Meet: Pieter Kallemeyn
Navigation Team Leader
Jet Propulsion Laboratory, Pasadena, California
Who I Am
The role of the navigator on a ship or airplane is to determine where
you are and plot a course to get to the destination. That is no different
for me as a navigator for the Mars Pathfinder mission, except that the
ship is a 900-kg unmanned spacecraft and the destination is more than
150 million miles away. There are three navigators for Mars Pathfinder:
David Spencer, Robin Vaughan and myself as NAV team leader. We're responsible
for determining where the spacecraft is, predicting where it will go in
the near future, and determining the means to correct the path in order
for us to reach the surface of Mars.
The flight path, or trajectory, of the spacecraft is decided on early
in the mission's development. Considerations such as mission objectives,
launch vehicle capability and arrival geometry are just a few of the things
that are optimized in designing the trajectory. After the spacecraft is
launched, the navigators measure the range and velocity from the Earth
to the spacecraft at regular intervals. These measurements are compared
to predicted measurements based on computer models of the trajectory.
Any errors in the models are corrected until the ground-based computer
model matches the actual trajectory. If the actual trajectory is found
to be off from the predetermined path, the spacecraft's propulsion system
is fired in a certain direction to add (or subtract) just enough velocity
to correct the error and put us back on course. These events are called
TCMs, short for trajectory correction maneuvers. Mars Pathfinder is planning
to do four of these during the cruise from Earth to Mars.
My Career Journey
My career really started while I was obtaining my B.S. degree in Aerospace
Engineering Sciences from the University of Colorado. In between my classes
in mathematics, physics, computer programming and astrodynamics (the study
of spacecraft motion around planets) I had the opportunity to work part-time
at the Solar Mesosphere Explorer control center. This satellite control
station was owned by the university and staffed primarily by undergraduate
students who gained experience in spacecraft operations on a real satellite.
I learned about spacecraft orbits, communications, power systems and other
systems vital to keeping a spacecraft and its mission healthy. I enjoyed
it so much, I stayed on another year-and-a-half while I finished my M.S.
degree. I eventually became responsible for programming the attitude control
system for the satellite. After I graduated I was fortunate to get a job
at the Jet Propulsion Laboratory (JPL) with the Galileo project's Navigation
Team as an orbit determination analyst. After five years on Galileo I
was asked to join Mars Pathfinder as "chief navigator."
I had two teachers in high school who encouraged me to pursue interesting
extracurricular activities. One was my math teacher who taught me calculus
in my senior year. She recommended I visit the University of Colorado
during the summer before my senior year to see what the engineering college
had to offer. The other was an influential science teacher who encouraged
me to participate in a space shuttle experiment proposal program for students.
Although my experiment (which involved the study of thermodynamics in
microgravity) wasn't selected to fly, I learned a lot from the research
it required and I had fun doing it.
Likes/Dislikes About Career
The best thing by far is knowing I'm playing a small but important role
in the ongoing exploration of Mars and I'm having fun doing it. Mars is
our next logical choice for a manned landing, but before we can do that
we need a wealth of information obtained from the unmanned missions we're
sending today. The work I do not only builds on the success of previous
interplanetary missions, but will help future missions navigate their
way to Mars.
What do I like the least? I don't know... Maybe when the computers go
down and there's no way to get work done. Or maybe it's when things get
too busy? Or maybe it's the coffee? Actually, there's so much I like about
the job I barely notice things I don't like.
As a kid, I built and flew model airplanes and rockets. Through those
hobbies I learned a lot about flight mechanics, stability and Newton's
laws of motion. School taught me that those same principles apply to launch
vehicles in the same way they apply on model rockets. I still build and
fly them today, when I have time!
I read a lot in school, too, mostly science fiction and history. I encourage
students I meet to read as much history as they can because it helps us
understand how people and governments behave and how events shape lives
and vice versa. Reading about the history of the Space Age is most interesting
to me because it's so recent (only 30-40 years) and I can relate to it
I've been married for six years and we have a 19-month old son. It's
going to be interesting to watch him grow up in this age where we've already
been to the Moon, computers are commonplace, and the planets of our solar
system have been photographed.
In addition to flying model airplanes and rockets, I like to go hiking
and camping. We like to spend the day at the beach flying kites and looking
for shells and top it off with dinner at a great local Japanese restaurant.
One of these days I'd love to go on a cattle drive. When I retire I'd
like to live on a ranch in Colorado.