For immediate release: June 21, 2005

MDA to Study Assembly of Earth Imaging Structure in Space

Richmond, B.C. - MacDONALD, DETTWILER AND ASSOCIATES LTD. (TSX:MDA ), a provider of essential information solutions, announced today that it has been awarded a study by DARPA, the U.S. Defense Advanced Research Projects Agency, to define a demonstration system for the LASSO program. LASSO (which stands for Large Aperture Surveillance of Space Optical) will examine technology options for in-space manufacturing and assembly of a very large optical sensor surface and structure outside the confines of Earth's gravity.

Assembly in space draws upon MDA's extensive robotic expertise in manned and unmanned space exploration missions and is expected to enable the construction of large scale optical structures with resolution and accuracy superior to what can be built on Earth. The LASSO information solution envisioned consists of an in-orbit 150-metre optical system offering high resolution imaging of the Earth's surface. Such systems are too large to be launched in one piece and too sensitive to survive the forces experienced during a launch into space.

This study is another building block in MDA’s ongoing efforts to position itself for a future where space-based information solutions will be assembled, repaired and serviced in space.

The contract for this study has been facilitated through the Canadian Commercial Corporation, a Crown corporation of the Government of Canada mandated to facilitate international trade, particularly in government markets.

About MacDONALD, DETTWILER AND ASSOCIATES LTD. (MDA)

MDA provides advanced information solutions that capture and process vast amounts of data, produce essential information, and improve the decision making and operational performance of business and government organizations worldwide.

Focused on markets and customers with strong repeat business potential, MDA delivers a broad spectrum of earth and space based information solutions, ranging from complex operational systems, to tailored information services, to electronic information products.

MDA employs more than 2,500 people in locations across the United States, the United Kingdom, and Canada. The Company's common shares trade on the Toronto Stock Exchange under the symbol TSX:MDA.

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Related Websites:
www.mdacorporation.com
www.darpa.mil