The ongoing miniaturization of electronics has made it feasible to create a chip weighing about the same as a paper clip (1 gram, or 0.035 ounces) that could include the communications lasers, cameras, nuclear battery, computer and other devices needed for an interstellar space probe. The “Starchip” would be about the size of a postage stamp.
Many Starchips would be launched at a time, propelled by a 100-gigawatt laser blast from a ground-based light-beamer array. This is about the same amount of energy required to launch a space shuttle. The probes would be accelerated to 20 percent of the speed of light in about two minutes (an acceleration of 60,000 times that of the Earth’s gravity). This velocity would get the probe past the orbit of Pluto in three days and to the nearest star in 20 years.
Building and cooling a ground-based light-beamer array
Overcoming atmospheric interference on the laser beams as they exit Earth’s atmosphere
Precise aiming of the probes at an exoplanet
Integrity and stability of the sail under thrust
Fast travel through the interstellar medium (dust, gas, cosmic rays)
Maintaining fuctionality over decades in space
Precision aiming of cameras at target
Precision aiming of transmitter at Earth
Transmitting images using a laser as a transmitter and the sail as an antenna
Power generation and storage