Lagrange Magshield, The

Artificial planetary magnetic shielding

Interplanetary Age concept, which was developed from research into magsails and Ram-assisted magscoops.
Image from Steve Bowers ">Largrange Magshield
Image from Steve Bowers
Interplanetary Age concept, which was developed from research into magsails and Ram-assisted magscoops.

When the first efforts were made to terraform the planet Mars the lack of a protective magnetic field left that planet largely unprotected from the solar wind. An artificial magnetosphere was eventually constructed called the Lagrange Magshield, at the L1 Sun/Mars Lagrange point; this device is powered by solar energy and maintained in position by active control mechanisms.

Living on the surface of a terraformed world which does not have a magnetic field of its own exposes a human population to the full force of any solar wind events. These events can produce a lethal flux of charged particles, especially during a coronal mass ejection, when protons stream in relatively tight formation, which may hit an unprotected world (with dire consequences). Mars did once have a protective magnetic field, but when the small iron core cooled it lost that protection, and so the first great cities on Mars were all built partly or wholly beneath the surface to hide from the blustering solar wind.

In 2210 c.e. (Old Earth calendar) the franchise Exopower (Mars) began converting a small silicaceous asteroid 2133 PPTK into a flat ring of solar energy collectors at the Mars/Sun L1 Lagrange point, 1,081,000 km from Mars towards the Sun. Mars needed vast amounts of energy to continue the terraforming process, and this ring provided much of that power. However the repeated solar flux incidents threatened to make all the investment of time and energy worthless.

Exopower (Mars) in 2257 c.e. successfully demonstrated their new Lagrange Magshield concept, which had developed from research into magsails and ram-assisted magscoops. The whole array of solar power collectors at the L1 point were formed into a flat ring with a hole in it (to allow visible sunlight and heat to reach Mars. Later a thin UV filter was added in this space; as the oxygen content of Mars' atmosphere increased, ultraviolet radiation from the Sun heated the topmost layer of the atmosphere (the Exosphere), and this caused the new atmosphere to be gradually lost. Introducing a UV filter between Mars and the Sun reduced this loss significantly.

Whenever the solar wind threatened to dump charged particles on the planet's surface, the magshield would adjust the anchorweight which pulled the structure towards the Sun against light pressure. An array of superconducting loops strung between the ring and the anchorweight produced a vast magnetic field of controlled strength. When the magnetic coils were energised, the whole array was blown outwards from the sun by solar wind, but adjustment to the anchorweight could prevent the magshield moving too far off station. Using stored energy a peak field strength of up to 10 petawatts could be produced, stronger than the field around the Earth; the solar wind could be diverted safely away from the Martian surface in this way.

Lagrange Magshield 2
Image from Steve Bowers
The Magshield ring is seen in the distance as a freight ship makes its way towards Mars in the foreground

Together with an artificially maintained ozone layer, this magshield made the colonisation of Mars a viable proposition. Lessons learned during the partial terraforming of Mars have been used to good effect in other planetary systems, as many worlds need protection from the winds of the local star. Similar magshields are standard kit throughout the Terragen sphere, wherever a planet with no magnetic field is being terraformed.

Many paraterraformed worlds have an artificial magnetic field built into the worldhouse roof, and may have a lagrange magshield as well to protect against outbursts. The magshield can be designed to act as a parasol to cut down on unwanted radiation influx, and can collect a respectable amount of usable energy as well.

Advanced anti-radiation genemodding is also almost universal, turning the galaxy from an inhospitable death-trap to the home for millions of clades of humanity and other biont organisms.

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Development Notes
Text by Steve Bowers
Space freighter design by Eric Bury; model by RC2000.
Initially published on 12 May 2004.