A Cosmologist Found a Shortcut to Mars. The Window Opens in 2031 and the Round Trip Takes 153 Days.

A study published in the journal Acta Astronautica by cosmologist Marcelo de Oliveira Souza of the State University of Northern Rio de Janeiro has identified what it calls a “hidden shortcut” to Mars — one that uses the orbital path of an asteroid as the anchor for a trajectory plan that could bring a complete round trip to the Red Planet down to approximately 153 days. The asteroid in question is called 2001 CA21. It crosses the orbits of both Earth and Mars at a consistent five-degree tilt. And in 2031, the orbital alignment of Earth and Mars will be favorable enough that two complete sub-year round trips become mathematically possible using this trajectory. No new propulsion technology is required. No exotic physics. Just a more precise understanding of where everything is going to be and when.

First, some context on why this matters.

Getting to Mars is hard for reasons that go beyond the distance. The average gap between Earth and Mars is about 140 million miles, but that average hides a very wide range. At their closest, Earth and Mars are about 34 million miles apart. At their farthest, they are over 250 million miles apart. The geometry of their orbits means that the window for an efficient trip — called a Mars opposition, when the two planets are on the same side of the sun and relatively close — only opens approximately every 26 months. Miss the window and you are waiting two years for the next one.

Using the best currently available propulsion technology and an optimal launch window, a trip to Mars still takes between five and eleven months one way. Then, once you arrive, you typically have to wait on the surface for the next opposition before the return journey becomes efficient. A round trip under those constraints can easily take two to three years. That is a long time for a human crew to be away from Earth, exposed to radiation, reliant on consumables shipped from home, and living in extremely confined quarters.

Even reducing the round trip by a few months matters enormously for crew health, mission safety, and the logistics of keeping people alive far from any rescue capability.

How the Asteroid Shortcut Works

The key insight in the Acta Astronautica paper is about orbital planes. Earth and Mars orbit the sun at slightly different angles. The standard approach to calculating trajectories between them treats each planet’s orbit in a simplified way. What de Oliveira Souza did was look for an asteroid whose orbit already bridges the orbital planes of both planets — an asteroid whose path through space represents, in effect, a pre-existing highway connecting the two.

Asteroid 2001 CA21 orbits at a five-degree tilt relative to Earth’s orbital plane, crossing the orbits of both Earth and Mars consistently. By anchoring a Mars trajectory to the plane defined by this asteroid’s orbit, de Oliveira Souza calculated that the flight path becomes significantly more efficient than standard approaches, cutting down both the outbound and return legs of the journey.

For the 2031 Mars opposition specifically, he calculated two outbound trajectory options: a 33-day trip and a 56-day trip. With return legs calculated to match, the total round trip architectures come out to approximately 153 days and 226 days respectively. That is not the nine-month to three-year range of current mission planning. That is a round trip to Mars within a single calendar year, using existing technology.

The Caveats

De Oliveira Souza is a cosmologist working from trajectory mathematics, and the paper itself is explicit about what it is and is not claiming. The asteroid is not a physical shortcut — you do not ride it or use it as a gravity assist in the way some missions use Jupiter or Venus for a speed boost. The asteroid’s orbit is used as a geometric reference frame for planning a more efficient trajectory.

The real-world constraints remain substantial. Any Mars mission requires not just trajectory optimization but propulsion capacity, fuel mass, life support, payload weight, radiation shielding, landing and launch systems on the Martian surface, and a hundred other engineering problems that no trajectory calculation resolves. A faster route is not automatically a feasible route.

What the paper provides is a target. The 2031 opposition, mapped against the CA21 orbital plane, offers a geometry that current mission planners have not fully exploited. Whether any space agency or private company is in a position to take advantage of it in five years is a separate question.

But the fact that the shortcut exists in the mathematics — that a faster round trip to Mars is geometrically possible using known physics, not wishful thinking — is exactly the kind of finding that shifts mission timelines from “someday” toward something more specific.

Sources: Acta Astronautica — de Oliveira Souza, Optimized Earth-Mars Round Trip Trajectories Using the CA21 Orbital Plane (2026). DOI: 10.1016/j.actaastro.2026.02.456 — Futurism — There’s a Hidden Shortcut to Mars, Scientific Paper Finds (April 30, 2026) — Earth.com — An Asteroid May Hold the Key to Cutting Mars Travel Times Far More Than Anyone Expected (April 2026) — Unexplained Mysteries — Cosmologist Discovers Potential New Way to Reduce Mars Travel Time (April 30, 2026)