<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED BALANCE SHEETS AND CONSOLIDATED STATEMENTS OF EARNINGS  AT AND FOR
THE THREE MONTHS ENDED MARCH 31,1998 AND IS QUALIFIED IN ITS ENTIRETY BY
REFERENCE TO SUCH FINANCIAL STAATEMENTS.

<CIK> 0000820736
<NAME> ORBITAL SCIENCES CORP /DE/
<MULTIPLIER> 1000

                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                              JAN-1-1998
<PERIOD-END>                               JUN-30-1998
<CASH>                                          45,757
<SECURITIES>                                       439
<RECEIVABLES>                                  221,978
<ALLOWANCES>                                   (8,101)
<INVENTORY>                                     36,398
<CURRENT-ASSETS>                               306,674
<PP&E>                                         221,128
<DEPRECIATION>                                (91,041)
<TOTAL-ASSETS>                                 833,990
<CURRENT-LIABILITIES>                          196,727
<BONDS>                                        156,109
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           368
<OTHER-SE>                                     445,281
<TOTAL-LIABILITY-AND-EQUITY>                   833,990
<SALES>                                        367,953
<TOTAL-REVENUES>                               367,953
<CGS>                                          273,436
<TOTAL-COSTS>                                  273,436
<OTHER-EXPENSES>                                     0
<LOSS-PROVISION>                                   721
<INTEREST-EXPENSE>                               4,740
<INCOME-PRETAX>                               (25,944)
<INCOME-TAX>                                     2,760
<INCOME-CONTINUING>                           (28,704)
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                  (28,704)
<EPS-BASIC>                                      (.83)
<EPS-DILUTED>                                    (.83)