We assessed the integrated safety, health, and performance risk to crews on long-duration missions, specifically to Mars. Using a systems approach rather than one focused on individual countermeasures, we examined the trade space around several such risks to identify high-potential risk mitigation strategies and characterize aspects of Mars mission architectures that could lower aggregated risk. Current Mars Design Reference missions would require durations well over two years and would increase crew exposure to radiation and microgravity well beyond ISS levels, likely resulting in significantly reduced performance beyond our current capability to mitigate that could jeopardize mission success. A “fast Mars transit” round-trip mission concept was studied using an innovative flight dynamics approach to quantify the minimum total mission energy required for a Mars transit with total mission duration less than 400 days. This approach holds promise for sending humans to Mars and returning them safely with acceptable, potentially mitigatable, exposure to microgravity and radiation using current or near-term technologies. The fast transit concept would also result in fewer time-driven vehicle failures and enable sustainable deployment of humans and infrastructure to Mars on a regular cadence, allowing steady exploration and colonization of Mars. Finally, we conclude that reliance on the Low Earth Orbit (LEO) mission operations paradigm – i.e., one of near-complete real-time dependence on experts at Mission Control to manage the combined state of the mission, vehicle, and crew – is high risk given the communication delays and limited resupply of any Mars mission, and this risk is not eliminated by the shorter missions durations of fast transit scenarios. Based on historical trends, it is highly likely that the crew will face a high-consequence problem of uncertain origin during Mars transit when ground support will be greatly reduced. While it may be possible to reduce anomaly rates through improved reliability analysis and testing, and to reduce anomaly impacts through added robustness, such mitigations address only known failure modes and known uncertainties. Therefore, a radical shift in the Human-Systems Integration Architecture (HSIA) that defines the operational paradigm, systems design, and human-systems interactions is required to improve the risk posture to an acceptable level regardless of mission duration.

我们评估了长期任务（特别是火星任务）中机组人员的综合安全、健康和绩效风险。我们使用系统方法而不是专注于个别对策的方法，检查了几种此类风险的交易空间，以确定高潜力的风险缓解策略并描述了可以降低总体风险的火星任务架构的各个方面。当前的火星设计参考任务将需要两年多的时间，并且将增加机组人员暴露于远远超出国际空间站水平的辐射和微重力的程度，可能导致性能显着降低，超出我们目前的能力，从而危及任务的成功。使用创新的飞行动力学方法研究了“快速火星凌日”往返任务概念，以量化总任务持续时间少于 400 天的火星凌日所需的最低总任务能量。这种方法有望将人类送上火星，并利用当前或近期的技术，在可接受的、可能可缓解的微重力和辐射下安全返回。快速运输概念还将减少时间驱动的车辆故障，并能够定期将人员和基础设施可持续部署到火星，从而实现对火星的稳定探索和殖民。最后，我们得出的结论是，对近地轨道（LEO）任务操作范例的依赖程度很高，即近乎完全实时地依赖任务控制中心的专家来管理任务、飞行器和机组人员的综合状态。考虑到任何火星任务的通信延迟和补给有限，这种风险并不能因为快速过境场景的任务持续时间较短而消除。根据历史趋势，宇航员在火星凌日期间很可能会面临来源不明的严重问题，地面支持将大幅减少。虽然可以通过改进可靠性分析和测试来降低异常率，并通过增加稳健性来减少异常影响，但此类缓解措施仅解决已知的故障模式和已知的不确定性。因此，无论任务持续时间如何，都需要对定义操作范式、系统设计和人机交互的人机系统集成架构 (HSIA) 进行根本性转变，以将风险状况改善到可接受的水平。