- TARS uses sunlight to spin a sail and fling probes interstellar.
- The system weighs 1.6 kg and uses existing carbon nanotube materials.
- Enhanced versions could theoretically reach 0.3% of light speed.
David Kipping had spent years watching interstellar travel concepts die on arrival.
The Columbia University astronomer knew the physics of Breakthrough Starshot, the $100 million plan to send an interstellar probe at 20% of light speed using giant lasers. Almost a decade after its 2016 announcement, the project kept hitting engineering walls.
Building a 100-gigawatt laser array remained politically and financially out of reach.
Key figure
1.6 kg
Total mass of a TARS system built from commercially available materials
A Flywheel Powered by Sunlight
So Kipping asked a different question: could sunlight alone fling a probe beyond the solar system?
His answer, published on arXiv in July 2025 with Columbia engineering student Kathryn Lampo, is called TARS: a Torqued Accelerator using Radiation from the Sun. The name nods to the robot companion in Christopher Nolan's film "Interstellar."
The concept works like a mechanical battery. Two thin surfaces, one reflective silver and one dark, connect through a ribbon of carbon nanotube material just 2.8 microns thick.
In orbit around the Sun, differential radiation pressure on each side makes the whole structure spin, storing energy with every rotation.
What is a quasite orbit?
A quasite is an artificial orbit where solar radiation partially offsets gravity, letting a structure circle the Sun more slowly than Kepler's laws predict. This keeps TARS stationed close to the Sun for maximum energy collection instead of drifting outward.
After roughly a year of spinning up, TARS reaches its critical breakup speed.
A phone-sized microchip payload at the tip is flung free, like a stone from a sling.
How Fast Can a Solar-Flung Interstellar Probe Go?
In its basic configuration, the payload departs at 40.4 kilometers per second, barely exceeding the solar system's escape velocity.
The interstellar probe needs no onboard fuel.
The entire ribbon spans 63 meters long and 7 meters wide, yet weighs just 1.6 kilograms. Kipping and Lampo chose carbon nanotube sheets sprayed with nanostructured silver, all commercially available today.
That baseline speed matches Voyager 1, which is respectable but far from relativistic.
Kipping and Lampo outline several ways to push further: eccentric orbits exploiting the Oberth effect, gravity assists from Jupiter, and using the released payload as a small solar sail on its way out. The most ambitious option involves electrically charging the ribbon's tips, creating a rotating dipole that resists centrifugal force and permits much faster spins.
Their calculations suggest a theoretical ceiling of about 1,000 kilometers per second, or 0.3% of the speed of light. At that velocity, reaching Alpha Centauri would take roughly 1,300 years.
People say, why not wait three centuries until someone invents a warp drive. I say, why not get started now because there's no guarantee of that happening.
David Kipping, Columbia University
Building for Generations, Not Headlines
Kipping is candid about the limits. No human passenger would survive the g-forces involved. No single interstellar probe will reach another star system in anyone's lifetime. The paper stops short of claiming the design is definitively practical.
What makes TARS compelling is its accessibility.
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→The materials already exist. The physics requires no new discoveries. And the system can launch multiple probes in sequence, forming daisy-chain relay networks across deep space for data transmission back to Earth.
Kipping also envisions closer applications. Multiple TARS units parked in Mars orbit could generate localized magnetic fields, potentially shielding surface bases from ionized solar radiation.
The concept emerged from Kipping's Cool Worlds Lab at Columbia, partly funded by donations from his YouTube audience. He has placed TARS in the public domain, inviting engineers worldwide to refine the design.
Interstellar travel remains a problem of patience as much as physics. TARS does not solve it. But it offers something most grand proposals cannot: a starting point built from materials already on the shelf.
Sources
- Primary Source: Torqued Accelerator using Radiation from the Sun (TARS) for Interstellar Payloads (arXiv, Kipping & Lampo, July 2025)
- Additional Context:
Fact Check: Claim-by-Claim Verification Verified
The article accurately summarizes the TARS concept from the primary arXiv paper by Kipping and Lampo, with correct details on design, performance, and limitations.
Commentary
- Baseline spin-up ~1 year approximate; paper gives examples like 3 years for similar config.
- Breakthrough Starshot announced 2016 with ~100 GW laser challenges, as stated.
- Mars shielding and daisy-chain relays are speculative extensions discussed in paper.
Sources used for verification
Academic/Peer-reviewed:
Other reliable sources:
- A Space Catapult with Interstellar Potential - centauri-dreams.org
- Spacecraft launcher named for robot in 'Interstellar'... - space.com
- Breakthrough Starshot - breakthroughinitiatives.org
- David Kipping - astro.columbia.edu
Fact-checked by Perplexity Sonar Pro on 2026-03-11
