A probe to another star

How far are we from a laser-pushed probe that could reach another star?

A laser can push a very light reflective sail, and a 2000 NASA JPL test showed this effect in a vacuum chamber. No laser-propelled spacecraft has flown. The sail stability work reviewed is computer modelling. The beam array, the energy system and the probe's return link to Earth have not been shown to work at the scale an interstellar mission would need. Breakthrough Starshot, the best-known proposal, was reported in September 2025 to be on hold.

AI illustration · Illustrative scene, not a photograph of the specific device or experiment.
WHERE WE AREScience demonstrated

Far away. The science works, but nobody has built a working system yet.

The basic effect has been demonstrated. In 2000 NASA's Jet Propulsion Laboratory reported laser-driven sails moving in a vacuum chamber, with thrust calculated from the sail's motion rather than measured directly. The next stage, an engineering prototype, has not been reached for the whole system: in the sources reviewed, no laser-driven sail has flown and no free-flying sail has been accelerated by a laser, and the sail-stability results for large sails come from simulation. The stage describes the whole capability, so it is set by the least advanced part, the beam system and the interstellar probe.

The tech tree

Everything recorded on Vrulum that this future needs, oldest foundations at the top and the goal at the bottom. Lines show what each step requires.

What it takes: A probe to another star Unlocked Being researched Locked
  1. 1955Nuclear space propulsion and powerResearch and prototypes Being researched.
  2. 2010Solar sailsResearch and prototypes Being researched.
  3. 2011Metasurface optics and flat lensesResearch and prototypes Being researched.
  1. 2000Laser radiation pressure on a sail shown in a vacuum chamberDone Unlocked.
  2. 2016Funded Breakthrough Starshot research phaseIn progress Being researched.
  3. 2020Communication from a low-mass probe at interstellar distance worked outIn progress Being researched.
  4. 2024Direct force measurement on very thin membranes proposedIn progress Being researched.
  5. 2024Beam-riding stability of flexible sails modelledIn progress Being researched.
  6. Date not recordedFree-flying sail deployed and manoeuvred by light in orbitNot started Locked.
  7. Date not recordedKilometre-scale laser array tracking and accelerating a free-flying sailNot started Locked.
  8. Date not recordedProbe returns science data from another star systemNot started Locked.
  1. GoalA probe to another starGoalRequires: Metasurface optics and flat lenses, Nuclear space propulsion and power, Solar sails, Laser radiation pressure on a sail shown in a vacuum chamber, Direct force measurement on very thin membranes proposed, Beam-riding stability of flexible sails modelled, Communication from a low-mass probe at interstellar distance worked out, Funded Breakthrough Starshot research phase, Free-flying sail deployed and manoeuvred by light in orbit, Kilometre-scale laser array tracking and accelerating a free-flying sail, Probe returns science data from another star system. Locked.

The road so far

1 of 8 steps done, 4 in progress.

  1. Done · Jul 2000Laser radiation pressure on a sail shown in a vacuum chamber

    JPL reported tests in 2000 with lasers of 7.9 to 13.9 kilowatts directed at small sails mounted on pendulums. The photon thrust was calculated from how far the sails moved, not measured directly. The tests were laboratory demonstrations in vacuum chambers, not flights in space. [1]

  2. In progress · Feb 2024Direct force measurement on very thin membranes proposed

    A 2024 arXiv preprint reports direct radiation pressure measurements on a 50-nanometre silicon nitride membrane suspended on compliant micromechanical springs. The authors report radiation pressure forces of 80 femtonewtons at a pump intensity of 100 W/cm². This is a small-scale instrument study. The arXiv page lists no journal publication. It is not a flight test and does not show sail-scale forces. [2]

  3. In progress · May 2024Beam-riding stability of flexible sails modelled

    A 2024 Nature Communications paper develops a multiphysics simulator for flexible lightsails and uses it to analyse their dynamic stability during radiation pressure acceleration. The authors describe laser acceleration to relativistic speeds as conceptually feasible. The results rest on simulation, and the sources reviewed report no sail accelerated in an experiment. [3]

  4. In progress · Jan 2020Communication from a low-mass probe at interstellar distance worked out

    A 2020 arXiv preprint by Messerschmitt, Lubin and Morrison discusses technological challenges in communication from low-mass interstellar probes, framed near Proxima Centauri. The abstract gives no data rates or numeric distances. No probe has yet returned science data from interstellar distance. [4]

  5. In progress · Apr 2016Funded Breakthrough Starshot research phase

    Breakthrough Starshot was announced in April 2016 with a $100 million investment for research and development, aiming at light-pushed nanocraft to Alpha Centauri, with an intended flight time of about 20 years. A September 2025 Scientific American article reports that the programme is on hold, based on an emailed statement from its executive director. The article says one insider put the funding actually disbursed far below $100 million, and notes there was no final announcement. Breakthrough has not made a formal statement in the sources reviewed. [5][6]

  6. Not startedFree-flying sail deployed and manoeuvred by light in orbit

    No source reviewed shows a free-flying spacecraft that deploys a sail and uses photon pressure to manoeuvre in orbit. A demonstration of this kind would test deployment and manoeuvring at lower power and speed before any interstellar mission.

  7. Not startedKilometre-scale laser array tracking and accelerating a free-flying sail

    The Starshot concept needs a ground-based or orbital beam array that is coherent over a large aperture and points accurately at a fast-moving sail. No source reviewed reports an array of this kind, or a test of tracking and accelerating a free-flying sail at any distance.

  8. Not startedProbe returns science data from another star system

    No probe has yet returned science data from interstellar distance. A flyby would have only minutes to observe, and an orbiting mission would need a braking method that no source reviewed has chosen.

Why it matters

A laser-pushed probe would carry very little mass, so it could in principle reach a nearby star in decades rather than millennia. The idea is attractive because the power plant stays at home. The same design choice moves the difficulty into a very large, precisely aimed beam system, which raises questions about cost, energy, safety and governance. Keeping measured results, modelling and proposals apart helps the public judge how close the idea is to working.

What stands in the way

  • No laser-propelled spacecraft has flown, and no source reviewed reports a laser accelerating a free-flying sail.
  • No source reviewed reports a built or tested beam array, energy store or probe at the scale an interstellar mission would need.
  • Sail survival: the stability results for large sails reviewed come from simulation, not from tests at sail scale under full laser intensity.
  • Return link: the 2020 Messerschmitt, Lubin and Morrison preprint identifies communication challenges for low-mass probes, and no source reviewed reports science data returned from interstellar distance.
  • Arrival: a probe accelerated from Earth coasts unless something slows it, and no source reviewed chooses a braking method for a rendezvous.

Signals to watch

  • A free-flying spacecraft deploys a sail and uses photon pressure to manoeuvre in orbit.
  • A laser force experiment shows stable beam-riding under lateral and angular disturbances, not only a static force.
  • A published mass and energy budget for a complete beam array, energy store and probe.
  • Breakthrough Initiatives makes a formal statement on the status of Breakthrough Starshot.
  • Peer-reviewed results from a sail-scale laser acceleration test with a documented uncertainty budget.

Sources

  1. news
    Sail Technology Beamed to Future Space Exploration
    NASA Jet Propulsion Laboratory, 5 Jul 2000.
  2. preprint
    Direct Radiation Pressure Measurements for Lightsail Membranes
    Lior Michaeli, Ramon Gao, Michael D. Kelzenberg et al.. arXiv, 29 Feb 2024.
  3. peer reviewed paper
    Dynamically stable radiation pressure propulsion of flexible lightsails for interstellar exploration
    Ramon Gao, Michael D. Kelzenberg, Harry A. Atwater. Nature Communications, 17 May 2024.
  4. preprint
    Technological Challenges in Low-mass Interstellar Probe Communication
    David Messerschmitt, Philip Lubin, Ian Morrison. arXiv, 24 Jan 2020.
  5. news
    Russian billionaire Yuri Milner invests $100M to send a fleet of spacecraft to Alpha Centauri
    Jordan Crook. TechCrunch, 12 Apr 2016.
  6. news
    How a Billionaire's Plan to Reach Another Star Fell Apart
    Sarah Scoles. Scientific American, 16 Sept 2025.

Last reviewed 21 Oct 2026.