Yubileiny: Russia’s Launch of an Experimental “Reactionless” Drive

December 29, 2025

In 2009, Russian headlines carried an unexpected story: the educational satellite Yubileiny—launched the year before to commemorate the 50th anniversary of Sputnik 1—was reportedly testing an experimental “reactionless” drive: no propellant, no exhaust, just a sealed device meant to produce thrust from internal motion. If it worked, it would have rewritten propulsion overnight. If it didn’t, it would still provide a revealing case study in how unconventional ideas move from private benches into public missions—where data decides what’s real.

Mission Context: How Yubileiny Became a Testbed

In May 2008, Russia launched the educational satellite Yubileiny on a Rokot/Briz-KM from the Plesetsk Cosmodrome’s LC-133/3—a commemorative spacecraft tied to the 50th anniversary of Sputnik 1.

Within roughly a year, the satellite became linked—at least in press reporting and commentary—to an unusual experiment: a device that allegedly could generate propulsion without expelling reaction mass. The terminology varied—“reactionless,” “supportless,” “inertial,” “without reactive mass ejection”—but the promise stayed the same.

“The Moscow-region Institute of Space Systems reports that it tested in space a thruster that operates without expelling reaction mass.”
— Infox.ru, “A Perpetual-Motion Machine Puts Space to the Test” (translated)

As soon as those claims surfaced, the story split into two narratives. In one, Yubileiny was a quiet test of a potentially transformative technology for small spacecraft and long-duration missions. In the other, it was a textbook setup for false positives: a bench effect elevated to an orbital claim without the measurement discipline needed to survive scrutiny.

Either way, Yubileiny became a rare case where a “reactionless propulsion” idea wasn’t confined to conference whispers or lab anecdotes. It was tied to a named spacecraft and a specific period of alleged testing—inviting a public dispute about what telemetry and orbit tracking did, or did not, show.

People and Institutions: Polyakov, Menshikov, and the Khrunichev Ecosystem

At the center of many accounts is Spartak M. Polyakov, often described as the originating inventor behind a propellantless concept—an idea pursued for years and framed in some sources as a “gravity engine” or “gravitation engine,” and in others as a mechanical way to extract net thrust from internal motion.

The institutional champion most often associated with moving the concept toward a flight opportunity is Valery A. Menshikov, a senior figure in the Khrunichev-adjacent space-industrial ecosystem. In the public storyline, Menshikov plays the bridge role: translating an inventor’s apparatus into something that can be integrated, manifested, and plausibly defended as a “space experiment.”

Because Russian reporting and later commentary often compresses names, titles, and institutional relationships, secondary discussions can sometimes blur attribution—especially when the topic sits on the boundary between engineering work, promotional framing, and skeptical critique. That name-blurring is part of why this episode became as much a media and governance story as a technical one.

A parallel documentary trail appears in Alexander V. Frolov’s New Energy Technologies magazine, which preserved mechanism descriptions and recurring names that mainstream reporting often treated as too fringe—or too awkward—to detail carefully.

The Proposed Mechanism: Vortex Trajectories, Mercury, and Axial Impulse

The most concrete descriptions of the device family are disarmingly physical: a conical or spiral path and a working mass—often described as mercury—driven into a controlled swirling motion. The central claim is that a “tornado-like” internal trajectory can yield a net force along the device’s axis.

One frequently described configuration uses a cone-spiral tube aligned with the axis. A motor and pump drive the working fluid through a helical geometry, and the claimed thrust appears when the fluid’s motion differs from the structure’s motion—especially during regimes where the working mass is perpetually “catching up.”

“‘Gravitsapa’ is ‘a device for continuous movement without consuming working mass,’ a ‘thruster without expelling reaction mass.’”
— Gazeta.ru, “What ‘Gravitsapa’ Are Russian Scientists Testing?” (translated)

That speed-differential detail also contains the warning label. In multiple accounts, the effect is strongest during startup and then fades as the system approaches steady state—once the working mass and the structure “match,” the claimed axial thrust collapses toward zero. This is a familiar signature in many inertial-drive demonstrations.

Designers tried to engineer around that limitation by shaping geometry so the mismatch persists: conical rotors, spiral channels, changing radii, and deliberate non-equilibrium flow intended to keep the working mass perpetually out of sync. In that framing, what begins as a transient impulse is meant to become a sustained, controllable push.

Conceptual Backstory: Why “Reactionless Propulsion” Keeps Returning

The Yubileiny device didn’t emerge in a vacuum. It belongs to a long-running family of proposals often grouped under inertial drives or inertioids—mechanisms attempting to create net thrust by cycling internal masses, changing radii, shifting angular momentum, or shaping trajectories in ways proponents argue don’t fully cancel.

This family has a distinctive global pattern. Bench demonstrations can look persuasive—especially on flexible rigs or imperfect scales—because vibration, asymmetric friction, structural compliance, thermal drift, and subtle couplings to the environment can produce a one-direction “walk” that disappears in better-controlled conditions.

Russia’s version of the story is shaped by language and institutional culture. Labels like “supportless motion” and “engines on new physical principles” can create an umbrella where unconventional proposals sit near legitimate advanced propulsion work, sometimes in the same media stream—making boundary policing as much institutional as scientific.

Russian innovators frequently cited in “reactionless propulsion” discussions include Valery A. Menshikov, Vladimir N. Tolchin, Gennady I. Shipov, Anatoly E. Akimov, Spartak M. Polyakov, Vladimir S. Leonov, and Viktor S. Masalov.

Why Orbit Matters: Testing Propellantless Thrust in Free Fall

On Earth, almost any “reactionless” claim has a built-in enemy: hidden coupling to the environment. Bearings push on axles; axles push on frames; frames push on floors; floors push on Earth—and small unaccounted forces can masquerade as propulsion when they’re really bookkeeping errors.

Orbit is supposed to end that argument. A satellite is a free body: no floor, no tether, no traction. If an internal machine generates net thrust, the spacecraft’s motion should show it—not as vibration, but as a measurable change in orbit or tracking residuals correlated with commanded activation windows.

That is why the Yubileiny experiment mattered even to skeptics. An on-orbit test doesn’t automatically prove a claim, but it raises the standard: if thrust exists, it should leave a signature that survives careful modeling of drag, solar radiation pressure, attitude effects, and other known perturbations.

Once a claim is tested in space, the scoreboard becomes unforgiving. If the orbit doesn’t respond in the expected way, there is little room left for interpretation—only narrowing explanations for what was actually being measured in ground tests.

Authorization and Risk: How an Unconventional Payload Gets Flown

If this were purely an engineering story, the sequence would be simple: launch, activation, telemetry, conclusion. Instead, Yubileiny’s propulsion claim unfolded like a procedural drama—who had authority to activate it, who would claim success, and who would carry the reputational cost if it failed publicly.

Some reporting framed the project as requiring sensitive approvals and creating internal discomfort—suggesting the controversy was institutional as much as technical. That matters because flight experiments are never just hardware; they are commitments of credibility.

Another recurring thread is ambiguity about ownership and certification. When experimental payloads fly on small educational or auxiliary spacecraft, oversight and branding can be looser than on flagship missions—creating space for borderline ideas to be manifested with fewer bureaucratic barriers.

This is the paradox at the heart of the story. The device was pitched as ambitious innovation, yet also carried the posture of something not everyone wanted to endorse officially. Yubileiny’s educational identity became part of the pathway that allowed the experiment to fly.

On-Orbit Claims vs. Public Evidence: What Can Be Verified

By mid-2009, accounts described preliminary tests as “mixed” or “ambiguous,” with developers and supporters arguing the results were encouraging while critics argued the effect would not survive proper orbital verification. The stated goal remained consistent: maneuvering without propellant—moving between orbits using internal motion powered by electricity.

Later reporting described more explicit activation windows and “full-scale” experimentation. But the central verification question never changed: did the satellite’s orbit change in a way that required a propellantless thrust explanation?

“The thruster—renamed ‘gravitsapa’ by journalists—did not change the satellite’s orbit by even a micron.”
— In Defense of Science, “Bulletin No. 9” (translated)

Publicly available reporting did not converge on an engineering-grade dataset capable of settling this transparently—no complete thrust-versus-time profile, no released orbit determination residuals, no full thermal/attitude coupling analysis. That absence of open telemetry became part of the story.

The most explicit high-profile rejection came from Eduard P. Kruglyakov, associated with the Russian Academy of Sciences’ anti-pseudoscience efforts. His assessment was blunt: the device did not produce the claimed orbital effect—often summarized as failing to shift the orbit by even a tiny, measurable amount.

Failure Modes and Competing Explanations: Artifact or New Physics?

The mainstream physics objection is direct: internal forces cannot accelerate the center of mass of an isolated system. A mechanism can slosh a working mass around a cone and trade momentum between components—spin up, spin down, vibrate—but the total momentum remains what it was unless something external is pushed on.

The engineering critique focuses on the most common failure mode in this genre: transient effects misread as thrust. When a working fluid spins up, friction regimes change, mounts flex, and vibration can bias scales or create directionality through asymmetric constraints. These effects can look like a real force on the bench while producing zero net external thrust in free fall.

At the same time, proponents often aim beyond transients. The vortex-drive logic is an attempt to create a continuous asymmetry—preserve a persistent mismatch between the working mass and the structure through geometry and flow, forcing the system away from equilibrium in a way that proponents hope yields steady axial force.

That is the emotional core of reactionless propulsion: the belief that inertia has a “handle” geometry can grab, and that internal choreography can be rectified into one-way motion. It’s also exactly where standard mechanics insists the bookkeeping won’t allow a closed system to cheat.

A Modern Test Plan: What Would Settle the Question Today

A credible modern retest would start with measurement, not rhetoric. A contemporary spacecraft can carry precise orbit determination, high-rate inertial sensors, and exhaustive power/thermal/attitude logging—enough to separate genuine along-track acceleration from internal vibration or thermal effects.

The protocol would be designed to discriminate internal dynamics from external thrust: controlled duty cycles, multiple attitudes, matched thermal conditions, and observation windows long enough to extract small accelerations against drag, solar radiation pressure, and outgassing models.

Most importantly, the hypothesis and detection threshold would be pre-registered. A claim like “an along-track acceleration of X ± Y occurs during on-windows and disappears during off-windows at confidence Z” can be tested cleanly, and a null result becomes scientifically valuable rather than politically ambiguous.

Such a test would either produce the first credible, instrumented reactionless thrust signal in history—or it would confirm what the Yubileiny episode suggests: a device can appear persuasive on the bench, fly on a real mission, and still produce no propellantless push once the only judge that matters is the math of motion.