The article limits itself to chemical rockets. They work well enough on Earth so that's what we are using, but we can do better. Replace chemistry with nuclear,

The article limits itself to chemical rockets. They work well enough on Earth so that's what we are using, but we can do better. Replace chemistry with nuclear, and use the air in the atmosphere as a reaction mass. On Earth, that would cause more problems than it would solve, that's why we don't do that despite having the tech to do it. But on a higher gravity planet it may be what we would do. Harder, but not impossible. It is interesting how we got nuclear technology that would allow for way more capable rockets at the same time we perfected chemical rockets enough to get to orbit. So much that we could have been able to escape a 10g planet almost as soon as we have escaped Earth.