Table 1.

Summary of the characteristics and limitations of the selected analogue environments

	LEO	LMIC/humanitarian	Combat	ICE
Description	Use of LEO as analogue for interplanetary travel research	Resource-poor setting with lack of equipment and medical expertise	Out of hospital austere setting, high prevalence of severe trauma and blast injuries	Expeditions in environments such as: mountain, high altitude, polar, jungle, desert
Volume of surgical proceduresa	Nil	High	High	Low
Technological and equipment constraints	++	+++	++	++
Human constraints	++	+++	++	++
Patient physiological alterations	++ secondary to exposure to microgravity	±	Soldiers are healthy individuals before injury	± (possible hypoxia, hypo/hyperthermia)
Limitations for applicability to SEM	No experience of surgery or anaesthesia. Lacks total isolation (option to evacuate, real-time telemedicine)	Does not provide microgravity and/or radiation exposures. Anaesthesia providers very different from astronaut population	Does not provide microgravity and/or radiation exposures. Pathology nearly exclusively traumatic. Well trained providers	Does not provide microgravity and/or radiation exposures

LEO low earth orbit, LMIC low and middle income country, ICE isolated and confined environment

+: present; ++: important; +++: major

^askill erosion is not expected in environments with a high caseload