Exhibit 31.1  CERTIFICATION OF CHIEF EXECUTIVE OFFICER  I,
  Mark W. DeYoung, certify that:1.
  I
  have reviewed this annual report on Form 10-K of Alliant Techsystems
  Inc.;2.
  Based on my knowledge, this report does
  not contain any untrue statement of a material fact or omit to state a
  material fact necessary to make the statements made, in light of the
  circumstances under which such statements were made, not misleading with
  respect to the period covered by this report;3.
  Based
  on my knowledge, the financial statements, and other financial information
  included in this report, fairly present in all material respects the
  financial condition, results of operations and cash flows of the registrant
  as of, and for, the periods presented in this report;4.
  The
  registrants other certifying officer and I are responsible for establishing
  and maintaining disclosure controls and procedures (as defined in Exchange
  Act Rules 13a-15(e) and 15d-15(e)) and internal control over
  financial reporting (as defined in Exchange Act Rules 13a-15(f) and
  15d-15(f)) for the registrant and have:a)
  Designed
  such disclosure controls and procedures, or caused such disclosure controls
  and procedures to be designed under our supervision, to ensure that material
  information relating to the registrant, including its consolidated
  subsidiaries, is made known to us by others within those entities,
  particularly during the period in which this report is being prepared;b)
  Designed
  such internal control over financial reporting, or caused such internal
  control over financial reporting to be designed under our supervision, to
  provide reasonable assurance regarding the reliability of financial reporting
  and the preparation of financial statements for external purposes in accordance
  with generally accepted accounting principles;c)
  Evaluated
  the effectiveness of the registrants disclosure controls and procedures and
  presented in this report our conclusions about the effectiveness of the
  disclosure controls and procedures, as of the end of the period covered by
  this report based on such evaluation; andd)
  Disclosed
  in this report any change in the registrants internal control over financial
  reporting that occurred during the registrants most recent fiscal quarter that
  has materially affected, or is reasonably likely to materially affect, the
  registrants internal control over financial reporting; and5.
  The
  registrants other certifying officer and I have disclosed, based on our most
  recent evaluation of internal control over financial reporting, to the
  registrants auditors and the audit committee of the registrants board of
  directors (or persons performing the equivalent functions):a)
  All
  significant deficiencies and material weaknesses in the design or operation
  of internal control over financial reporting which are reasonably likely to
  adversely affect the registrants ability to record, process, summarize and
  report financial information; andb)
  Any
  fraud, whether or not material, that involves management or other employees
  who have a significant role in the registrants internal control over
  financial reporting.  Date:
  May 18, 2010
  By:
  /s/
  Mark W. DeYoungName:
  Mark
  W. DeYoungTitle:
  President and Chief Executive Officer