SCIENCE: A scientist explains how a solar storm can easily destroy satellites.

On Feb­ru­ary 4, 2022, SpaceX launched 49 satel­lites as part of Elon Musk’s Star­link Inter­net project, most of which burned up in the atmos­phere a few days lat­er. The cause of the US$50 mil­lion-plus fail­ure was a geo­mag­net­ic storm caused by the Sun.

Geo­mag­net­ic storms occur when space weath­er strikes and inter­acts with the Earth. Space weath­er is caused by fluc­tu­a­tions with­in the Sun that pro­pel elec­trons, pro­tons, and oth­er par­ti­cles into space.

I study the haz­ards that space weath­er pos­es to space assets and how sci­en­tists can improve space weath­er mod­els and pre­dic­tion to pro­tect against these hazards.

When space weath­er reach­es Earth, it trig­gers a lot of com­pli­cat­ed process­es that can cause a lot of prob­lems for any­thing in orbit. And engi­neers like me are work­ing to bet­ter under­stand these haz­ards and defend satel­lites against them.

What caus­es space weath­er?
The Sun always releas­es a con­stant amount of charged par­ti­cles into space. This is called the solar wind. The solar wind also car­ries with it the solar mag­net­ic field.

Some­times local­ized fluc­tu­a­tions on the Sun will pro­pel unusu­al­ly strong par­ti­cle bursts in a par­tic­u­lar direc­tion. If the Earth is in the path of the enhanced solar wind gen­er­at­ed by one of these events and is affect­ed, you get a geo­mag­net­ic storm.

The two most com­mon caus­es of geo­mag­net­ic storms are coro­nal mass ejec­tions — explo­sions of plas­ma from the Sun’s sur­face — and the solar wind escap­ing through coro­nal holes — low-den­si­ty spots in the Sun’s out­er atmosphere.

The speed at which the eject­ed plas­ma or solar wind arrives at Earth is an impor­tant fac­tor — the faster the speed, the stronger the geo­mag­net­ic storm. Nor­mal­ly, the solar wind trav­els at about 900,000 mph (1.4 mil­lion km/h). But strong solar events can release winds up to five times faster.

The strongest geo­mag­net­ic storm ever record­ed was caused by a coro­nal mass ejec­tion in Sep­tem­ber 1859. When the mass of par­ti­cles hit the Earth, they caused elec­tri­cal surges in tele­graph lines that shocked oper­a­tors and, in some extreme cas­es, actu­al­ly set fire to tele­graph instruments.

Research sug­gests that if a geo­mag­net­ic storm of this mag­ni­tude hit Earth today, it would cause about $2 tril­lion in damage.

Emis­sions from the Sun, includ­ing the solar wind, would be incred­i­bly dan­ger­ous to any life form unlucky enough to be direct­ly exposed to them. For­tu­nate­ly, the Earth­’s mag­net­ic field does much to pro­tect humanity.

The first thing the solar wind hits as it approach­es the Earth is the mag­ne­tos­phere. This region sur­round­ing the Earth­’s atmos­phere is filled with plas­ma com­posed of elec­trons and ions. It is dom­i­nat­ed by the plan­et’s strong mag­net­ic field. When the solar wind hits the mag­ne­tos­phere, it trans­fers mass, ener­gy and momen­tum into this layer.

The mag­ne­tos­phere can absorb most of the ener­gy from the dai­ly lev­el of the solar wind. But dur­ing strong storms, it can be over­loaded and trans­fer excess ener­gy to the upper lay­ers of the Earth­’s atmos­phere near the poles. This redi­rec­tion of ener­gy to the poles caus­es fan­tas­tic auro­ra events, but it also caus­es changes in the upper atmos­phere that can harm space assets.

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