Crew Survival Considerations for Manned Spaceflight Programs - Past, Present, and Future
Pate, D
SAIC

Crew survival concepts, which have been employed in the US manned spaceflight effort since the first missions, gained a renewed emphasis after the loss of the crew of the space shuttle Columbia on February 1, 2003. The Columbia Accident Investigation Board (CAIB) report included the observation that "Future crewed-vehicle requirements should incorporate the knowledge gained from the Challenger and Columbia accidents in assessing the feasibility of vehicles that could ensure crew survival even if the vehicle is destroyed" . This concept of crew survival is one of mitigating the effects of a hazardous event (i.e. surviving the "bad day") once it has occurred and differs from the traditional emphasis of safety engineering, which focuses on preventing hazardous events (i.e. preventing the "bad day"). Current efforts at NASA go beyond just the lessons learned from the Challenger and Columbia accidents to include reviewing all manned spaceflight accidents as well as applicable aviation and automobile information.

The current development of crew survival engineering within NASA can be divided into six capabilities:

  • abort - early termination of the mission or mission phase due to a failure
  • escape - in-flight removal of the crew due to an imminent catastrophic event
  • emergency egress - unassisted crew exit of the vehicle within a specified time in the event of an emergency
  • emergency medical - treatment of crew for manifested medical conditions
  • safe haven - providing life support requirements until escape or rescue given a catastrophic event
  • rescue - assisted retrieval of the crew due to off-nominal events These capabilities are tailored for each phase of a mission (pre-launch, ascent, on-orbit, entry, descent, touchdown, post-touchdown) and are being further tailored to address the unique requirements for lunar and planetary missions.

    Crew survival engineering within NASA is an evolutionary process. During Project Mercury, crew survival concepts were manifested by design features such as the use of a pressure suit, a launch escape system, life rafts, first aid kit, survival pack, and the design of the seat and restraints. During Project Gemini the launch escape rocket was replaced with ejection seats. Project Apollo returned to using the launch escape rocket. The Space Shuttle design did not include the use of pressure suits and only the first few flights included ejection seats and pressure suits for the Commander and Pilot positions. Once the shuttle was deemed operational, the ejection seats and pressure suits were removed. Pressure suits were only added back after the loss of the space shuttle Challenger. The Crew Exploration Vehicle returns to using a launch escape system.

    All of the hazards associated with life can never be fully mitigated. This is especially true when pushing to expand the frontiers of engineering and exploration. However, there are measures that can be employed to increase the likelihood of crew survival in the event of a "bad day".