Nobody doubts: getting there physically would be much more interesting than observing stars and exoplanets through distant observations. Still, distances measured in light-years are not so easy to cover even for the light itself. But if viewed purely from technical perspective, ultra-long-distance space travel is feasible. The most important question remains: how long would it take to get to the nearest star, beyond the edge of our Solar system?
The shortest time frame required for a space probe (or a spaceship) to reach our closest stellar neighbor – Alpha Centauri – is approximately 70 years. This data is based on the recently announced research, where astrophysicists evaluated modern means of interstellar travel based on the lightweight high-velocity photon sail technology. Their calculations included combination of gravitational assists and stellar photon pressure which could be used to decelerate the incoming lightsail from Earth.
The aim of Breakthrough Starshot project which was announced last year is to send a fleet of small probes to the planetary system of Alpha Centauri. It would be a fly-by mission: these probes could reach their destination in 20 years, but their substantial velocity achieved by using lasers and solar radiation would also mean that this fleet would quickly cross their target and leave Alpha Centauri behind in a matter of several hours. Such limited time is not enough to gather any substantial scientific data.
Another alternative is to send probes containing larger but light-weight photon sails which could be used to decelerate the probe before reaching the destination and later could enter a stationary orbit around the distant star. According to the calculations, it would take 90 years for such a probe to reach Alpha Centauri.
It is quite interesting to note that in order to reach the brightest star of our night sky – Sirius – such spaceship would require only approximately 70 years. Sirius is roughly two times more distant than Alpha Centauri, but its luminosity is ~16.7 times greater and therefore it could provide much more efficient probe deceleration which also permits using higher flight velocities. While orbiting a distant star, the probe could explore and gather data from its surroundings for several months or even years, not hours.
Source: research paper on arXiv