Sometimes writing history means fixing our own mistakes.
Where do mistakes in history come from? I can think of four examples.
In The First Space Race: Launching the World's First Satellites, 499 endnotes and six years of work didn't prevent us from being wrong about a test launch of the Viking sounding rocket. I had used a single source, an interview, and I'd written a comment down wrong and never went back to check. So this is a case where the historian (me) wasn't careful.
Other times, we just miss something. I'd written that the model of the US Explorer 1 satellite displayed at a post-flight press conference was black and white, based on a photograph. It wasn't: in all that research, co-author Erika Vadnais (nee Lishock) and I never learned that there was a color version of the photo which showed the model was colored copper and blue. Another way to miss something is not to talk to the original sources if available: all museum models of Explorer 1 are black and white, but the payload engineer, then (1999) still alive, told us the flight article was bare stainless steel with white striping, and historian John Bluth at NASA JPL dug out a previously unpublished photograph that demonstrated that recollection was right. (The museum models, all of them, are still wrong, and we've made no headway in getting that fixed.)
Explorer 1 (shown here with Sputnik 1) as it did NOT appear.
Third, a historian can publish the best available material only to have future material declassified or discovered after publication. This isn't the historian's fault, but it needs to be fixed whenever possible. (alas, First Space Race didn't sell well enough to get a second edition. I have covered all the mistakes and new information in this blog and elsewhere: you may think that's not really adequate, but I've done the best I can.)
Fourth, historians can repeat something without checking. The memoir of Wernher von Braun's US Army boss, General Bruce Medaris, said that the first orbit of Explorer 1 was verified by the announcement "Goldstone has the bird." This seemingly authoritative quote went into every subsequent book that touched on Explorer 1, including William Burroughs' 1986 Pulitzer Prize winner ...the Heavens and the Earth. But no one had ever checked the quote, and we found that Medaris, despite being a principal actor in the Explorer 1 drama, was wrong: the tracking station at Goldstone in California did not yet exist. So we discussed this in The First Space Race, theorizing that Medaris accidentally ascribed an announcement from a later mission to Explorer 1.
Richard Easton points out in this column in The Space Review that two authors, both of whom could have accessed the right information easily (as in Wikipedia-easily) misstated the origin of the GPS satellites, including conflating them with the earlier Transit program. Transit was the first satellite navigation system, developed by the Navy for use in ship and sub navigation, but it wasn't technically related to the Air Force's later GPS. Easton notes that Stephen Johnson's book, Where Good Ideas Come From, gets this wrong. It's ok to make a mistake if you correct it, but Johnson blew him off when he pointed out the error, and that's inexcusable. Likewise, Annie Jacobson's The Pentagon's Brain, about DARPA, makes a hash out of the origins of GPS, including giving DARPA a role it never had. I already distrusted Jacobson for some ridiculous pseudoscience crap in her book about Area 51 and many errors in her Operation Paperclip. The trouble is that her books sell very well and the errors will likely carry into the future.
These seem to be cases where the writers didn't do enough research and self-checking: they may have seen something incorrect in a source, or read but misremembered something, and just went with it. I get it: I've done all that: but you have to be willing to fix it. I don't have a solution, except to remind all writers of history that they have a responsibility to get it right. We can't draw the right lessons from history of we don't get history right.