Expanding its existing relationship with NASA, Google on Wednesday said it plans to lease 42.2 acres of unimproved land at the NASA Ames Research Center in Moffett Field, Calif., to construct up to 1.2 million square feet of offices and research space.

Google has provided a visual overview of the site on Google Maps.

Under the terms of the 40-year lease agreement, Google will pay rent of $3.66 million annually. The lease allows for the possibility of five 10-year extensions, making the maximum term 90 years, assuming both parties agree. The lease allows for periodic rent increases.

NASA Ames director S. Pete Worden heralded the agreement as the beginning of a new era of collaboration with Google in support of NASA's mission.

Google began working with NASA in September 2005, when the two companies signed a memorandum of understanding concerning future collaboration. Fruits of that relationship include the Planetary Content project, to make it easier to publish planetary data online, maps in Google Moon, and the NASA layer in Google Earth.

The NASA Ames Research Center is located near Google's Mountain View, Calif. headquarters. (The cozy relationship with NASA has also led to a deal that allows jets used by Google's executives to land at NASA's Moffett Field.)

The Google-NASA construction project will happen in three phrases, the first ending by September 2013, the second ending by 2018, and the third ending by 2022. The project will consist of office and research facilities, company housing, facilities for dining, sports, child care, conferences and parking, as well as improvements for NASA's use.

David Radcliffe, Google's VP of real estate and workplace services, held the arrangement up as an example "of the mutually beneficial partnerships that can be created between the public and private sectors."

Given the tensions that have emerged in other partnerships between the public and private sector -- the relationship between the National Weather Service and private companies that market weather data, for example -- it remains to be seen whether Google's interests will always be so well aligned with those of NASA.

But until such conflicts appear, the arrangement will serve to reinforce Google's image as a scientific powerhouse. Had Google chosen to partner with a less popular federal agency -- the IRS, for instance -- the brand benefits might not be so noteworthy.