What I Do
Robotic spacecraft, like Mars Pathfinder, are controlled by computers. The computer
onboard Mars Pathfinder controls thrusters, a sun sensor, a star scanner, a radar
altimeter, explosive charges, a parachute and much, much more. Almost every activity
performed by the spacecraft is controlled by a central computer. The computer that
controls our spacecraft is just like the personal computers found in schools and in
Like all computers, the computer controlling Mars Pathfinder follows a set of
instructions called a program. It is my job, along with several others, to write the
program that allows the computer to control the spacecraft. This is very challenging
because the computer must fly the spacecraft during the seven-month cruise to Mars as
well as control the atmospheric entry, descent and landing on the surface of the planet.
I have worked at the Jet Propulsion Laboratory (JPL) for seven years and have written
flight control software for several planetary spacecraft. The last spacecraft that I
worked on was the Galileo Orbiter, which placed a probe into the atmosphere of Jupiter in
The programs that control spacecraft, or anything else that operates in the "real
world," are called real-time systems. The programs that control the anti-lock brakes for
a car, a microwave oven, or a jet airplane are examples of real-time systems. These
systems are especially exciting to me because they have to operate in the "real world"
where the amount of time it takes the program to perform a task is very important. It is
also critical that these systems operate correctly, even when something goes wrong.