EX-10.5.1: MEMORANDUM OF AGREEMENT

Exhibit 10.5.1

ORBCOMM Inc.
2115 Linwood Avenue, Suite 100
Fort Lee, NJ 07024

October 10, 2007

Re: Memorandum of Agreement by and between ORBCOMM Inc. (“ORBCOMM”) and Orbital Sciences Corporation (“Orbital”) concerning modification to Amendment #1, dated as of April 21, 2006 (the “Amendment”) of ORBCOMM Concept Demonstration Communication Payload Procurement Agreement B10LG1192, dated November 3, 2004 (the “Procurement Agreement”). Capitalized terms not otherwise defined herein shall have the meanings ascribed to them in the Amendment.

Ladies and Gentlemen:

This Memorandum of Agreement sets forth the parties’ agreement to amend certain particulars of the Amendment and, in consideration therefore, Orbital shall deliver and convey to ORBCOMM all right, title, interest and possession to certain equipment as described below.

The liquidated delay damages set forth under Section 3(i) of the Amendment associated delivery of Additional Payloads #3, 4, 5 and 6 are amended to commence on and including the following dates:

Additional Payload #3:		October 4, 2007
Additional Payload (& antenna) #4:		October 11, 2007 (also includes antenna for PL #3)
Additional Payload (& antenna) #5:		October 21, 2007
Additional Payload (& antenna) #6:		The date that is 75 days from the receipt by Orbital of the payload plate.

The restarted liquidated delay damages will be assessed at a rate of $8,500 USD per payload per day starting on the onset dates shown above. The maximum liquidated delay damages shall not exceed a cap of $850,000.00 USD as set forth in the Amendment.

The parties agree that the Holdback Amount of $680,000 under Section 3(vii) of the Amendment shall be paid by ORBCOMM to a mutually agreeable third party escrow agent prior to the launch of one or more of the Additional Payloads and shall be released to ORBCOMM or Orbital, on a pro rata basis, in accordance with the terms of the Amendment.

AP Milestone #9 shall be split to account for the later delivery of Additional Payload #6 as follows: Payment for successful completion of delivery of (i) Additional Payload # 5 and

Orbital Sciences Corporation • Space Systems Group • 21839 Atlantic Blvd., Dulles, VA 20166 • 703 ###-###-####

antenna shall be $350,000 USD and (ii) Additional Payload #6 and antenna shall be $150,000 USD.

Finally, Orbital shall deliver and convey to ORBCOMM all right, title, interest and possession of the EGSE rack of equipment described on attached Schedule 1 (the “EGSE Equipment”) currently in use by Orbital for the purpose of Additional Payload testing together with the delivery of Additional Payload #5. Orbital agrees that its representations and warranties set forth in Section 9.1 of the Procurement Agreement are true and correct with respect to the EGSE Equipment.

Except as expressly modified in this Memorandum of Agreement, all other terms of the Amendment, including all exhibits thereto, shall remain in full force and effect.

IN WITNESS WHEREOF, the parties have caused this Memorandum of Agreement to be executed as of the day and year first written above.

ORBCOMM INC.						ORBITAL SCIENCES CORPORATION
By:		/s/ John J. Stolte				By:		/s/ Rob Cramer

Name:		John J. Stolte				Name:		Rob Cramer
Title:		EVP TECH & OPS				Title:		Director of Contracts
Date:		10/15/07				Date:		10/16/07

Orbital Sciences Corporation • Space Systems Group • 21839 Atlantic Blvd., Dulles, VA 20166 • 703 ###-###-####

Schedule 1

ITEM		DESCRIPTION		PART NUMER		QTY.
#
1		EGSE PAYLOAD RACK A ASSEMBLY		###-###-####-01			1
2		GPS RECEIVER — SYMMETRICOM		XL-AK			1
3		PRECISION C/N GENERATOR — NOISE/COM		UFX-BER-IF1			1
4		FREQUENCY COUNTER — FLUKE		PM6685			1
5		POWER METER — AGILENT		E4418B			1
6		POWER HEAD — AGILENT		E9301H			1
7		SPECTRUM ANALYZER — HP/AGILENT		8560B			1
8		SIGNAL GENERATOR — AGILENT		E4434B			1
9		SIGNAL GENERATOR — AGILENT		E4438C			1
10		ACE-360 COMM INTERFACE — ORBITAL		4AA80000132-01			1
11		VME RACK MOUNT CHASSIS — SYNERGY		N/A			1
12		TORREY MODEM CARD — TORREY SCIENCE		N/A			1
13		DSP CARD — SYNERGY		DSP-440			1
14		VTI CARD 48V — SYNERGY		N/A			1
15		POWER SUPPLY CHASSIS — AGILENT		N6700B			1
16		POWER SUPPLY CHASSIS — AGILENT		N6700B			1
17		POWER SUPPLY CHASSIS — AGILENT		N6700B			1
18		POWER MODULE 0-20V — AGILENT		N6743B			1
19		POWER MODULE 0-20V 15A — AGILENT		N6773A			1
20		POWER MODULE 0-8V — AGILENT		N6732B			1
21		PAYLOAD MONITOR PANEL — ORBITAL		###-###-####-01			1
22		EGSE PAYLOAD RACK B ASSEMBLY		###-###-####-01			1
23		SIGNAL GENERATOR — HP/AGILENT		8643A			1
24		RF SWITCH MATRIX — ORBITAL		S158720303Y0-01			1
25		ANTENNA SIMULATOR — ORBITAL		S158720304Y0-01			1
26		RF MONITOR PANEL — ORBITAL		###-###-####-01			1
27		Sun Workstation w/pasissim and atlas card software		TBD			1
28		Sun Keyboard		TBD			1

Orbital Sciences Corporation • Space Systems Group • 21839 Atlantic Blvd., Dulles, VA 20166 • 703 ###-###-####

29		Sun Mouse		TBD			1
30		Sun Monitor		TBD			1
31		Desktop PC w/Labview license and Orbital Labview software		TBD			1
32		PC Keyboard		TBD			1
33		PC Mouse		TBD			1
34		PC Monitor		TBD			1
35		PAYLOAD EXTERNAL POWER INTERFACE CABLE		###-###-####-01			1
36		PAYLOAD EXTERNAL DATA INTERFACE CABLE		###-###-####-01			1
37		[Removed]
38		RF TEST PORT CABLES		TBD			3

Orbital Sciences Corporation • Space Systems Group • 21839 Atlantic Blvd., Dulles, VA 20166 • 703 ###-###-####