NASA image of a super-Earth

Why real-life aliens might actually be stuck on their home planets

Contributed by
Apr 24, 2018

Earth may not be the only planet to have spawned intelligent life, but is it the only one that allows that life to escape?

Exoplanets, otherwise known as “super-Earths,” are mega versions of the orb we live on (and possibly uber-habitable), but found out that could mean a failure to launch. More mass means amplified gravity. More gravity means it would take that much more power to break through the atmosphere. More power means more fuel and other resources, which inevitably translates to a higher cost in whatever alien currency might exist out there.

“Many rocky exoplanets are heavier and larger than the Earth, and have higher surface gravity,” said researcher Michael Hippke, who recently published a study on what it would take to launch from a super-Earth in the International Journal of Astrobiology. “This makes space-flight on these worlds very challenging, because the required fuel mass for a given payload is an exponential function of planetary surface gravity.”

Alien civilizations on these types of planets who may be thinking of launching something similar to an Apollo moon mission would need a 440,000-ton rocket — with a significant amount of that being fuel weight — just to achieve liftoff. Super-Earth Kepler-20b is almost as wide as two Earths and ten times more massive, with an escape velocity 2.4 times greater than what is needed to get off our own planet. The rockets that could potentially handle that would make the Falcon Heavy look microscopic.

Satellite TV and anything else that requires spacecraft sent into orbit would also be out of the question unless these hypothetical aliens are exponentially more advanced than we are and have possibly figured out ways to bend the laws of physics.

"I am surprised to see how close we as humans are to end up on a planet which is still reasonably lightweight to conduct spaceflight," Hippke admitted to "Other civilizations, if they exist, might not be as lucky." 

Even aliens whose brains may have not dreamed up anything more extraordinary than human tech could possibly find ways to propel themselves into space. Not that it would be easy; they would probably need some hardcore rocket modifications. A SpaceX Falcon Heavy can blast over 100 tons off Earth, which is more than a loaded Boeing 737 jet, into orbit. Launching a payload like NASA’s James Webb Space Telescope off an exoplanet like Kepler-20b would need 60,000 tons of fuel to burn. That’s an extra 60,000 tons added to over 3 million pounds of metal, still minus the payload.

So when we hear from aliens, if we hear from aliens, it looks like we’re much more likely to get the laser or radio signals that the SETI Institute is constantly watching out for.