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                                                                     EXHIBIT 5.1


                           OPINION OF LATHAM & WATKINS

                               December 11, 1998


ViaSat, Inc.
2290 Cosmos Court
Carlsbad, California 92009

         Re:      Form S-8 Registration Statement; 500,000 Shares of Common
                  Stock

Ladies and Gentlemen:

                  In connection with the registration by ViaSat, Inc., a
Delaware corporation (the "Company"), of 500,000 shares of common stock, par
value $.0001 per share (the "Shares"), of the Company to be issued pursuant to
The 1996 Equity Participation Plan of ViaSat, Inc. (the "1996 Plan") under the
Securities Act of 1933, as amended (the "Act"), on a Registration Statement on
Form S-8 filed with the Securities and Exchange Commission on December 11, 1998
(as amended from time to time, the "Registration Statement"), you have requested
our opinion with respect to the matters set forth below.

                  In our capacity as your counsel in connection with such
registration, we are familiar with the proceedings taken and proposed to be
taken by the Company in connection with the authorization, issuance and sale of
the Shares, and for the purposes of this opinion, have assumed such proceedings
will be timely completed in the manner presently proposed. In addition, we have
made such legal and factual examinations and inquiries, including an examination
of originals or copies certified or otherwise identified to our satisfaction of
such documents, corporate records and instruments, as we have deemed necessary
or appropriate for purposes of this opinion.

                  In our examination, we have assumed the genuineness of all
signatures, the authenticity of all documents submitted to us as originals, and
the conformity to authentic original documents of all documents submitted to us
as copies.

                  We are opining herein as to the effect on the subject
transaction only of the General Corporation Law of the State of Delaware, and we
express no opinion with respect to the applicability thereto, or the effect
thereon, of the laws of any other jurisdiction or any other laws, or as to any
matters of municipal law or the laws of any other local agencies within the
state.

                  Subject to the foregoing, it is our opinion that as of the
date hereof the Shares have been duly authorized, and, upon the issuance of and
payment for the Shares in accordance 


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with the terms set forth in the 1996 Plan, the Shares will be validly issued,
fully paid and nonassessable.

                  We consent to your filing this opinion as an exhibit to the
Registration Statement.


                                          Very truly yours,

                                          /s/ LATHAM & WATKINS
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