Laptops in Space: A Sparing Analysis Case Study for Personal Computers Used in Deep Space Exploration

As NASA seeks to extend human exploration into deep space in an era of increasingly tight budgets, there is a push to utilize more commercial off-the-shelf (COTS) components to accomplish mission tasks such as utilizing COTS personal computers to perform flight safety critical software responsibilities. Further, as missions advance into deep space, resupply missions to replace failed components become cost prohibitive or, as in the case of a Mars transit, all but impossible. With this problem in mind, the authors sought to know the reliability of personal computers in the intravehicular activity (IVA) space environment and how many personal computers would be needed for a given deep space mission profile considering the resultant reliability. In this paper, the authors analyze the life distributions of several generations of personal computers used on the International Space Station (ISS). The data are used to determine a failure rate for personal computers used on-orbit and are compared to failure rates for similar devices used terrestrially to show that personal computers fail more frequently on orbit than anticipated. Using the data, the authors generate a sparing analysis for adequate personal computers for reference missions for both a lunar orbiting station mission and a Mars transit mission.