully inadequate and impractical for human interstellat travel, just like so many of the other proposals. But it may be useful for inter-solar system travel, however. To read more, click here.