Although Mars is our cosmic neighbor, traveling there – about 225 million kilometers away of the Earth, on average – is far from a short walk. With current propulsion technology, a spacecraft would take between five and eleven months to reach the red planet. And that’s just on the outward journey.

The most complicated thing is that the manned missions planned today could last about three years, since the astronauts would have to wait for the proper alignment to undertake the return: an orbital window that only opens approximately every 26 months during the so-called “Mars oppositions”, when the distance between the two planets is reduced.

An unexpected trajectory discovered by accident

But a new orbital analysis raises an unexpected possibility. Brazilian cosmologist Marcelo de Oliveira Souza, from the State University of the North of Rio de Janeiro, believes he has found a shortcut – and he found it by accident –: a theoretical trajectory that would allow a round trip to Mars to be completed in less than five months.

In 2015, while studying near-Earth asteroids, Souza noticed one in particular: 2001 CA21. The first estimates of its trajectory – recorded before later observations refined its real orbit – drew an unusual orbit, capable of approaching both the path of the Earth and that of Mars within a plane inclined just five degrees. “This was a surprise to me; I wasn’t looking for this,” he told Live Science.

The trick is that those initial estimates are technically wrong. As observations accumulate, the asteroid’s actual orbit is refined and the original trajectory is discarded. But Souza saw something useful in that error: an orbital configuration that seemed to favor fast trajectories between the two planets. “Maybe I was in the right place at the right time,” he admitted.

How to calculate the shortest route to Mars

From that peculiar orbital configuration, Souza resorted to Lambert analysis – a standard method for calculating trajectories between two points in space – and restricted the routes to a margin of five degrees with respect to the inclination of CA21. He then examined the Mars oppositions predicted for 2027, 2029 and 2031. According to calculations, only the 2031 scenario offered a geometry compatible with such a short transfer.

The results, published in the journal Astronautics Act, They are striking. According to the study, the fastest configuration contemplates a departure from Earth on April 20, 2031, an arrival at Mars on May 23 after just 33 days of travel, about 30 days on the surface and a return on September 20. Complete round trip: 153 days. A second option, less energy demanding, would complete the mission in about 226 days.

Extreme speeds, new generation rockets

The necessary speeds are high – about 27 kilometers per second in the fast option – but comparable to those of missions such as New Horizons, the probe that was launched in 2006 at 16.26 km/s towards Pluto. Next-generation rockets such as SpaceX’s Starship or Blue Origin’s New Glenn could approach the necessary speeds, according to Souza himself. Live Science.

For now, everything remains in the realm of simulations and orbital models. Whether these routes can one day be used will depend on multiple technical factors, from the weight of the ship to the power of its engines. But the discovery opens a methodological door: preliminary asteroid orbits, historically used to assess impact risks and then archived, could help identify faster interplanetary trajectories. “Maybe this can change the idea that we need more than two years to go to Mars and back,” Souza said.