Why You Can't Launch into Space from Certain Planets
Planets are now evaluated not just by whether they can host life, but by whether you can ever leave them. Simulations show: if a planet is more than 11 times Earth's mass, even the mightiest chemical rockets can't loft a payload into space. The gravity of such super-Earths is a trap for any advanced civilization. So which worlds might gift us cosmic neighbors?
Often we talk about searching for life on other planets. But what if even with life present, a civilization simply can’t leave its home world? Researchers from Blue Marble Space built a model to answer this question. They looked at how gravity and an atmospheric blanket hinder ordinary chemical rockets from reaching space. Imagine a deep well: to climb out, you need to push off hard. A planet’s gravity creates just such a “well.” The more massive the planet, the deeper the pit.
Their model combined everything: the size and density of the planet, the thickness of the atmosphere, and engine performance. It turned out that if an exoplanet is about 11.5 times more massive than ours, building the necessary rocket becomes impossible. You’d need over a hundred engines on the first stage—too many for them to work together smoothly. And dense air only noticeably hinders light planets—on large ones, gravity plays the main role. This discovery is important: perhaps many worlds with water and carbon-based organic substances, detected via the transit method, are actually forever closed to space travel.
Such worlds are called super-Earths, and studying them is one of the tasks of the James Webb Space Telescope. Using spectroscopy, it will be able to determine the composition of their atmospheres. Perhaps there is plenty of hydrogen—the most abundant element in the Universe, as first proven by Cecilia Payne-Gaposchkin. But even an abundance of fuel won’t help if there isn’t enough force to overcome gravity. The idea of searching for planets transiting the disk of the Sun or other stars came to William Borucki, and now such observations are revealing more and more distant worlds.
🎯 Even for Earth, the model predicts that one engine would be enough to lift a ton of cargo, but in reality the Voyagers were launched on huge rockets due to complex trajectories.
🎬 This idea recalls the plot of the book 'The Three-Body Problem', where a civilization can't leave its planet because of a chaotic orbit—only in our case, the obstacle is the planet's mass itself.