Encyclopedia of Bioastronautics

Living Edition
| Editors: Laurence R. Young, Jeffrey P. Sutton

Physiological Effects of Spaceflight – Weightlessness: An Overview

  • Peter NorskEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-10152-1_126-1


The term “space physiology” means how bodily functions adapt to the environment of spaceflight, and how these adaptations affect performance and health. Thus, space physiology is a subdiscipline of “space biology” and encompasses how the systems of the body are affected by the spaceflight environment from the level of molecular interactions in the cells up to the integrated bodily functions. The spaceflight environmental factors that affect physiology and health are several of which weightlessness (microgravity) is dominant in low Earth orbit.

An object is weightless when it is not subjected to any external mechanical forces. A mechanical force is a force whereby an object accelerates another object through contact between their surfaces. This force is also referred to as the surface force or normal force. According to this definition, an object not subjected to any forces at all or only to gravitational forces without any intervening surface forces is weightless. Thus, a...

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  1. Alfrey CP, Udden MM, Leach-Huntoon C, Driscoll T, Pickett MH (1996) Control of red blood cell mass in spaceflight. J Appl Physiol 81:98–104CrossRefGoogle Scholar
  2. Baevsky RM, Baranov VM, Funtova II, Diedrich A, Pashenko AV, Chernikova AG, Drescher J, Jordan J, Tank J (2007) Autonomic cardiovascular and respiratory control during prolonged spaceflights aboard the international Space Station. J Appl Physiol 103:156–161CrossRefGoogle Scholar
  3. Baldwin KM, Caiozzo VJ (2017a) Muscle wasting in space: impact on design constraints. Encyc BioastroGoogle Scholar
  4. Baldwin KM, Caiozzo VJ (2017b) Muscle wasting in space: mechanisms and countermeasures. Encyc BioastroGoogle Scholar
  5. Bloomberg JJ, Reschke MF, Clement GR, Mulavara AP, Taylor LC (2016) Risk of Impaired control of spacecraft/associated systems and decreased mobility due to vestibular/sensorimotor alterations associated with space flight. Evidence report (June 6), NASA, Lyndon B. Johnson Space Center, HoustonGoogle Scholar
  6. Bloomfield SA (2017) Bone loss chapter. Encyc BioastroGoogle Scholar
  7. Buckey JC Jr, Lane LD, Levine BD, Watenpaugh DE, Wright SJ, Moore WE, Gaffney FA (1996) Orthostatic intolerance after spaceflight. J Appl Physiol 81:7–18CrossRefGoogle Scholar
  8. Crucian B, Kunz H, Sams CF (2015) Risk of crew adverse health event due to altered immune response. evidence report (May 14), NASA, Lyndon B. Johnson Space Center, HoustonGoogle Scholar
  9. Eckberg DL, Halliwill JR, Beigthol LA, Brown TE, Taylor JA, Goble R (2010) Human vagal baroreflex mechanisms in space. J Physiol 588:1129–1138CrossRefGoogle Scholar
  10. Ertl AC, Diedrich A, Biaggioni I, Levine BD, Robertson RM, Cox JF, Zuckerman JH, Pawelczyk JA, Ray CA, Buckey JC Jr, Lane LD, Shiavi R, Gaffney FA, Costa F, Holt C, Blomqvist CG, Eckberg DL, Baisch FJ, Robertson D (2002) Human muscle sympathetic nerve activity and plasma noradrenaline kinetics in space. J Physiol 538:321–329CrossRefGoogle Scholar
  11. Foldager N, TAE A, Jessen FB, Ellegaard P, Stadeager C, Videbaek R, Norsk P (1996) Central venous pressure in humans during microgravity. J Appl Physiol 81:408–412CrossRefGoogle Scholar
  12. Fritsch-Yelle JM, Charles JB, Jones MM, Wood ML (1996) Microgravity decreases heart rate and arterial pressure in humans. J Appl Physiol 80:910–914CrossRefGoogle Scholar
  13. Heer M, Paloski WH (2006) Space motion sickness: incidence, etiology, and countermeasures. Auton Neurosci 129(1–2):77–79CrossRefGoogle Scholar
  14. Kirsch KA, Rocker L, Gauer OH, Krause R, Leach C, Wicke HJ, Landry R (1984) Venous pressure in man during weightlessness. Science 225:218–219CrossRefGoogle Scholar
  15. Lawley JS, Petersen LG, Howden EJ, Sarma S, Cornwell WK, Zhang R, Whitworth LA, Williams MA, Levine BD (2017) Effect of gravity and microgravity on intracranial pressure. J Physiol 595:2115–2127CrossRefGoogle Scholar
  16. Lee SM, Stenger MB, Laurie SS, Macias BR (2017) Risk of cardiac rhythm problems during spaceflight. Evidence report (June 12), NASA, Lyndon B. Johnson Space Center, HoustonGoogle Scholar
  17. Norsk P (2014) Blood pressure regulation IV: adaptive responses to weightlessness. Eur J Appl Physiol 114:481–497CrossRefGoogle Scholar
  18. Norsk P, Damgaard M, Petersen L, Gybel M, Pump B, Gabrielsen A, Christensen NJ (2006) Vasorelaxation in space. Hypertension 47:69–73CrossRefGoogle Scholar
  19. Norsk P, Drummer C, Rocker L, Strollo F, Christensen NJ, Warberg J, Bie P, Stadeager C, Johansen LB, Heer M, Gunga H-C, Gerzer R (1995) Renal and endocrine responses in humans to isotonic saline infusion during microgravity. J Appl Physiol 78:2253–2259CrossRefGoogle Scholar
  20. Norsk P, Asmar A, Damgaard M, Christensen NJ (2015) Fluid shifts, vasodilatation and ambulatory blood pressure reduction during long duration spaceflight. J Physiol 43:573–584CrossRefGoogle Scholar
  21. Paloski WH, Charles JB (2014) 2014 International workshop on research and operational considerations for artificial gravity countermeasures. NASA/TM-2014-217394Google Scholar
  22. Perhonen MA, Franco F, Lane LD et al (2001) Cardiac atrophy after bed rest and spaceflight. J Appl Physiol 91:645–653CrossRefGoogle Scholar
  23. Ploutz-Snyder L, Ryder J, English K, Haddad F, Baldwin K (2015) Risk of impaired performance due to reduced muscle mass, strength, and endurance. Evidence report, NASA, Lyndon B. Johnson Space Center, HoustonGoogle Scholar
  24. Reschke MF, Good EF, Clement GR (2017) Neurovestibular symptoms in astronauts immediately after space shuttle and international space station missions. Otolaryngol Head Neck Surg (22-Aug, OTO Open – OPN-170032)Google Scholar
  25. Seidler RD, Mulavara AP (2017) Sensorimotor adaptation, including space motion sickness. Encyc BioastroGoogle Scholar
  26. Shykoff BE, Farhi LE, Olszowka AJ, Pendergast DR, Rokitka MA, Eisenhardt CG, Morin RA (1996) Cardiovascular response to submaximal exercise in sustained microgravity. J Appl Physiol 81:26–32CrossRefGoogle Scholar
  27. Stenger MB, Lee SM, Ribeiro LC, Phillips TR, Ploutz-Snyder RJ, Willig MC, Westby CM, Platts SH (2014) Gradient compression garments protect against orthostatic intolerance during recovery from bed rest. Eur J Appl Physiol 114:597–608CrossRefGoogle Scholar
  28. Stenger MB, Laurie SS, Lee SMC, Platts SH (2017a) Cardiovascular deconditioning and exercise. Encyc BioastroGoogle Scholar
  29. Stenger MB, Tarver WJ, Brunstetter T, Gibson CR, Laurie SS, Lee SMC, Macias BR, Mader TH, Otto C, Smith SM, Zwart SR (2017b) Risk of spaceflight associated neuro-ocular syndrome (SANS). Evidence report (Nov 30), NASA, Lyndon B. Johnson Space Center, HoustonGoogle Scholar
  30. Videbaek R, Norsk P (1997) Atrial distension in humans during microgravity induced by parabolic flights. J Appl Physiol 83:1862–1866CrossRefGoogle Scholar

Copyright information

© This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2018

Authors and Affiliations

  1. 1.Center for Space MedicineBaylor College of MedicineHoustonUSA
  2. 2.Biomedical Research & Environmental Sciences DivisionNASA, Johnson Space CenterHoustonUSA

Section editors and affiliations

  • Peter Norsk
    • 1
  1. 1.Division of Space Life SciencesUSRAHoustonUSA