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                                                                   Exhibit 10.15

                                 SUB-SUBLEASE
                                 ------------

        THIS SUB-SUBLEASE is made this 2nd day of July 1998, by and between IT 
Corporation, a California corporation, hereinafter called "Sub-Sublessor," and 
US Digital Satellite, Inc. a Delaware corporation, hereinafter called 
"Sub-Sublessee."

                                   RECITALS
                                   --------

I.      The American Association of Museums (Sublessor) and IT Corporation, a
        California corporation (Sublessee), entered into a sublease agreement,
        which for reference purposes is dated June 6, 1997, with respect to the
        premises known as 1575 Eye Street, NW, Suite 425, Washington, D.C. said
        sublease and amendments being hereinafter referred to as the "Master
        Sublease", a copy of which is attached hereto as Exhibit A and
        incorporated by reference.

II.     Sub-Sublessor desires to sublease to Sub-Sublessee approximately 2,650
        rentable square feet for twenty one (21) months and 14 days of the 
        above-described property being subleased by Sub-Sublessor under the
        terms of the Master Sublease, a copy of which is attached hereto, and
        Sub-Sublessee desires to sublease such space from Sub-Sublessor.

        THEREFORE, Sub-Sublessor and Sub-Sublessee agree as follows:

        A.  Demise and Description of Property. Sub-Sublessor hereby subleases 
            -----------------------------------
            to Sub-Sublessee, and Sublessee hereby hires from Sub-Sublessor, on
            and subject to the terms, conditions, and covenants hereinafter set
            forth, the property described above; hereinafter referred to as the
            "Subleased Premises", located at 1575 Eye Street, NW, Suite 425,
            Washington, D.C. as further described in the Master Sub-Sublease
            attached hereto.

        B.  Term.  The term of this sub-sublease shall be for a period of 
            ----
            Twenty One (21) months and 14 days, commencing on September 1, 1998,
            and terminating on June 14, 2000, unless sooner terminated as
            outlined in the Master Sublease.

        C.  Rent.  Upon execution of this sub-sublease, Sub-Sublessee shall 
            ----
            provide advance payment of the two (2) month's rent which includes
            a security deposit of one (1) months rent and the first months rent 
            in advance. The rent is $4,858.33 per month full service, excluding
            any taxes based upon rent through July 31, 1998 and $5,004.08 per
            month thereafter to the termination of the Sub-Sublease on June 14,
            2000.  The following schedule shall be the rent which shall be paid
            directly to Sub-Subleaser.

            September 1, 1998 to July 31, 1999          $4,858.33 per month
            August 1, 1999 to June 14, 2000             $5,004.08 per month

        D.  Use of Premises.  The subleased premises shall be used by 
            ---------------
            Sub-Sublessee for office and for uses normally incident thereto.  No
            storage of any kind or hazardous materials will be allowed or any
            materials used in the subleased premises that would be
            environmentally dangerous to the subleased premises.

        E.  Obligations of Sublessee.
            ------------------------

            1.  Sub-sublessee will be required to submit a security deposit of 
                $4,858.33 due upon execution of this Sub-Sublease.

            2.  Sub-Sublessee shall pay rent directly to Sub-Sublessor at 
                IT Corporation, Accounts Payable, 2790 Mosaide Blvd., 
                Martinsville, PA, 15148-2792.

            3.  Sub-Sublessee will confine its operations to the designated
                office space and will not use any office space whether used or
                occupied by Sub-Sublessor, or other Tenant or Subtenant.

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        4. Sub-Sublessee will provide a Certificate of Insurance to evidence the
            following coverages: Workers Compensation/statutory coverage,
            Employers Liability/$2,00,000, Commercial or General
            Liability/$2,000,000, Automotive Liability/$2,000,000 and All Risk
            Property Insurance for replacement value for all of Sub.-Sublessee's
            property and improvements. Such insurance will provide a Waiver of
            Subrogation to Sub-Sublessor, and list the Sublessor and Sub-
            Sublessor as an Additional Insured on the Commercial or General
            Liability. Employers Liability and Automotive Liability policies.
            Such certificate must be sent to: Mr. Frank C. Rice, Vice President,
            IT Corporation, 2790 Mosside Blvd., Monroeville, Pennsylvania,
            15146, prior to the effective date of this Sub-Sublease and any
            occupancy of the premises in accordance with this Agreement. In the
            event that such insurance is canceled or discontinued, or a current
            certificate is not on file at the above-mentioned address, this Sub-
            Sublesse may be canceled at the sole discretion of Sub-Sublessor.

        5.  Sub-Sublessee accepts the space in an "As IS, WHERE IS" condition,
            with all faults, except that Sub-Sublessor will permit the Sub-
            Subleased Premises with a color selected by Sub-Sublessee, subject
            to Sublessor's approval, shampoo the existing carpet, and

            (a)  Sub-Sublessee covenants and agrees to pay the rent herein
                 reserved, used the premises for the purpose hereinbefore
                 stated, and to surrender the leased premises on expiration, or
                 earlier termination, of the term hereof, in as good as
                 condition as when received, reasonable wear and tear expected.

            (b)  Sub-Sublessee agrees that it will protect and save and keep in 
                 Sublessor and Sub-Sublessor forever harmless and indemnified
                 against, and from, any penalty or damage or changes imposed for
                 any violation of any laws or ordinances, whether occassioned by
                 the neglect Sub-Sublessee or those holding under Sub-Sublessee,
                 and that Sub-Sublessee will, at all times, protect, indemnify,
                 save and keep harmless the Sublessor and Sub-Sublessor against,
                 and from, any and all loss, cost, damage or expense arising out
                 of, or from, any accident or other occurrence on or about said
                 premises, causing injury to any person or property whomsoever
                 or whatsoever, and will protect, indemnify, save and keep
                 harmless the Sublessor and Sub-Sublessor against and from any
                 and all claims, and against, and from, any and all loss, cost
                 or damage, or expense arising out of any failure of Sub-
                 Sublessee in any respect to comply with and perform all of the
                 requirements and provisions hereof. All of the above expect for
                 any liability or damage caused by the negligence of Sub-
                 Sublessee.

            (c)  Sub-Sublessee will insure any personal property it maintains in
                 the sub-subleased premises at replacement value with no more
                 than a $5,000.00 deductible.

            (d)  Sub-Sublessee will make a good faith effort to keep the 
                 subleased premises secure and in good, clean and orderly
                 condition.

            (e)  Sub-Sublessor will use it's reasonable efforts to assist 
                 Sub-Sublessee to obtain parking in the Building garage. Any
                 such parking is at the Sub-Sublessee's expenses.

            (f)  Sub-Sublessee will pay the direct costs associated with any
                 additional HVAC required after customary billing operating
                 hours as additional rent to the extent that such billing hours
                 are clearly identified in the utility bill.

        F.  Other Provisions of Sub-Sublease.  All applicable forms and 
            -------------------------------
            conditions of the Master Sublease are incorporated into and made a
            part of the Sub-Sublease as if Sub-Sublessor were Sublessor
            thereunder, Sub-Sublessee the Sublessee thereunder, and the
            Subleased


   




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                Premises the Master Sublease Premises, except for the following 
                Master Sublease provisions:

                Sub-Sublessee assumes and agrees to perform the Sublessee's
                obligation under the Master Sublease during the Term to the
                extent that such obligations are applicable to the Sub-Subleased
                Premises, except that the obligation to pay rent to Sublessor
                under the Master Sublease shall be considered performed by Sub-
                Sublease to the extent and in the amount rent is paid to Sub-
                Sublessor in accordance with Section C. above of this Sub-
                Sublease. Sub-Sublessee shall not commit of suffer any act or
                omission that will violate any of the provisions of the Master
                Sublease. Sub-Sublessor shall exercise due diligence in
                attempting to cause Sublessor to perform its obligations under
                the Master Sublease for the benefit if Sub-Sublease. Section 12
                (Pre-Occupancy Tenant Work) Section 58 (Financial Statements
                Rent Section 4 Deposits) Section 5 Term Section 2

           G.   Signage. The Sub-Sublessor will provide the Sub-Sublessee with
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                building standard suite signage in the building directory and at
                the suites entrance.

           H.   Master Sublessor Consent. This Sub-Sublease is subject to the
                ------------------------
                consent of the Master Sublessor, which shall be attached hereto,
                and is incorporated herein by reference. If the Master Sublessor
                does not consent, then the Sub-Sublease is terminated and both
                Parties are released from all obligations under this Sub-
                Sublease. Further, this Sub-Sublease shall be modified to
                incorporate any reasonable terms and conditions required by the
                Master Sublessor or Landlord to obtain such consent.

           I.   Severability and Survival of Covenants. If any provisions of
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                this Sub-Sublease shall be invalid under any law, it shall be
                inapplicable and deemed omitted, but the remaining provisions
                shall be given effect in accordance with the intent of the Sub-
                Sublease.

           J.   This Sub-Sublease does not replace, negate, or otherwise
                invalidate the Sublease Agreement (Master Sublease) dates June
                18, 1997 between IT Corporation and American Association of
                Museums, nor the Office Lease Agreement between 1575 Eye Street
                Associates and the American Association of Museums (Overlease).
                Sub-Sublessee acknowledges that it has received a copy of the
                referenced Master Sublease and Overlease, that it has reviewed
                both, and that it is familiar with the contents thereof.

Executed at Monroeville, PA and _________________, __ on the day and year first 
written above. Sublessee must notarize its signature.


SUB-SUBLESSOR:   ITS CORPORATION      SUB-SUBLESSEE:  US DIGITAL SATELLITE, INC.


Signature: /s/ Frank C. Rice          Signature: /s/ Philip Kernan
          ---------------------                 --------------------------------
Name:     Frank C. Rice               Name:     Philip Kernan  
          ---------------------                 --------------------------------
Title:    Vice President              Title:    President
          ---------------------                 --------------------------------

                                                  (ATTACH NOTARY STATEMENT HERE)

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