Gravity Systems Provide Deep Insight for Earth Exploration


Lockheed Martin builds multiple versions of gravity gradiometer instruments, like those (top center) used in Full Tensor Gradiometer (FTG) systems. Other gradiometers (left and right) are used for partial-tensor systems, such as the CGG Falcon™ and the Land Gradiometer System, while smaller instruments (bottom center) are targeted for navigation applications.

Look at the world around us, and it’s easy to see the differences: The flat farm fields of the Midwest. The hills and valleys of rural Pennsylvania. The rugged peaks of the Rocky Mountains. Venture a bit farther and the differences show themselves through the lush rainforests in South America. Desert landscapes in Africa. Vast coniferous forests in Siberia. Glaciers in Greenland.

But try to peek beneath the Earth’s amazing topography, and it becomes nearly impossible to tell what’s there. Is there water? Oil? Valuable minerals? Anything at all worth exploring?

That’s where a unique technology available only from Lockheed Martin comes into play.

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For more than 20 years, gravity gradiometers have been commercially used to investigate small variations in the earth’s density. The technology is based on the scientific principle that earth’s gravity field varies with location, local topography and subsurface geologic features. Measuring the gravity variation caused by items beneath the earth’s surface can help identify unique underground and undersea geologic structures – from natural resource deposits to potential national security threats.



“Gravity cannot be spoofed,” explains Dan DiFrancesco, business development lead for gravity systems, Lockheed Martin Mission Systems and Training. “Think of it this way: A brick and a piece of wood have very different densities. Even if you put them side-by-side, they’re not going to have the same gravity signature. We can tell the difference. That’s what gravity gradiometers can do – show the differences in what’s beneath the earth’s surface by measuring the pull of gravity from the top and the sides, which greatly improves the ability to detect objects.”

Originally created as a tool to help launch and direct ballistic missiles, Lockheed Martin transitioned gravity gradiometers to commercial surface ship and airborne applications in the 1990s. Today, the technology is gaining increasing interest as countries around the world look to identify new options for natural resources, energy supplies and mining.

“The days of stumbling upon an unknown lode of gold or a geyser of oil are over,” says DiFrancesco. “Future deposits of natural resources lie deeper beneath the earth’s surface, are likely smaller in size, and will be harder to find. But businesses don’t have unlimited exploration budgets. They have to be smart about where they look.”

Information from gravity gradiometers is used in conjunction with other measurements, like magnetic field intensity and seismic data, to provide a robust data set that helps identify areas that are good candidates for further exploration. For instance, gravity signals associated with mineral or hydrocarbon deposits are a key element of most resource exploration pursuits.

And while the fundamental physics behind today’s gravity gradiometer technology aren’t changing, how the technology is applied is continually evolving. Unconventional ways to deploy gravity gradiometers so customers can see smaller and deeper targets could range from autonomous underwater or aerial vehicles to fixed-wing aircraft or other airborne platforms that can provide advantageous survey conditions.

“The goal is to help customers get the information they need to have a great degree of confidence about where resources are and some initial indication of the amount of resource that might be down there,” says DiFrancesco. “It’s ironic, but gathering information to decide where NOT to proceed on a project may be the most valuable. It will save on limited budgets and focus efforts where they’ll be most valuable.”

May 14, 2014

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