Earth-dwellers probably thought the space storm had completely blown over. Indeed, the
clouds of plasma had passed, and their immediate effects had died down; the longer-term
effects, however, had just begun. Two rings of plasma
called the Van Allen radiation belts normally lie trapped around the Earth
between the orbits of high-flying geosynchronous
satellites and the low-orbiting Space Shuttle. When the shock wave associated with
the May 4 storm smashed into the radiation belts, the electrons trapped there were
energized to new heights and were spun around the Earth to new locations. Satellite data showed that a new
radiation belt had formed between the normal two by the end of May 4 and did not subside until
the middle of June.
That the high-energy electrons of the radiation belts are known as "killer electrons" does
not bode well for satellites flying near the belts. During the period of disturbed
conditions that May, the Equator-S satellite failed; the Polar satellite
suffered blackouts; four of Motorola's Iridium satellites were lost.
The most famous failure, however, was that of the Galaxy IV communications satellite,
handler of some 90 percent of U.S. pager transmissions and several television and
radio feeds. At 6:00 PM EDT on May 19, Galaxy IV's onboard control
system and backup switch failed, proving to at least 40 million pager customers across the
United States the fragility of satellite communications. Over the next few days, PanAmSat,
Galaxy IV's owner, scrambled to transfer signals to other satellites and fix
the communications blackout.
Although PanAmSat dismissed any solar causes for the satellite
outage, blaming instead circuit-damaging "tin whiskers", some scientists disagree.
An October 1998 article in the newspaper Eos
stated boldly that "killer electrons" flooded the satellite and damaged its electronics.
Since high-energy electron levels were far above normal for at least three weeks, the
article stated, Galaxy IV slowly fried to death. The true cause can never be determined, but the
concept suggested is striking -- extended periods of space weather such as the week of activity in early May
1998 can create highly abnormal conditions for satellites and inconvenience millions
of people at one blow.
Quotes and Anecdotes:
- "The magnetic storm expected from the X1 event of 29 April arrived late
on 01 May and is now of major proportions."
Patrick S. McIntosh (from ISTP SEC Event, May 1998)
- "Last night (mainly between 10 & 11 pm (but really from 9 pm to
beyond midnight) I witnessed, with my wife the best aurora here at WW that
I have seen for 40 years. The 10-11 time span was the best with aurora
covering up to 60-65% of the night sky. Mostly blue green but a light
pink background at times. [...]
There were multiple horizontal bands with vertical striations. Some pulsating.
Parts would come and go. Then there would appear shooting dark & light bands
that would go from horizon nearly to zenith. A rather intense glow of blue
green appeared in the NW. [...] Around 10:30 (all times PDT) I noticed some shooting
shortened streaks from the East toward the zenith. At first I had to view
this with averted vision. But then in a few minutes we saw these shooting
patches (like "spirits" flying or like variable water from a fire hose
(coming out in packets) and curving left and right) go from horizon (East)
to west horizon and pass overhead SOUTH of the zenith. We watched them best
by facing south! By this time 60-65% of the night sky was involved with
aurora. [...] At its peak, the display
was bright enough to nearly obscure the bright stars in Cassiopeia."
Thomas Thompson on May 4 aurora at Walla Walla, Washington (from Aurora Monitor Project
- "Galaxy IV is simply in a prime orbital location to cover all
the United States. For pages that want to cover all the area they can, that was the
satellite to be on."
Rebecca Petruck, a PanAmSat spokeswoman
- "There was circumstantial evidence that a solar storm afflicted the
satellite. The sun has its seasons that run on an 11-year cycle, but we weren't
in the bad part of the cycle last year. We identified the [primary control]
computer as the component that failed. Space weather looked possible, but the review
of data didn't back up the theory."
Michael Bodeau, manager of survivability activity at Hughes (from "'Whiskers' Caused
- "We have ruled out any external causes and believe the satellite failure
was due to a spacecraft component problem."
Robert Bednarek, PanAmSat executive (from "The Satellite Fix Is In")
Chronology (all times Universal Time):
[April 29, 1998]
16:00 -- Halo CME first visible in SOHO/EIT images
16:58 -- CME appears in SOHO/LASCO-C2
[May 1, 1998]
21:15 -- Shock detected by SOHO/PM
23:56 -- Partial halo CME in progress, seen from LASCO
[May 2, 1998]
13:40 -- X-class flare from region 8210
14:06 -- Bright partial halo CME begins in NW quadrant of Sun
14:20 -- High-energy protons arrive near Earth from flare
[May 4, 1998]
02:30 -- Solar wind speed jumps from 500 to 700 km/s (at Wind)
03:30 -- Wind speed jumps again to 800 km/s
[May 6, 1998]
00:02 -- Bright partial halo CME appears in LASCO-C2
02:28 -- Small, slow CME appears in LASCO-C2
05:29 -- Wide, fast CME associated with X-class flare appears
[May 19, 1998]
22:00 -- Galaxy IV satellite's onboard control system fails
22:30 -- ABC and CBS video feeds freeze
[May 21, 1998]
10:30 -- 85% of PageNet customers back online
16:00 -- Most of Galaxy IV's transmissions switched to another satellite
Aurora Monitor Project Status:
Some background on the storm, with a focus on auroral observations
from early May 1998.
Russell, C.T. et al. "The Extreme Compression of the Magnetosphere on
May 4, 1998, as Observed by the Polar Spacecraft."
Scientific article discussing the compression of the Earth's magnetic
field during the May event.
"'Whiskers' Caused Satellite Failure," Wireless Week, 5/17/99:
Article on the cause of the Galaxy IV failure, dismissing solar
activity as a possible contributor.
"The Satellite Fix Is In," ABC News, 5/22/98:
From ABC News, this article covers the Galaxy IV outage, effects,
and attempts to recover from the outage.
- ISTP Sun-Earth Connections Event, May 1998:
- A listing of the scientific data available for the event, with
some summary information about the satellite observations.
Images from the Event:
SOHO's EIT captures the May 2 solar flare
X-ray flux plot shows an X-class flare on May 2
May 2 aurora seen by UVI on Polar
VIS on Polar sees the aurora on May 3
Plot shows auroral oval from DMSP, with white dots indicating ground
The aurora, as observed May 4 by Polar's PIXIE
Brian Rachford's image of the May 4 aurora from Laramie, WY
SOHO/LASCO images a CME on May 6
X-ray flux plot shows an X-class flare on May 6