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Micrometeoroid

August 26, 2023

A micrometeoroid is a tiny meteoroid: a small particle of rock in space, usually weighing less than a gram. A micrometeorite is such a particle that survives passage through Earth's atmosphere and reaches Earth's surface.

Micrometeorite, collected from the Antarctic snow, was a micrometeoroid before it entered the Earth's atmosphere

The term "micrometeoroid" was officially deprecated by the IAU in 2017, as redundant to meteoroid.[1]

Origins and orbits Edit

See also: Cosmic dust

Micrometeoroids are very small pieces of rock or metal broken off from larger chunks of rock and debris often dating back to the birth of the Solar System. Micrometeoroids are extremely common in space. Tiny particles are a major contributor to space weathering processes. When they hit the surface of the Moon, or any airless body (Mercury, the asteroids, etc.), the resulting melting and vaporization causes darkening and other optical changes in the regolith.

Micrometeoroids have less stable orbits than meteoroids, due to their greater surface area to mass ratio. Micrometeoroids that fall to Earth can provide information on millimeter scale heating events in the solar nebula. Meteorites and micrometeorites (as they are known upon arrival at the Earth's surface) can only be collected in areas where there is no terrestrial sedimentation, typically polar regions. Ice is collected and then melted and filtered so the micrometeorites can be extracted under a microscope.

Sufficiently small micrometeoroids avoid significant heating on entry into Earth's atmosphere.[2] Collection of such particles by high-flying aircraft began in the 1970s,[3] since which time these samples of stratosphere-collected interplanetary dust (called Brownlee particles before their extraterrestrial origin was confirmed) have become an important component of the extraterrestrial materials available for study in laboratories on Earth.

Historical studies Edit

In 1946 during the Giacobinid meteor shower, Helmut Landsberg collected several small magnetic particles that were apparently associated with the shower.[4] Fred Whipple was intrigued by this and wrote a paper that demonstrated that particles of this size were too small to maintain their velocity when they encountered the upper atmosphere. Instead, they quickly decelerated and then fell to Earth unmelted. In order to classify these sorts of objects, he coined the term "micro-meteorite".[5]

Velocities Edit

Whipple, in collaboration with Fletcher Watson of the Harvard Observatory, led an effort to build an observatory to directly measure the velocity of the meteors that could be seen. At the time the source of the micro-meteorites was not known. Direct measurements at the new observatory were used to locate the source of the meteors, demonstrating that the bulk of material was left over from comet tails, and that none of it could be shown to have an extra-solar origin.[6] Today it is understood that meteoroids of all sorts are leftover material from the formation of the Solar System, consisting of particles from the interplanetary dust cloud or other objects made up from this material, like comets.[7]

Flux Edit

 
Lunar sample 61195 from Apollo 16 textured with "zap pits" from micrometeorite impacts

The early studies were based exclusively on optical measurements. In 1957, Hans Pettersson conducted one of the first direct measurements of the fall of space dust on Earth, estimating it to be 14,300,000 tons per year.[8] This suggested that the meteoroid flux in space was much higher than the number based on telescope observations. Such a high flux presented a very serious risk to the high-orbiting Apollo capsules and for missions to the Moon. To determine whether the direct measurement was accurate, a number of additional studies followed, including the Pegasus satellite program, Lunar Orbiter 1, Luna 3, Mars 1 and Pioneer 5. These showed that the rate of meteors passing into the atmosphere, or flux, was in line with the optical measurements, at around 10,000 to 20,000 tons per year.[9] The Surveyor Program determined that the surface of the Moon is relatively rocky.[10] Most lunar samples returned during the Apollo Program have micrometeorite impacts marks, typically called "zap pits", on their upper surfaces.[11]

Effect on spacecraft operations Edit

See also: Space debris
 
Electron micrograph image of an orbital debris hole made in the panel of the Solar Max satellite

Micrometeoroids pose a significant threat to space exploration. The average velocity of micrometeoroids relative to a spacecraft in orbit is 10 kilometers per second (22,500 mph). Resistance to micrometeoroid impact is a significant design challenge for spacecraft and space suit designers (See Thermal Micrometeoroid Garment). While the tiny sizes of most micrometeoroids limits the damage incurred, the high velocity impacts will constantly degrade the outer casing of spacecraft in a manner analogous to sandblasting. Long term exposure can threaten the functionality of spacecraft systems.[12]

Impacts by small objects with extremely high velocity (10 kilometers per second) are a current area of research in terminal ballistics (although accelerating objects up to such velocities is difficult; current techniques include linear motors and shaped charges). The risk is especially high for objects in space for long periods of time, such as satellites.[12] They also pose major engineering challenges in theoretical low-cost lift systems such as rotovators, space elevators, and orbital airships.[13][14]

Spacecraft micrometeoroid shielding Edit

 
The "energy flash" of a hypervelocity impact during a simulation of what happens when a piece of orbital debris hits a spacecraft in orbit

Whipple's work pre-dated the Space Race and it proved useful when space exploration started only a few years later. His studies had demonstrated that the chance of being hit by a meteoroid large enough to destroy a spacecraft was extremely remote. However, a spacecraft would be almost constantly struck by micrometeorites, about the size of dust grains.[6]

Whipple had already developed a solution to this problem in 1946. Originally known as a "meteor bumper" and now termed the Whipple shield, this consists of a thin foil film held a short distance away from the spacecraft's body. When a micrometeoroid strikes the foil, it vaporizes into a plasma that quickly spreads. By the time this plasma crosses the gap between the shield and the spacecraft, it is so diffused that it is unable to penetrate the structural material below.[15] The shield allows a spacecraft body to be built to just the thickness needed for structural integrity, while the foil adds little additional weight. Such a spacecraft is lighter than one with panels designed to stop the meteoroids directly.

For spacecraft that spend the majority of their time in orbit, some variety of the Whipple shield has been almost universal for decades.[16][17] Later research showed that ceramic fibre woven shields offer better protection to hypervelocity (~7 km/s) particles than aluminium shields of equal weight.[18] Another modern design uses multi-layer flexible fabric, as in NASA's design for its never-flown TransHab expandable space habitation module,[19] and the Bigelow Expandable Activity Module, which was launched in April 2016 and attached to the ISS for two years of orbital testing.[20][21]

Footnotes Edit

  1. ^ IAU Commission F1 (April 30, 2017). "Definition of terms in meteor astronomy" (PDF). International Astronomical Union. Retrieved 25 Jul 2020.{{cite web}}: CS1 maint: url-status (link)
  2. ^ P. Fraundorf (1980) The distribution of temperature maxima for micrometeorites decelerated in the Earth's atmosphere without melting Geophys. Res. Lett. 10:765-768.
  3. ^ D. E. Brownlee, D. A. Tomandl and E. Olszewski (1977) Interplanetary dust: A new source of extraterrestrial material for laboratory studies, Proc. Lunar Sci. Conf. 8th:149-160.
  4. ^ Fred Whipple, "The Theory of Micro-Meteorites, Part I: In an Isothermal Atmosphere" 24 September 2015 at the Wayback Machine, Proceedings of the National Academy of Sciences, Volume 36 Number 12 (15 December 1950), pp. 667 – 695.
  5. ^ Fred Whipple, "The Theory of Micrometeorites." 17 October 2015 at the Wayback Machine, Popular Astronomy, Volume 57, 1949, p. 517.
  6. ^ a b Whipple, Fred (1951). "A Comet Model. II. Physical Relations for Comets and Meteors". Astrophysical Journal. 113: 464–474. Bibcode:1951ApJ...113..464W. doi:10.1086/145416.
  7. ^ Brownlee, D. E.; Tomandl, D. A.; Olszewski, E. (1977). "1977LPI.....8..145B Interplanetary dust: A new source of extraterrestrial material for laboratory studies". Proceedings of the 8th Lunar Scientific Conference. 1977: 149–160. Bibcode:1977LPI.....8..145B.
  8. ^ Hans Pettersson, "Cosmic Spherules and Meteoritic Dust." Scientific American, Volume 202 Issue 2 (February 1960), pp. 123–132.
  9. ^ Andrew Snelling and David Rush, "Moon Dust and the Age of the Solar System" 12 May 2011 at the Wayback Machine Creation Ex-Nihilo Technical Journal, Volume 7 Number 1 (1993), p. 2–42.
  10. ^ Snelling, Andrew and David Rush. "Moon Dust and the Age of the Solar System." 2012-03-09 at the Wayback Machine Creation Ex-Nihilo Technical Journal, Volume 7, Number 1, 1993, p. 2–42.
  11. ^ Wilhelms, Don E. (1993), To a Rocky Moon: A Geologist's History of Lunar Exploration, University of Arizona Press, p. 97, ISBN 978-0816510658
  12. ^ a b Rodriguez, Karen (April 26, 2010). . www.nasa.gov. Archived from the original on October 28, 2009. Retrieved 2018-06-18.
  13. ^ Swan, Raitt, Swan, Penny, Knapman, Peter A., David I., Cathy W., Robert E., John M. (2013). Space Elevators: An Assessment of the Technological Feasibility and the Way Forward. Virginia, USA: International Academy of Astronautics. pp. 10–11, 207–208. ISBN 9782917761311.{{cite book}}: CS1 maint: multiple names: authors list (link)
  14. ^ Swan, P., Penny, R. Swan, C. Space Elevator Survivability, Space Debris Mitigation, Lulu.com Publishers, 2011
  15. ^ Brian Marsden, "Professor Fred Whipple: Astronomer who developed the idea that comets are 'dirty snowballs'." 11 February 2018 at the Wayback Machine The Independent, 13 November 2004.
  16. ^ Fred Whipple, "Of Comets and Meteors" 29 June 2008 at the Wayback Machine Science, Volume 289 Number 5480 (4 August 2000), p. 728.
  17. ^ Judith Reustle (curator), "Shield Development: Basic Concepts" 27 September 2011 at the Wayback Machine, NASA HVIT. Retrieved 20 July 2011.
  18. ^ Ceramic Fabric Offers Space Age Protection 9 March 2012 at the Wayback Machine, 1994 Hypervelocity Impact Symposium
  19. ^ Kim Dismukes (curator), "TransHab Concept" 1 June 2007 at the Wayback Machine, NASA, 27 June 2003. Retrieved 10 June 2007.
  20. ^ Howell, Elizabeth (2014-10-06). "Private Inflatable Room Launching to Space Station Next Year". Space.com. from the original on 4 December 2014. Retrieved 2014-12-06.
  21. ^ "ISS welcomes CRS-8 Dragon after flawless launch". 9 April 2016. from the original on 23 April 2016. Retrieved 14 May 2016.

See also Edit

External links Edit

  • Melted Crumbs from Asteroid Vesta article about micrometeorites collected in Antarctica in Planetary Science Research Discoveries educational journal

August 26, 2023
micrometeoroid, micrometeoroid, tiny, meteoroid, small, particle, rock, space, usually, weighing, less, than, gram, micrometeorite, such, particle, that, survives, passage, through, earth, atmosphere, reaches, earth, surface, micrometeorite, collected, from, a. A micrometeoroid is a tiny meteoroid a small particle of rock in space usually weighing less than a gram A micrometeorite is such a particle that survives passage through Earth s atmosphere and reaches Earth s surface Micrometeorite collected from the Antarctic snow was a micrometeoroid before it entered the Earth s atmosphereThe term micrometeoroid was officially deprecated by the IAU in 2017 as redundant to meteoroid 1 Contents 1 Origins and orbits 2 Historical studies 2 1 Velocities 2 2 Flux 3 Effect on spacecraft operations 3 1 Spacecraft micrometeoroid shielding 4 Footnotes 5 See also 6 External linksOrigins and orbits EditSee also Cosmic dust Micrometeoroids are very small pieces of rock or metal broken off from larger chunks of rock and debris often dating back to the birth of the Solar System Micrometeoroids are extremely common in space Tiny particles are a major contributor to space weathering processes When they hit the surface of the Moon or any airless body Mercury the asteroids etc the resulting melting and vaporization causes darkening and other optical changes in the regolith Micrometeoroids have less stable orbits than meteoroids due to their greater surface area to mass ratio Micrometeoroids that fall to Earth can provide information on millimeter scale heating events in the solar nebula Meteorites and micrometeorites as they are known upon arrival at the Earth s surface can only be collected in areas where there is no terrestrial sedimentation typically polar regions Ice is collected and then melted and filtered so the micrometeorites can be extracted under a microscope Sufficiently small micrometeoroids avoid significant heating on entry into Earth s atmosphere 2 Collection of such particles by high flying aircraft began in the 1970s 3 since which time these samples of stratosphere collected interplanetary dust called Brownlee particles before their extraterrestrial origin was confirmed have become an important component of the extraterrestrial materials available for study in laboratories on Earth Historical studies EditIn 1946 during the Giacobinid meteor shower Helmut Landsberg collected several small magnetic particles that were apparently associated with the shower 4 Fred Whipple was intrigued by this and wrote a paper that demonstrated that particles of this size were too small to maintain their velocity when they encountered the upper atmosphere Instead they quickly decelerated and then fell to Earth unmelted In order to classify these sorts of objects he coined the term micro meteorite 5 Velocities Edit Whipple in collaboration with Fletcher Watson of the Harvard Observatory led an effort to build an observatory to directly measure the velocity of the meteors that could be seen At the time the source of the micro meteorites was not known Direct measurements at the new observatory were used to locate the source of the meteors demonstrating that the bulk of material was left over from comet tails and that none of it could be shown to have an extra solar origin 6 Today it is understood that meteoroids of all sorts are leftover material from the formation of the Solar System consisting of particles from the interplanetary dust cloud or other objects made up from this material like comets 7 Flux Edit Lunar sample 61195 from Apollo 16 textured with zap pits from micrometeorite impactsThe early studies were based exclusively on optical measurements In 1957 Hans Pettersson conducted one of the first direct measurements of the fall of space dust on Earth estimating it to be 14 300 000 tons per year 8 This suggested that the meteoroid flux in space was much higher than the number based on telescope observations Such a high flux presented a very serious risk to the high orbiting Apollo capsules and for missions to the Moon To determine whether the direct measurement was accurate a number of additional studies followed including the Pegasus satellite program Lunar Orbiter 1 Luna 3 Mars 1 and Pioneer 5 These showed that the rate of meteors passing into the atmosphere or flux was in line with the optical measurements at around 10 000 to 20 000 tons per year 9 The Surveyor Program determined that the surface of the Moon is relatively rocky 10 Most lunar samples returned during the Apollo Program have micrometeorite impacts marks typically called zap pits on their upper surfaces 11 Effect on spacecraft operations EditSee also Space debris Electron micrograph image of an orbital debris hole made in the panel of the Solar Max satelliteMicrometeoroids pose a significant threat to space exploration The average velocity of micrometeoroids relative to a spacecraft in orbit is 10 kilometers per second 22 500 mph Resistance to micrometeoroid impact is a significant design challenge for spacecraft and space suit designers See Thermal Micrometeoroid Garment While the tiny sizes of most micrometeoroids limits the damage incurred the high velocity impacts will constantly degrade the outer casing of spacecraft in a manner analogous to sandblasting Long term exposure can threaten the functionality of spacecraft systems 12 Impacts by small objects with extremely high velocity 10 kilometers per second are a current area of research in terminal ballistics although accelerating objects up to such velocities is difficult current techniques include linear motors and shaped charges The risk is especially high for objects in space for long periods of time such as satellites 12 They also pose major engineering challenges in theoretical low cost lift systems such as rotovators space elevators and orbital airships 13 14 Spacecraft micrometeoroid shielding Edit The energy flash of a hypervelocity impact during a simulation of what happens when a piece of orbital debris hits a spacecraft in orbitWhipple s work pre dated the Space Race and it proved useful when space exploration started only a few years later His studies had demonstrated that the chance of being hit by a meteoroid large enough to destroy a spacecraft was extremely remote However a spacecraft would be almost constantly struck by micrometeorites about the size of dust grains 6 Whipple had already developed a solution to this problem in 1946 Originally known as a meteor bumper and now termed the Whipple shield this consists of a thin foil film held a short distance away from the spacecraft s body When a micrometeoroid strikes the foil it vaporizes into a plasma that quickly spreads By the time this plasma crosses the gap between the shield and the spacecraft it is so diffused that it is unable to penetrate the structural material below 15 The shield allows a spacecraft body to be built to just the thickness needed for structural integrity while the foil adds little additional weight Such a spacecraft is lighter than one with panels designed to stop the meteoroids directly For spacecraft that spend the majority of their time in orbit some variety of the Whipple shield has been almost universal for decades 16 17 Later research showed that ceramic fibre woven shields offer better protection to hypervelocity 7 km s particles than aluminium shields of equal weight 18 Another modern design uses multi layer flexible fabric as in NASA s design for its never flown TransHab expandable space habitation module 19 and the Bigelow Expandable Activity Module which was launched in April 2016 and attached to the ISS for two years of orbital testing 20 21 Footnotes Edit IAU Commission F1 April 30 2017 Definition of terms in meteor astronomy PDF International Astronomical Union Retrieved 25 Jul 2020 a href Template Cite web html title Template Cite web cite web a CS1 maint url status link P Fraundorf 1980 The distribution of temperature maxima for micrometeorites decelerated in the Earth s atmosphere without melting Geophys Res Lett 10 765 768 D E Brownlee D A Tomandl and E Olszewski 1977 Interplanetary dust A new source of extraterrestrial material for laboratory studies Proc Lunar Sci Conf 8th 149 160 Fred Whipple The Theory of Micro Meteorites Part I In an Isothermal Atmosphere Archived 24 September 2015 at the Wayback Machine Proceedings of the National Academy of Sciences Volume 36 Number 12 15 December 1950 pp 667 695 Fred Whipple The Theory of Micrometeorites Archived 17 October 2015 at the Wayback Machine Popular Astronomy Volume 57 1949 p 517 a b Whipple Fred 1951 A Comet Model II Physical Relations for Comets and Meteors Astrophysical Journal 113 464 474 Bibcode 1951ApJ 113 464W doi 10 1086 145416 Brownlee D E Tomandl D A Olszewski E 1977 1977LPI 8 145B Interplanetary dust A new source of extraterrestrial material for laboratory studies Proceedings of the 8th Lunar Scientific Conference 1977 149 160 Bibcode 1977LPI 8 145B Hans Pettersson Cosmic Spherules and Meteoritic Dust Scientific American Volume 202 Issue 2 February 1960 pp 123 132 Andrew Snelling and David Rush Moon Dust and the Age of the Solar System Archived 12 May 2011 at the Wayback Machine Creation Ex Nihilo Technical Journal Volume 7 Number 1 1993 p 2 42 Snelling Andrew and David Rush Moon Dust and the Age of the Solar System Archived 2012 03 09 at the Wayback Machine Creation Ex Nihilo Technical Journal Volume 7 Number 1 1993 p 2 42 Wilhelms Don E 1993 To a Rocky Moon A Geologist s History of Lunar Exploration University of Arizona Press p 97 ISBN 978 0816510658 a b Rodriguez Karen April 26 2010 Micrometeoroids and Orbital Debris MMOD www nasa gov Archived from the original on October 28 2009 Retrieved 2018 06 18 Swan Raitt Swan Penny Knapman Peter A David I Cathy W Robert E John M 2013 Space Elevators An Assessment of the Technological Feasibility and the Way Forward Virginia USA International Academy of Astronautics pp 10 11 207 208 ISBN 9782917761311 a href Template Cite book html title Template Cite book cite book a CS1 maint multiple names authors list link Swan P Penny R Swan C Space Elevator Survivability Space Debris Mitigation Lulu com Publishers 2011 Brian Marsden Professor Fred Whipple Astronomer who developed the idea that comets are dirty snowballs Archived 11 February 2018 at the Wayback Machine The Independent 13 November 2004 Fred Whipple Of Comets and Meteors Archived 29 June 2008 at the Wayback Machine Science Volume 289 Number 5480 4 August 2000 p 728 Judith Reustle curator Shield Development Basic Concepts Archived 27 September 2011 at the Wayback Machine NASA HVIT Retrieved 20 July 2011 Ceramic Fabric Offers Space Age Protection Archived 9 March 2012 at the Wayback Machine 1994 Hypervelocity Impact Symposium Kim Dismukes curator TransHab Concept Archived 1 June 2007 at the Wayback Machine NASA 27 June 2003 Retrieved 10 June 2007 Howell Elizabeth 2014 10 06 Private Inflatable Room Launching to Space Station Next Year Space com Archived from the original on 4 December 2014 Retrieved 2014 12 06 ISS welcomes CRS 8 Dragon after flawless launch 9 April 2016 Archived from the original on 23 April 2016 Retrieved 14 May 2016 See also EditExtraterrestrial materials Interplanetary dust cloudExternal links EditMelted Crumbs from Asteroid Vesta article about micrometeorites collected in Antarctica in Planetary Science Research Discoveries educational journal Retrieved from https en wikipedia org w index php title Micrometeoroid amp oldid 1169982099, wikipedia, wiki, book, books, library,

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