Probing Our Neck of the Woods

Earth and MoonI’ve spent some time recently writing about very large-scale distances, speeds, masses, and things very much out and beyond not only our every day experience, but beyond even the every day experience of our little planet.

It doesn’t seem quite fair. I’m even guilty of using the pejorative “little planet” when referring to our rocky island home. So I’m going to take a slightly different tact this time, by staying at home, and first, looking at the sky.

Well, ok, fish first. They breathe water, in and out of their gills. You can watch them floating around, gasping away at it. We can’t do that. Instead, we constantly gasp away at a gas, or rather gases, that always surround us and stretch way up into the sky.

I won’t even talk about the crud we’re pumping into it. I’ll talk about our rocky Earth – the big sphere we live on, this giant rock covered almost entirely by water with a little, tiny thin film of gas surrounding it, held in place by gravity. That stuff we breathe.

Now, when we look up at the sky it seems pretty big up there, in all directions, way up high — there’s just a lot of it. But if our Earth were the size of a basketball, the atmosphere would be paper thin. It is paper thin.

If you were to drop down, falling from even higher than passenger jets fly, you’d enjoy a couple minutes of weightless and breeziness before you reached the ground.

But if somehow you managed to fall into a hole in the Earth that continued clean through, you’d keep falling for a long time – more than a day, before you’d reach the center. Hours and hours of falling – you could sleep the night through, wake up the next day, and still be falling.

Unless there was no air in that tunnel. Then you’d fall through the hole pretty fast, accelerating to over 15,000 miles per hour, taking only 21 minutes to reach the core of the Earth, and another 21 to pop out of the ocean on the other side. As you reached the center of the Earth, you would be weightless, having reached to center of mass, but you could continue to pendulum back and forth from one side of the earth to the other, emerging from your starting hole every 84 minutes, which is, interesting, about how long it would take a satellite to orbit the earth (near the surface).

But really, you wouldn’t last more than a minute or two, falling into the earth. The temperature and pressure build quite rapidly. At the core of our planet, most scientists believe molten iron churns, while a very few believe a nuclear reaction is taking place from naturally-occurring uranium (and with some good evidence).

MagnetosphereIn any event, a tremendous magnetic field is produced by something at our Earth’s core that stretches thousands of miles out into space. Our sun, continually bombarding us with high energy plasma, is thwarted in large part by this magnetic field. This is why our paper-thin atmosphere remains, and is not stripped away by the highly energized bombardment.

But other things do happen. These polarized particles bend back Earth’s magnetic field, a little like long hair in a convertible, only more frizzy and wiry. Most of the radiation is deflected around the planet, but some very little gets trapped, or through, and the movement of our magnetic lines creates electrical currents, eventually resulting in auroras, disrupted communications, power outages and irradiated stewardesses.

So, in a noble effort to save them, or, perhaps to answer the question, “which comes first, the break in current or magnetic reconnection?”, scientists and governments are launching the Themis probes today. That’s really the secret reason I’m writing this, giving myself a good excuse to dig.

Themis ProbesIt’s actually really cool. One Delta II rocket – 3-stage. And not just one probe, but 5-in-one, or 6-in-one if you count the Earth itself. The five probes are clustered together in this flower-pod-like configuration and will emerge into space, then separate out from each other, traveling to very distant positions from each other, one clear out toward the moon. They’ll let these long wire tendrils out from themselves, stretching out into the space around them, “listening” to the Earth’s magnetic field and the interactions it has with the solar winds.

There’s a nifty animation of the launch and deployment you can view, provided by Berkeley. If, for some reason, that link disappears, I’ll be saving a copy locally as well.

Each probe will be orbiting differently around the Earth yet all will work in tandem with their observations. If one of the probes fails, the one that headed out toward the moon will come back in closer to take its place.

Scientists want to know how the solar winds interact with our magnetic field. How much energy is deflected? How much comes in? Where does it go? How is it stored? How does it move into the Van Allen radiation belt? What amount of solar activity constitutes how much radiation? And yes, of course, what kicks off the aurora, the break in electrical currents that let the magnetic fields snap back, or the snapping of the magnetic fields that let loose the currents? And where, exactly, in our magnetotail is this happening?

It’s basically learning weather science as we move further into space, getting to know our neighborhood. Charting and predicting storms, and their degrees. These orbiting probes are very versatile for this purpose, as they move in their various configurations around the planet, sometimes observing and making comparisons on the “day-side” of Earth (when they’re all between us and the sun) and sometimes back on the night-side, where it seems all the fireworks originate.

Oh, and like the sun, it seems our Earth occasionally decides to flip its polarity as well, where North becomes South, and South becomes North. We can verify this by examining old rocks. Also, we have some other satellites up there measuring the strengths of the magnetic field, too. Some are saying the magnetic field is weakening. Others are saying, it’s getting ready to flip.

Some say the earth’s core is molten because our planet is still cooling from its wilder days of smashing into Mars-sized planets. Others say, once it’s cooled enough, the magnetic field will disappear, leaving our atmosphere, and ourselves, exposed to solar radiation like the atmosphere, if you can call it that now, of Mars.

Then again, Venus doesn’t have a magnetic field, except for an induced one from the solar wind’s interaction with its ionosphere, and Venus certainly does not lack for an atmosphere. Yet.

So what does it matter, burning all this fossil fuel, gaining oil profits, etc? We’re not going to be destroying the planet. And that’s true. We don’t possess nearly the expertise for such a large-scale accomplishment. So, no matter what we do, the planet will survive, as will whatever life forms in the future happen to climb out to mull about. We can only destroy ourselves.

But why not save the stewardesses? Even though they jet across the white polar regions burning their prehistoric remains and dropping black ash all over? I mean, we’re stuck down here for now and will need a good deal of time to work up the chutzpah to go elsewhere.

There has to be more to this all than just greed and self-interest, in our little corner of things. There has to be some reason Themis exists, other than saving the cost of replacing blown-out power transformers, planning military maneuvers at times when communications will be safe, and saving airlines money by saving them the hassle of diverting and grounding on their polar routes?

There is, isn’t there?

  • Feb. 17, 2007

    Dwayne Brown/Tabatha Thompson
    Headquarters, Washington

    George H. Diller
    Kennedy Space Center, Fla.

    RELEASE: 07-47


    CAPE CANAVERAL, Fla. – NASA’s THEMIS mission successfully launched
    Saturday, Feb. 17, at 6:01 p.m. EST from Pad 17-B at Cape Canaveral
    Air Force Station, Fla.

    THEMIS stands for the Time History of Events and Macroscale
    Interactions during Substorms. It is NASA’s first five-satellite
    mission launched aboard a single rocket. The spacecraft separated
    from the launch vehicle approximately 73 minutes after liftoff. By
    8:07 p.m. EST, mission operators at the University of California,
    Berkeley, commanded and received signals from all five spacecraft,
    confirming nominal separation status.

    The mission will help resolve the mystery of what triggers geomagnetic
    substorms. Substorms are atmospheric events visible in the Northern
    Hemisphere as a sudden brightening of the Northern Lights, or aurora
    borealis. The findings from the mission may help protect commercial
    satellites and humans in space from the adverse effects of particle

    THEMIS’ satellite constellation will line up along the sun-Earth line,
    collect coordinated measurements, and observe substorms during the
    two-year mission. Data collected from the five identical probes will
    help pinpoint where and when substorms begin, a feat impossible with
    any previous single-satellite mission.

    “The THEMIS mission will make a breakthrough in our understanding of
    how Earth’s magnetosphere stores and releases energy from the sun and
    also will demonstrate the tremendous potential that constellation
    missions have for space exploration,” said Vassilis Angelopoulos,
    THEMIS principal investigator at the University of California,
    Berkeley. “THEMIS’ unique alignments also will answer how the
    sun-Earth interaction is affected by Earth’s bow shock, and how
    ‘killer electrons’ at Earth’s radiation belts are accelerated.”

    The Mission Operations Center at the University of California,
    Berkeley, will monitor the health and status of the five satellites.
    Instrument scientists will turn on and characterize the instruments
    during the next 30 days. The center will then assign each spacecraft
    a target orbit within the THEMIS constellation based on its
    performance. Mission operators will direct the spacecraft to their
    final orbits in mid-September.

    During the mission the five THEMIS satellites will observe an
    estimated 30 substorms in process. At the same time, 20 ground
    observatories in Alaska and Canada will time the aurora and space
    currents. The relative timing between the five spacecraft and ground
    observations underneath them will help scientists determine the
    elusive substorm trigger mechanism.

    “I am proud to manage the fifth medium class mission of the Explorer
    Program,” said Willis S. Jenkins, the THEMIS program executive. “As
    we seek the answer to a compelling scientific question in geospace
    physics, we are keeping up the tradition that began with Explorer I.”

    NASA’s Launch Services Program at the Kennedy Space Center was
    responsible for the launch of THEMIS aboard a Delta II rocket. The
    United Launch Alliance, Denver, provided launch service.

    For additional information about THEMIS, news media should contact
    Cynthia O’Carroll, Goddard Space Flight Center, Md., at 301-286-4647
    or Robert Sanders, University of California, Berkeley, at

    The Explorer Program Office at Goddard manages the NASA-funded THEMIS
    mission. The Space Sciences Laboratory at the University of
    California, Berkeley, is responsible for project management, space
    and ground-based instruments, mission integration, mission operations
    and science. Swales Aerospace, Beltsville, Md., built the THEMIS
    probes. THEMIS is an international project conducted in partnership
    with Germany, France, Austria and Canada.

    For more information about the THEMIS mission and imagery on the Web,