Farmer in the Sky by Robert A. Heinlein

cynical type. Me, I'm cynical, but George is usually naive. “In that case, George, there is no use in having psycho tests at all, not if people like that can sneak past.”
    “Contrariwise. The tests are usually honest. As for those who sneak past, it doesn't matter. Old Mother Nature will take care of them in the long run. Survivors survive.” He finished dealing and said, “Wait till you see what I'm going to do to you this hand. You haven't a chance.”
    He always says that. I said, “Anybody who would use public office like that ought to be impeached!”
    George said mildly, “Yep. But don't bum out your jets, son; we've got human beings, not angels, to work with.”
    On the twenty-fourth of August Captain Harkness took spin off and started bringing us in. We decelerated for better than four hours and then went into free fall about six hundred thousand miles out from Jupiter and on the opposite side from where Ganymede was then. Weightlessness still wasn't any fun but this time we were ready and everyone got shots for it who wanted them. I took mine and no nonsense.
    Theoretically the Mayflower could have made it in one compound maneuver, ending up at the end of deceleration in a tight circular orbit around Ganymede. Practically it was much better to sneak in easy and avoid any more trouble with meteorites—with the “false rings,” that is.
    Of course Jupiter doesn't have rings like Saturn, but it does have quite a lot of sky junk traveling around in the same plane as its moons. If there were enough of it, it would show up like Saturn's rings. There isn't that much, but there is enough to make a pilot walk on eggs coming in. This slow approach gave us a fine front seat for a tour of Jupiter and its satellites.
    Most of this stuff we were trying to avoid is in the same plane as Jupiter's equator, just the way Saturn's rings are—so Captain Harkness brought us in over the top of Jupiter, right across Jupiter's north pole. That way, we never did get in the danger zone until we had curved down on the other side to reach Ganymede—and by then we were going fairly slow.
    But we weren't going slow when we passed over Jupiter's north pole, no indeedy! We were making better than thirty miles a second and we were close in, about thirty thousand miles. It was quite a sight.
    Jupiter is ninety thousand miles thick; thirty thousand miles is close—too close for comfort.
    I got one good look at it for about two minutes from one of the view ports, then had to give up my place to somebody who hadn't had a turn yet and go back to the bunk room and watch through the vision screen. It was an odd sight; you always think of Jupiter with equatorial bands running parallel across it. But now we were looking at it end on and the bands were circles. It looked like a giant archery target, painted in orange and brick red and brown— except that half of it was chewed away. We saw it in half moon, of course.
    There was a dark spot right at the pole. They said that was a zone of permanent clear weather and calm and that you could see clear down to the surface there. I looked but I couldn't see anything; it just looked dark.
    As we came over the top, Io—that's satellite number one—suddenly came out of eclipse. Io is about as big as the Moon and was about as far away from us at the time as the Moon is from the Earth, so it looked about Moon size. There was just black sky and then there was a dark, blood red disc and in less than five minutes it was brilliant orange, about the color of Jupiter itself. It simply popped up, like magic.
    I looked for Barnard's satellite while we were close in, but missed it. It's the little one that is less than one diameter from the surface of Jupiter—so close that it whirls around Jupiter in twelve hours. I was interested in it because I knew that the Jovian observatory was on it and also the base for Project Jove.
    I probably didn't miss anything; Barnard's satellite is only about a hundred and fifty