(14) Commitments and Contingencies Contractual Obligations The following table summarizes our contractual cash obligations at September 30, 2011 (in thousands) : Payments due by year Less than 1 Year 1 to 2 years 2 to 3 years 3 to 4 years 4 to 5 years Thereafter Total (in thousands) Long-term debt obligations $ - $ - $ - $ - $ 400,000 $ 125,000 $ 525,000 Interest expense on long-term debt (1) 49,281 49,281 49,281 49,281 30,031 5,391 232,546 Operating lease obligations 3,060 3,974 3,122 2,419 2,466 15,909 30,950 Purchase obligations (2) 140,891 59,028 840 630 - - 201,389 Total contractual obligations $ 193,232 $ 112,283 $ 53,243 $ 52,330 $ 432,497 $ 146,300 $ 989,885 (1) Represents contractual interest payment obligations on the $400.0 million outstanding principal balance of our 2015 Notes, which bear interest at a rate per annum of 9.625% and contractual interest payment obligations on the $125.0 million outstanding principal balance of our 2016 Notes, which bear interest at a rate per annum of 8.625%. (2) Purchase obligations include all commitments to purchase goods or services of either a fixed or minimum quantity that are enforceable and legally binding. As of September 30, 2011, purchase obligations include EnhancedView-related commitments, ground systems and communication services. Operating Leases We have commitments for operating leases primarily relating to office and operating facilities and equipment. We lease various real properties under operating leases that generally require us to pay taxes, insurance, maintenance and minimum lease payments. These leases contain escalation provisions for increases as a result of increases in real estate taxes and operating expenses. We recognize rent expense under such leases on a straight-line basis over the term of the lease. Substantially all of these leases have lease terms ranging from three to twelve years. Some of our leases have options to renew. Total rental expense under operating leases was $0.9 million for each of the three month periods ended Septembe