Case study: The choice is endless in space

From keeping ice and woodpeckers off the Space Shuttle's fuel tank to studying the physics of Moon dust, Philip Metzger outlines the wide range of opportunities for physicists and engineers in the field of space science

Growing up on the east coast of Florida, I used to look of out my bedroom window and watch as rockets lifted off towards the Moon. I always assumed that one day I would become an engineer and work in the space programme. Although I fulfilled that dream, what I did not anticipate was that I would later fall in love with physics; leaving engineering to pursue a PhD in statistical mechanics.

Fortunately for me, the space programme has proved to be a fantastic place for both physicists and engineers. Spaceflight produces a steady supply of new problems to be solved, and working as a research scientist at the Kennedy Space Center (KSC) – as I have done for the last 20 years – is tremendously rewarding. No two days are ever the same.

What a blast
I joined the KSC in 1985 after graduating with a degree in electrical engineering from Auburn University. Initially, I worked as an engineer on the Space Shuttle programme, before moving to the International Space Station programme in 1995. Gradually, however, my interests shifted to physics, and in 2000 I began studying for a PhD at the University of Central Florida, while continuing to work full-time. For the past three years I have been employed as a research physicist at the KSC's Applied Physics Laboratory.

The lab consists of a team of seven physicists, all of whom work closely with chemists, engineers, biologists and other researchers both within NASA and various external companies. We carry out a mixture of long-term fundamental research and very urgent short-term work, where we have to solve critical problems at the launch site when a mission is about to blast off. The advantage of doing the long-term research is that it gives us the knowledge and ability to rapidly solve the urgent problems, which can arise at very short notice.

When a problem arises at the launch site, we generally have to invent a new way to address the issue, prove it experimentally and then put it into practice – all within the space of a few months. Over the past two years, for example, I have looked at how electromagnetic fields can be used to repel dangerous cosmic radiation from spacecraft. I have studied how water gets sucked from thermal protection tiles covering the Space Shuttle and looked at what happens when the craft re-enters the atmosphere. I have also examined ways of preventing ice from forming on the shuttle's external fuel tank, and even tried to find environmentally friendly ways of repelling woodpeckers from it.

The joys of sand
My own specialization is the statistical mechanics of granular media. I originally became interested in this field when I was studying how to protect infrastructure located on the Moon from the blast of sand and dust that is created when a rocket lands or launches nearby. I quickly discovered that sand is one of the least-understood substances in nature, despite it being such a familiar material and having been the subject of intense scrutiny for more than 200 years since the time of Coulomb.

Physicists may have equations for everything from electromagnetism and quantum mechanics to astrophysics and cosmology, yet they have no fundamental understanding for the simple pouring or squeezing of a pile of sand. Well, if humans are going to travel to the Moon or Mars, and rely on the resources that are found there, it would help to have a pretty good understanding of sand, which is mostly what their surfaces consist of. After all, astronauts will have to land on sand, drive on it, dig it, process it and build with it.

Moreover, sand does not behave on the Moon or Mars as it does on Earth for a number of environmental reasons. It is also very hard to access these remote planetary environments to do routine technology development or tests. We therefore have to rely on theory and modelling to study this material. Sand – such an ordinary substance – is so little understood that it is of profound importance to physicists interested in space travel.

My current research has three main strands. First, I have been using statistical mechanics to create a theoretical model of how forces spread out in sand; I then compare its predictions with computer simulations. Second, I have an experimental programme to explain the surprisingly complex fluid flows that occur when a rocket blasts off from, or lands on, a planet, its supersonic exhaust jet cratering the sand. Third, my colleagues and I are beginning a series of experiments to help guide the development of predictive computer models for excavating materials from the Moon.

From physics to engineering
Some of the other Kennedy scientists specialize in fields like sensing, optics, thermodynamics and even quantum mechanics. Indeed, sensors that can detect and measure physical properties in unusual circumstances are critically important in spaceflight. For example, most spacecraft use hydrogen as a fuel, but it burns invisibly to the human eye, which means that it is difficult to detect if the gas is, say, leaking slowly from a large tank. A broad knowledge of physics is therefore useful for our team to think of different ways of detecting various materials – whether acoustically, spectrally or in a vacuum – and then to invent a suitable sensor to perform those tasks.

Although most KSC staff are engineers, quite a few of them originally studied physics at university. They choose to work on engineering problems because they find it even more fun than research. Indeed, much as I now love my current job in physics research, I still find that my time working on launch operations is some of the most exciting of my life.

Many physics students mistakenly think that they will not be able to get a job in engineering unless they become a qualified engineer or take a lot of specialized courses at university. While that might be true in civil engineering, it is not the case in other branches of the subject. Indeed, most people working in the aerospace industry only gain a specialized engineering knowledge once they have been hired.

What that means is that a physics degree is perfectly suitable if you want to apply for an entry-level job as an engineer in the space sector. Furthermore, physicists make outstanding engineers because a physics education gives you the confidence to think physically instead of by rote, which makes you an excellent problem solver. Sure, specialized engineering courses can help you land that first job, particularly when the employment market is lean, however, you can always study those courses after graduating. If you go down this path, you may even find that you can apply for more specialist entry-level positions, such as those that involve design work.

Ironically, if you do take a job as an engineer in the space industry, you may eventually find yourself doing something that looks more like science than when you were hired. I know quite a few physicists (myself including) who started their careers as engineers and later moved into research. This happens because industry is very competitive, and successful employers are those who do not waste their employees' abilities.

So, if you work hard and prove your loyalty – while remembering to have fun – you may find that a job that was not initially what you wanted may transform into the career of your dreams. Careers are long and rarely end in the way they begin. This is especially true in space exploration, where employers constantly have to solve very unusual problems. Physicists in the sector will never stay unnoticed for long.

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About the author
Philip Metzger is a research physicist at the Kennedy Space Center in Florida, US