The NRAO is working with the astronomical community to develop the scientific and technical concepts for the next generation of centimeter- and meter-wavelength telescopes after the Expanded Very Large Array (EVLA). These concepts comprise the Square Kilometer Array (SKA) Program, which ultimately may be realized by building several large international telescopes. The role of NRAO in the SKA was presented by the NRAO Director at the US SKA Consortium meeting in May 2008. Within NRAO, we have formed an NRAO-SKA Working Group as part of our participation in SKA. The primary working group goals are to coordinate and plan NRAO participation in the various SKA activities, to ensure a coherent Observatory approach, and to work with our US and international colleagues in preparing a compelling scientific and technical case for the SKA Program in the US decadal survey for astronomy, expected to take place between 2008 and 2010.

The current outline of the SKA Program revolves around three concepts:

• SKA-low: Covering a frequency range of roughly 0.07 to 0.3 GHz, the low-frequency component of the SKA Program will investigate the Epoch of Reionization and a variety of transient sources.
• SKA-mid: Covering a frequency range of roughly 0.5 GHz to 3 GHz or higher, the mid-frequency component of the SKA Program will be primarily a survey instrument, exploring the evolution of galaxies, Dark Energy, transient sources, and the realm of strong gravity.
• SKA-high: Covering a frequency range from 3 GHz or higher to ~25-50 GHz, the high-frequency component of the SKA Program will be primarily a pointed instrument, exploring the formation of stars and planets, strong gravity, and searching for extraterrestrial intelligence.