Do Super-Earths Trap the Civilizations On Them?https://www.psychologytoday.com/us/blog/world-wide-mind/201211/do-super-earths-trap-the-civilizations-themSuper-Earths are massive, but that doesn't mean their gravity is crushing. In fact, bigger planets may be even better for space travel than Earth is.
... the formula for calculating a planet’s surface gravity: mass divided by the radius squared. That is, SG=M/R^2.
Let’s try it with HD 40307g, using data from the Habitable Exoplanet Catalog. Mass, 8.2 Earths. Radius, 2.4 times that of Earth. That gets you a surface gravity of 1.42 times Earth.
It seems counterintuitive, doesn’t it? How can a planet be so much more massive than Earth yet have only 1.42 times the gravity at the surface? The answer lies in the radius. The further you are from the planet’s center, the less its gravity pulls at you. Another way of putting it is that the greater the planet’s radius is for its mass, the less dense it is.
So it’s all about the radius.
That just leaves tornado-like winds and UV & radiation from flares. Which may not be a 'given'
It doesn't follow that a tidally-locked planet would not have a magnetic field. If anything, it would have a very strong field.
Exoplanet, Mass, Radius, Surface Gravity
Gliese 581g 2.60 1.4 1.33
Gliese 581d 6.90 2.2 1.43
Gliese 667Cc 4.90 1.9 1.36
Kepler 22b 6.40 2.1 1.45
HD40307g 8.20 2.4 1.42
HD85512b 4.00 1.7 1.38
Gliese 163c 8.00 2.4 1.39
Fictional Planet 8.00 2.83 1.00
Escape velocity, however, would be higher.
It’s a function of both mass and size. If Fictional Planet was four times Earth’s mass and had two Earth radii, its surface gravity would still be 1g, but you’d need to go only 41% faster to get away from it permanently.
Surface gravity and escape velocity are both related to size and mass, but differently. Fictional Planet would be just as comfortable as Earth in terms of gravity, but more expensive to leave.
Far from being gravitational traps, super-Earths should be positive incubators of spacefaring civilizations. They have 8 times the resources.