Faculty Highlight: Rod Heelis

Faculty Highlight: Rod Heelis

Dr. Rod Heelis

You are watching your favorite show on cable TV when suddenly your reception dramatically loses quality. All you see is a snowy image. You immediately call the cable company and after impatiently holding on the phone for a while—complete with boring music and recorded prompts—you receive the bad news: the problem is not with the cable company but rather with the satellite that relays the signal to it.

Many important systems that we rely on daily, ranging from television to satellite (GPS) navigation, and even long-range telephone communications, depend on satellites that orbit in a hostile environment above the earth. “This volatile environment suffers from weather phenomena much like we experience on the surface of the earth,” says Roderick Heelis, the Cecil H. and Ida Green Chair in Systems Biology Science #2 Professor of Physics and Director of the William B. Hanson Center for Space Sciences at UTD.

Heelis’ research interests range from planet-star interaction to the differences between planets with magnetic fields, and more. He measures weather in space by means of sophisticated instruments that fly on satellite ‘space labs,’ and creates computer models that aim to predict space weather phenomena and to determine to what extent they will affect space-based assets.

Space is not empty

Heelis introduces the concept of a space that is not empty as is commonly perceived.

“If you say ‘space,’ some people think about space travel, space ships, and astronauts. They think of outer space travel from one body to another in a vacuum. But from a scientific point of view, the medium between the planets surrounding the sun is not a vacuum.

“There is a continuous flow of gas streaming away from the sun, and it represents a very hostile environment to anybody that’s in it. Every human sitting on the surface of the Earth is in it, because the Earth itself is in this environment.

“When sending astronauts to space, the big worry is that the activity of the sun and all the particles and radiation are going to be harmful—not just to the astronauts themselves—but to the hardware that makes up a mission,” Heelis said.

Understanding the interaction of the Earth, the space around it, and the sun addresses the intellectual question of how planets interact with their neighboring star. It also allows us to learn about our environment in space and how it affects current technology.

Research headed by Heelis focuses on taking that concept one step further with the ultimate goal of being able to specify and predict space weather, determining when and where the communication and navigation systems that we rely upon daily will encounter hazardous conditions.

The magnetosphere protects us from violent radiation

To be in an environment that allows for the existence of life is extremely fortunate. And there’s more to it than an oxygen-rich atmosphere and the presence of water. One of Heelis’ many research interests is the magnetosphere.

“One of the big differences between Earth, Mars, and Venus is that the Earth has a very strong magnetic field. The charged particles coming off the sun encounter the Earth’s magnetic field and that deflects them around the planet. But if you go to a place like Mercury, that has no atmosphere and no magnetic field, the particles directly impact the surface of the planet,” Heelis states with a grin. “It would not be a very good place to be.”

The northern and southern lights are a luminous phenomenon caused by the emission of light from atoms excited by electrons accelerated along the planet’s magnetic field lines.

“You can’t really see a magnetic field, but you can see its effects on the charged particles—because the velocity or motion of charged particles is different. There are signs indicating the presence of magnetic fields. For instance, on the Earth we have aurorae— both the northern lights [aurora borealis] and the southern lights [aurora australis] are a direct consequence of the magnetic field. In fact, anytime you see an aurora you could be pretty sure that planet has a magnetic field.

“There are observed aurorae on Jupiter and Saturn, but as far as we know there are none on Venus. Up until just recently there were none observed on Mars; therefore, it was thought that Mars did not have a magnetic field. But we know now that Mars does have a weak-structured crustal magnetic field—a field that’s not in the core, but near the surface. The observation of the aurora on Mars is very recent, [and] not quite confirmed. It is thought that a planet that has an atmosphere with a magnetic field will evolve differently and at a different rate from one with an atmosphere that does not have a magnetic field.”

Measuring and predicting space weather is a challenge

Space weather may be a difficult concept to grasp, especially because it cannot be seen.

“Perhaps the best way to envision the space environment [that affects the Earth] is to imagine a separate envelope around the Earth above you that has all the properties of the atmosphere,” Heelis explains.

“In that envelope there are weather systems just like the ones that you have on the surface of the Earth. Those features, instead of existing in a neutral gas—what we breathe on the surface of the Earth—exist in a gas of charged particles. That’s why they are so hazardous to electronics, radio communications, and so on. These charges move around and create their own electric and magnetic fields that interfere with the ones you’re trying to transmit.

“If you were a weather forecaster and you wanted to know what the weather is like in Sydney, Australia you could get on the Internet to view the data of thousands of weather stations, or you could telephone someone in Sydney and ask them. In space, there is no one to call and [there are] too few weather stations.

“I find space [weather prediction] very challenging because the problems are so similar to surface weather prediction—all the kinds of questions and challenges you can imagine about the surface weather are the same kind of problems that you have in space,” he said.

Adding to the challenge of predicting the weather in space, there are very few operational “weather stations” in space, and the area involved is many times bigger than the surface of the Earth. Heelis hopes to contribute to expanding the number of weather observation points in space.

UT Dallas builds instruments that orbit aboard satellites in space

For a very long time UT Dallas has been actively involved in space sciences, hands-on, Heelis explains.

“At UT Dallas we build instruments that fly on those [satellite] weather stations and we analyze the data that is returned.

“When you are doing experiments in space, you get only one shot at it. So you have to think of all the experiments that you have to do. You have to think of everything that can go wrong and devise a workaround in case it does go wrong. You have to design flexibility in case what you thought was going to happen is not what happens.

“It’s really a very complex procedure before you conduct an experiment [in space]. Taking the experiment and putting it into space on a rocket can cost $100 million so we collaborate with other scientists to try to do experiments in common so that we can all share the cost of launching the lab into space. UT Dallas might have a few instruments and experiments that we want to do, and Boston University might have a few experiments that they want to do, as well as other space [research programs].

“I remember very well our first time we saw our payload launch. It was exciting—smoke and fire in the sky. It was also nerve-wrecking: there’s a time when they press the button to turn your instrument on…and you watch the charts impatiently to see whether your instrument is going to work or not.”

“It’s not like doing it in the lab. In the lab you set it up and if it did not give you what you needed, then you do it over again. If you accidentally turn on the power and you slow cook a piece of equipment then you replace the piece of equipment and you do it again. All those things can happen in space equipment but if they do—it’s over. So you have to imagine what you would do if something like that happened and you try to avoid it.”

The William B. Hanson Center for Space Sciences at UT Dallas, receives a constant influx of data from the orbiting instruments it builds. There is a large team of research scientists, students, and faculty headed by Heelis that is always looking at this data, interpreting it and applying it with the goal of creating better prediction models.

“After spending years looking at the data, we decide what is the next thing we need to know. Then we design another experiment and we go at it again,” Heelis adds.

The launch of Heelis’ career in space sciences

“When I was a graduate student, computers had made their transition from vacuum tubes to transistors and numerical mathematics was a fairly natural thing for somebody with a mathematics and physics background to get into. I wanted an interesting problem that was engaging—not just solving equations but rather solving something interesting.

“One of my professors was involved in atmospheric science and he gave me a problem that we knew could not be solved analytically but maybe we could use numerical methods on the computer to do this.

“I spent my PhD research doing numerical analysis trying to get the computer to solve equations. I was buried in this model analysis with numerical instability—it was very mathematical. I was fortunate in that when I finally got a result, it was one that could be shared by looking at observations. In another part of the world there were people working on experiments measuring what I was modeling. I was able to take the results of my model and compare them to the real measurements. Until I did that, I didn’t really have a lot of feel for the physics of the atmosphere.

“My model results were smooth and beautiful but it wasn’t until I saw the counterpart, which was ragged and had a lot of error bars, that I became fascinated and inquired further. It was very satisfying to those guys who made measurements and didn’t really know if they were agreeing with the physical picture of what they thought was going on and to me when I was modeling this physical picture but didn’t know whether it represented reality. If you put the two together—in some places it does. I got a surge of enthusiasm—it was a real light bulb moment!

“It turned out the guy who did the data was here at UT Dallas. It was Bill Hanson. I remember very well the letter he sent me. I sent him a letter asking him if he would send me his data. And he sent me a letter back to say, ‘I have a better idea, why don’t you come down and get it?’ That was my invitation to come to Dallas, so I did, and I’ve been here ever since.”

In addition to research activities, Dr. Heelis has also served on a number of advisory committees and working groups. He served as chairman of the committee on qualifications and as a member of the core curriculum committee at UT Dallas. Dr. Heelis has recently served as a member of the NASA Space Science Advisory Committee, as a member of the National Research Council Space Science Decadal Survey Committee, as a member of the NASA Geospace Mission Definition Team, and as a co-chair of the NASA Global Electrodynamic Connections Science Definition Team.