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Human-rating certification, also known as man-rating or crew-rating, is the certification of a spacecraft or launch vehicle as capable of safely transporting humans. There is no one particular standard for human-rating a spacecraft or launch vehicle, and the various entities that launch or plan to launch such spacecraft specify requirements for their particular systems to be human-rated.
One entity that applies human rating is the US government civilian space agency, NASA. NASA's human-rating requires not just that a system be designed to be tolerant of failure and to protect the crew even if an unrecoverable failure occurs, but also that astronauts aboard a human-rated spacecraft have some control over it. This set of technical requirements and the associated certification process for crewed space systems are in addition to the standards and requirements for all of NASA's space flight programs.
The development of the Space Shuttle and the International Space Station pre-dates the current NASA human-rating requirements. After the Challenger and Columbia accidents, the criteria used by NASA for human-rating spacecraft were made more stringent.
Commercial Crew Program (CCP)
The NASA CCP human-rating standards require that the probability of a loss on ascent does not exceed 1 in 500, and that the probability of a loss on descent did not exceed 1 in 500. The overall mission loss risk, which includes vehicle risk from micrometeorites and orbital debris while in orbit for up to 210 days, is required to be no more than 1 in 270. Maximum sustained acceleration is limited to 3 g.
The United Launch Alliance (ULA) published a paper submitted to AIAA detailing the modifications to its Delta IV and Atlas V launch vehicles that would be needed to conform to NASA Standard 8705.2B. ULA has since been awarded $6.7 million under NASA's Commercial Crew Development (CCDev) program for development of an Emergency Detection System, one of the final pieces that would be needed to make these launchers suitable for human spaceflight.
SpaceX is using Dragon 2, launched on a Falcon 9 rocket, to deliver crew to the ISS. Dragon 2 made its first uncrewed test flight in March 2019 and has been conducting crewed flights since Demo-2 in May 2020.
Boeing is developing the Starliner spacecraft as part of the Commercial Crew Program.
Other space agencies
The Russian state corporation Roscosmos, Indian space agency ISRO, Chinese space agency CNSA, and each private spaceflight system builder typically sets up their own specific criteria to be met before carrying humans on any space transport system.
- "Human Rating Requirements for Space Systems". NASA. 10 July 2017.
- "Atlas and Delta Capabilities to Launch Crew to Low Earth Orbit" (PDF). United Launch Alliance. n.d. Retrieved 2011-11-27.
- Chaikin, Andrew (2011-11-16). "Certified Safe: Planning to operate a taxi service for NASA astronauts? Here's what's required". Air and Space Smithsonian. Retrieved 2011-11-27.
We've separated [the "loss of crew" criteria] into what you need for ascent and what you need for entry. For ascent, it's 1 in 500, and independently for entry, it's 1 in 500... The probability for the mission itself is 1 in 270. That is an overall number. That's the loss of crew for the entire mission profile, including ascent, on-orbit, and entry. The thing that drives the 1 in 270 is really micrometeorites and orbital debris... whatever things that are in space that you can collide with. So that's what drops that number down, because you've got to look at the 210 days, the fact that your heat shield or something might be exposed to whatever that debris is for that period of time. NASA looks at Loss of Vehicle the same as Loss of Crew. If the vehicle is damaged and it may not be detected prior to de-orbit, then you have a loss of crew.
- "NASA and ULA confirm Atlas V baseline for human rated launches". NASASpaceflight.com. 19 July 2012. Retrieved July 24, 2014.
- "Live coverage: NASA astronauts launch from U.S. soil for first time in nine years". Spaceflight Now. 30 May 2020.
- "Suits from Vadodara, parachutes from Agra: Inside ISRO's plan to launch India's first astronauts". The Economic Times. 18 January 2019. Retrieved 17 May 2019.