Note 4 Property, Plant, and Equipment, net

Property, plant, and equipment, net is stated at historical cost less accumulated depreciation. Cost for company-owned satellite assets includes amounts related to design, construction, launch, and commission. Cost for ground stations includes amounts related to construction and testing. Interest is capitalized on certain qualifying assets that take a substantial period of time to develop for their intended use. Depreciation expense is calculated using the sum-of-the-years’ digits or straight-line method over the estimated useful lives of the related assets as follows:

The determination of the estimated useful life of company-owned satellites involves an analysis that considers design life, random part failure probabilities, expected component degradation and cycle life, predicted fuel consumption and experience with satellite parts, vendors and similar assets.

Depreciation expense was $911 thousand and $885 thousand during the three months ended September 30, 2022 and 2021, respectively, and $2.6 million and 2.2 million during the nine months ended September 30, 2022 and 2021, respectively. Repairs and maintenance expenditures are expensed when incurred.

Construction-in-process includes company-owned satellites, ground station equipment, and machinery not yet placed into service. The Company capitalized interest to construction-in-process of $648 thousand and $360 thousand during the three months ended September 30, 2022 and 2021, respectively, and $1.8 million and $798 thousand during the nine months ended September 30, 2022 and 2021, respectively.

The Company reviews property, plant, and equipment, net for impairment whenever events or changes in business circumstances indicate that the net carrying amount of an asset or asset group may not be fully recoverable. The Company groups assets at the lowest level for which cash flows are separately identified. Recoverability is measured by a comparison of the net carrying amount of the asset group to its expected future undiscounted cash flows. If the expected future undiscounted cash flows of the asset group are less than its net carrying amount, an impairment loss is recognized based on the amount by which the net carrying amount exceeds the fair value less costs to sell. The calculation of the fair value less costs to sell of an asset group is based on assumptions concerning the amount and timing of estimated future cash flows and assumed discount rates, reflecting varying degrees of perceived risk.

There were no impairments of property, plant, and equipment during the three and nine months ended September 30, 2022 and 2021.