Plotting a new trajectory is never a simple task. Just ask Dave Doody, a senior engineer at NASA’s Jet Propulsion Laboratory (JPL).

A recent image of the Sun, captured by NASA's Solar and Heliospheric Observatory. (Photo courtesy of NASA.)

Doody is the lead flight engineer of NASA’s Cassini Solstice Mission, a mission in which the Cassini spacecraft is gathering and sending back information on the planet Saturn, its rings, moons and magnetosphere. Once a year, he also teaches Basics of Interplanetary Flight at Art Center at Night (ACN), a course in which curious students from all walks of life explore what it takes to navigate spacecraft across the solar system.

We recently trekked across the arroyo to JPL to ask Doody about his class.

Dotted Line: What do you explore in Basics of Interplanetary Flight?
Doody: We look at results from NASA’s probes, whether it’s from Voyager, the Mars Exploration Rovers, Cassini or the others. In each session we touch on a few other topics as well. We ask a lot of questions like: What is the spacecraft all about? How does it work? What are all its pieces and what do they do? How do you design it? How does it travel?

We also explore the environment that it has to operate in, whether it’s the vacuum in space or plasma from the sun. Can the spacecraft go straight to its destination in the solar system or does it have to follow certain pathways?

And we cover the up-and-coming spacecraft and anything that’s happening right now, like a launch or a landing. We also touch on some historical information.

Doody.

Dotted Line: What kind of students do you get in the class?
Doody: Of course we get some students from Art Center, both undergraduates and graduates.

We also get filmmakers and transportation designers. But the class is not just limited to artists and designers. It’s wide open to the public, so we get everyone from surgeons to secretaries. Anybody can take the class.

We don’t depend on any previous experience or knowledge. We just need people who are interested in the fact that today we’re looking at new worlds. And we’re looking at them with robots that have new senses on them. These robots can see not only in visual light but also in infrared and ultraviolet. And they also have expanded sensory regions, so they can analyze magnetic fields and high-energy particles.

Dotted Line: In class you discuss the different types of sensors found on spacecraft?
Doody: Yes, but we’re not just discussing. This course takes place after dinner after all! We get into all sorts of activities where the students are experimenting and seeing how different sensors work. I try to keep it interesting and informative and get everybody working together and talking to one another.

Dotted Line: Give me an example of the type of activity you do in class.
Doody: Well, once you leave the Earth, you’re outside the magnetic bubble that protects us from the Sun, which is constantly shedding protons and electrons, which we call the solar wind. In fact, if the magnetic field on Earth were to vanish, the Sun’s solar wind would blow off the atmosphere, dry off the oceans and there’d be little hope for life.

It’s not the easiest concept to grasp, so I bring some plasma, which are highly charged particles, into the classroom. And the students take a very strong magnet and they can actually see how magnetic fields interact with plasma. It’s real simple and helps illustrate this environmental concept. And that’s what I try to do with the course in general. I try to take something abstract, put it right in your face and let you play with it.

Doody and a "Basics of Interplanetary Flight" class on a field trip to JPL.

Dotted Line: Sounds fun.
Doody: It is. Another example is when we start talking about plotting a trajectory, we get to the concept of a “gravity assist.” Whether it’s Cassini to get to Saturn, Galileo to get to Jupiter or Voyager to get to the outer solar system, they all get a “gravity assist.” How does that work? Gravity is just like riding a bicycle downhill and then back up again. If you’re approaching a planet, you speed up as you go in and you slow down as you go out. But since the planet is going around the sun, it has a huge amount of momentum. So a spacecraft can sneak up behind it and, using gravity, connect to the planet’s momentum and get an extra kick.

Since that’s not something you run into in normal everyday life, Art Center helped me build a gravity assist mechanical simulator to demonstrate the concept in class. The simulator looks a bit like a pinball game. The Sun is represented by an orange dot [Editor’s note: Ahem!], Jupiter orbits the Sun and is represented by a magnet, and the magnetism substitutes for Jupiter’s gravity. If you time your “launch” just right, you can steal some of Jupiter’s momentum and reach your destination. It takes a few times to be able to do it right. Of course with exact knowledge of the solar system and good computer programs, the navigators in reality don’t fail.

Saturn in the infrared, as captured by NASA's Cassini orbiter. (Photo courtesy of NASA.)

Dotted Line: Any homework assignments?
Doody: No, all you have to do is show up. Of course you can always do more reading. There’s plenty of reference materials. We don’t do much math either. But if you’re interested enough to delve into the math, its all in my book, Deep Spacecraft: An Overview of Interplanetary Flight, which I wrote for my Art Center at Night students who really wanted the math. So during the sessions, we give you a good overview and an intuitive understanding of the concepts involved and then you can go home and read all about the math, follow the references and go as deep as you want into any subject.

Dotted Line: Anything else?
Doody: There’s always at least one stellar guest speaker. One year, Michelle Thaller visited the class. She’s a primary scientific investigator on the Spitzer Space Telescope, which has renovated our views of the universe. And she brought with her a set-up where students could see themselves and other objects in the infrared.

Registration for Art Center at Night’s Summer Term is now open. Courses begin May 16.