It's the 'unintentional' that is a stickler. With the shuttle entries I think they had a 2 degree window on the angle of their trajectory. Shallower than that, and you skip like stone off the top of atmosphere. Deeper than that and you hit thick atmosphere before you've shed enough speed, and you crisp.
The second factor is that an unintentional landing puts you down in a random place. On this planet random gives you a big chance of going 'splash' Early space flights deliberately did wet landings because they couldn't maneuver. A carrier can maneuver.
On LEO orbits, the change in velocity isn't big. 1/2 to 1 km/sec? Rest is done by the atmosphere. On something like the shuttle loss of power would doom the ship. It was fly by wire with a lot of computing happening between the joystick and the controls. I don't know if a fully manual landing was even possible.
The shuttle goes through several regimes -- initially there's not enough air for controls to bite, so it's done with thrusters. Then there is a hypersonic phase where it's at many multiples of the speed of sound. Then supersonic, then subsonic. The controls react differently at each stage. Without power you don't have instruments.
On a blunt re-entry body, I don't know how much it matters, as long as the load is balanced. There were reasons the early astronauts make jokes about being 'spam in a can'
The blunt capsules required parachutes to land.
The effect of a jovian mass passing the earth at a distance that didn't destroy the earth with tides I don't think would have much effect on an Earth orbiter, but I'd have to spend couple of days playing with an orbital simulator to convince myself one way or the other.
However: Our jupiter has an intense magnetic field, whcih traps lots of protons from the solar wind. They are lethal. So your re-entry isn't planned, but it is intentional. Someone realizes that there is a cloud of high energy particles and you have to scramble to get to the re-entery vehicle. The magnetic field can fry the main ships electronics. The initial descent scenario is blast. Shut down all electronics. Wait to swing around to the back side of earth. start the electronics, and make a landing.
In passing a two body encounter cannot make a capture. Baring collision they do a hyperbolic orbit around each other. If there is a third body involved, then it's possible.
This is relevant only if you are planning on the jovian body grabbing the earth and taking it with it. A far more likely event is that the earth will be thrown in a far more elliptic orbit, or just ejected from the system.
Gravitational energy is a conservative field. No friction. A body approaches, speeds up, passes, slows down. The slowing is equal to the speeding. The flypast is symmetrical. The total of gravitational potential energy and kinetic energy remains constant.
This one is a bit clearer:
However real captures are extremely improbable. But we've had 4-5 billion years to play cosmic pool with our solar system. You're seeing the pool sharks. The chumps and marks ended up in Jupitar, the sun, or cast into the outer darkness where there is much wailing and gnashing of teeth.