I know what it means. I've seen delta-V charts. But I don't know if Robert Heinlein wrote this down, or simply said it off-the-cuff to somebody.

Variations include:

  • "Reach low orbit, and your halfway ..." (See Space Access Society logo http://space-access.org)

  • "Make orbit, and you're halfway ..."

If we want to attribute this to him, a citable source would be handy.

  • 1
    $\begingroup$ This might possibly be on-topic here (not sure), but there is also Science Fiction SE and you are probably going to get faster, better, and more answers there than here. Consider asking there instead? $\endgroup$
    – uhoh
    Commented Mar 24, 2019 at 1:20
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    $\begingroup$ Just for the record, it should be noted that Heinlein seemed to have a good understanding of orbital mechanics. Books he wrote as early as the 1940' describe maneuvers that sound reasonable, not the usual "shoot from earth to mars in a couple hours". $\endgroup$ Commented Mar 24, 2019 at 10:30
  • $\begingroup$ I think 3/4 is more realistic, or even more. $\endgroup$
    – peterh
    Commented Mar 24, 2019 at 12:52
  • $\begingroup$ I don't know where, but it is true because if you escape elliptic gravity then it is so much cheaper to go anywhere you want. Any little thrust any direction is effective immediately. $\endgroup$ Commented Mar 24, 2019 at 14:15
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    $\begingroup$ @DiegoSánchez He not only understood orbital mechanics, he did the math. He and his wife laboriously worked out the orbits by hand any time he had to describe how long or what procedures it would take to get somewhere in the solar system. $\endgroup$
    – Dan Hanson
    Commented Jul 4, 2020 at 18:52

1 Answer 1


This phrase was quoted by Jerry Pournelle in an article entitled "Halfway to Anywhere" first published in the Galaxy Magazine in the April 1974 Issue in his column "A Step Farther Out". This article was then collected with others into his book of the same name.

Here's the article's opening:

One of my rivals in the science-writing field usually begins his columns with a personal anecdote. Although I avoid slavish imitation, success is always worth copying. Anyway, the idea behind this column came from Robert Heinlein and he ought to get credit for it.
    Mr. Heinlein and I were discussing the perils of template stories—interconnected stories that together present a future history. As readers may have suspected, many future histories begin with stories that weren't necessarily intended to fit together when they were written. Robert Heinlein's box came with The Man Who Sold the Moon. He wanted the first flight to the moon to use a direct Earth-to-moon craft, not one assembled in orbit—but the story had to follow Blowups Happen in the future history.
    Unfortunately, in Blowups Happen a capability for orbiting large payloads had been developed. "Aha," I said. "I see your problem. If you can get a ship into orbit, you're halfway to the moon."
    "No," Bob said. "If you can get your ship into orbit, you're halfway to anywhere."
    He was very nearly right.

You can also read the whole article.

  • $\begingroup$ Okay, this seems to be the unanimous answer. $\endgroup$
    – Rick 0xfff
    Commented Mar 26, 2019 at 0:20

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