Could Humans Ever Travel to Another Star?

Voyager 1 has been travelling since 1977. It has crossed the boundary of the heliosphere, entered interstellar space and become the most distant human-made object from Earth.
Yet compared with the distance to another star, Voyager has barely begun its journey.
Our nearest stellar neighbour, Proxima Centauri, lies about 4.24 light-years away. That is roughly 40 trillion kilometres — a distance so large that even light needs more than four years to cross it.
For humans, the challenge is considerably greater.
In our previous article about Voyager 1 in interstellar space, we saw how a spacecraft built in the 1970s can survive for decades beyond the major planets. Reaching another star, however, would require an entirely different level of propulsion, engineering and endurance.
So could humanity ever make the journey?
Physics does not necessarily forbid it. Our present technology simply makes it extraordinarily difficult.

How Far Away Is the Nearest Star?

The closest star to the Sun is Proxima Centauri, a small red dwarf located about 4.24 light-years from Earth.
A light-year is a measure of distance rather than time. It is the distance light travels through a vacuum in one year — approximately 9.46 trillion kilometres.
That puts Proxima Centauri more than 40 trillion kilometres away.
The star belongs to the wider Alpha Centauri system, alongside Alpha Centauri A and Alpha Centauri B. At least one confirmed planet, Proxima Centauri b, orbits Proxima. Our guide to Proxima Centauri b explores the closest known exoplanet to Earth, its potential habitability and the challenges of studying a planet around an active red dwarf. It belongs to the much larger population of planets beyond our Solar System that astronomers call exoplanets. Astronomically, this is our neighbourhood.
For spacecraft engineering, it is an enormous gulf.

How Long Would Voyager 1 Take?

Voyager 1 travels at roughly 17 kilometres per second relative to the Sun.
That sounds extraordinarily fast on Earth. At interstellar distances, it is slow.
Voyager 1 is not travelling towards Proxima Centauri, so it cannot simply be used as a real mission timetable. But its speed gives us a useful sense of scale.
At approximately Voyager-like speeds, crossing a distance of more than four light-years would take tens of thousands of years. At a constant speed of roughly 17 kilometres per second, a spacecraft would need approximately 75,000 years to cover the 4.24 light-years separating the Sun from Proxima Centauri. This is a simplified calculation, not a prediction for Voyager 1 itself: the spacecraft is travelling in a different direction and was never designed to visit another star.
Voyager itself is heading in the general direction of another star, AC +79 3888, also known as Gliese 445. NASA estimates that in roughly 40,000 years it will pass within about 1.7 light-years of that star.
It will not actually visit the star.
This illustrates the fundamental problem with interstellar travel: spacecraft that appear fast within our Solar System become painfully slow when the destination is measured in light-years.

Why Can't We Simply Build a Faster Rocket?

Conventional rockets carry propellant and expel it to create thrust.
This approach has successfully taken spacecraft to the Moon, planets, asteroids and the outer Solar System. But accelerating a spacecraft to a meaningful fraction of the speed of light would require vastly more energy.
The faster the spacecraft must travel, the more demanding the problem becomes.
A crewed spacecraft would make matters harder still.
It would need to carry people, life-support systems, radiation protection, equipment, food or food-production systems and potentially enormous quantities of energy.
Then there is the question of stopping.
Reaching another star at tremendous speed is only part of the challenge. A spacecraft intended to enter orbit or explore a planetary system would also need some way to slow down after crossing interstellar space.

Could Nuclear Propulsion Help?

Nuclear technologies have long been considered for advanced space propulsion.
There are several very different concepts under this broad description.
Nuclear thermal propulsion, for example, could potentially offer advantages for missions within our Solar System by using a reactor to heat propellant.
More ambitious concepts have proposed using nuclear fusion or sequences of nuclear explosions to accelerate spacecraft to far higher velocities.
These ideas should not be confused with an existing interstellar transport system.
Some are serious areas of physics and engineering research; others remain conceptual because the necessary technology, scale, cost or performance has not yet been demonstrated.
Even significantly faster propulsion would not automatically make crewed interstellar travel practical.
The distances remain immense.

What About Laser-Powered Light Sails?

One of the most interesting modern concepts removes much of the propulsion system from the spacecraft itself.
Instead of carrying enough fuel to accelerate throughout the journey, an extremely lightweight spacecraft could be attached to a reflective light sail.
Powerful lasers located far behind the probe would shine onto the sail. Photons carry momentum, so the beam could gradually — or under sufficiently powerful systems, rapidly — accelerate the spacecraft without requiring conventional onboard propellant for that acceleration.
Concept studies associated with ideas such as Breakthrough Starshot have examined whether gram-scale probes might eventually reach a substantial fraction of the speed of light.
NASA researchers have also studied technical questions related to miniature laser-driven interstellar probes and beamed propulsion.
Under highly ambitious concepts, a tiny robotic probe travelling at around 20 per cent of light speed could cross the distance to Alpha Centauri in roughly two decades rather than tens of thousands of years.
But there is a crucial distinction:
No such operational interstellar spacecraft currently exists.
Producing the laser power, building an extraordinarily durable sail, keeping a tiny spacecraft functional and returning useful data across more than four light-years are all major engineering challenges. Another difficulty is slowing down. A probe accelerated by lasers near Earth might reach a neighbouring star relatively quickly, but without a suitable braking system it would pass through the target system at enormous speed. A fast flyby could still return valuable observations, yet it would offer much less time to study planets than a spacecraft capable of entering orbit.

Interstellar Dust Becomes a Serious Problem

Interstellar space is extremely thin, but it is not empty.
As explored in our guide to interstellar space, the enormous distances between stars contain gas, microscopic dust, magnetic fields and energetic particles.
At ordinary spacecraft velocities, collisions with tiny particles are manageable engineering considerations.
At a significant fraction of the speed of light, the situation changes.
Even a very small particle striking a spacecraft at enormous relative velocity could release considerable energy and damage sensitive components.
A future high-speed probe might therefore require shielding, careful spacecraft geometry or other methods of reducing the risk.
The faster we try to travel, the more important the interstellar environment becomes.

Communication Would Still Take Years

Suppose a robotic probe somehow reached Proxima Centauri.
Its photographs and measurements could not arrive instantly.
Nothing carrying information can simply ignore the distance between the stars.
A radio or laser signal travelling from the Proxima Centauri system to Earth would require roughly 4.24 years to reach us.
If mission controllers sent a command from Earth, they would wait more than four years for the command to arrive and another four years for a reply.
A spacecraft that far away would therefore need an extraordinary degree of autonomy.
It could not depend on Earth to solve problems in real time.

Could Humans Survive the Journey?

Sending a tiny robotic probe is one problem.
Sending humans is another.
Even if a spacecraft could reach another star within several decades, a crew would need protection from radiation, reliable life support and enough resources to remain healthy for an extremely long journey.
Every critical system would need to operate or be repairable far beyond any possibility of rescue from Earth.
Some speculative proposals imagine generation ships, where several generations of people would live and die aboard a spacecraft before their descendants reached the destination.
Others discuss suspended-animation technologies that do not currently exist for long-duration human spaceflight.
These ideas are interesting because they reveal the scale of the challenge, but they should not be mistaken for available technology.
At present, humanity has never sent people farther than the Moon.

What About Warp Drives and Wormholes?

Science fiction offers much faster solutions.
Warp drives are often described as manipulating spacetime around a spacecraft, while wormholes are hypothetical shortcuts connecting distant regions of spacetime.
Both ideas have connections to mathematical concepts studied within general relativity.
That does not mean engineers know how to build them.
Proposed warp-drive geometries can involve extreme physical requirements, including forms or distributions of energy that have not been demonstrated as practical engineering resources.
Traversable wormholes face similarly profound theoretical problems.
There is currently no experimental evidence that humans can create a practical warp drive or traversable wormhole for interstellar travel.
They remain fascinating subjects for theoretical physics — not transportation systems waiting to be constructed.

Will Humanity Ever Reach Another Star?

Nobody can responsibly give a date.
The first attempt may not involve humans at all.
A more realistic early step could be a tiny robotic probe designed to travel far faster than today's spacecraft and return limited scientific observations from a nearby stellar system.
Even that would represent one of the most ambitious engineering projects ever attempted.
Voyager demonstrates how far careful engineering can carry a spacecraft.
Future propulsion research may eventually allow machines to travel much faster.
But the transition from exploring our own Solar System to visiting another star is enormous.
Before deciding where humanity might travel, however, we should understand what is actually waiting nearby.
The Alpha Centauri system remains one of the most compelling potential destinations for future interstellar exploration. Its nearest member, Proxima Centauri, hosts a confirmed planet that astronomers continue to investigate. Whether a human-made probe will ever reach that distant world is still an open question, but the scientific reasons to study it are already clear.

Sources and Further Reading