Entry, descent and landing (EDL) is probably the most difficult and risky phase of a human mission to Mars. Whatever the EDL systems for Mars, the qualification might be very difficult, very expensive and the risks could still be very high, especially for the first missions. Risks could nevertheless be mitigated if backup options existed during the final phase of EDL. If an important problem is encountered during the last minutes of the descent and if the velocity is lower than Mach 3, a possible option is to use an ejection seat, an individual parachute and small thrusters, which could be attached to the seat of the astronaut. The total mass of such a rescue system would be of the order of 230 kg, which does not include the mass of the astronaut. In the event of an emergency landing, the astronaut will still have to reach a safe haven quickly to survive because of his limited life support system autonomy. An automatic rover can be sent to rescue the astronaut and increase the maximum rescuing distance. A probabilistic risk assessment has been performed. Provided that the autonomy of the life support system is 8 h and that there is no insurmountable obstacle, it is shown that the probability of reachability is 0.9 at 50 km from the safe haven.

进入、下降和着陆 (EDL) 可能是人类火星任务中最困难和风险最大的阶段。无论火星的 EDL 系统是什么，资格都可能非常困难，非常昂贵，而且风险仍然很高，尤其是对于第一次任务。如果在 EDL 的最后阶段存在备份选项，则可以降低风险。如果在下降的最后几分钟遇到重要问题并且速度低于 3 马赫，则可能的选择是使用弹射座椅、单独的降落伞和小型推进器，它们可以连接到宇航员的座椅上. 这种救援系统的总质量约为 230 公斤，其中不包括宇航员的质量。在紧急降落的情况下，由于生命支持系统的自主性有限，宇航员仍必须迅速到达安全港才能生存。可派自动漫游车救援宇航员，增加最大救援距离。已执行概率风险评估。假设生命支持系统的自主性为 8 h，且没有不可逾越的障碍物，则表明距离避风港 50 km 处可达概率为 0.9。