In addition, in connection with the proposed merger, a management information circular of MDA, describing details of the transaction and other information, has been mailed to MDA's shareholders. The management information circular contains important information about the proposed merger and related matters. SHAREHOLDERS OF MDA ARE URGED TO READ ALL RELEVANT DOCUMENTS FILED WITH CANADIAN SECURITIES REGULATORY AUTHORITIES, INCLUDING THE MANAGEMENT INFORMATION CIRCULAR, CAREFULLY AND IN THEIR ENTIRETY BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT MDA AND THE MERGER. Additional information about MDA, including all relevant documents filed with Canadian securities regulatory authorities, can be found under its corporate profile on SEDAR at www.sedar.com or by contacting the contact above.

PARTICIPANTS IN THE SOLICITATION

This communication is not a solicitation of proxies in connection with the proposed merger. However, DigitalGlobe, MDA and their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from DigitalGlobe's stockholders in respect of the proposed merger.  Information about the directors and executive officers of DigitalGlobe, including their respective interests by security holdings or otherwise, is set forth in the definitive proxy statement/prospectus mailed to DigitalGlobe stockholders in connection with the proposed merger.  Additional information about DigitalGlobe's directors and executive officers is also available in DigitalGlobe's proxy statement for its 2017 annual meeting of stockholders filed with the SEC on May 1, 2017.  Information about the directors and executive officers of MDA, including their respective interests by security holdings or otherwise, is set forth in the definitive proxy statement/prospectus for the proposed merger and in the management information circular mailed by MDA to its shareholders. Additional information about MDA's directors and executive officers is also available in the management proxy circular for MDA's 2017 annual and special meeting of shareholders, which was filed on MDA's SEDAR profile on June 22, 2017 and which is available at sedar.com.  These documents can be obtained free of charge from the sources indicated above.

ABOUT MDA

MDA (TSX: MDA), is a global communications and information company providing operational solutions to commercial and government organizations worldwide.

MDA's business is focused on markets and customers with strong repeat business potential, primarily in the Communications sector and the Surveillance and Intelligence sector. In addition, the Company conducts a significant amount of advanced technology development.

MDA's established global customer base is served by more than 4,800 employees operating from 15 locations in the United States, Canada, and internationally.

MacDonald, Dettwiler and Associates Ltd. (MDA) common shares trade on the Toronto Stock Exchange under the symbol "MDA."

ABOUT SSL MDA HOLDINGS

SSL MDA Holdings, Inc., based in San Francisco, CA, is a wholly owned subsidiary of MacDonald, Dettwiler and Associates Ltd. and serves as the operating company for all MDA businesses.

ABOUT DIGITALGLOBE

DigitalGlobe is a leading global provider of high-resolution Earth-imagery products and services sourced from our own advanced satellite constellation and third-party providers. Our imagery solutions support a wide variety of users in defense and intelligence, civil agencies, mapping and analysis, environmental monitoring, oil and gas exploration, infrastructure management, Internet portals, and navigation technology. Each day users depend on us to better understand our changing planet in order to save lives, resources and time.

MDA CONTACTS

Investor Relations
Marissa Poratto
MDA Investor Relations
(604) 331-2044
mporatto@mdalimited.ca  

Media relations (Canada):
Wendy Keyzer
MDA Media Relations
(604) 231-2743
wendy@mdacorporation.com

Media relations (United States):
Trevor R. Martin
Abernathy MacGregor
(415) 926-7961
trm@abmac.com

DIGITALGLOBE CONTACTS

Investor Relations
Fred Graffam
DigitalGlobe, Inc.
(303) 684-1692
ir@digitalglobe.com

Media Relations
Turner Brinton
DigitalGlobe, Inc.
(303) 684-4545
turner.brinton@digitalglobe.com

Eric Brielmann / Scott Bisang / Matthew Gross
Joele Frank, Wilkinson Brimmer Katcher
(212) 355-4449

SOURCE MacDonald, Dettwiler and Associates Ltd.