Astronaut selection involves rigorous medical screening, ensuring that candidates possess the optimal health for the unique challenges of spaceflight. Especially for extended missions, where immediate and comprehensive medical care might be lacking, selecting the fittest individuals becomes paramount.  NASA has recently disclosed their medical standards for astronaut selection.   Other agencies are likely to have similar criteria.

For a broad overview of the medical elements in astronaut selection, please refer to the article Astronaut Medical Selection 101.   Another article, NASA’s Medical Standards - Broken Down, provides insights into the expected medical evaluations.  This article describes the specific disqualifying medical conditions for astronaut candidacy.

Disclaimer: This article is tailored for readers with a keen interest in the intricacies of astronaut medical selection criteria. For most applicants, the Astronaut Medical Selection 101 article should suffice. Importantly, the content here does not constitute medical advice or recommendations. Anyone with health concerns should seek counsel from a licensed medical professional. Please refrain from contacting Astro Perform for detailed medical selection inquiries.

General

  • Any medical condition that, in the judgement of the executive medical team, may compromise mission operations, performance of duties, or crew health or safety.
  • All injuries, contusions, fractures, or surgery unless healed and not associated with functional deficit that could interfere with the performance of duties.
  • History of heat stroke, temperature intolerance, or environmental injuries associated with significant sequelae that could interfere with performance of duties.
  • History of sensitivity or demonstrated allergy of sufficient severity as to interfere with the performance of duties.
  • Habitual use of tobacco products.
  • Chronic use of any medication requires AMB review.
  • All malignancies or history of malignancies, except those permitted within the medical standards.
  • Any foreign body or implant, unless considered not to be a hazard during the performance of duties.
  • Any condition or situation that precludes completion of the NASA medical evaluation process.
  • Sarcoidosis, all forms.
  • Decompression Illness (DCI):
  • Type II decompression sickness (DCS) or Arterial Gas Embolism (AGE) (involving the central nervous system, spinal cord, pulmonary DCS, or cardiovascular collapse) unless all signs and symptoms resolve with treatment. Such cases require specialist evaluation.
  • Type I DCS involving joint pain, the peripheral nervous system, or skin is not disqualifying if adequately treated and completely resolved.
  • Presence or history of systemic exertion intolerance disease or myalgic encephalomyelitis (previously known as chronic fatigue syndrome) and fibromyalgia.
  • Autoimmune disorders, including conditions such as systemic lupus erythematosus and dermatomyositis.
  • Any standard invalidated by new medical information may be appended by the AMB with CHMO approval.

Head, Face, and Neck

  • Deformities (e.g., scars, depressions, or exostoses) or chronic muscular contractions or spasms (e.g., torticollis) of the skull/head, face, and neck that interfere with wearing equipment/headgear and/or performance of duties.
  • Loss or congenital absence of bony substance of the skull.
  • Maxillofacial skeletal deformities that interfere with the performance of duties or wearing of equipment.
  • Temporomandibular disorders.
  • Congenital branchial cleft or thyroglossal duct cysts.
  • Chronic draining fistulae, regardless of cause.
  • Cervical ribs with signs or symptoms of thoracic outlet compression.
  • Deformities, injuries, or diseases that interfere with breathing, speech, mastication, and/or swallowing.
  • Deviation of the nasal septum.
  • Chronic rhinitis.
  • Perforation of the nasal septum.
  • Sino-nasal polyps.
  • Anosmia.
  • Chronic sinusitis.
  • Cleft lip and/or palate.
  • Loss or mutilation of a lip.
  • Malformations of the tongue.
  • Presence or history of marked stomatitis or ulcerations.
  • Ranulae.
  • Salivary fistula.
  • Enlarged tonsils or adenoids.
  • Recurrent salivary gland calculi.
  • Obstructive sleep apnea.
  • Disorders affecting clarity of speech.
  • Tracheostomy or tracheal fistula.
  • Recurrent epistaxis.
  • Disorders interfering with normal ventilation.
  • Zenker’s diverticulum.

Ears

  • Diseases of the ear with residual dysfunction.
  • Congenital deformation of the external ear.
  • Tumors of the external auditory canal.
  • Chronic external otitis.
  • Chronic otitis media.
  • Persistent tympanic membrane perforation.
  • History of stapedectomy.
  • Chronic mastoiditis or fistula.
  • Abnormal labyrinthine function.
  • Meniere’s disease.
  • Inability to equalize middle ear pressure.
  • Tinnitus that interferes with performance.

Hearing Standards

  • History of acute or sudden sensorineural hearing loss.
  • Inability to meet the pure tone audiometry hearing thresholds.
  • Annual examination requirements.

Frequency (Hz) Hearing Thresholds

  • 500 Hz: Both Ears - 30
  • 1000 Hz: Both Ears - 25
  • 2000 Hz: Both Ears - 25
  • 3000 Hz: Both Ears - 35
  • 4000 Hz: Both Ears - 50

Eyes

  • Disease, defect, or deformity of either eye or supporting structure that may interfere with the performance of duties.

Lids and Ocular Adnexae:

  • Any condition of the eyelids that impairs normal eyelid function.
  • Chronic blepharitis.
  • Blepharospasm.
  • Ptosis, unless a benign etiology that is not progressive and does not interfere with vision in any field of gaze or direction.
  • Growths on the eyelid unless small, asymptomatic, non-progressive, and benign.
  • Dacryocystitis or history of dacryocystitis.

Conjunctivae:

  • Chronic or recurrent conjunctivitis requires specialist evaluation.
  • History of trachoma requires specialist evaluation.
  • Dry eye syndromes requiring treatment, including xerophthalmia, requires specialist evaluation.
  • Pterygium that encroaches on the cornea more than 2 millimeters or recurs after two operative procedures (evaluation will be performed no earlier than 6 months postoperatively).

Cornea:

  • Chronic or recurrent keratitis requires specialist evaluation.
  • History of corneal ulcer or erosion requires specialist evaluation.
  • Herpetic ulcer or history of herpetic ulcer.
  • Vascularization, haze, or opacification of the cornea from any cause when it is progressive or interferes with vision.
  • Corneal dystrophy of any type, including keratoconus of any degree.
  • History of orthokeratology treatments within the previous 6 months.
  • History of penetrating or lamellar keratoplasty.
  • Refractive surgical procedures other than Photorefractive Keratectomy (PRK) (or other excimer laser surface procedures) or laser-assisted in-situ keratomileusis (LASIK). Wavefront guided procedures with a femtosecond laser are preferred. The following criteria apply:
  • All standard accepted clinical eligibility criteria for the procedure are met (e.g., corneal thickness).
  • Pre-operative cycloplegic refractive error is between +4.00 to -8.00 sphere, and astigmatism is 3.00 or less in minus cylinder format.
  • At least 6 months since last refractive/augmenting procedure, with no ongoing active ophthalmologic treatment or need for ophthalmic medications.
  • Post-operative refraction stable as demonstrated by two separate refractions ≥ 1 month apart differing by ≤ +/-0.50 diameter (D) (sphere) and ≤ +/-0.25 D (cylinder).
  • Post-operative manifest refractive errors within applicant standards.
  • No demonstrated adverse sequelae, including contrast sensitivity, glare, or night vision problems. All other vision standards are met.

Uveal Tract:

  • Acute, chronic, or recurrent inflammation of the uveal tract (iris, ciliary body, choroid).
  • History of uncomplicated post-traumatic iritis requires specialist evaluation.

Retina and Vitreous:

  • History or evidence of retinal detachment, unless traumatic with no sequelae, retinal tears, or edema.
  • Retinal hole with presence of fluid or vitreous traction. Other retinal holes require specialist evaluation.
  • Degeneration or dystrophies of the central or peripheral retina, including lattice degeneration, require specialist evaluation.
  • Pigmentary degenerations require specialist evaluation.
  • Retinitis, chorioretinitis, or other inflammatory conditions of the retina, unless single episode that has healed and does not impair central or peripheral vision.
  • Hemorrhages, exudates, or other retinal vascular conditions that potentially impair vision require specialist evaluation.
  • Vitreous opacities or conditions that may cause loss of central acuity or peripheral visual field require specialist evaluation.
  • Previous retinal treatment of any type requires specialist evaluation.

Optic Nerve:

  • Any history of optic nerve disease, including but not limited to, optic nerve inflammation, optic nerve swelling, or optic nerve atrophy.
  • Any optic nerve anomaly requires specialist evaluation.

Lens:

  • Aphakia.
  • Lens opacities that interfere with vision or are considered progressive require specialist evaluation.
  • Lens dislocation, partial or complete.
  • Intraocular implants or intraocular contact lenses.

Malignancy, and Other Defects and Disorders:

  • History or presence of malignant tumors of the eye or orbit.
  • Resected basal cell cancers or benign tumors require specialist evaluation.
  • Exophthalmos, anophthalmos, or microphthalmos.
  • Pathologic nystagmus.
  • Abnormal pupil(s) or loss of normal pupillary reflexes requires specialist evaluation.
  • Coloboma.

Refractive Standards—Inability to Meet the Following Refractive Requirements:

  • Distance or near visual acuity not correctable to 20/20 in each eye.
  • Refractive error (distant vision):
  • Cycloplegic refractive error of more than +5.50 or -5.50 diopters in any meridian.
  • Astigmatism requiring more than 3.00 diopters of cylinder correction.
  • Anisometropia of more than 3.50 diopters.

Visual Fields:

  • Any visual field defect, whether active, inactive, or migrainous requires specialist evaluation.

Extraocular Muscle Balance:

  • Esophoria greater than 10 prism diopters measured at 6 meters or 20 feet.
  • Exophoria greater than 10 prism diopters measured at 6 meters or 20 feet.
  • Hyperphoria greater than 2 prism diopters measured at 6 meters or 20 feet.
  • Any heterotropia measured at any distance.
  • Point of convergence (PC) greater than 100 millimeters.
  • Paralysis of ocular motion in any of gaze.
  • Diplopia, suppression, or a history of diplopia or suppression.

Depth Perception:

  • Lack of adequate depth perception on objective testing, with a minimum of 40 arcseconds.

Abnormal Night Vision:

  • Including retinitis pigmentosa, requires specialist evaluation.

Color Vision Deficiency:

  • Greater than mild deficiency on red-green or blue-yellow color vision testing.

Intraocular Pressure:

  • History of glaucoma, ocular hypertension, pre-glaucoma, or glaucoma suspect.
  • Pigmentary Dispersion Syndrome requires specialist evaluation.

Medically Required Use of a Contact Lens.

Lungs and chest wall

  • Any condition of the lungs, pleura, mediastinum, and chest wall that could interfere with performance of duties.
  • Pneumothorax or pneumomediastinum:
  • History of spontaneous pneumothorax or pneumomediastinum unless surgically corrected with apical pleurodesis or pleurectomy and free of complications, with full expansion of lungs on chest X-ray (CXR), normal pulmonary function tests (PFTs), and thin-cut CT showing no pathology predisposing to recurrence. This requires specialist evaluation.
  • Presence or history of traumatic pneumothorax, unless total resolution and free of complications, with full expansion of lungs on CXR, normal PFTs, and thin-cut CT showing no pathology predisposing to recurrence. This requires specialist evaluation.
  • Chronic pulmonary processes:
  • Chronic obstructive pulmonary disease (chronic bronchitis or emphysema) with evidence of pulmonary dysfunction and causing impairment or increased risk for pulmonary barotrauma.
  • Chronic pulmonary processes such as interstitial pneumonias, pulmonary injury, neuropulmonary disorders, hypersensitivity, and pneumoconiosis are disqualifying.
  • Abnormal pulmonary function tests require specialist evaluation.
  • Bronchiectasis. History of childhood bronchiectasis requires specialist evaluation
  • Asthma:
  • Current asthma of any degree.
  • History of asthma will require provoked bronchoconstriction testing and specialist evaluation.
  • Pulmonary blebs, bullae, or cysts
  • History of lung abscess requires specialist evaluation.
  • Granulomatous inflammation:
  • Non-infectious granulomatous inflammation (such as sarcoidosis, Wegener’s, allergic, or bronchocentric).
  • History of infectious causes, including mycotic infection (such as coccidioidomycosis, histoplasmosis) or protozoal infection (such as dirofilariasis, pneumocystis) requires specialist evaluation.
  • History of intrathoracic surgery requires specialist evaluation:
  • History of lobectomy or multiple segmental resections with normal pulmonary function requires specialist evaluation.
  • Removal of more than one lobe is cause for rejection
  • Any malignant tumor of the trachea, bronchi, lungs, pleura, or mediastinum: History of a benign tumor requires specialist evaluation.
  • History of suppurative periostitis, osteomyelitis, or necrosis of the ribs, sternum, clavicle, scapulae, or vertebrae with complete resolution and normal lung function requires specialist evaluation.
  • Chronic or recurrent mastitis.
  • Benign tumor or surgery of the breast or chest wall that interferes with the performance of duties.
  • History of unprovoked or recurrent pulmonary embolus. History of single provoked pulmonary embolus requires specialist evaluation.
  • History of empyema or sinus tracts of the chest wall require specialist evaluation.
  • History of surgically corrected tracheoesophageal fistula requires specialist evaluation.
  • History of pleural effusion of unknown etiology.
  • History of hemoptysis requires specialist evaluation.
  • History of breast cancer.

Cardiovascular

  • Any condition of the cardiovascular system that interferes with the performance of duties.
  • Cardiomyopathy such as hypertrophic or right ventricular cardiomyopathy (other than physiologic heart changes). History of acquired cardiomyopathy if recovered and left ventricular ejection fraction is > 50% requires specialist evaluation.
  • Hypertension, as defined by sustained systolic blood pressure of 140 mmHg or greater or diastolic of 90 mmHg or greater.
  • Recurrent syncope or symptomatic orthostatic intolerance (e.g., medication-induced, autonomic dysfunction, or other causes not otherwise specified), excepting post-space flight orthostasis. Recurrent neurally mediated syncope with clear precipitating factors requires specialist evaluation
  • History of pericarditis, myocarditis, and endocarditis without residual dysfunction requires specialist evaluation.
  • Congenital abnormalities:
  • History or findings of major congenital abnormalities of the heart and vessels.
  • History of atrial septal defect (ASD), ventricular septal defect (VSD), or patent ductus arteriosus (PDA), that has been surgically repaired requires specialist evaluation.
  • A patent foramen ovale (PFO) requires specialist evaluation.
  • Clinical evidence (angiographic, imaging, symptoms, history of prior event) of coronary artery disease.
  • Electrocardiographic abnormalities: Any cardiac dysrhythmia, conduction defect, or other ECG abnormalities on resting ECG, ambulatory ECG monitor, or any monitoring ECG rhythm strips require specialist evaluation.
  • Supraventricular arrhythmias:
  • Require AMB review and may be disqualifying:
  • Supraventricular tachycardia (SVT) assessed at least 6 months after ablation.
  • Atrial fibrillation/flutter assessed at least 6 months after ablation.
  • Presence or history of SVT or atrial fibrillation/flutter > 5 seconds.
  • Atrial ectopy (premature atrial complexes) > 1% and ≤ 20% of total beats on ambulatory ECG.
  • Presence of sustained (> 1 hour) sinus tachycardia at rest > 130 beats/min not related to physical activity during evaluation.
  • Disqualifying (other than those due to identifiable, reversible causes):
  • Presence or history of SVT or atrial fibrillation/flutter that is recurrent after intervention.
  • Presence of SVT with hemodynamic compromise.
  • Presence or history of atrial ectopy (premature atrial complexes) > 20% of total beats on ambulatory ECG
  • Ventricular arrhythmias:
  • Require AMB review and may be disqualifying:
  • Presence or history of ventricular tachycardia of 11 beats or greater without hemodynamic compromise.
  • Presence or history of frequent ventricular ectopy (frequent premature ventricular contractions [PVC]) > 1% and ≤ 20% of total beats on ambulatory ECG.
  • Right ventricular outflow tract tachycardia at least 6 months after ablation.
  • Disqualifying (other than those due to identifiable, reversible causes), presence or history of:
  • Ventricular tachycardia > 11 beats with ventricular dysfunction.
  • Ventricular tachycardia > 30 seconds.
  • Ventricular tachycardia with hemodynamic compromise.
  • Ventricular flutter/fibrillation or sudden cardiac arrest requiring resuscitation.
  • Frequent ventricular ectopy (frequent premature ventricular complexes) > 20% of total beats on ambulatory ECG.
  • Conduction/repolarization defects:
  • Require AMB review and may be disqualifying:
  • First degree atrioventricular (AV) block.
  • Presence or history of left bundle branch block (LBBB) without hemodynamic compromise.
  • Presence or history of second-degree type I AV block.
  • Presence or history of isolated early repolarization pattern.
  • Presence or history of Mobitz II, third degree AV block, complete right bundle branch block (RBBB), or bifascicular block without a pacemaker.
  • Presence or history of prolonged QTc (corrected QT interval) > 470 ms or QTc > 480 ms.
  • Disqualifying:
  • Presence or history of long QT syndrome, or presence of a genetic marker for long QT syndrome.
  • Any symptomatic or asymptomatic rhythm abnormality associated with ventricular dysfunction.
  • Presence or history of Mobitz II, third-degree AV block, RBBB, or bifascicular block with a pacemaker.
  • Other rhythm disturbances:
  • Disqualifying:
  • Presence or history of sick sinus syndrome or sinoatrial block.
  • Presence or history of other unspecified rhythm disturbance causing hemodynamic compromise.
  • Presence or history of catecholaminergic polymorphic ventricular tachycardia or presence of a genetic marker for CPVT.
  • Presence or history of tachy-brady syndrome.
  • Sinus node dysfunction:
  • Disqualifying:
  • Presence or history of sinus node dysfunction or arrest with pacemaker.
  • Presence or history of symptomatic sinus node dysfunction without a pacemaker.
  • Pacemakers and defibrillators:
  • Disqualifying:
  • Presence or history of a permanent pacemaker.
  • Presence or history of a defibrillator.
  • History of ablation or intervention:
  • Require AMB review and may be disqualifying:
  • Atrial fibrillation/flutter assessed at least 6 months after ablation.
  • AV junctional reentry tachycardia, AV nodal reentry tachycardia, or Wolff-Parkinson-White syndrome assessed at least 6 months after ablation.
  • Disqualifying:
  • Presence or history of post-ablation with ventricular dysfunction.
  • Presence or history of recurrent arrhythmias after ablation.
  • Presence or history of atrial fibrillation/flutter, AV junctional reentry tachycardia, AV nodal reentry tachycardia, or Wolff-Parkinson-White syndrome that has not been ablated or is recurrent after ablation.
  • History of palpitations:
  • Require AMB review and may be disqualifying:
  • Presence or history of recurrent palpitations with abnormal heart rhythm.
  • Disqualifying:
  • Presence or history of recurrent palpitations with abnormal heart rhythm and hemodynamic compromise.
  • Drug-induced rhythm disturbances:
  • Disqualifying:
  • Presence or history of drug-induced rhythm disturbance causing hemodynamic compromise.
  • Presence or history of drug-induced rhythm disturbance that is recurrent.
  • Other rhythm disturbances:
  • Disqualifying:
  • Presence or history of Brugada syndrome or presence of a genetic marker for Brugada syndrome.
  • Presence or history of short QT syndrome or presence of a genetic marker for short QT syndrome.
  • Presence or history of arrhythmogenic right ventricular cardiomyopathy/dysplasia.
  • Ectopic foci:
  • Disqualifying:
  • Presence or history of ectopic foci causing hemodynamic compromise.
  • Presence or history of ectopic foci that is recurrent.
  • History of supraventricular tachycardia.
  • History of cardiac trauma causing impairment.
  • History of aortic aneurysm or dissection.
  • Clinical evidence of peripheral vascular disease or arteritis.
  • History of rheumatic fever.
  • History of thromboembolic disease.
  • Presence of artificial valves.
  • History of unprovoked or recurrent deep vein thrombosis. History of single provoked deep vein thrombosis requires specialist evaluation.
  • Presence or history of heart transplant.
  • Presence or history of major congenital heart disease.
  • Presence or history of systemic vascular disorder.
  • Presence or history of valvular heart disease.
  • Presence or history of venous disease.
  • Use of drugs to treat cardiovascular disease.
  • Uncontrolled hyperlipidemia or other cardiovascular risk factors.
  • Any disqualifying condition listed in section on ECG abnormalities.
  • Any condition requiring pacemaker or defibrillator.
  • Presence or history of catecholaminergic polymorphic ventricular tachycardia.

Vascular

  • Any condition of the vascular system that interferes with the performance of duties.
  • Arteriosclerosis obliterans.
  • Raynaud’s disease or phenomenon.
  • History of systemic arteritis.
  • Presence or history of aneurysm of any artery or dissection of aorta.
  • Presence or history of arteriovenous malformation.
  • History of arterial embolus or thrombosis.
  • History of venous embolus or thrombosis.
  • History of chronic venous insufficiency or varicose veins.
  • History of deep vein thrombosis or pulmonary embolus. History of single provoked deep vein thrombosis or pulmonary embolus requires specialist evaluation.
  • History of superficial thrombophlebitis.
  • History of unprovoked or recurrent deep vein thrombosis. History of single provoked deep vein thrombosis requires specialist evaluation.

Blood Conditions

  • Red Cell Disorders:
  • Anemias require specialist evaluation.
  • Hemoglobin sickle cell (SS) and sickle-hemoglobin C (SC) disease.
  • Hemoglobin S trait with a history of complications such as renal papillary necrosis, pulmonary sequestration, or splenic infarct condition.
  • Hemoglobinopathies other than hemoglobin SS or SC disease, or S trait (example: thalassemias) require specialist evaluation for physiologic impairment (such as magnitude of anemia, level of anaerobic impairment, splenomegaly).
  • Hemolytic anemia with laboratory evidence of hemolysis or physiologic impairment.
  • Polycythemia requires specialist evaluation.
  • Miscellaneous red cell disorders (example, hereditary spherocytosis) require specialist evaluation for physiologic impairment. Glucose-6-phosphate dehydrogenase deficiency is not disqualifying.
  • White Cell Disorders:
  • Absolute leukopenia and absolute leukocytosis require specialist evaluation.
  • History of leukemia.
  • History of Hodgkin or non-Hodgkin lymphoma.
  • History of lymphoproliferative disorders.
  • Plasma cell dyscrasias, including monoclonal gammopathy of undetermined significance (MGUS), require specialist evaluation.
  • Lymphadenopathy requires specialist evaluation.
  • Platelet Disorders:
  • Thrombocytopenia requires specialist evaluation.
  • History of idiopathic thrombocytopenic purpura (ITP), unless isolated episode in childhood with complete recovery.
  • History of thrombotic thrombocytopenic purpura (TTP) or hemolytic uremic syndrome (HUS).
  • Thrombocytosis requires specialist evaluation.
  • History of chronic myeloproliferative diseases or myelodysplastic syndromes.
  • Hypercoagulable Disorders:
  • Vascular thrombosis or embolism requires specialist evaluation.
  • Two or more episodes of deep venous thrombosis are disqualifying.
  • Disorders of Hemostasis:
  • Personal history of bleeding disorder requires specialist evaluation.
  • Hemophilias.
  • Splenic Disorders:
  • Splenomegaly requires specialist evaluation.
  • Hyposplenism or post-splenectomy state requires specialist evaluation.
  • Other hematologic or reticuloendothelial disorders that could interfere with the performance of duties.

Abdomen and Digestive Systems

  • Chronic diseases or disorders of the gastrointestinal tract that interfere with the performance of duties.
  • Wounds, injuries, scars, or weaknesses of the muscles of the abdominal wall sufficient to interfere with function.
  • Abdominal wall hernias other than small asymptomatic umbilical hernias unless surgically corrected.
  • Relaxed inguinal ring or a diastasis recti without herniation is not disqualifying.
  • Any other herniations of clinical significance require specialist evaluation.
  • Sinus or fistula of the abdominal wall that is associated with underlying disease or is not surgically corrected.
  • Diseases of the esophagus such as strictures or Barrett’s esophagus.
  • Diverticula, rings, or webs unless corrected.
  • History of mild reflux esophagitis requires specialist evaluation.
  • Chronic abdominal pain is disqualifying unless asymptomatic for 5 years and after specialist evaluation.
  • History of gastric or duodenal ulcers. Medication or H. pylori-induced ulcers, unless resolved and documented by endoscopy.
  • Chronic dependence on acid-reduction medication.
  • History of gastrointestinal surgery for malignant or recurrent conditions.
  • Benign gastrointestinal neoplasm that is likely to enlarge or show malignant potential, unless removed.
  • History of intestinal obstruction due to any chronic or potentially recurrent disease. Surgery to relieve childhood pyloric stenosis, intussusception, volvulus, or Meckel’s diverticulum is not disqualifying if there are no sequelae.
  • Adhesive disease. Asymptomatic adhesive disease requires specialist evaluation.
  • Inflammatory bowel disease such as Crohn’s disease and ulcerative colitis.
  • Functional bowel disorder that interferes with the performance of duties.
  • Malabsorption Syndromes:
  • Celiac Disease.
  • Food sensitivities/intolerances are not considered malabsorption syndromes but require specialist evaluation.
  • Chronic diarrhea.
  • Chronic constipation requiring chronic or continuous medication or therapy.
  • History of diverticulitis. Diverticulosis requires specialist evaluation.
  • Gastrostomy, ileostomy, or colostomy unless surgically corrected and resulting in no postoperative dysfunction.
  • History of gastrointestinal bleeding from any cause except for post-traumatic bleeding, medication-induced gastritis, or minor bleeding (such as hemorrhoids or resolved infectious colitis).
  • Acute or chronic diseases of the rectum or anus. External or internal hemorrhoids that cause marked symptoms that could interfere with the performance of duties.
  • Liver:
  • History of non-viral or self-limited hepatitis (e.g., drug-induced) within the previous year requires specialist evaluation.
  • Benign liver tumors such as hemangiomas that are under 2 cm and demonstrated to be stable with serial scanning for 2 years require specialist evaluation.
  • Any chronic, recurrent, or progressive liver disease
  • Pancreas:
  • Chronic, recurrent, or progressive pancreatic disorders (e.g., pseudocyst).
  • Biliary tract:
  • Any chronic, progressive biliary tract disorder

Hormones

  • Any endocrine disease or disorder that may affect the performance of duties.
  • Presence or history of diseases of the hypothalamus or pituitary gland.
  • History of prolactin secreting pituitary adenoma 5 years after surgical resection requires specialist evaluation.
  • Diseases of the thyroid gland:
  • Presence or history of multi-nodular goiter, autoantibodies, benign cysts, or palpable nodules of the thyroid require specialist evaluation.
  • History of toxic adenoma 1 year after surgical resection requires specialist evaluation.
  • Diseases of the parathyroid gland.
  • Parathyroid adenoma after surgical resection requires specialist evaluation.
  • Diseases of the adrenal medulla or cortex.
  • Adrenal androgen excess requires specialist evaluation.
  • Metabolic disorders:
  • Diabetes mellitus, type 1 or 2.
  • Presence or history of gout or pseudogout.
  • Familial hyperlipidemias.
  • Inborn errors of metabolic pathways (except for Gilbert’s disease).
  • Acquired errors of metabolic pathways with potential pathologic sequelae require specialist evaluation.
  • Metabolic syndrome, in accordance with established guidelines.
  • Presence or history of malignant endocrine tumor.
  • Carcinoid syndrome:
  • History of carcinoid tumors requires specialist evaluation.
  • Pancreatic endocrine tumors (e.g., islet cell tumor or gastrinoma).

Urinary and Reproductive System

  • Any disorder of the genitourinary tract that may interfere with the performance of duties.
  • Anatomical abnormalities of one or both kidneys and lower urinary tract producing functional impact to the urogenital system:
  • A duplicated collecting system is considered a variant of normal anatomy and is not disqualifying unless associated with other pathology (e.g., hydronephrosis, nephrolithiasis, or recurrent episodes of infection).
  • Loss or absence of one or both kidneys.
  • Polycystic kidney disease.
  • Acute nephropathy or history of chronic nephropathy (e.g., hypertensive nephrosclerosis, diabetic nephropathy, and glomerulonephritis).
  • Autoimmune parenchymal disorders.
  • Vascular renal disorders.
  • History of tubular necrosis from any cause if associated with residual renal dysfunction that may interfere with the performance of duties.
  • Presence or history of urinary calculus (crystalline concretion within the urine-collecting system).
  • History of recurrent (≥ 3 per year) infections of the urinary tract require specialist evaluation.
  • Bladder, prostate, or urethral diseases that result in urinary retention, or interfere with micturition.
  • History of the above requires specialist evaluation.
  • Hydrocele or varicocele that is symptomatic or interferes with the performance of duties.
  • Any disorders of the testes, genitalia, or associated anatomical structures that interfere with the performance of duties.
  • Penile prosthetic implants.
  • History of primary or secondary neoplastic disorders of the urinary tract (kidneys, ureter, and bladder) and male genitals (testes, scrotal contents, prostate, and seminal vesicles).

Musculoskeletal Disorders

  • Any disorder of the bone, joint, muscle, or supporting structure that may interfere with the performance of duties.
  • Arthritic disorders:
  • Chronic osteoarthritis with functional disability that may interfere with the performance of duties.
  • Presence or history of inflammatory arthropathies requires specialist evaluation.
  • Infections:
  • Active infections of bone, joint, muscle, tendon, or supporting structures.
  • History of recurrent osteomyelitis.
  • History of non-traumatic avascular necrosis.
  • Presence or history of musculoskeletal malignancy.
  • Benign tumors or cysts of the bone require specialist evaluation.
  • Cartilaginous/Intra-articular disorders:
  • Osteochondromatosis or multiple cartilaginous exostoses that interfere with performance of duties.
  • History of osteochondromatosis or multiple cartilaginous exostoses that have been successfully surgically excised require specialist evaluation.
  • Intra-articular loose bodies in any joint (osteocartilaginous or foreign objects) that interfere with performance of duties.
  • History of intra-articular loose bodies in any joint surgically removed with no residual dysfunction requires specialist evaluation.
  • Joint instability:
  • Joint instability (recurrent subluxations or dislocations of an articulation).
  • History of joint instability that has been medically or surgically corrected requires specialist evaluation.
  • Fractures:
  • Non-union of fractures.
  • Mal-union of fractures that interferes with performance of duties.
  • Retained orthopedic hardware requires specialist evaluation.
  • Range of Motion: Deviations from the following range of motion or unexplained asymmetry requires specialist evaluation:
  • Shoulder:
  • Forward elevation to 170º-180º.
  • Abduction to 170º-180º.
  • Adduction 30º-40º.
  • Extension to 50º-60º.
  • Internal rotation in abduction to 60º-90º or in neutral to 45º.
  • External rotation in abduction to 60º-104º or in neutral to 40º-60º.
  • Elbow:
  • Flexion to 135º-150º.
  • Extension to 0º in males and ≤ -5º in females.
  • Forearm supination in neutral to 80º-90º.
  • Forearm pronation in neutral to 80º-90º.
  • Wrist:
  • Dorsal extension to 65º-85º.
  • Palmar flexion to 70º-80º.
  • Ulnar deviation in neutral to 30º-45º.
  • Radial deviation in neutral 15º-20º.
  • Hand/fingers: Any limitation in range of motion, strength, or dexterity that impairs functional performance requires evaluation by a specialist:
  • Limitation in full composite grip.
  • Limitation in full finger extension, i.e., palm flat on table.
  • Atrophy of intrinsic hand muscles or thenar eminence.
  • Inability to fully oppose thumb and fingers.
  • Hip:
  • Flexion to 125º-130º.
  • Extension to 10º-20º.
  • Abduction to 30º-45º.
  • Adduction to 20º-30º.
  • Internal rotation at 90º hip flexion to 40º-50º.
  • External rotation at 90º hip flexion to 30º-45º.
  • Knee:
  • Extension to 0º in males and ≤ -10º in females.
  • Flexion to 125º-135º.
  • Ankle:
  • Dorsiflexion to 10º.
  • Plantar flexion to 45º.
  • Inversion 50º-60º.
  • Eversion 20º-30º.
  • Spine:
  • Cervical Range of Motion (CROM):
  • Forward flexion between 50º-60º.
  • Extension between 65º-75º.
  • Lateral bending between 35º-45º.
  • Rotation between 70º-80º.
  • Lumbar Range of Motion (LROM):
  • Forward flexion from the waist to 70º-80º.
  • Extension from the waist to 30º-40º.
  • Lateral bending from the waist to 30º-45º.
  • Rotation from the waist to 25º-40º.
  • Spine disorders:
  • Symptomatic disorders of the spine, including but not limited to, herniated nucleus pulposus, spondylolisthesis, spina bifida, fractures and dislocations, scoliosis, kyphosis, or lordosis.
  • History of ankylosing spondylitis.
  • History of disorders of the spine that are asymptomatic, including but not limited to, osteoarthritis, herniated nucleus pulposus, spondylolisthesis, spina bifida occulta, fractures and dislocations, scoliosis, kyphosis, and lordosis require specialist evaluation.
  • Presence or history of herniated nucleus pulposus, fractures, or dislocations of the spine resulting in persistent neurologic deficit.
  • History of recurrent mechanical spinal or sacroiliac pain with disabling episodes of pain, muscle spasm, postural deformities, or chronic limitation of motion of the spine (range of motion) or pelvis requires specialist evaluation.
  • Any amputation that interferes with the performance of duties.
  • Hand disorders:
  • Hyperdactyly.
  • Syndactyly (webbed fingers) that interferes with the performance of duties or wearing of equipment.
  • Scars and deformities of the fingers or hand that impair dexterity, grip strength, circulation, are symptomatic, interfere with the performance of duties, or preclude the wearing of equipment.
  • Chronic or recurrent bursitis, tendinitis, and synovitis sufficient to interfere with the performance of duties.
  • Lower extremity disorders:
  • Disorders of the foot that compromise the wearing of equipment or are associated with chronic pain, including but not limited to, clubfoot, pes planus, pes cavus, hammer toes, hallux valgus, overriding digits, hallux rigidus, and bunions.
  • Varus or valgus deformities that interfere with the performance of duties.
  • Leg length discrepancy of more than 3.0 cm (from the anterior superior iliac spine to the distal tip of the medial malleolus).
  • Disqualifications for Abnormal Bone Mineral Density:
  • Osteoporosis, defined as the presence or history of a fragility fracture or T-score < -2.5 at the femoral neck, total hip, or lumbar spine using the female, white, age 20-29 years Third National Health and Nutrition Examination Survey (NHANES III) reference database.
  • Osteopenia, defined as T-score between -1.0 and -2.5 at the femoral neck, total hip, or lumbar spine using the female, white, age 20-29 years NHANES III reference database.
  • Individuals with abnormal bone mineral density, as defined above, require specialist evaluation.

Skin Disorders

  • Presence or history of disorders of the skin or nails, acute or chronic, that is severe enough to interfere with the performance of duties or the wearing of flight equipment.
  • Extensive or deep scars, burns, keloids, or body piercings that interfere with muscular movements or with the wearing of equipment or that show a tendency to break down.
  • Acne, furunculosis, atopic dermatitis, eczema, or other chronic dermatitis that interferes with the wearing of equipment.
  • Cysts, nevi, or benign tumors of the skin of a size or location that interfere with the wearing of equipment, unless surgically corrected.
  • Hyperhidrosis, if chronic or severe that may interfere with the performance of duties.
  • Infections of the skin if communicable, extensive, or not amenable to treatment. Chronic tinea pedis and onychomycosis require specialist evaluation.
  • Primary malignancies of the skin or secondary cutaneous manifestations of systemic malignancies.
  • Basal cell carcinoma that has been adequately excised is not disqualifying.
  • Squamous cell carcinoma that has been adequately excised requires specialist evaluation.
  • Neurofibromatosis.
  • History of inflammation or discharging sinus in the preceding 2 years.
  • History of pilonidal sinus with surgery without postoperative signs or symptoms indicative of residual disease for > 6 months requires specialist evaluation.
  • Presence or history of psoriasis, unless limited to < 1% total body surface area and asymptomatic.
  • History of secondary bullous disorders that are resolved require specialist evaluation.

Disorders Affecting the Brain, Spinal Cord, and Nervous System

  • Any neurological disorders that may interfere with the performance of duties.
  • Primary or secondary malignancies of the nervous system. Benign tumors or history of benign tumors of the nervous system, including acoustic neuromas, require specialist evaluation.
  • Vascular disorders of the nervous system (e.g., arteriovenous malformation, intracranial aneurysms, Moya-Moya disease). Cavernous angiomas require specialist evaluation.
  • History of a cerebrovascular accident (stroke, transient ischemic attack [TIA], subarachnoid hemorrhage). Asymptomatic disease of the carotid or vertebral arteries requires specialist evaluation.
  • History of infection of the nervous system within 2 years, or with residual neurologic defects that may compromise performance of duties.
  • Uncomplicated viral meningitis and other central nervous system infections without residual neurologic sequelae are evaluated on a case-by-case basis.
  • History of encephalitis is disqualifying.
  • Peripheral or central nervous system demyelinating disease (e.g., multiple sclerosis). Acute inflammatory demyelinating polyneuropathy without neurologic sequelae after 5 years requires specialist evaluation.
  • History of metabolic, toxic, or nutritional disorders of the nervous system without residual neurologic sequela requires specialist evaluation.
  • History of elevated intracranial pressure.
  • Congenital or developmental abnormalities of the nervous system that interfere with the performance of duties.
  • Personal history of diseases of hereditary neurologic disorders or hereditary disorders with neurologic features (e.g., neurofibromatosis, Huntington’s chorea, hepato-lenticular degeneration, spinocerebellar ataxia, muscular dystrophy, familial periodic paralysis, and congenital lower spastic paraparesis). Family history of neurologic disorders or hereditary disorders with neurologic features such as the above unless it is determined that such disorders have not been transmitted to or will not be expressed in a given subject and requires specialist evaluation.
  • History of seizure disorders.
  • Febrile convulsions before the age of 5 years are not disqualifying.
  • History of single seizure without neurologic sequelae after 5 years requires specialist evaluation.
  • Benign age-related seizures (e.g., Juvenile Myoclonic Epilepsy) require specialist evaluation.
  • History of craniotomy or skull defects that interfere with the performance of duties. Craniotomy performed more than 5 years earlier with no skull defects requires specialist evaluation.
  • History of traumatic brain injury associated with any of the following:
  • Any loss of consciousness or amnesia requires specialist evaluation.
  • Intracerebral and/or subdural hemorrhage.
  • Penetrating injuries or laceration of the brain.
  • Skull fractures require specialist evaluation.
  • Imaging evidence of retained intracranial metallic or bony fragments.
  • Absence of bony substance of skull.
  • Parenchymal central nervous system injury with persistent neurologic deficits.
  • Cerebral leptomeningeal cysts, aerocele, brain abscess, traumatic central nervous system (CNS) infections, or arteriovenous fistula.
  • Transient cerebrospinal fluid rhinorrhea or otorrhea requires specialist evaluation.
  • Post-traumatic syndrome manifested by changes in personality, deterioration of higher intellectual functions, anxiety, headaches, or disturbances of equilibrium for more than 3 months is disqualifying, and for less than 3 months may be disqualifying and requires specialist evaluation.
  • Migraine headache with visual or motor involvement, or any continuous or incapacitating headache.
  • History of acephalgic migraine requires specialist evaluation.
  • History of chronic headaches without recurrence for 10 years requires specialist evaluation.
  • History of electroencephalogram (EEG) abnormalities with historical, clinical, or supporting laboratory evidence of a neurologic abnormality requires specialist evaluation.
  • Disorders or injuries of peripheral nerves that interfere with performance of duties.
  • Uncomplicated Bell’s palsy without sequelae after 6 months is considered on a case-by-case basis.
  • Cervical or lumbar radiculopathy. History of cervical or lumbar radiculopathy requires specialist evaluation.
  • Movement disorders (e.g., Tourette’s syndrome, dystonia, or chorea). Essential tremor requires specialist evaluation.
  • Disorders of neuromuscular transmission (e.g., myasthenia gravis) and myopathies.
  • Neurodegenerative disorders (e.g., Parkinson’s and related disorders or amyotrophic lateral sclerosis [ALS]).
  • History of chronic pain syndromes requiring medical intervention or medical therapy within last 10 years is disqualifying; if greater than 10 years prior, requires specialist evaluation.

Psychiatric Disorders and Suitability for Space Flight

The NASA Clinical Psychiatrist/Psychologist ensures, based on available data, that a past or present diagnosis of a psychiatric disorder meets the criteria established in the most recent edition of DSM-5, Diagnostic and Statistical Manual of Mental Disorders (DSM):

  • Any behavior or mental condition that, in the opinion of the examiner, makes or is likely to make, the individual a hazard to flight safety, crew coordination, or mission execution.
  • Neurodevelopmental disorders that interfere with social or occupational functioning or that require ongoing treatment.
  • Presence or history of schizophrenia spectrum and other psychotic disorders.
  • Presence or history of bipolar and related disorders.
  • Presence or history of depressive disorders.
  • Presence or history of anxiety disorders.
  • Presence or history of obsessive-compulsive and related disorders.
  • Presence of trauma- and stressor-related disorders, or history of trauma- and stressor-related disorders that may interfere with the performance of duties.
  • Presence or history of dissociative disorders. Presence or history of somatic symptom and related disorders.
  • Presence or history of feeding and eating disorders.
  • Presence of sleep-wake disorders or a history of sleep-wake disorders that may interfere with the performance of duties.
  • Presence of dysphoria, affective distress, or other affective states (e.g., elevated mood) of any etiology that may interfere with the performance of duties.
  • Presence or history of disruptive, impulse-control and conduct disorders, present or history of substance-related and addictive disorders.
  • Presence of neurocognitive disorders or history of neurocognitive disorders if there is a likelihood of recurrence or evidence of residual deficits of cognition, memory, judgment, insight, or behavior.
  • Presence or history of personality disorders (an inflexible, maladaptive, and enduring pattern of personal interaction that has been present since early adulthood).
  • Presence or history of paraphilic disorders.
  • Presence or history of abuse or neglect of a child or adult.
  • Other conditions that may be a focus of clinical attention (V-Codes) that may interfere with the performance of duties.

The NASA Psychologist/Psychiatrist ensures, based on available evidence from comprehensive assessment of mission-relevant space flight psychological competencies such as performance under stress, group living, self-management, teamwork, communication, judgment, and decision-making that an individual is deemed suitable for space flight:

  • An individual can be deemed unsuitable for space flight for characterological behaviors or personality traits that represent lower levels of signs and symptoms than those required for a disorder under Table 10, paragraph 4.22.1, if in the opinion of the examiner, such characteristics present risks to crew cohesion, flight safety, or mission execution. A determination of unsuitability is not a medical diagnosis.
  • Difficulties functioning as a team member or crewmate in an operational setting. A history of poor or unstable work or interpersonal relationships or personality traits that interfere with the forming and maintenance of social connections or functioning cooperatively with others as a teammate or astronaut. This may include personality traits or characteristics such as self-centeredness (egocentrism), lack of concern for others, arrogance, entitlement, lack of empathy, insensitivity, and social avoidance or withdrawal.
  • Poor self-management or regulation. A pattern of behavior or traits that suggest poor impulse control. Examples may include a history of arrests, illicit drug use, social “acting out,” or other misconduct or irresponsible behaviors that indicate poor impulse control, lack of judgment, difficulty with authority, or disregard for social norms and rules; maladaptive internalizing behaviors such as self-damaging behaviors, and substance misuse.
  • Limited or poor stress tolerance. A history of physical or psychological problems when under stress, evidence of poor stress-coping skills or resilience, emotional instability, or other traits or behaviors that suggest an impaired capacity to adapt to stressful situations.
  • Poor self-awareness or emotion management. Poor insight or awareness into one’s impact on others such as deficiencies in self-knowledge and emotional awareness, or in the ability to understand or manage emotions that disrupt personal relationships or team or crew cohesion and effectiveness.

Women’s Health

  • Any disorder of the gynecologic system that may interfere with the performance of duties.
  • Any acute or chronic disorder of the uterus and/or adnexa that may interfere with the performance of duties (e.g., endometriosis). History of any chronic disorder of the uterus and/or adnexa that is adequately managed requires specialist evaluation.
  • Dysmenorrhea or other irregularities of the menstrual cycle such as premenstrual syndrome that may interfere with performance of duties.
  • History of recurrent abnormal uterine bleeding or menorrhagia may require specialist evaluation.
  • Chronic or recurrent infections or inflammation of the endopelvic organs. History of a single episode of pelvic inflammatory disease requires specialist evaluation.
  • History of gynecological malignancies. History of carcinoma in situ of the cervix requires specialist evaluation.
  • History of recurrent, symptomatic ovarian cysts or history of recurrent corpora hemorrhagica unless definitively resolved.
  • Any menstrual abnormality caused by polycystic ovarian conditions, anovulation, or disorders of the hypothalamic-pituitary-ovarian axis requires specialist evaluation.
  • Any chronic dermatologic condition of the vulva and/or vestibule requires specialist evaluation.
  • Obstetrical:
  • All candidates are examined while not pregnant. Pregnancy itself will not be cause to deny appointment as a candidate.
  • Pregnancy is disqualifying for space flight until complete post-partum recovery.

Dental

  • Any dental defects that interfere with clear speech or cause changes in the contours of the face that interfere with the performance of duties.
  • Complete edentulism in either the mandible and/or maxilla or insufficient number of natural healthy teeth to masticate a normal diet or enunciate clearly.
  • Dental prostheses:
  • Any removable dental prosthesis, which if lost or broken, would not leave enough natural healthy teeth to masticate a normal diet or enunciate clearly.
  • Any unilateral removable dental prosthesis that could be swallowed.
  • Diseases and abnormalities of the jaws or associated structures, including periodontal disease, that are not easily remedied or may interfere with the performance of duties.
  • Severe malocclusion that interferes with the mastication of a normal diet or clear enunciation.
  • Any dental defects such as dental caries, dental dysplasia, enamel dysplasia, symptomatic cracked teeth, defective restorations, defective prosthesis, and defective implants until resolved.
  • Partially erupted or impacted third molar teeth with the potential to cause erosion of adjacent teeth, pericoronitis, or periodontal defect until corrected.
  • Infections of endodontic or periodontic origin until resolved.
  • Active orthodontic treatment requires dental consultation. Active orthodontic treatment is disqualifying for space flight duties.

Disease

  • Acute or chronic infectious disease until appropriately treated that might compromise mission operations, performance of duty, or crew health and safety.
  • Tuberculosis:
  • Active tuberculosis.
  • History of active tuberculosis, unless 2 years have elapsed following appropriate therapy (as per current Centers for Disease Control and Prevention [CDC] guidelines) and evaluations show the individual free from active disease.
  • Documented conversion of the Tuberculin Skin Test or positive Interferon Gamma Release Assay without documentation of appropriate evaluation and management.
  • History of malaria or other blood-borne parasites, unless adequately treated and cured
  • Clinical or laboratory evidence of HIV infection or Acquired Immune Deficiency Syndrome (AIDS).
  • Lyme disease, unless adequately treated
  • Viral hepatitis:
  • History of hepatitis B, unless laboratory evidence of seroconversion and at least 1 year has passed since full recovery. Chronic hepatitis B carrier state is disqualifying.
  • History of hepatitis C until 1 year after completion of CDC-approved treatment with eradication of viral load.
  • Herpes simplex virus type I or type II that may interfere with performance of duties or compromise crew health.
  • History of Herpes zoster, unless resolved for greater than 1 month and without post-herpetic neuralgia
  • H. pylori carrier state, until adequately treated
  • Syphilis, gonorrhea, and chlamydia, unless adequately treated without sequelae
  • Non-immune status or lack of documented vaccination status against the following: Measles, mumps, rubella, tetanus, polio, diphtheria, pertussis, meningococcus, and pneumococcus.

Radiation

Per NASA-STD-3001, Volume 1, Revision A, section 4.2.10, the short-term radiation exposure limits shown in the following table (also table 12), NASA Short-term Ionizing Radiation Exposure Limits, have not been exceeded for any NASA astronaut. The current values are based on the use of Gray-Equivalents (Gy-eq) and relative biological effectiveness values provided by the National Council on Radiation Protection and Measurements (NCRP) Reports No. 132, Radiation Protection Guidance for Activities in Low-Earth Orbit.

Short-term exposure limits are designed to prevent deterministic effects resulting from acute exposure. Each planned exposure is managed in adherence to the as low as reasonably achievable (ALARA) principle, which directs that exposures always be maintained as low as reasonably achievable.

Organ specific exposure limits for short term ionizing radiation exposure

Exposure intervalBone marrowEyeSkin30 days0.251.01.5Annual0.502.03.0

Per NASA-STD-3001, Volume 1, Revision A, section 4.2.10, occupationally related sources of exposure throughout the career of any NASA astronaut result in no more than 3% probability of lifetime excess cancer mortality risk. NASA will ensure that these limits are not exceeded at a 95% confidence level based on a statistical assessment of the uncertainties.

Physical characteristics

Failure to satisfy anthropometric criteria, including height and weight, which should be compatible with human factors for crewed space vehicles.

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