Brazilian cosmologist identifies potential 153-day shortcut to Mars

Getting to Mars has always been a problem of patience. The planet sits roughly 225 million kilometers away on average, and with current rocket technology, a spacecraft needs five to eleven months just to make the journey one way. But the real constraint isn't the outbound trip—it's the return. Astronauts would have to wait for the planets to realign properly, a window that opens only every 26 months or so during what astronomers call Mars oppositions. This means a crewed mission to Mars, in practice, would consume nearly three years of time: months getting there, months on the surface, months waiting, months coming home.

Marcelo de Oliveira Souza, a cosmologist at the State University of Northern Rio de Janeiro, stumbled onto something that might change that arithmetic. In 2015, while examining asteroids that pass near Earth, he noticed one called 2001 CA21. The preliminary orbital calculations for this asteroid—made before later observations refined its actual path—showed something unusual: a trajectory that could swing close to Earth's orbit and then close to Mars's orbit, all within a plane tilted just five degrees from the ecliptic. "This was a surprise to me; I wasn't looking for this," Souza told Live Science. He had found something by accident.

The irony is that those initial calculations were technically wrong. As astronomers gather more data on an asteroid, they refine its true orbit, and the old estimates get filed away and forgotten. But Souza recognized that this discarded trajectory—this error—described an orbital geometry that could theoretically enable fast transfers between Earth and Mars. He wasn't studying Mars routes at all. He was looking at asteroid data and saw a door that nobody else had noticed was there.

Using a standard mathematical method called Lambert analysis, Souza restricted his search to orbital paths within five degrees of the asteroid's inclination, then examined the Mars oppositions scheduled for 2027, 2029, and 2031. Only the 2031 alignment, his calculations showed, would offer the right geometry for such a dramatic shortcut. The numbers he published in the journal Acta Astronautica are striking: a spacecraft could depart Earth on April 20, 2031, arrive at Mars on May 23 after just 33 days of travel, spend 30 days on the surface, and return on September 20. Round trip: 153 days. A second, less demanding option would stretch the mission to about 226 days.

The catch is speed. The fastest route would require velocities around 27 kilometers per second—faster than most spacecraft have ever traveled, though comparable to the New Horizons probe, which launched toward Pluto in 2006 at 16.26 kilometers per second. Souza believes next-generation rockets like SpaceX's Starship or Blue Origin's New Glenn could theoretically approach these velocities. But everything remains theoretical for now. Whether such a route could actually be flown depends on countless variables: the weight of the spacecraft, the power of its engines, the ability to sustain human life at such speeds and accelerations.

What makes this discovery methodologically significant is that it suggests a new use for old data. Preliminary asteroid orbits have historically been calculated to assess impact risks and then archived. Souza's work hints that these discarded trajectories might contain hidden pathways for faster interplanetary travel. The conventional wisdom has long held that Mars missions require more than two years from launch to return. If this route proves viable, that assumption might need revision. For now, it remains a mathematical possibility—but one that opens a question nobody was quite asking before.