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Q&A: Missions, Meetings, and the Radial Tire Model of the Magnetosphere
October 1, 2010
Tom Moore › Larger image
Magnetospheric MultiScale Project Scientist Tom Moore Credit: NASA

Goddard scientist Tom Moore has recently been named Project Scientist for the Magnetospheric MultiScale mission (or MMS), four spacecraft that will launch in 2014 to study "magnetic reconnection" – a crossing of magnetic field lines that can produce solar flares as powerful as a billion atomic bombs and is responsible for magnetic storms and auroras in Earth's atmosphere. Tom's primary research focus is on how the solar wind affects or damages planetary atmospheres and the subsequent implications for life. His previous project work at Goddard includes, among other roles, being project scientist for the Polar Mission, Project Study scientist for the NASA Magnetospheric Constellation Mission, Mission Scientist for IMAGE, and Mission Scientist for SpaceLab/Space Plasma Laboratory. We sat down with him for a little Q & A session about his new role within NASA's Heliophysics Division, which studies the Sun-Earth connection.

How did you get your start in Heliophysics?

I grew up in a blue-collar family and I didn't know what a scientist was for a long time. I could kind of see what an engineer was, so I started out as an electrical engineer. But there was some point in college . . . well, engineering was kind of hard. They wanted you to work ungodly hours or they were going to flunk you out. At some point along the way I read a line from Alan Watts that talked about how we don't come into the world from somewhere else, we come out of the world. We're the universe becoming conscious. It was a similar idea to Carl Sagan's point that we're all star stuff. After that I started reading about science more – and I switched to a physics major.

After I graduated, I started teaching, because it's hard to get a job in physics with only an undergrad degree. One of the things I enjoyed most was explaining astronomy to the students. Eventually I realized you have to get a graduate degree if you want to do research, so after three or four years of teaching, I quit and took off for grad school.

The way I got into this business, specifically, was because when you start trying to launch a career in space or astronomy you have to choose between astrophysics or the solar system. For me that was no contest – because there's no known life out there in the stars, but there is in the solar system. So my interests are in what conditions do you need to make a planet friendly, to turn it into the kind of thing we have here on Earth.

What are some of the highlights of your career at Goddard?

When you get something – anything - that you worked with ready to go up. You watched it take shape and you helped design it and it actually does what you want it to do. It's just an incredible feeling. It's almost like you defied the odds. So many things can go wrong that you just feel jubilant when it goes right. Of course, it usually does go right, since people here are so careful. But it still feels like you're defying the odds.

And then it works. And you get data that makes sense. And you see things you never thought you were going to see. And there's the whole process of arguing over what you saw and how it makes sense and how it differs from what you thought you'd see. Then, writing it up is a long tedious process, of course, but it's really satisfying when you publish and everyone agrees that you've really got something there.

What is your role as project scientist for the Magnetospheric MultiScale mission?

Basically my role is to try to remind people why we're doing this mission. When push comes to shove and compromises have to be made, my real function is to keep everyone reminded about the science goals and how to achieve them given the resources we have. There are a million choices that have to be made to figure out how to perform the best science.

And of course I have to go to plenty of meetings.

The science this mission will focus on is the study of magnetic reconnection. What is that?

I have a metaphor I use that I call the Radial Tire Model of the Magnetosphere. Imagine a tire rolling down the street on a planet where the atmosphere has this weird property that it's laced with microscopic fibers – when it rains, the water runs down these fibers. Normally the tire rolls right through, the air and the fibers just separate around it. But the fibers have this weird property: under just the right conditions the fibers connect up with the radial plies of the tire in a solid way. Now, the tire is moving, but it's attached to the fibers in the atmosphere. These pull on the tire. They tear it apart from the outside, and destroy it.

This happens in Earth's magnetosphere. The magnetic field lines act like a connective tissue of fibers. Magnetic reconnection is when those fibers in the solar wind connect up to the magnetosphere and start yanking on it. The magnetosphere is standing still, and the solar wind is moving as fast as greased lightning – so it tears things apart, stirs the whole thing up, peels off outer layers, drags them down-stream. This causes auroras near earth and is also the root cause of huge explosions around the sun.

How does MMS study this?

Weather in space has two very localized small regions that control all of this reconnection: connection on the upstream side, and disconnection on the downstream side. You can think of them like the eye of a hurricane. A hurricane can be really big, but it has a teensy weensy eye and aircrafts are sometimes flown into the eye to find out what's going on in the storm. MMS is trying to find that tiny region. We're flying four spacecraft in formation right into the eye of the storm.

We've gone through these regions before, but so quickly that we barely spot them. We know there's something going on in there that we've never quite caught. Now we're going in with instruments that are kind of like high speed cameras that can measure plasmas and magnetic fields and photons at 30 times per second. The plasma analyzer is 100 times faster than anything that has ever flown before.

MMS is certain to fly through the right place and we're going to see these regions for the first time. We're hoping to encounter those reconnection sites, or "diffusion regions" as they're sometimes called, dozens of times over the two and a half years of the mission.

How big are these two regions?

Each one is just a few kilometers across, about the size of Greenbelt. And the spacecraft are going by so fast – at 50 to 100 kilometers per second – that the region goes by in a tenth of a second. It's like trying to study Goddard from the International Space Station flying overhead at 10 km/s. By the time you've spotted it, you've gone by. But now we'll have those high speed cameras running. We'll still go by in a tenth of a second, but we'll get good movies of what's going on.

What information are you hoping MMS will provide about magnetic reconnection in those regions?

Basically in my Radial Tire model, when I talk about "just the right conditions" the whole question is about what are those special conditions that make the magnetic lines connect up to the magnetosphere - what makes it connect at a particular place and at a particular time. At the most simple level, the special conditions could just be that a magnetic line crosses another one at the right angle – but things are hardly ever that simple.

There are widely different theories - some six or eight - with really fundamental differences between them. Are the boundary conditions important and the small-scale stuff takes care of itself? Or does the small-scale stuff turn the whole process on and off sporadically, like a valve that has its own mind? MMS has gone all out to have the instruments we need to really distinguish between these theories.

Reconnection is the most controversial theory I've been involved with in 35 years of my career. It's just been non-stop controversy the whole time, so it's really neat to think we might be able to figure it out. You get incredibly polarized positions: some say it's the fundamental process of the whole space weather system versus others who say it's a bunch of baloney. At this point, it's pretty much proven that magnetic reconnection exists and is real, but there's still a lot of controversy on how it works.

We need to resolve it and this is the mission to do it.


Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, Md.

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