User:Chrisjj/Mars Ed

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Differences between Earth and Mars[edit]

Atmospheric pressure comparison
Location Pressure
Olympus Mons summit 0.03 kPa (0.0044 psi)
Mars average 0.6 kPa (0.087 psi)
Hellas Planitia bottom 1.16 kPa (0.168 psi)
Armstrong limit 6.25 kPa (0.906 psi)
Mount Everest summit[1] 33.7 kPa (4.89 psi)
Earth sea level 101.3 kPa (14.69 psi)

Gravity and magnetosphere[edit]

The surface gravity of Mars is 38% that of Earth. Although microgravity is known to cause health problems such as muscle loss and bone demineralization,[2][3] it is not known if Martian gravity would have a similar effect. The Mars Gravity Biosatellite was a proposed project designed to learn more about what effect Mars' lower surface gravity would have on humans, but it was cancelled due to a lack of funding.[4]

Due to the lack of a magnetosphere, solar particle events and cosmic rays can easily reach the Martian surface.[5][6][7]

The atmosphere[edit]

Atmospheric pressure on Mars is far below the Armstrong limit at which people can survive without pressure suits. Since terraforming cannot be expected as a near-term solution, habitable structures on Mars would need to be constructed with pressure vessels similar to spacecraft, capable of containing a pressure between 30 and 100 kPa. The atmosphere is also toxic as most of it consists of carbon dioxide (95% carbon dioxide, 3% nitrogen, 1.6% argon, and traces totaling less than 0.4% of other gases including oxygen.

This thin atmosphere does not filter out ultraviolet sunlight, which causes instability in the molecular bonds between atoms. For example, ammonia (NH3) is not stable in the Martian atmosphere and breaks down after a few hours.[8] Also due to the thinness of the atmosphere, the temperature difference between day and night is much larger than on Earth, typically around 70 °C (125 °F).[9] However, the day/night temperature variation is much lower during dust storms when very little light gets through to the surface even during the day, and instead warms the middle atmosphere.[10]

Water and climate[edit]

Water on Mars is scarce, with rovers Spirit and Opportunity finding less than there is in Earth's driest desert.[11][12][13]

The climate is much colder than Earth, with mean surface temperatures between 186 and 268 K (−87 and −5 °C; −125 and 23 °F) (depending on the season and latitude).[14][15] The lowest temperature ever recorded on Earth was 184 K (−89.2 °C, −128.6 °F) in Antarctica.

Because Mars is about 52% farther from the Sun, the amount of solar energy entering its upper atmosphere per unit area (the solar constant) is only around 43.3% of what reaches the Earth's upper atmosphere.[16] However, due to the much thinner atmosphere, a higher fraction of the solar energy reaches the surface.[17][18] The maximum solar irradiance on Mars is about 590 W/m2 compared to about 1000 W/m2 at the Earth's surface; optimal conditions on the Martian equator can be compared to those on Devon Island in the Canadian Arctic in June.[19]

Global dust storms are common throughout the year and can cover the entire planet for weeks, blocking sunlight from reaching the surface.[20][21] This has been observed to cause temperature drops of 4 °C (7 °F) for several months after the storm.[22] In contrast, the only comparable events on Earth are infrequent large volcanic eruptions such as Krakatoa which threw large amounts of ash into the atmosphere in 1883, causing a global temperature drop of around 1 °C (2 °F). Perhaps more importantly, these storms affect electricity production from solar panels for long periods, as well interfering with communications with Earth.[10]

Mars has no rain and virtually no clouds, so although cold, it is permanently sunny (apart from during dust storms). This means solar panels can always operate at maximum efficiency on dust-free days. And Mars' orbit is more eccentric than Earth's, increasing temperature and solar constant variations over the course of the Martian year.

Soil[edit]

The Martian soil is toxic due to relatively high concentrations of chlorine and associated compounds which are hazardous to all known forms of life.[23][24]

Survivability[edit]

Although there are some extremophile organisms that survive in hostile conditions on Earth, including simulations that approximate Mars, plants and animals generally cannot survive the ambient conditions present on the surface of Mars.[25]

  1. ^ West, John B. (1 March 1999). "Barometric pressures on Mt. Everest: new data and physiological significance". Journal of Applied Physiology (Bethesda, Md. : 1985). 86 (3). Jap.physiology.org: 1062–6. doi:10.1152/jappl.1999.86.3.1062. PMID 10066724. Retrieved 2012-05-15.
  2. ^ Fong, MD, Kevin (12 February 2014). "The Strange, Deadly Effects Mars Would Have on Your Body". Wired. Retrieved 2014-02-12.
  3. ^ "Gravity Hurts (so Good)". NASA. 2001.
  4. ^ "Mars Mice". science.nasa.gov. 2004.
  5. ^ Phillips, Tony (January 31, 2001). "The Solar Wind at Mars". NASA.
  6. ^ "What makes Mars so hostile to life?". BBC News. January 7, 2013.
  7. ^ Keating, A.; Goncalves, P. (November 2012). "The impact of Mars geological evolution in high energy ionizing radiation environment through time". Planetary and Space Science – Eslevier. 72 (1): 70–77. Bibcode:2012P&SS...72...70K. doi:10.1016/j.pss.2012.04.009.
  8. ^ Whitehouse, David (July 15, 2004). "Dr. David Whitehouse – Ammonia on Mars could mean life". BBC News. Retrieved August 14, 2012.
  9. ^ "Mars Weather". Centro de Astrobiología. 2015. Archived from the original on October 25, 2015. Retrieved May 31, 2015.
  10. ^ a b "Opportunity Hunkers Down During Dust Storm". NASA. 8 June 2018. Retrieved 26 November 2018.
  11. ^ "Why is Mars So Dry?". Universe Today. 16 February 2004. Retrieved 26 November 2018.
  12. ^ Hecht, M. H. (2002). "Metastability of Liquid Water on Mars". Icarus. 156 (2): 373–386. Bibcode:2002Icar..156..373H. doi:10.1006/icar.2001.6794.
  13. ^ Webster, Guy; Brown, Dwayne (10 December 2013). "NASA Mars Spacecraft Reveals a More Dynamic Red Planet". NASA. Retrieved 2014-03-02.
  14. ^ Hamilton, Calvin. "Mars Introduction".
  15. ^ Elert, Glenn. "Temperature on the Surface of Mars".
  16. ^ Kluger, J. (1992). "Mars, in Earth's Image". Discover Magazine. 13 (9): 70. Bibcode:1992Disc...13...70K. Retrieved 12 June 2015.
  17. ^ Haberle, R. M.; McKay, C. P.; Pollack, J. B.; Gwynne, O. E.; Atkinson, D. H.; Appelbaum, J.; Landis, G. A.; Zurek, R. W.; Flood, D. J. (1993). Atmospheric Effects on the Utility of Solar Power on Mars (PDF). Bibcode:1993rnes.book..845H. Archived from the original (PDF) on 2016-03-05.
  18. ^ Sharonov, V. V. (1957). "1957SvA.....1..547S Page 547". Harvard.edu. 1: 547. Bibcode:1957SvA.....1..547S.
  19. ^ "Sunlight on Mars – Is There Enough Light on Mars to Grow Tomatoes?". first the seed foundation. Retrieved 26 November 2018.
  20. ^ Viorel Badescu (2009). Mars: Prospective Energy and Material Resources. Springer Science & Business Media. p. 83. ISBN 978-3-642-03629-3.
  21. ^ Tomatosphere. "Teachers guide – Sunlight on mars – Tomatosphere". tomatosphere.org. Archived from the original on 23 June 2015. Retrieved 12 June 2015.
  22. ^ Fenton, Lori K.; Geissler, Paul E.; Haberle, Robert M. (2007). "Global warming and climate forcing by recent albedo changes on Mars" (PDF). Nature. 446 (7136): 646–649. Bibcode:2007Natur.446..646F. doi:10.1038/nature05718. PMID 17410170. Archived from the original (PDF) on July 8, 2007.
  23. ^ "Mars covered in toxic chemicals that can wipe out living organisms, tests reveal". The Guardian. Retrieved 26 November 2018.
  24. ^ "Toxic Mars: Astronauts Must Deal with Perchlorate on the Red Planet". space.com. Retrieved 26 November 2018.
  25. ^ "Can Life exist on Mars?". Mars Academy. ORACLE-ThinkQuest. Archived from the original on February 22, 2001.
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