> The primary cause of this discrepancy was that one piece of ground software supplied by Lockheed Martin produced results in a United States customary unit,
contrary to its Software Interface Specification (SIS), while a second system, supplied by NASA, expected those results to be in SI units, in accordance with the SIS. Specifically, software that calculated the total impulse produced by thruster firings produced results in pound-force seconds.
The trajectory calculation software then used these results – expected to be in newton seconds (incorrect by a factor of 4.45)[15] – to update th…