Mars Climate Orbiter and Mars Polar Lander

As part of the NASA Mars Surveyor Program, the Mars Climate Orbiter was to orbit Mars and collect environmental and weather data. But as the spacecraft approached its destination, telemetry signals fell silent, and a $125 million mission failed.

The root cause identified by NASA was the failure to convert between metric and English units. When the fatal error was detected, Noel Hinners, vice-president for flight systems at Lockheed, the company that built the spacecraft, said in disbelief, “It can’t be something that simple that could cause this to happen.” But it was.

Apparently Lockheed had used pounds during the design of engines, while NASA scientists, responsible for the operation and flight, thought the information was in metric units.

There were early signs during its flight that something was wrong with the craft’s trajectory and an internal review later confirmed that it may have been off course for months (Pollack, 1999) (Oberg, 1999). Project culture, however, required that engineers prove that something was wrong rather than “prove that everything was right.” This difference in perspective prevented the team from looking into the problem. Edward Weiler, NASA associate administrator for space science, said, “The problem here was not the error; it was the failure of NASA’s systems engineering, and the checks and balances in our processes to detect the error” (Oberg, 1999).

The Mars Investigation Panel report identified several contributing factors to the failure: the system engineering process did not adequately address the transition from development (Lockheed) to operations (NASA); inadequate communications between project elements; and inadequate staffing and training.

Within a few months of the Orbiter failure, the Mars Polar Lander, a related NASA project with a price tag of $165 million, suffered the same fate. Its flight was uneventful until it began its landing approach. Then, during its descent into the rough terrain of the polar cap, telemetry signals fell silent. With no data to pinpoint the precise cause of failure, the teams investigating the accident speculated that the vehicle’s descent engines prematurely shut down. Unable to slow the descent, the speculation was that the engines quit when the Lander was 130 feet high, crashing into the surface of Mars at about 50 miles per hour. The inappropriate response of its engines was attributed to software glitches (Leary, 2000).

The prevailing culture at NASA of “Better, Faster and Cheaper, that defined the period when these projects were in development, has been highlighted many times as the contributing factor behind these failures. Thomas Young, a former NASA official said that they were trying “to do too much with too little.” He continued, “No one had a sense of how much trouble they were actually in.” (Broad, 1999).

The prevailing culture was best expressed in an internal memo written by a laboratory official at the Jet Propulsion Lab. “There might have been some overconfidence, inadequate robustness in our processes, designs or operations, inadequate modeling and simulation of operations, and failure to heed early warnings.” (Oberg, 1999).

While the trajectory problem associated with the Orbiter and the engine ignition problem associated with the Lander could be characterized as technical, The Mars Climate Orbiter Failure Board (2000) said that management failures were also to blame. They found that these projects suffered from a lack of senior management involvement and too much reliance on inexperienced project managers. The Board also criticized the strategy where project managers in one organization were responsible for development (Lockheed) and a separate organization (NASA) was responsible for operations after launch.

Lessons Learned
If the orbiter did not launch on schedule, it would have to wait several months before its next opportunity to launch. With launch windows far apart, and with budgets unable to tolerate a substantial delay, managers were under pressure to meet the deadline; it was important not to “waste” the effort put into the project to that point. This suggests that decision makers fell into the “sunk cost” trap, a situation in which past expenditures of time and money continue to propel a project into the future even when evidence suggests that this would be unwise.

Selective perception explains why the engineers at the Jet propulsion Lab, the design team, failed to coordinate with the operational team at NASA. In large-scale complex projects, such as the Orbiter and Lander, with countless activities, contractors, and suppliers, it is very possible that teams may take a narrow view of their own activities. The risk is that the work of one team may be incompatible with the work of another.

Conservatism, the failure to consider new data, explains why engineers did not take action when they noticed that the trajectory of the spacecraft was off. They even held a meeting in Denver to address the issue, but it was never resolved. Even as the spacecraft approached its destination and data showed that it was drifting off course, controllers attempted to ignore the real data and assume it was on-course (Oberg, 1999).

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