Astronaut & candidate

What happens to your spine in space

Why astronauts grow taller in space, why many get back pain, and what long missions do to back muscles and discs. Plain English, with sources.

What happens to your kidneys in space

Why spaceflight raises kidney stone risk: calcium lost from bone, less urine and changed diet. What crews do about it and what it means after landing.

What happens to your muscles in space

Why muscles that hold us up shrink in space, how much strength and fitness astronauts lose, how hours of daily exercise help, and how recovery goes.

What happens to your sleep in space

Why astronauts sleep about six hours a night, how 16 sunrises a day and shifting schedules upset the body clock, and what lighting and medicines do.

What happens to your immune system in space

How spaceflight unsettles the immune system, why dormant viruses such as chickenpox and Epstein-Barr wake up, and what rashes and allergies mean.

Behavioral health monitoring

What psychological problems have occurred in spaceflight, how agencies select, train, monitor and support crews, what isolation analogs teach us, and how to help with reintegration after return.

◆◆◇◇ Low · F A E

Bone loss countermeasures

How much bone astronauts lose, what prevents it (resistance exercise, nutrition, and in research, bisphosphonates), how NASA monitors BMD with DXA, T-scores and FRAX, and what a primary care clinician should do after a long flight.

◆◆◆◇ Moderate · F A E

DCS & EVA

Why spacewalks carry decompression risk, how prebreathe protocols prevent it, how DCS is recognized and treated without a hyperbaric chamber, and other EVA hazards (CO2, water in the helmet, hand injuries) — with links to dive and altitude medicine.

◆◆◆◇ Moderate · E A F

Exercise countermeasures

What spaceflight does to aerobic capacity and muscle, NASA's fitness standards in plain numbers, how in-flight exercise works, and how to prescribe reconditioning after return.

◆◆◆◇ Moderate · F A E

Medical standards overview

What NASA's crew health standard actually requires, how astronauts are medically selected and recertified, and what that means for a clinician who sees space travelers.

◆◆◆◆ High · E F

Orthostatic intolerance on landing

Why returning space travelers get lightheaded or faint when they stand, how agencies prevent it (fluid/salt loading, compression garments, recumbent seating), and how to assess and treat it in the ED or clinic.

◆◆◆◇ Moderate · F A E

Postflight recovery & surveillance

A timeline of what to expect after landing — day 0 to day 45 and beyond — what NASA measures and when, which problems can persist for months or years, and how lifelong occupational surveillance works.

◆◆◆◇ Moderate · F E

Radiation limits & monitoring

NASA's radiation limits in plain clinical terms, how crew dose is monitored, what shielding can and cannot do, and what it means for a patient's lifetime cancer screening.

◆◆◆◇ Moderate · E C F M

Space motion sickness

Who gets space motion sickness, how it is graded, why promethazine is NASA's treatment of choice, what else is used, and how to manage the same symptoms after landing.

◆◆◆◇ Moderate · F E

SANS management

How space agencies screen for and manage optic disc edema, globe flattening, choroidal folds and hyperopic shift in long-duration flyers — and how to evaluate a returning astronaut's eyes.

◆◆◆◇ Moderate · F A E

Mission Medical Kits

What medical equipment, drugs and supplies are carried on suborbital flights, short commercial orbital flights, a low Earth orbit station, lunar and Gateway missions, and Mars-class missions, and how distance, duration, drug shelf life and the loss of evacuation change the kit.

◆◆◆◇ Moderate · F C E

Pre-Flight & Post-Flight Clinic

A plain-language design guide for a clinic that certifies people before flight and evaluates them after landing: equipment by evaluation domain, what to do in-house versus refer out, a room-by-room layout and an essential / recommended / advanced build.

◆◆◆◇ Moderate · F E

Learn

Start here to learn space medicine: a plain-language primer, reading paths for eight audiences, teaching cases, a self-check question bank, and how to train in aerospace medicine.

Learning paths

Eight ordered reading lists built from pages already on the site, each with a short note on what you will learn.

Astronauts

For career astronauts, astronaut candidates and people applying to become one, and for professional crew on government or commercial missions. It follows the medical side of a career in order: selection, preparing for flight, living in space, coming home and lifelong follow-up.

19 steps

Tools

Six interactive, educational tools: radiation dose, oxygen prebreathe, post-flight recovery timeline, commercial flyer screening checklist, Earth–Moon/Mars signal delay, and medical kit scope. Plus live space weather.

Radiation dose estimator

Estimate a mission's space radiation dose and compare a career total with NASA's 600 millisievert limit, using NASA reference missions or days × daily rate.

Prebreathe planner

See how breathing 100% oxygen before a spacewalk washes out nitrogen, using NASA's 360-minute tissue model and the tissue ratio (R-value) limits for U.S. and Russian suits.

Recovery timeline

Enter a landing date to see typical recovery milestones as calendar dates: orthostatic tolerance, balance, fitness, reconditioning, bone scans and eye follow-up for spaceflight-associated neuro-ocular syndrome.

Communication delay calculator

How long a message takes to reach a crew at the Moon or Mars on any date, with send and arrival times in Eastern Time and what the delay means for remote medical support.