[HoustonHam] Possible Solar Storm

[Chris Boone]

A s t r o A l e r t

09 September 2005

Solar Terrestrial Dispatch
www.spacew.com

INTENSE SOLAR FLARING CONTINUES

Active sunspot complex 10808 (also known as Region 808) continues to
impress. It is now more fully in-view and is presenting itself as a very
large sunspot complex that will (if its present size persists) be visible to
the unaided (protected) eye over the next week to 10 days.

Aside from the very large class X17 flare reported in the last Astroalert,
it has managed to produce two additional major flares: a class X5 and a
smaller class X1 within six hours of each other (the X5 occurred at 21:06
UTC [5:06 pm EDT] on 8 September, and the X1 occurred at 03:00 UTC on 9
September [11 pm EDT on 8 September]).
...
These recent events (the three X-class flares observed thus far) have
elevated the population of energetic protons in the near-Earth space
environment to levels that are now roughly 100 times more dense than normal
background levels. Energetic protons are being redirected by the Earth's
magnetic field toward the polar ionospheres, where they are bombarding and
ionizing the polar ionosphere to levels sufficient to produce a phenomenon
known as Polar Cap Absorption (or PCA).

PCA is not harmful to human health, but can be disastrous to high-frequency
radio communications through the polar regions. Such radio signals are
normally bounced off the lower side of the ionosphere and are returned back
to the Earth, permitting long-distance radio communications to take place.

But the energetic protons have ionized the lower ionospheric layers to
levels capable of absorbing most radio signals that attempt to pass through
that region. As a result, for large regions of the Earth where radio paths
traverse the high and polar latitudes, a radio blackout is currently in
effect.

Additional strong solar flare activity could significantly elevate proton
populations over and above what is currently being observed, during the next
two weeks. This could prove to be hazardous to the health of spacecraft in
orbit around the Earth. Indeed, it is possible for vulnerable spacecraft to
become crippled or even irrevocably lost.  It is also possible that
spacecraft reliant upon solar arrays for power may observe permanent
degradations in performance. In other words, another effect of strong space
radiation is to permanently reduce the efficiency of solar panels, causing a
reduction in electrical output and therefore reduced lifetimes.

Space weather storms caused by the high velocity mass that is often ejected
from such powerful solar events can also significantly reduce the lifetime
of spacecraft through another method as well. During strong storms, the
outer reaches of the Earth's atmosphere heats up and bloats outward into
space. This bloating effect increases the atmospheric drag on spacecraft in
near-Earth orbits and can cause their orbital parameters to change rapidly.
Their lifetimes can therefore be reduced simply because the drag reduces
their altitude, which can result in early re-entry of the spacecraft back to
the Earth.

The intense radio bursts associated with these solar flares can produce
interference with antennas that happen to be directed toward the Sun during
the bursts. For example, if a strong solar flare occurs when the Sun is just
rising and a cellular phone or other radio communications network (wireless
internet, etc.) happens to be aligned in the direction of the rising Sun,
the intense radio emissions from the Sun may interfere with the
communications occurring in the network. This can result in poorer
communications performance.
...
**  End of AstroAlert  **