Don Eyles comments on the coverage of Apollo 11 in the July 2019 issue of SpaceFlight

Dear SpaceFlight Readers

It is with deep regret that we have to announce a significant number of errors in some of the articles published in the July 2019 edition of SpaceFlight magazine.  In a letter to the Editor dated 11 July 2019, Don Eyles states “Your coverage in the July 2019 issue contains a large number of important mistakes, especially in the two articles on pages 20-26.” Mr Eyles’ biography is given below and we know that all our readers will agree with us that he is extremely well qualified to judge the factual accuracy of these articles.

Given the considerable quantity of faults, it has been decided to publish the full text of Don’s letter, which can be viewed here. The Editor will publish an apology and a short article about this in the next edition of SpaceFlight, with the website address of the letter so that readers who aren’t members/Fellows of the Society can read the corrections in their entirety. The Editor has expressed his sincere regret and humility to Mr Eyles and to the Council for the errors.

We convey our earnest thanks to Don for the highly detailed corrections.

Yours faithfully
Gerry Webb

About Don Eyles (courtesy of

Don Eyles worked on the Apollo project from 1966 to 1972, and on the NASA space program until 1998, as a computer scientist at the MIT Instrumentation Lab and the Charles Stark Draper Laboratory in Cambridge, Massachusetts.

He created programs for the computer of the Apollo Lunar Module, responsible for the software that successfully guided the LM during the critical lunar landing phases of every Apollo mission that was able to attempt a landing. He worked with astronauts and NASA flight controllers to improve the software in response to the operational goals for each mission, and he received the NASA Public Service Award in 1971 for devising a timely workaround for a problem that jeopardized Alan Shepard’s mission to the Moon.

After Apollo he helped develop several simulations of the Space Shuttle, and led the development of a Space Station simulation that explored the use of computer graphics aboard a manned spacecraft. For simulation purposes he developed a sequencing system called Timeliner, built around a language based on temporal constructs such as “when,” “before” and “until.” After further development Timeliner was chosen by NASA for use as the “user interface language” aboard the International Space Station, where it is in continuous operation.

Eyles is the author, besides technical papers, of stories and opinion pieces in the New York Times, the Boston Globe, and other publications. He regularly lectures about the Apollo project for a course given at MIT.

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