The discovery of an atmosphere around the rocky planet LHS 1140b has brought the possibility of sending tiny spacecraft to other solar systems back into the headlines. Miniaturized electronics, light sails, and powerful laser arrays make the idea a real engineering research topic, but even at 20% of the speed of light, the journey to the planet, 48 light years away, would take about 240 years.
In a study published in July 2026 in the journal Science, astronomers reported the discovery of helium escaping from the upper atmosphere of LHS 1140b, a rocky planet in the habitable zone of a red dwarf. The discovery has made it one of the most intriguing targets in the study of planets outside the solar systemThe observation does not prove that it has life or even liquid water, but the researchers say it provides direct evidence that a rocky planet in the habitable zone is capable of holding an atmosphere.
The discovery raises a question that goes beyond observational astronomy: Will we ever be able to send a spacecraft there and examine this world up close? The cautious answer is that the technologies that make up a first interstellar mission are already being explored, and some have even been demonstrated in space, but there is still no system capable of carrying out such a mission. Moreover, the distance to LHS 1140b illustrates the magnitude of the difficulty.
Not every star is close enough.
LHS 1140b is about 48 light-years away. A spacecraft traveling at 20% of the speed of light—an ambitious goal in itself—would take about 240 years to reach it, even before development and launch time are factored in. After passing the planet, the data would take another 48 years to reach Earth.
Therefore, the more likely target for a first interstellar mission is a system Alpha Centauri, which is only about 4.37 light years away. At a similar speed, it would be possible to reach it in a little over 20 years, and then wait another four and a quarter years to receive the first data.
Solar sails have already flown in space
The physical principle is simple: photons have no rest mass, but they do carry momentum. When light bounces off a thin, shiny surface, it exerts a tiny pressure on it. In space, where there is no air friction, a small but continuous push can gradually change the speed and trajectory of a spacecraft.
Sun sails, which use sunlight, have already proven that the idea works. In 2010, the Japanese spacecraft IKAROS demonstrated propulsion and navigation using a sail on an interplanetary journey. In 2019, the Planetary Society’s LightSail 2 showed that even a tiny CubeSat satellite could change its orbit using light alone. NASA deployed the ACS3 system’s sail, which had an area of about 80 square meters, in 2024; the sail deployed successfully, but the mission was decommissioned in 2026 without being able to complete the planned propulsion demonstration.
An interstellar light sail would be a much more extreme system. Instead of relying on sunlight, which fades with distance, an array of lasers would direct a powerful beam at a reflective sail a few meters across and weighing only a few grams.
A hundred-gigawatt laser and a gram-weight spacecraft
project Breakthrough Starshot An idea is being explored in which a laser array with a total power of about 100 gigawatts would accelerate a tiny spacecraft attached to a light sail to speeds of up to 20% of the speed of light. The acceleration is expected to last only a few minutes. The energy source and propulsion system remain near Earth, so the spacecraft does not need to carry much fuel.
Developments in cameras, processors, and tiny sensors make it possible, in principle, to compress scientific capabilities into a very small mass. The spacecraft's computer and its artificial intelligence systems will have to operate in almost complete autonomy: it will be impossible to control a spacecraft light-years away in real time, and it will have to identify its targets, point cameras, take measurements, and transmit the information on its own. It is possible that most systems will remain in an economical mode for the decades of the journey and will only be fully activated in preparation for the encounter.
But miniaturizing the sensors only solves part of the problem. The sail must remain stable in the center of the laser beam and survive intense heating during acceleration. The array of lasers must act as a single coherent light source and focus on a small sail from a vast distance. The spacecraft must survive decades of radiation and interstellar dust, maintain a power supply, and direct a very weak transmitter to Earth. Receiving a useful amount of data from a transmitter that weighs several grams, several light years away, is also a challenge that has not yet been solved in a complete system.
Fast passage without brakes
The method has another fundamental limitation: Once the laser array has accelerated the spacecraft, there is no parallel system near the target star to slow it down. The spacecraft will not enter orbit around the planet, but will instead pass through the system at enormous speed. The main observation window will last hours or days, depending on the orbit and the size of the area being studied, after which the collected data will need to be slowly transmitted.
In the near term, solar sails could aid in missions within the solar system: encounters with comets in difficult orbits, tours among asteroids, extended observations of the Sun, and even unconventional orbits over the Earth's poles. Such missions would provide experience in deploying large membranes, navigating using light pressure, and operating lightweight spacecraft for extended periods of time.
Sails of light They do not therefore guarantee a close visit to LHS 1140b, but they mark an important transition from science fiction to engineering research that can be defined, calculated and tested. The first interstellar journey, if it comes to fruition, will probably not be a manned flight or even a large spacecraft, but a smart chip attached to a thin sail – a small robotic messenger that will quickly pass through the nearest star system.
Questions and Answers
Does a spacecraft already exist that can reach another planet?
No. Several components, including solar sails, tiny sensors, and phase-locked laser arrays, are in various stages of development, but an integrated system capable of accelerating a spacecraft to 10%–20% of the speed of light does not yet exist.
How long will a journey to LHS 1140b take?
The star is about 48 light years away. At 20% of the speed of light, the journey would take about 240 years, and signals from the spacecraft would need another 48 years to return to Earth.
What is the difference between a solar sail and a laser-powered light sail?
A solar sail harnesses the pressure of sunlight and is best suited for travel within the solar system. A laser-powered sail is pushed by a much more powerful artificial beam, so it can reach speeds suitable forInterstellar travel.
Why won't the spacecraft stop near the target star?
The accelerating laser array remains near Earth, and there is no parallel array in the target system to slow the spacecraft. Therefore, the basic design is for a rapid transit and for taking photographs and measurements during it, not for entering orbit.
More on the subject on the science website
- Hidden physics complicates the dream of launching sailing spacecraft to distant stars
- How to fly to the star Alpha Centauri at almost the speed of light
- The Israeli astrophysicist's journey to Proxima Centauri
- A small satellite with a solar sail could catch the next passing interstellar object
- A planet has been discovered that may allow liquid water - a necessary condition for life
For the scientific article: Opening the scientific article
One response
A fascinating article and pure escapism.
I didn't think about the challenge of stopping a spacecraft at such speed so that it reaches its destination and doesn't just fly past it, and I don't understand how to prevent it from being burned by the powerful laser.
In addition, the main challenge for engineers is to develop a panacea that will help us live 240 years to see it come.