Mars Climate Orbiter

The picture in the previous slide is a scientific space ship. Another scientific spaceship, the Mars Climate Orbiter, was completely destroyed on September 1999. The reason for this disaster was that two different NASA teams were using different systems of units. Somewhere in the conversion a mistake was made that caused the loss of the spacecraft. This probably would have been avoided if the same system of units had been used. 

On 23 September 1999 the Mars Climate Orbiter,one of the missions in a long-tenn program of Mars exploration, birned out completely. 

The fate of the Mars Climate Orbiter clearly shows the need for standardization of units... 

Chemists are not alone. The Mars Climate Orbiter crashed into Mars in September 1999 following a confusion in programming of software that modeled forces in English units instead of the metric units that were expected by the thruster controllers and other programs. This incident is related in the delightfully titled NASA document Mars Climate Orbiter Mishap Investigation Report. (Stephenson 1999) The mishap cost around 125,000,000. 

Laboratories must use calibration standards that are metrological trace-ability to an embodiment of the unit in which they are expressed. This requires use of certified reference materials, usually to make up working standards that calibrate instruments in the laboratory. Implicit is that results will be expressed in common units, and while this is increasingly the case, the example of the Mars Climate Orbiter (chapter 1) should signal those still using versions of imperial units that it might be time to join the rest of the world and use SI units. 

Write the units In 1999, the 125 million Mars Climate Orbiter spacecraft was lost when it entered the Martian atmosphere 100 km lower than planned. The navigation error would have been avoided if people had labeled their units of measurement. Engineers who built the spacecraft calculated thrust in the English unit, pounds of force. Jet Propulsion Laboratory engineers thought they were receiving the information in the metric unit, newtons. Nobody caught the error. 

Use print or electronic resources to find out what caused the loss of the Mars Climate Orbiter spacecraft in September 1999. How is this incident related to the Gimli Glider story Could a similar incident happen again Why or why not ... 

Artist s conception of the lost Mars Climate Orbiter. 

Using the wrong units to solve a problem can be a costly error. In 1999, the Mars Climate Orbiter crashed into the atmosphere of Mars instead of flying closely by as planned. The probe was destroyed before it could collect any data. Two teams of engineers working on the probe had used different sets of units—English and metric—and no one had caught the error in time. 

The intention of the Green Book ever since its appearance was not to present a list of recommendations as commandments, but rather its aim was and still is to help the user in what may be called a good practice of scientific language . Many well-established conventions are used in science and technology, but mixing conventions can lead to misunderstandings or even cause severe errors. One of those errors, caused by confusion of metric and imperial units, led to the loss of the NASA Mars Climate Orbiter (MCO) in 1999, worth about 200 Million USD of equipment and a non-quantified loss of scientific data and work. The reason for tlie loss of MCO was that Lockheed Martin Astronautics (LMA) software used imperial units (Ibf s) and Jet Propulsion Laboratory expected output from the LMA software... 

NASA s 125 million Mars Climate Orbiter was lost because of a data transfer where units were not included as part of the number. Most students first learn the importance of associating numbers with units in their high school chemistry class. 

How important are conversions from one unit to another If you ask the National Aeronautic and Space Administration (NASA), very important In 1999, NASA lost a 125 million Mars Climate Orbiter because of a failure to convert from English to metric units. 

Euler, E. E., S. D. Jolly, and H. H. Curtis. 2001. The failures of the Mars climate orbiter and Mars polar lander A perspective from the people involved. Guidance and Control, American Astronautical Society, paper AAS 01-074. 

Stephenson, A. Mars Climate Orbiter Mishap Investigation Board Report. NASA, November 10, 1999. 

Near-simultaneous tracking with Mars Climate Orbiter or Mars Global SurveyOT during approach... 

Data relay via Mars Climate Orbiter, Mars Global Surveyor, or direct-to-Earlh high-gain antenna... 

On September 23,1999, the Mars Climate Orbiter crashed on the planet Mars because engineers had neglected to take into account that some design data had been provided in metric units and some in U.S. customary units. 

A design flaw in the programming of the Mars Climate Orbiter caused it to spin out of control and crash because part of the program called for data in metric units and another part called for data in U.S. customary units. 

The Mars Climate Orbiter, launched in December 1998, crashed on Mars nine months later because of a computational error. The orbiter s approach altitude to the planet was set at 160 kilometers, when, in fact, it was just under 60 kilometers. This is an example of human, not computer, error. 

Stephenson, A.G., et al. 2000. Report on Project Management in NASA by the Mars Climate Orbiter Mishap Investigation Board. NASA, March 13. 

In the second half of 1999, there were mission failures involving the Columbia shuttle and then dual failures with the Mars probe. The Mars probe failures came after a big success in 1997. The Mars Climate Orbiter failed to find a proper trajectory around Mars and the Mars Polar Lander was lost, believed crashed. Including the 1999 mission failures NASA attempted to fly 16 FBC missions in 1992-2000, with a 63 percent success rate. 

NASA is certainly not free from concerns of coordination neglect and communication breakdown. NASA s size, geographical distribution, and cultural variation make effective communication and coordination difficult (McCurdy, 1994). One particularly glaring example of an accident caused in part by a failure of coordination is the September 23, 1999 loss of NASA s Mars Climate Orbiter spacecraft. NASA s investigation of the accident revealed that it came about at least in part because NASA engineers used metric units in their calculations while Lockheed Martin engineers used English units (www.cnn.eom/TECH/space/9909/30/mars.metric.02/). 

---