There are several challenges for search and rescue robots: mobility, perception, autonomy, and communication. Inspired by the DARPA Subterranean (SubT) Challenge, we propose an autonomous blimp robot, which has the advantages of low power consumption and collision-tolerance compared to other aerial vehicles like drones. This is important for search and rescue tasks that usually last for one or more hours. However, the underground constrained passages limit the size of blimp envelope and its payload, making the proposed system resource-constrained. Therefore, a careful design consideration is needed to build a blimp system with on-board artifact search and SLAM. In order to reach long-term operation, a failure-aware algorithm with minimal communication to human supervisor to have situational awareness and send control signals to the blimp when needed.We carry out experiments in a controlled environment with the blimp's pose tracked when performing trajectory following in remote control and autonomous scenarios. Artifact search and communication performances are evaluated in real environments. Finally, we show that the "situational awareness" human intervention under limited communication allows the blimp to escape from getting stuck (such as in a constrained passage) and prolong the search operation time. Lesson learnt is discussed for future develops of the proposed blimp in different subterranean environments.