"What is Chemistry Good For?"

### The for-credit questions are available at the end of this page. Please respond before 5 AM, Monday, January 22nd, 2001.

Chemistry is Good for Building Math Skills
Unit Conversions

One of your most difficult tasks in life is to build skills in many areas and then to successfully apply them in situations when they are needed. Even rocket scientists are not immune from making mistakes on very simple problems. If only they had studied more chemistry, these problems could have been averted !

Hopefully these examples will convince you that unit analysis and unit reporting are ESSENTIAL skills for you to master and be diligent about.

On July 23, 1983, Air Canada flight 143 was on route from Montreal to Edmonton. Suddenly a warning buzzer sounded, indicating that a fuel pump had failed. Then a second buzzer indicated that another fuel pump had failed. Soon the pilots realized that the problem was not with the fuel pumps, they were out of fuel. Before takeoff, the mechanics and first officer calculated how much fuel they had by multiplying 7682 L by the conversion factor 1.77 to go from volume of fuel to mass of fuel.

7682 L x 1.77 = 13597

Unfortunately for the pilots, mechanics and passengers, the mechanics made an improper assumption about the units of the conversion factor. They thought that the fuel had a density of 1.77 kilograms per litre, and that they had 13597 kilograms of fuel. In reality, the fuel has a density of 1.77 pounds per liter and they really only had 6180 kg of fuel. Thus, they did not add nearly the fuel that they needed to complete the flight.

Luckily, there was a small airport in the town of Gimli, Manitoba within gliding distance of the aircraft's position. It was abandoned by the Canadian Air Force and had been converted into a racetrack. In fact, at the time the plane ran out of fuel, there was a race going on. Thankfully, after gliding for 29 minutes without fuel, the "Gimli Glider" successfully landed on the abandoned airfield and skidded to a stop.

An amusing side-note to the Gimli story is that after Flight 143 had landed safely, a group of Air Canada mechanics were dispatched to drive down and begin effecting repair. They piled into a van. They reportedly ran out of fuel en-route, finding themselves stranded somewhere in the backwoods of Manitoba

More recently, the rocket scientists of NASA made a slightly more costly mistake. In the development and missions planning of projects, NASA engineers contract much of the design and construction out to private companies. The Mars Orbiter was recently built and launched with the mission to explore the Volatiles and Climate history of the planet Mars. Lockheed Martin Astronautics built part of the spacecraft and transmitted information about the operation of the craft to the NASA Engineers at the Jet Propulsion Laboratory in Pasadena California. In December of 1999, the spacecraft (which cost 357 million dollars to build, launch and fly) was lost.

Artist's conception of the orbiter, immediately prior to its disappearance

Here is an excerpt from the government report on the cause of the loss:

"The 'root cause' of the loss of the spacecraft was the failed translation of English units into metric units in a segment of ground-based, navigation-related mission software, as NASA has previously announced," said Arthur Stephenson, chairman of the Mars Climate Orbiter Mission Failure Investigation Board. "The failure review board has identified other significant factors that allowed this error to be born, and then let it linger and propagate to the point where it resulted in a major error in our understanding of the spacecraft's path as it approached Mars.

At this point, NASA is reviewing plans for the mars polar lander to make sure it does not suffer a similar fate.

Hopefully all the numbers you rely on will be reported with the proper units so you won't make any multimillion-dollar errors any time soon. This all reminds me of "The Hitchhiker's Guide to the Galaxy" by Douglas Adams. A supercomputer painstakingly calculated the answer to the meaning of the universe. The answer is 42. Useful?

And here are a few good links to get you started.

1. 2. 3. 4.

Research Questions (You will receive 1 point of extra credit for each correct answer up to a total of two points for this assignment)

I received no help from anyone on this assignment.

These questions can be answered by exploring the links provided to you above.
1. Why were the mechanics calculating the mass of fuel that they had? How do pilots and mechanics normally know how much fuel they have?
2. What additional experience did the pilot of the Air Canada flight have that allowed him to land the plane successfully?
3. What is "aerobraking"? What source of energy does the orbiter lose while aerobraking?
4. The orbiter was supposed to map the planet Mars for one Mars year. How many days is that?

You may change your mind as often as you wish. When you are satisfied with your responses click the SUBMIT button.

I received no help from anyone on this assignment.

This site is made possible by funding from the National Science Foundation (DUE-9981111).