Petascale computing refers to both petaflops, a million-billion calculations per second, and petabytes, a million-billion bytes of data. This level of computing power will enable the study of scientific problems at an unprecedented level of detail.

For example, current models allow scientists to design materials with thousands of atoms, while petascale computing will allow models with millions of atoms, yielding more accurate simulations of the properties of these materials.

During the past two decades, there have been many calls for investment in supercomputing resources in support of U.S. science and engineering research. The National Science Foundation (NSF) has responded by establishing a network of supercomputing centers and associated infrastructure that is open to the broad academic research community.

Despite this investment, recent assessments of cyber-infrastructure requirements have indicated that research at the frontiers of the geosciences in the U.S. is being impeded by an acute shortage of capability-class (the most powerful supercomputers used to solve the largest and most demanding problems) computing resources.

An ad-hoc committee of scientists working on behalf of the atmospheric-, solid Earth-, ocean- and space-science communities was formed with the NSF's encouragement to address the gap between the scientific requirements for, and the availability of, high-end computational resources. The committee's members are from universities, research centers and national laboratories.

Their report, "Establishing a Petascale Collaboratory for the Geosciences: Scientific Frontiers," is a landmark in petascale computing literature. It presents an overview of the scientific frontiers that would be opened by a national investment in leadership-class computing systems dedicated to geosciences research.

The report recommends an additional, complementary strategy for NSF investment in computational resources: deployment of the most powerful leadership-class systems available in the form of a "collaboratory."

This community-specific computational environment for research and education would provide high-performance computing services; data-, information- and knowledge-management services; human-interface and visualization services; and collaboration services.

The collaboratory concept is inspired by the report's observation that, in the past decade, the geosciences have progressed beyond traditional disciplinary organization that focused separately on problems of atmospheric, oceanic, solid Earth and space science. The challenges today demand integration across the disciplinary sciences because the individual systems and the planet's biota (including humans) interact to form a much larger system of systems whose components must ultimately be studied and understood together.

The challenges today also demand interaction among the disciplinary scientists, because there is a great deal of commonality in the way the various disciplines approach their respective problems. A principal commonality is that laws of hydrodynamics, magneto-hydrodynamics, and thermodynamics govern many central problems in the geosciences.

Based on the analysis in a companion report ("Technical Working Group and Ad Hoc Committee for a Petascale Collaboratory for the Geosciences, 2005"), it appears to be technically feasible to construct a highly capable petascale computing collaboratory that can deliver 200 teraflops (t-flops) aggregate peak in 2007 and achieve 1 petaflop (p-flop) peak by 2010.

Numerous areas of investigation will be enabled by petascale computing and the Petascale Collaboratory for the Geosciences (PCG). For example:

Global seismology. A petascale capability will facilitate the simulation of global seismic-wave propagation at periods of one second and longer, enabling the probe of Earth's deep interior with sufficient resolution to analyze the complex 3-D properties and structure of the core-mantle interface (the "D" layer) and the enigmatic inner core.

Multiscale modeling in mineral and rock physics. A petascale facility will allow integration of spatial information from the atomic, process and time scales for molecular dynamics to millions of years by coupling simulations of minerals' properties with geodynamic simulations.

Seismic tomography. Using modern data-assimilation techniques, a petascale facility would finally enable seismologists to tackle a fundamental problem: harnessing newfound 3-D modeling capabilities.

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