For decades, one of the biggest challenges of sending humans to Mars hasn’t just been getting there, it’s getting back. 

Under current mission plans, astronauts could spend nearly three years completing a round trip to the Red Planet. The journey to Mars alone typically takes seven to ten months, and crews then have to wait for Earth and Mars to align again before returning home. 

But now, an accidental discovery published in the journal Acta astronautica and inspired by asteroid trajectories suggests that future Mars missions might one day take less than a year-round trip.  

The idea came from a scientist who was studying near-Earth asteroids - specifically how scientists estimate their trajectories when first discovered. 

One asteroid caught his attention: 2001 CA21. 

Early calculations suggested the asteroid followed an unusual orbital path that crossed both Earth’s and Mars’ orbital regions. Later observations refined the asteroid’s true trajectory, and the original estimates were essentially discarded. 

But the scientist noticed something fascinating hidden inside those early calculations. 

The geometry of the asteroid’s path hinted at an ultra-fast route between Earth and Mars.  

Mars is much farther from the sun than Earth, and the planets are constantly moving around the sun at different speeds. 

To save fuel, spacecraft usually travel along carefully timed transfer orbits that take advantage of planetary alignment. These efficient routes are slower but practical. 

The problem is timing. Earth and Mars only line up properly for these fuel-efficient missions roughly every 26 months. Missing the return window means astronauts could be stranded waiting for another alignment. 

Using the new asteroid-inspired geometry, the researchers calculated that an extremely fast route to Mars could theoretically take as little as 34 days.  

The spacecraft would need to travel at around 32.5 kilometres per second which is far beyond the capabilities of current rockets. 

Also, arriving at Mars would be even more challenging. The spacecraft would hit the Martian system traveling so fast that current landing technologies couldn’t safely slow it down. 

So while the 34-day mission is mathematically possible, it remains impractical with today’s technology. 

Rather than focusing on the impossible extreme case, the researchers explored whether similar geometric paths could work during future Mars alignments using technology that may exist in the near future. 

And one opportunity stood out: the 2031 Mars opposition. 

According to the calculations, astronauts could potentially complete a round trip to Mars in about 153 days (roughly five months), or a lower-energy version lasting around 226 days (about 7.5 months)  

That’s still dramatically shorter than the multi-year missions currently envisioned. 

The proposed mission profile would involve: 

• A 33-day trip to Mars 
• About one month on the Martian surface 
• A 90-day return journey to Earth  

NASA’s NASA probe New Horizons became the fastest spacecraft ever launched from Earth when it left for Pluto at around 16.26 kilometres per second.  

Future rockets like SpaceX Starship or Blue Origin New Glenn may eventually push those limits even further. 

One of the most fascinating parts of this story is that the discovery wasn’t the result of a grand Mars mission plan. It came from a scientist noticing something unusual in old asteroid calculations that everyone else had moved past. 

Breakthroughs don’t always emerge from people searching directly for answers. 

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