More than $21000$ objects fly in outer space and are exposed to the harsh space environment. The size of space objects considerably varies. Our research focuses on nanosatellites, such as CubeSats, which have to respect time, spatial and energy constraints. To tackle this issue, this paper presents and evaluates two fault tolerant online scheduling algorithms: the algorithm scheduling all tasks as aperiodic (called OneOff) and the algorithm placing arriving tasks as aperiodic or periodic tasks (called OneOff&Cyclic). Based on several scenarios, we analyse how much the performance (in terms of both the rejection rate and the scheduling time) of ordering policies are influenced by the system load and the proportions of simple and double tasks to all tasks to be executed. The “Earliest Deadline” and “Earliest Arrival Time” ordering policies for OneOff or the “Minimum Slack” ordering policy for OneOff&Cyclic reject the least tasks in all tested scenarios. The paper also deals with the analysis of scheduling time to evaluate real-time performance of ordering policies and shows that OneOff requires less time to find a new schedule than OneOff&Cyclic. Finally, it was found that the studied algorithms perform well also in a harsh environment and provide the same availability as systems based on triple modular redundancy with very much less system power consumption.

多于 $21000$物体在外层空间飞行，暴露在恶劣的空间环境中。空间物体的大小差异很大。我们的研究侧重于纳米卫星，例如立方体卫星，它们必须遵守时间、空间和能量限制。为了解决这个问题，本文提出并评估了两种容错在线调度算法：将所有任务调度为非周期性（称为OneOff）的算法和将到达任务作为非周期性或周期性任务的算法（称为OneOff&Cyclic）。基于几个场景，我们分析了排序策略的性能（在拒绝率和调度时间方面）受系统负载和简单任务和双任务占所有要执行的任务的比例的影响有多大。OneOff的“最早截止日期”和“最早到达时间”排序策略或OneOff&Cyclic的“最小 Slack”排序策略在所有测试场景中拒绝最少的任务。该论文还分析了调度时间以评估订购策略的实时性能，并表明OneOff比OneOff&Cyclic需要更少的时间来找到新的调度. 最后，发现所研究的算法在恶劣的环境中也表现良好，并提供与基于三重模块冗余的系统相同的可用性，而系统功耗却少得多。