15, 1999. It was intended to place the spacecraft at an optimal position for an orbital insertion maneuver that would bring the spacecraft around Mars at an altitude of on September 23, 1999. However, during the week between TCM-4 and the orbital insertion maneuver, the navigation team reported that it appeared the insertion altitude could be much lower than planned, at about . Twenty-four hours prior to orbital insertion, calculations placed the orbiter at an altitude of . was the minimum altitude that Mars Climate Orbiter was thought to be capable of surviving during this maneuver. During insertion, the orbiter was intended to skim through Mars' upper atmosphere, gradually aerobraking for weeks, but post-failure calculations showed that the spacecraft's trajectory would have taken it within of the surface. At this altitude, the spacecraft would likely have skipped violently off the denser-than-expected atmosphere, and it was either destroyed in the atmosphere, or re-entered heliocentric space. 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) – to update the predicted position of the spacecraft. Still, NASA does not place the responsibility on Lockheed for the mission loss; instead, various officials at NASA have stated that NASA itself was at fault for failing to make the appropriate checks and tests that would have caught the discrepancy. The discrepancy between calculated and measured position, resulting in the discrepancy between desired and actual orbit insertion altitude, had been noticed earlier by at least two navigators, whose concerns were dismissed because they "did not follow the rules about filling out [the] form to document their concerns". A meeting of trajectory software engineers, trajectory software operators (navigators), propulsion engineers, and managers was convened to consider the possibility of executing Trajectory Correction Maneuver-5, which was in the schedule. Attendees of the meeting recall an agreement to conduct TCM-5, but it was ultimately not done. Project costs According to NASA, the cost of the mission was $327.6 million ($ million