For [[exovivaria]], whose rotation for artificial gravity would already provide [[http://en.wikipedia.org/wiki/Spin-stabilized_satellite | spin-stabilization]], the only likely long-term attitude control requirement would be to keep the axis sun-pointing as the Earth travels around the sun. Attitude control would also be important for establishing sun-pointing in the first place. Magnetorquers have been used for small satellites in equatorial orbits to maintain sun-pointing.[^See e.g., Sedlund, C.A. [[http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F4813823%2F4839294%2F04839544.pdf%3Farnumber%3D4839544&authDecision=-203 | "A simple sun-pointing magnetic controller for satellites in equatorial orbits"]]. IEEE 2009 Aerospace Conference. DOI 10.1109/AERO.2009.4839544^]

* Christopher T. Lefèvre, Fernanda Abreu, Ulysses Lins and Dennis A. Bazylinski, [[http://books.google.com/books?id=K71WeEHPCvcC&lpg=PP1&dq=Metal%20Nanoparticles%20in%20Microbiology&pg=PA75#v=onepage&q=magnetosomes&f=false | "A Bacterial Backbone: Magnetosomes in Magnetotactic Bacteria"]] (doi 10.1007/978-3-642-18312-6_4) in ''Metal Nanoparticles in Microbiology'', Mahendra Rai, Nelson Duran (eds), Springer (April 12, 2011) ISBN 3642183115

''Biomagnetorquing'' would use magnetic fields generated by living organisms -- specifically, [[http://en.wikipedia.org/wiki/Magnetotactic_bacteria | magnetotactic bacteria]] but possibly also magnetotactic algae[^[[http://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1140&context=phy_fac | Magnetite  and  Magnetotaxis  in  Bacteria  and  Algae]], R.B.  Frankel, Francis  Bitter  National  Magnet  Laboratory, MIT, 1986^] which have a much higher [[http://en.wikipedia.org/wiki/Magnetic_moment | magnetic moment]].[^See e.g., ^F.F. Torres de Araujo, M.A. Pires, R.B. Frankel, C.E. M. Bicudo, [[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1329754/pdf/biophysj00176-0166.pdf | "Magnetite and Magnetotaxis in Algae"]], Biophys. J. '''50'''(2) Aug '86, pp. 375-378 doi:10.1016/S0006-3495(86)83471-3^] Inside these magnetotactic microorganisms, [[http://en.wikipedia.org/wiki/Magnetosome | magnetosomes]] -- cuboidal building blocks of magnetized metal -- naturally form; these blocks self-assemble into larger magnets, nanometric strands of ferric material that are still too small to resolve with an optical microscope.

''Biomagnetorquing'' would use magnetic fields generated by living organisms -- specifically, [[http://en.wikipedia.org/wiki/Magnetotactic_bacteria | magnetotactic bacteria]] but possibly also magnetotactic algae which have a much higher [[http://en.wikipedia.org/wiki/Magnetic_moment | magnetic moment]].[^See e.g., ^F.F. Torres de Araujo, M.A. Pires, R.B. Frankel, C.E. M. Bicudo, [[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1329754/pdf/biophysj00176-0166.pdf | "Magnetite and Magnetotaxis in Algae"]], Biophys. J. '''50'''(2) Aug '86, pp. 375-378 doi:10.1016/S0006-3495(86)83471-3^] Inside these magnetotactic microorganisms, [[http://en.wikipedia.org/wiki/Magnetosome | magnetosomes]] -- cuboidal building blocks of magnetized metal -- naturally form; these blocks self-assemble into larger magnets, nanometric strands of ferric material that are still too small to resolve with an optical microscope.

''Magnetorquing'' describes a class of techniques for [[http://en.wikipedia.org/wiki/Attitude_control_system | spacecraft attitude control]] that relies on interactions between spacecraft-generated magnetic fields and external magnetic fields -- usually just one external field, the Earth's, and usually only for small satellites in [[LEO]].

''Biomagnetorquing'' would use magnetic fields generated by living organisms -- specifically, [[http://en.wikipedia.org/wiki/Magnetotactic_bacteria | magnetotactic bacteria]] but possibly also magnetotactic algae.[^See e.g., ^F.F. Torres de Araujo, M.A. Pires, R.B. Frankel, C.E. M. Bicudo, [[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1329754/pdf/biophysj00176-0166.pdf | "Magnetite and Magnetotaxis in Algae"]], Biophys. J. '''50'''(2) Aug '86, pp. 375-378 doi:10.1016/S0006-3495(86)83471-3^]

* '''[[Orbital debris]] mitigation'''. If a biosatellite disintegrates (whether slowly or catastrophically), the magnetic components of the magnetorquers -- [[http://en.wikipedia.org/wiki/Magnetosome | magnetosomes]], nanometric strands of ferric material -- will be far too small to pose a threat to other spacecraft.

* No permanent moving parts to wear out or go awry, which cannot be said of some other propellantless attitude control parts like [[http://en.wikipedia.org/wiki/Reaction_wheel | reaction wheels]].

%rframe% http://genome.jgi.doe.gov/magm1/magm1.jpg | [[http://species.wikimedia.org/wiki/Magnetococcus | Magnetococcus]] strain MC-1[^"[[http://genome.jgi.doe.gov/magm1/magm1.home.html | Magnetococcus sp. MC-1]]", DOE Joint Genome Institute. This strain is the only one with a pure culture available.^]

%rframe% http://space.jpl.nasa.gov/msl/QuickLooks/pictures/tubsata.jpeg | [[http://www.raumfahrttechnik.tu-berlin.de/tubsat/TUBSAT-A | Tubsat-A]] used magnetorquers

* No permanent moving parts to wear out or go awry, which cannot be said of some other propellantless attitude control parts like [[http://en.wikipedia.org/wiki/Reaction_wheel | reaction wheels]].)

For attitude control applications such as these, which requiring little power, there might be a number of advantages of biomagnetorquing over conventional attitude control. Among these, one can list:

* strength - can strong enough magnets be grown?
* mechanics - how do you determine the optimal deployment of magnets?
* economics - could the investment required to culture magnetotaxic species and deploy them for attitude control be better spent elsewhere on exovivaria?

'''Biomagnetorquing''' would use magnetic fields generated by living organisms -- specifically, [[http://en.wikipedia.org/wiki/Magnetotactic_bacteria | magnetotactic bacteria]] but possibly also magnetotactic algae.[^See e.g., ^F.F. Torres de Araujo, M.A. Pires, R.B. Frankel, C.E. M. Bicudo, [[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1329754/pdf/biophysj00176-0166.pdf | "Magnetite and Magnetotaxis in Algae"]], Biophys. J. '''50'''(2) Aug '86, pp. 375-378 doi:10.1016/S0006-3495(86)83471-3^]

For [[exovivaria]], whose rotation for artificial gravity would already provide [[http://en.wikipedia.org/wiki/Spin-stabilized_satellite | spin-stabilization]], the only likely long-term attitude control requirement would be to keep the axis sun-pointing as the Earth travels around the sun. Magnetorquers have been used for small satellites in equatorial orbits.[^See e.g., Sedlund, C.A. [[http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F4813823%2F4839294%2F04839544.pdf%3Farnumber%3D4839544&authDecision=-203 | "A simple sun-pointing magnetic controller for satellites in equatorial orbits"]]. IEEE 2009 Aerospace Conference. DOI 10.1109/AERO.2009.4839544^] Attitude control would also be important for establishing sun-pointing in the first place. For applications such as these (requiring little power), there might be a number of advantages of biomagnetorquing  over conventional magnetorquers and over other propellantless attitude control systems such as [[http://en.wikipedia.org/wiki/Reaction_wheel | reaction wheels]]. Among these, one can list:

* '''Recyclability'''. If a "starter" microorganism culture can be maintained,[^The environmental requirements of magnetotaxic microorganisms are unlikely to be optimal for exovivaria ecosystems.^] biomagnetorquer magnets might be grown only as attitude control needs arose. Maintaining exovivaria sun-pointing might require adjustments only on a monthly basis or longer. Electromagnets that are ordinarily used on exovivaria only for robotic actuators might be used to orient the magnetotaxic microorganisms in a non-metallic matrix (some exovivarium-produced biodegradable material, or possibly ice) in order to make as many bio-magnets as needed for attitude change. These biomagnets could then be recycled.

For [[exovivaria]], whose rotation for artificial gravity would already provide spin-stabilization, the only likely long-term attitude control requirement would be to keep the axis sun-pointing as the Earth travels around the sun. Magnetorquers have been used for small satellites in equatorial orbits.[^See e.g., Sedlund, C.A. [[http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F4813823%2F4839294%2F04839544.pdf%3Farnumber%3D4839544&authDecision=-203 | "A simple sun-pointing magnetic controller for satellites in equatorial orbits"]]. IEEE 2009 Aerospace Conference. DOI 10.1109/AERO.2009.4839544^] Attitude control would also be important for establishing sun-pointing in the first place. For applications such as these (requiring little power), there might be a number of advantages of biomagnetorquing  over conventional magnetorquers and over other propellantless attitude control systems such as [[http://en.wikipedia.org/wiki/Reaction_wheel | reaction wheels]]. Among these, one can list:

== Further reading ==

[^#^]

''Magnetorquing'' describes a class of techniques for spacecraft attitude control that relies on interactions between spacecraft-generated magnetic fields and external magnetic fields -- usually just one external field, the Earth's, and usually only for small satellites in [[LEO]].

''Magnetorquing'' describes a class of techniques for propellantless spacecraft attitude control that relies on interactions between spacecraft-generated magnetic fields and external magnetic fields -- usually just one external field, the Earth's, and usually only for satellites in [[LEO]].

For [[exovivaria]], with rotation for artificial gravity already providing spin-stabilization, the only likely use for attitude control would be to keep the axis sun-pointing as the Earth travels around the sun. Magnetorquers can be used for small satellites in equatorial orbits.[^See e.g., Sedlund, C.A. [[http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F4813823%2F4839294%2F04839544.pdf%3Farnumber%3D4839544&authDecision=-203 | "A simple sun-pointing magnetic controller for satellites in equatorial orbits"]]. IEEE 2009 Aerospace Conference. DOI 10.1109/AERO.2009.4839544^] For applications such as these (requiring little power), there might be a number of advantages of biomagnetorquing  over conventional magnetorquers and over other propellantless attitude control systems such as [[http://en.wikipedia.org/wiki/Reaction_wheel | reaction wheels]]. Among these, one can list:

* '''[[Orbital debris]] mitigation'''. If a biosatellite disintegrates (whether slowly or catastrophically), the magnetic components of the magnetorquer -- [[http://en.wikipedia.org/wiki/Magnetosome | magnetosomes]], nanometric strands of ferric material -- will be far too small to pose a threat to other spacecraft.

* '''Recyclability'''. If a "starter" microorganism culture can be maintained,[^The environmental requirements of magnetotaxic microorganisms are unlikely to be optimal for exovivaria ecosystems.^] biomagnetorquer magnets might be grown only as attitude control needs arise. If exovivaria sun-pointing is not a daily concern, these needs might be infrequent. Electromagnets usually used as robotic actuators might also be used to orient the magnetotaxic bacteria in a non-metallic matrix (some exovivarium-produced biomaterial or possibly ice) in order to make as many bio-magnets as needed for a maneuver. These biomagnets might then be recycled.

* strength - can strong enough magnets be made?
* electromechanic - how do you determine the optimal deployment of magnets?
* economic - is the investment required to culture magnetotaxic species and deploy them for attitude control better spent elsewhere on exovivaria?

For [[exovivaria]] artificial gravity already providing spin-stabilization, the only purpose of attitude control would probably be to keep them sun-pointing. Magnetorquers can be used for small satellites in equatorial orbits.[^See e.g., Sedlund, C.A. [[http://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F4813823%2F4839294%2F04839544.pdf%3Farnumber%3D4839544&authDecision=-203 | "A simple sun-pointing magnetic controller for satellites in equatorial orbits"]]. IEEE 2009 Aerospace Conference. DOI 10.1109/AERO.2009.4839544^] For applications such as these (requiring little power), there might be a number of advantages of biomagnetorquing  over conventional magnetorquers and over other propellantless attitude control systems such as [[http://en.wikipedia.org/wiki/Reaction_wheel | reaction wheels]]. Among these, one can list:

For [[exovivaria]] already spin-stabilized by artificial gravity, the only purpose of attitude control would probably be to keep them sun-pointing. For applications such as these (requiring little power), there might be a number of advantages of biomagnetorquing  over conventional magnetorquers and over other propellantless attitude control systems such as [[http://en.wikipedia.org/wiki/Reaction_wheel | reaction wheels]]. Among these, one can list:

%lframe% http://genome.jgi.doe.gov/magm1/magm1.jpg | [[http://species.wikimedia.org/wiki/Magnetococcus | Magnetococcus]] strain MC-1[^"[[http://genome.jgi.doe.gov/magm1/magm1.home.html | Magnetococcus sp. MC-1]]", DOE Joint Genome Institute. This strain is the only one with a pure culture available.^]

%lframe% http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Geodynamo_After_Reversal.gif/219px-Geodynamo_After_Reversal.gif | Earth as a "geodynamo" magnet

* electromechanic - how do you compute the optimal deployment?

%rframe% http://genome.jgi.doe.gov/magm1/magm1.jpg | Magnetococcus strain MC-1[^"[[http://genome.jgi.doe.gov/magm1/magm1.home.html | Magnetococcus sp. MC-1]]", DOE Joint Genome Institute^]

'''Magnetorquing''' describes a class of techniques for propellantless spacecraft attitude control that relies on interactions between spacecraft-generated magnetic fields and external magnetic fields -- usually just one external field, the Earth's, and usually only for satellites in [[LEO]].

%lframe% http://space.jpl.nasa.gov/msl/QuickLooks/pictures/tubsata.jpeg | Student-built [[http://www.raumfahrttechnik.tu-berlin.de/tubsat/TUBSAT-A | Tubsat-A]] used magnetorquers

* '''Recyclability'''. If a "starter" bacterial culture can be maintained, biomagnetorquer magnets might be grown only as attitude control needs arise. If exovivaria sun-pointing is not a daily concern, these needs might be infrequent. Electromagnets usually used as robotic actuators might also be used to orient the magnetotaxic bacteria in a non-metallic matrix (some exovivarium-produced biomaterial or possibly ice) in order to make as many bio-magnets as needed for a maneuver. These biomagnets might then be recycled.

%rframe% http://upload.wikimedia.org/wikipedia/commons/thumb/8/89/Geodynamo_After_Reversal.gif/219px-Geodynamo_After_Reversal.gif | Earth as a "geodynamo" magnet

Biomagnetorquing faces a number of challenges, among them:

* electromagnetic - can strong enough magnets be made?
* electromechanical - how do you compute the optimal deployment?

%lframe% http://genome.jgi.doe.gov/magm1/magm1.jpg | Magnetococcus strain MC-1[^"[[http://genome.jgi.doe.gov/magm1/magm1.home.html | Magnetococcus sp. MC-1]]", DOE Joint Genome Institute^]

%rfloat% http://upload.wikimedia.org/wikipedia/commons/5/52/Ferromag_Matl_Sketch.JPG

* '''Recyclability'''. So long as a "starter" bacterial culture can be minimally maintained, new biomagnetorquer materials might be grown only as attitude control needs arose. These needs might be infrequent, if only approximate sun-pointing proves to be adequate for exovivaria. Electromagnets that would be ordinarily used on exovivaria as robotic actuators might be temporarily pressed into service for orienting the magnetotaxic bacteria in a non-metallic matrix (some exovivarium-produced biomaterial or possibly ice) in order to create as many bio-magnets as necessary for a particular maneuver.

%rfloat% http://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/VFPt_Earths_Magnetic_Field_Confusion.svg/120px-VFPt_Earths_Magnetic_Field_Confusion.svg.png

For [[exovivaria]] already spin-stabilized by artificial gravity, the only purpose of attitude control would probably be to maintain sun-pointing, which is a relatively low-power, low-speed requirement. In this case, there might be a number of advantages over conventional magnetorquers and over other propellantless attitude control systems such as [[http://en.wikipedia.org/wiki/Reaction_wheel | reaction wheels]]:

Biomagnetorqueing faces a number of challenges, among them:

'''Biomagnetorquing''' would use magnetic fields generated by living organisms -- specifically, [[http://en.wikipedia.org/wiki/Magnetotactic_bacteria | magnetotactic bacteria]] but possibly also magnetotactic algae.[See e.g., ^F.F. Torres de Araujo, M.A. Pires, R.B. Frankel, C.E. M. Bicudo, [[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1329754/pdf/biophysj00176-0166.pdf | "Magnetite and Magnetotaxis in Algae"]], Biophys. J. '''50'''(2) Aug '86, pp. 375-378 doi:10.1016/S0006-3495(86)83471-3^]

Biomagnetorquing is currently under consideration for a partial-proof-of-concept experiment on [=KickSat=].[^"[[http://www.kickstarter.com/projects/251588730/kicksat-your-personal-spacecraft-in-space | KickSat -- Your personal spacecraft in space!]]", Zachary Manchester, Cornell University Space Design Studio^]

'''Magnetorquing''' describes a class of techniques for spacecraft attitude control that depends on interactions between magnetic fields in the spacecraft and external magnetic fields -- usually just one external field, the Earth's, and usually only for satellites in low orbits.

'''Biomagnetorquing''' would use magnetic fields generated by living organisms -- specifically, [[http://en.wikipedia.org/wiki/Magnetotactic_bacteria | magnetotactic bacteria]] but possibly also magnetotactic algae[^F.F. Torres de Araujo, M.A. Pires, R.B. Frankel, C.E. M. Bicudo, [[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1329754/pdf/biophysj00176-0166.pdf | "Magnetite and Magnetotaxis in Algae"]], Biophys. J. '''50'''(2) Aug '86, pp. 375-378 doi:10.1016/S0006-3495(86)83471-3^]

For [[exovivaria]] already spin-stabilized by artificial gravity, the only purpose of attitude control would probably be to maintain sun-pointing, which is a fairly low-power, low-speed requirement. In this case, there might be a number of advantages over conventional magnetorquers and over other propellantless attitude control systems such as [[http://en.wikipedia.org/wiki/Reaction_wheel | reaction wheels]]: