Gravity Trap: Some Aliens Might Have A Hard Time Escaping Their Homeworlds

Are we alone in the universe? Is no one else out there, exploring the vast expanse of space? Well, according to a new study, our apparent solitude might have something to do with the gravity on other planets.

That is, some alien civilizations may not be able reach the stars at all.

Researcher Michael Hippke of the Sonneberg Observatory in Germany recently published a study titled “Spaceflight From Super-Earths Is Difficult.” In it, he explored the idea that aliens inhabiting massive planets, often known as “super-Earths,” would have a much harder time entering space than we do here on Earth, due to their planets’ much greater gravitational pulls.

The amount of fuel and other costs needed for the launch of a chemical rocket, he says, would likely “become unrealistic” for planets greater than 10 times the mass of Earth:

“We find that chemical rockets still allow for escape velocities on Super-Earths up to 10× Earth mass. More massive rocky worlds, if they exist, would require other means to leave the planet…”

Ironically, as Hippke points out, while these super-Earths might not be great for sending up rockets, they may be considered “super-habitable,” as their higher gravity would mean thicker atmospheres and, therefore, “better shielding for life on the surface against harmful cosmic rays.”

Even so, if chemical rockets are out of the question, super-Earthlings could employ nuclear propulsion or space elevators to get going. These, however, are not without their own problems.

Hippke also considers the fate of “waterworlds” — planets inhabited by intelligent life living in water or sub-surface oceans. Would they be able to launch anything?

“These aquatic launch complications make the theory of oceanic rocket launches appear at first quite alien; presumably land-based launches seem equally human to alien rocket scientists.”

It’s an interesting thought experiment. The same concept would likely mean that aliens living on planets with lower gravitational pulls would have an easier time lifting off, so maybe that would balance things out.

You can read Hippke’s paper in full at here (PDF here).

If you ask me, though, the single largest variable keeping us from running into other life in the universe, as in alien civilizations, is time. Well, timing.

Life might be very common throughout the cosmos, and it’s possible that spacefaring alien civilizations have cropped up and faded away many, many, many times. But the universe, from what we know, is about 13.8 billion years old. We’ve only been dipping our toes into outer space for about 57 years.

Entire galactic civilizations could have come and gone before we even opened our eyes, and we wouldn’t even know. Heck, we’re only just beginning to explore.

Maybe we’ll find some ancient technology someday, and things will really open up.


Rob Schwarz

Writer, blogger, and part-time peddler of mysterious tales. Editor-in-chief of Stranger Dimensions.

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