Question: In September of 1999, after almost 10 months of travel to Mars, the Mars
Climate Orbiter burned and broke into pieces. On a day when NASA engineers were
expecting to celebrate, the ground reality turned out to be completely different.
The Mars Climate Orbiter, built at a cost of $125 million, was a 338-kilogram robotic space
probe launched by NASA on December 11, 1998 to study the Martian climate, Martian
atmosphere, and surface changes. In addition, its function was to act as the
communications relay in the Mars Surveyor ‘98 program for the Mars Polar Lander. The
navigation team at the Jet Propulsion Laboratory (JPL) used the metric system of
millimetres and meters in its calculations, while Lockheed Martin Astronautics in Denver,
Colorado, which designed and built the spacecraft, provided crucial acceleration data in
the English system of inches, feet, and pounds. JPL engineers did not take into
consideration that the units had been converted, i.e., the acceleration readings measured
in English units of pound-seconds^2 for a metric measure of force called newton-
seconds^2. In a sense, the spacecraft was lost in translation. During the design phase, the
propulsion engineers at Lockheed Martin in Colorado expressed force in pounds.
However, it was standard practice to convert to metric units for space missions.
Engineers at NASA’s Jet Propulsion Lab assumed the conversion had been made. This
navigation mishap pushed the spacecraft dangerously close to the planet’s atmosphere
where it presumably burned and broke into pieces, killing the mission on a day when
engineers had expected to celebrate the craft’s entry into Mars’ orbit. The contributing
factors that led to the disaster, as reported by the Mars Climate Orbiter failure board,
were eight-fold. According to NASA’s board, errors were undetected within ground-based
computer models of how small thruster firings on the spacecraft were predicted and then
carried out on the spacecraft during its interplanetary trip to Mars. Furthermore, the
board added that the operational navigation team was not fully informed of the details of
the way that Mars Climate Orbiter was pointed in space, as compared to the earlier Mars
Global Surveyor mission.
The initial error was made by contractor Lockheed Martin Astronautics in Colorado,
which, like the rest of the U.S. launch industry, used English measurements. The
contractor, by agreement, was supposed to convert its measurements to metrics. The
systems engineering function within the project, whose responsibility was to track and
double-check all interconnected aspects of the mission, was not robust enough. The
board added that this was exacerbated by the first-time handover of a Mars-bound
spacecraft from a group that constructed it and launched it to a new, multi-mission
operations team.
Questions:
1. What could have been done in order to prevent the mishap from happening. Limit
your answer through the use of computers only. How could computer have
prevented the mishap from happening in NASA Mars Orbiter mission.
2. What device/devices/ (anything related to computers) you would have used to
prevent the mishap and how? Explain your answer with possible solution. How
could the device/ (anything related to computers) you suggest would have
prevented it? Explain how?
Answers
(1.) One of the ways to prevent the mishap in the Mars Climate Orbiter mission would have been the use of computer-based checks and balances to confirm that all calculations made and the data used were in the correct units. For example, the software used by the navigation team at Jet Propulsion Laboratory (JPL) could have been programmed such that it automatically converted any English unit measurements provided by Lockheed Martin Astronautics into metric units. Through this method, the team at JPL could have prevented the risk of human error by not relying on manual conversions.
(2.) Another potential solution could have been the use of a computer-based system to track and monitor the various systems and components of the spacecraft during its journey to Mars. The system could have been designed in such a way that it alerted the team at JPL if any critical data or calculations were in the incorrect units, thus allowing them to correct the error before it led to the mishap. Also, the system could have provided real-time data on the spacecraft's position and trajectory, giving the team an opportunity to make any necessary course corrections in order to avoid the planet's atmosphere.
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