Interstellar Exploration in its current form is merely hypothetical, but many propulsion systems have been proposed to facilitate travel over these immense distances and extended periods of time—both with and without human passengers.
A commonly-proposed method for unmanned spacecraft involves nanothrusters, which use ionised nanoparticles to gradually accelerate the spacecraft though space in a given direction. Others glide on solar winds using massive, ethereally thin sails.
When it comes to manned travel, the journeys must take considerable amounts of time—to even leave the solar system with current technologies would take thousands of years. Therefore, techniques such as cryogenic freezing or "generational ships" housing families over multiple centuries are required to allow humans to reach other solar systems and exoplanets.
The more immediate solution to the problems of interstellar travel is to do away with the human element and send sophisticated, independently-thinking probes—much less fragile than humans, though still much more expendable—to explore nearby star systems.
Sailing to the Stars
Project Starlight is a research program funded by NASA’s Innovative and Advanced Concepts division, which aims to create a fleet of ‘wafer-sats’ travelling at one-fifth of the speed of light. These craft, no larger than a DVD disc (classified as ‘femtosatelites’), will carry sensor arrays and be powered by plutonium generators.
Laser arrays on the order of gigawatts (billions of watts) will propel these craft into space by directing their beams onto the crafts’ reflective sails to push them to high speed. Such craft would be able to transmit observations of any planets, stars, and extraterrestrial matter as the spacecraft pass close to the exoplanets. Their incredible speed would allow interstellar missions to be completed within human lifetimes, on the span of decades rather than millennia.
Starshot is a proposed expedition by Breakthrough Initiatives to the nearby star system of Alpha Centauri. The project was put forward by cosmologist Stephen Hawking and venture capitalist Yuri Milner on April 12, 2016, and aims to be the first demonstration of ultra-fast, light-driven nano-spacecraft.
Starshot operates on the same principles as Project Starlight and would act as a definitive proof-of-concept for interstellar exploration using light-speed femtosatelites.
Getting to Minerva
If a planet like our hypothetical Minerva b were discovered, it would likely be first observed by a fleet of scouting satelites, similiar to those of Breakthrough Starshot. They would take preliminary readings and assess the suitability of the planet for further exploration.
The larger expedition would take the form of a massive spacecraft, powered through the darkness of interstellar space by a fusion reactor and ion thrusters. Travelling at incredible speeds, it would carry a cargo of autonomous probes, programmed to descend to the planet's surface.
A massive antenna would allow for the probes to transmit their data back to Earth.