Optimal lifetimes of communications spacecraft

Sperber, Ray

doi:10.2514/6.1993-950

Cited by 4 publications

(1 citation statement)

References 2 publications

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“…Based on the previous observations and on a suggestion by Sperber [5], we propose to model the instantaneous average load factor of a communications satellite % LðtÞ as a function of time with three parameters or degrees of freedom: an initial beginning-of-life average load factor % L BOL at t ¼ 0; a steady-state end-of-life average load factor, % L EOL ; and an exponential fill process with a time constant t: Equation (8) represents our model structure. Results of the regression analysis using this model are given in Table II.…”

Section: Load Factors Of Satellites Launched In the Late 1980smentioning

confidence: 99%

Beyond cost models: communications satellite revenue models. Integrating cost considerations into a value‐centric mindset

Saleh

Padilla

2006

Satell Commun Network

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SUMMARYWhile satellite cost models are pervasive throughout the aerospace industry, revenue models or utility models of space systems are quasi-inexistent. This situation perhaps conveys the false impression that satellites are either cost sinks or expensive artefacts whose value or utility profile over their design lifetime is difficult to quantify. In this paper, we propose that satellites, like any other complex engineering systems, should be perceived as value delivery artefacts, and the value delivered, or the flow of service that the spacecraft delivers over its design lifetime, deserves as much effort to quantify as the system's cost. To this effect, we build, in the case of a GEO communications satellite, revenue models based on (1) statistical analyses of spacecraft loading dynamics and (2) historical trends of market prices for the communications services provided. Results and discussions presented here should prove useful to satellite operators and industry observers.

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Section: Load Factors Of Satellites Launched In the Late 1980smentioning

confidence: 99%

Beyond cost models: communications satellite revenue models. Integrating cost considerations into a value‐centric mindset

Saleh

Padilla

2006

Satell Commun Network

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Impact of Subsystem Reliability on Satellite Revenue Generation and Present Value

Saleh

Hassan

Torres-Padilla

et al. 2005

Journal of Spacecraft and Rockets

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A new framework is developed that analytically links an engineering concept, a system's reliability, with both managerial and financial concepts, the system's revenue generation capability, and its present value. A communications satellite is used as an example to illustrate the use and insights that can be generated from this framework. For instance, after the development of a revenue model for a communications satellite, the cost of unreliability was quantified: the present value penalty for the lack of 100% payload reliability. Next, the value of redundancy was also analytically captured: the satellite incremental present value provided by payload redundancy. The central finding is that present value calculations of a technical revenue-generating system, in this instance, a communications satellite, that do not account for system's reliability overestimate the system's present value and, thus, can lead to flawed investment decisions. Finally, when sensitivity analysis is performed on the various drivers of the satellite present value, it was found, against conventional wisdom, that redundancy in communications satellite payload is overrated; in other words, that increasing payload redundancy provides limited incremental value to the spacecraft. Nomenclature F(t) = probability distribution function that item fails within time interval [0; t] L(t)= satellite load factor as function of time, number of transponders in use at time t divided by total number of transponders onboard spacecraft; also known as utilization factor L 0 = average load factor of all current geostationary orbit communications satellites, approximately 60% in 2003 P i = price of transponder i per unit time P T x (t) = average price of transponder onboard spacecraft per unit time R n = reliability of item at time n T R(t) = reliability of item r T = discount rate adjusted for time period T T f = random variable, time to failure of item T x total = total number of transponders onboard spacecraft t wear-out = beginning of wear-out period of item u i = expected revenues generated between (i − 1) T and i T u(t) = expected revenue model of spacecraft per unit time, or system's utility rate after it reaches operational capability T = time period, small enough over which it is appropriate to consider u(t) and λ(t) constant λ(t) = failure rate of item τ = fill rate time constant

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Utilization Rates of Geostationary Communication Satellites: Models of Loading Dynamics

Saleh

Torres-Padilla

Morgan³

et al. 2006

Journal of Spacecraft and Rockets

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Optimal lifetimes of communications spacecraft

Cited by 4 publications

References 2 publications

Beyond cost models: communications satellite revenue models. Integrating cost considerations into a value‐centric mindset

Beyond cost models: communications satellite revenue models. Integrating cost considerations into a value‐centric mindset

Impact of Subsystem Reliability on Satellite Revenue Generation and Present Value

Utilization Rates of Geostationary Communication Satellites: Models of Loading Dynamics

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