represent an entirely unique technology that has grown up simultaneously
with our understanding of the geospace environment. There has never existed
a time when we did not fully comprehend how space weather impacts satellite
technology. Despite the nearly 40 years that have gone by since the beginning
of the Space Age, satellite technology is, in many ways, still in its
infancy. The following is a summary of satellites that have been affected
by space weather events, and a description of the major satellite zones
surrounding Earth. The information is excerpted from The
23rd Cycle and a NASA
Report on Spacecraft anomalies. Because they are so numerous, not
all of the electrostatic discharging anomalies for satellites mentioned
in the NASA report are listed below.
Low Earth Orbit (LEO) spans a zone approximately
from 200 to 1,500 miles above the surface. The most common satellites
in LEO include ones designed for military 'espionage' applications, scientific
research, and a growing number of satellite phone networks (e.g. Iridium,
Globalstar, Orbcom). The biggest space weather effect to LEO satellites
is the atmosphere of Earth itself, and the way it inflates during solar
storm events. This causes high-drag conditions that lower satellite orbits
by tens of miles at a time. In addition, the most intense regions of the
van Allen radiation belts reach down to 400 miles over South America.
Satellites in LEO will spend part of their orbital periods flying through
these clouds of particles. The residents of this region that show space
weather impacts are:
- This $1.5 billion scientific research satellite launched in 1990, orbits
at an altitude of 360 miles (600 km) for easy servicing by the Space Shuttle.
It is scheduled to be decommissioned in ca 2009 when its gyros begin to
fail. The data are constantly affected by cosmic rays and by high-energy
particles, especially during solar storms. These 'glitches' are deleted
from the data during ground-based processing and scientific analysis.
The solar panels suffer the same degradation from cosmic rays as other
satellites. On May 7, 1990 'bit-flips caused when the satellite entered
the South Atlantic Anomaly region over South America caused controllers
to modify the onboard software. On June 20, 1990 the SAA also caused photomultiplier
tube anomalies in the FIne Guidance Sensor, producing guide star acquisition
errors. Subsequently, FGS use was suspended during SAA passage.
- A $ 95 billion manned operating platform with a 12-year lifespan, it
is in a high-inclination orbit with a Space Shuttle-accessible altitude
of 219 miles (perigee 354 km). It requires re-boosting several times every
year because atmospheric drag is constantly decreasing its altitude by
a kilometer every 12 days. Solar storms heat the upper atmosphere causing
increasres drag which accelerates the orbit decay. Data collected by NASA
and a Russian-Austrian collaboration show that astronauts on the ISS are
subjected to about 1 millisievert (100 milliRem) of radiation per day;
about the same radiation exposure as someone would get from natural sources
on Earth in a whole year.
- March 13, 1989 - Pressure sensor gives false readings during the 'Quebec
Blackout' space weather event. Atlantis (October 18-24, 1989) astronauts
report eye flashes even inside the most heavily shielded area of the space
shuttle. This pattern of astronaut eye flashes is a recurring phenomenon
for all the major solar flares recorded since the Space Shuttle began
- This $630 million research satellite (ADEOS-II) owned by Japan failed
as a result of the major solar storm that pummeled Earth between October
In an article "Space
Anomaly and Space Environment, Space Weather and Satellite Alert System"
by Tateo Goka et al. (Japan Aerospace Exploration Agency - JAXA) published
in 2004: "The Advanced Earth Observing Satellite II (ADEOS-II), also
called Midori-II in Japanese, a low-altitude polar sun-synchronous satellite
with an altitude of 800 km, suffered a catastrophic failure during an
October [space weather] storm. Solar cell power output dropped from 6
kW to 1 kW in three minutes from (16:13 to 16:16 (UT)) on October 24.
..It was probable that a short- or open- circuit failure occurred on the
solar array paddle or solar array paddle harness. For the latter, the
laboratory test verified that the sustained arcing between the harnesses
could destroy the bundled power lines. Space environment analysis demonstrated
that the >30keV electron fluence (observed by NOAA-17) was [one
hundred] times greater than during a quiet day, just
a quarter hour before the ADEOS-2 power down outage anomaly [occurred]
over the north pole auroral region" Reference: H. Maejima,
S. Kawakita, H. Kusawake, M.Takahashi, T. Goka, T. Kurosaki, M. Nakamura,
K. Toyoda, M. Cho, Investigation of Power System Failure of a LEO Satellite,
AIAA, Proceeding of 2nd International Energy Conversion Engineering Conference
(IECEC), Providence, RI, (2004). "
September 20, 1997, the $474 million Adeos research satellite launched
by Japan a year earlier into an 803-km orbit, began to malfunction. According
to a report in Space News, "...Cosmic
rays were found to have damaged the main onboard computer, which caused
it to shut down all nonessential systems, including the sensors, forcing
scientists to reprogram its software"
On May 1, 1998 , the $12 million German research satellite Equator-S owned
by the Max Planck Institute lost its backup processor. According to an
announcement by the Institute at the official web site for this satellite,
latch-up caused by penetrating particle radiation was the cause, there
is hope that it may heal itself upon the next eclipse because of the complete
temporary switch-off of the electrical system"
- On July 11, 1979 this abandoned, unmanned space station in a 435-km
orbit, prematurely re-entered Earth's atmosphere because of the increased
drag caused by heightened solar activity. This uncontrolled reentry was
a major news story.
Maximum Mission (SMM) -
This research satellite launched on February 14, 1980 into a 574-km orbit
lost 8k out of its 48k of onboard memory because of a 'hard' cosmic ray
hit in early January, 1986.
Launched on September 7, 1988 into a 900 km orbit, after 39 days in orbit,
this Chinese satellite experienced an electrostatic discharge caused a
failure of the attitude control system that ended the mission.
Earth Orbit (MEO) between 6,000 and 12,000 miles was originally
used by the Telstar 1 satellite, but is currently not economically worth
the incremental advantage it provides for communication satellites. Research
satellites such as NASA's IMAGE satellite, and certain types of military
communications and global positioning satellites are commonly found here.
The most famous occupant of these regions subject to solar storms are:
Positioning System (GPS)
- Originally used by the US military, there are now 100 times more clients
in the civilian sector using this satellite system to determine location
to better than 3-meter accuracy. This $6 billion network of 24 satellites
and 5 spares launched between 1978-2002 have been specifically designed
to be radiation-hardened so that they can survive constant encounters
with the high-energy particles in the van Allen radiation belts.
They orbit at an altitude of 10,900 miles, and have lifetimes of
10 years. There have been three systems (Block I, Block II and Block IIR)
installed since the first Navstar satellites were launched in 1973. The
next upgrade, Block III, is planned for 2005 or 2007 when the satellites
will be replaced at a cost of about $80 million each. The GPS system is
affected by solar storms, which cause the position error to increase by
factors of 3 to 4 times for the duration of the storm. Of
the 33 GPS satellites still operating, 19 are older than their 8-year
design lifetime and support a $22 billion a year civilian global positioning
first satellite to fall victim to space weather effects was, in fact,
the one of the first commercial satellites ever launched into orbit in
July 1962: Telstar 1. In November of that year, it suddenly ceased to
operate. From the data returned by the satellite, Bell Telephone Laboratory
engineers on the ground tested a working twin to Telstar by subjecting
it to artificial radiation sources, and were able to get it to fail in
the same way. The problem was traced to a single transistor in the satellites
command decoder. Excess charge had accumulated at one of the gates of
the transistor, and the remedy was to simply turn of the satellite for
a few seconds so the charge could dissipate. This, in fact, did work,
and the satellite was brought back into operation in January, 1963. The
source of this information was not some obscure technical report, or an
anecdote casually dropped in a conversation. This example of energetic
particles in space causing a satellite outage was so uncontroversial at
that time, it appeared under the heading 'Telstar' in the 1963 edition
of the World Book Encyclopedia's 1963 Yearbook.
This $415 million Japanese research satellite failed to reach its intended
geosynchronous orbit, and radiation from the van Allen Belts quickly eroded
the solar panel power levels causing the satellite to fail within one
year. The 98-foot solar panel had produced 5800 watts on t he day of deployment,
September 3, 1994, but after 10 days the levels were 5300 watts and by
the end of September 4700 watts, and by the end of the year the levels
would be near 2700 watts, which was too low to operate the satellite.
not technically in a MEO orbit, its 315 x 22,300 km elliptical orbit covers
most of MEO space. This astronomy research satellite failed on August
15, 1993 after three years of service. In June 1993, the satellite suffered
difficulties in communication between ground stations and the flight computer.
The cause of the problem was attributed to radiation damage to certain
components. Attempts to restart operations proved unsuccessful so the
mission was terminated.
Orbits (GEO) at 22,300 miles are unique in that, as Arthur C. Clarke
predicted in the 1940's, satellites positioned there will orbit Earth
once every 24-hours and appear to be 'stationary' above the surface.
Communications satellites are by far the most common and financially lucrative
satellites found in GEO orbits, along with military and civilian weather
satellites and satellites designed for espionage. The median age of GEO
satellites in 2004 is 9 years. Most satellites have a design life of 10-15
years, so nearly half of the known GEO satellites are already older than
their designed lifetimes.An extensive list of operating communication
satellites is found at LyngSat.com
and in Eric Johnson's 2004 tabulation. Some
famous examples that have has space weather problems are:
The new solar cell design on this satellite would be wired to produce
60 volts per module to keep the weight and size of the solar panels within
the limits set by the cost of the satellite. One of these panels, incidentally,
could comfortably supply the needs of a medium-sized house. But the Tempo-2
failure on April 11, 1997 uncovered a potentially fatal problem with these
new panels. They were susceptible to energetic particle impacts, which
caused miniature lightning bolts to flare-up and short circuit sections
of the panels.
much-publicised failure of this $200 million communication satellite is
widely acknowledged to have been caused by a massive solar storm that
disturbed the magnetosphere beginning on January 9, 1997 and ending with
the satellites failure on January 13th. This outage affected the $712
million sale of AT&Ts Skynet telecommunications resources to Loral
Space and Communications Ltd.
$55 million weather satellite loses half of its 10-year mission lifetime
from a single solar flare in March 1989. During an intense period of solar
flares from March 22-24, 1991, the solar panels were degraded so that
the satellite lost 2-3 years of planned lifetime from this one event alone.
15-16, 1989 - a powerful solar flare caused half of the GEOS-6 telemetry
circuits to fail immediately.
- On October 19, 1989 a powerful solar flare damaged the solar array electronics
and caused a 0.5 ampere decrease in solar panel output. Ten SEUs were
recorded in 1989, of which six were associated with solar flares.
- On March 13, 1989 the satellite experienced excessive x-axis gyro speeds
due to 'magnetic momentum unloading' that caused the roll / yaw coil to
switch to backup mode. Operators suspected the anomaly was caused by a
solar storm. On October 1, 1989 a 28-volt power switch indicated an undesired
'on' setting that required controllers to reset it. They suspected a solar
storm was the cause.
- High solar activity in mid-March 1989 caused unusual momentum wheel
activity that caused the roll / yaw coil to switch to backup mode. Operators
suspected the anomaly was caused by a solar storm - similar to the problems
January 20, 1994 at 12:40 PM the Canadian communication satellite began
to roll end-over-end uncontrollably. The Canadian Press was unable to
deliver news to over 100 newspapers and 450 radio stations for the rest
of the day, but was able to use the Internet as an emergency back-up.
Telephone users in 40 northern Canadian communities were left without
service. It took over seven hours for Telesat Canada's engineers to correct
Anik E1's pointing problems using a back-up momentum wheel system. Telesat
Canada publicly acknowledged the cause-and-effect relationship between
space weather and the satellite malfunction in press releases and news
conferences following the outage. They also admitted that the Anik space
weather disturbance which had ultimately cost their company nearly $5
million to fix, was consistent with past spacecraft-affecting events they
had noticed and that very similar problems had also bedeviled the Anik-B
satellite 15 years earlier.
- January 20, 1994 at 9:10 PM, the Anik E2 satellite's momentum wheel
system failed, but its backup system also failed, so the satellite continued
to spin slowly, rendering it useless. This time, 3.6 million Canadians
were affected as their major TV satellite went out of service. Popular
programs such as MuchMusic, TSN and the Weather Channel were knocked off
the air for three hours while engineers rerouted the services to Anik
E1. For many months, Telesat Canada wrestled with the enormous problem
of trying to re-establish control of Anik E2. They were not about to scrap
a $300 million satellite without putting up a fight. After five months
of hard work, they were at last able to regain control of Anik E2 4 on
21 June 1994. The bad news is that, instead of relying on the satellite's
now useless pointing system, they would send commands up to the satellite
to fire its thrusters every minute or so to keep it properly pointed.
Telesat Canada publicly acknowledged the cause-and-effect relationship
between space weather and the satellite malfunction in press releases
and news conferences following the outages. They also admitted that the
Anik space weather disturbance which had ultimately cost their company
nearly $5 million to fix, was consistent with past spacecraft-affecting
events they had noticed and that very similar problems had also bedeviled
the Anik-B satellite 15 years earlier.
first satellite in the NASA, Tracking and Data Relay Satellite System
was launched in April 1983, and from that time onwards, the satellite
has been continuously affected by soft SEUs. The satellite anomalies affected
the spacecraft's Attitude Control System, and like mosquitoes on a warm
day, they remain a constant problem today. The SEUs have been traced to
changes in the computer's RAM, and the most serious of these SEUs were
considered mission-threatening. If left uncorrected, they could lead to
the satellite tumbling out of control. Ground controllers have to constantly
keep watch on the satellite's systems to make certain it keeps its antennas
pointed in the right direction. This has become such an onerous task that
one of the ground controllers, the late Don Vinson, once quipped, "If
this [the repeated SEU's] keeps up, TDRS will have to be equipped with
a joystick" The
problems with TDRSS-1 quickly forced NASA to redesign the next satellites
in the series, TDRSS-3 and 4 (TDRSS-2 was lost in the Challenger accident),
and the solution was fortunately very simple. In engineering-speak, "The
Fairchild static, bi-polar 93L422 RAMS were swapped for a radiation-hardened
RCA CMM5114 device based on a different semiconductor technology".
began to wobble on January 20, 1994, and experienced a short outage of
service. The satellite had experienced an electrostatic discharge presumably
caused by a space weather event which had started in January 13th. The
discharge disabled the momentum wheel control circuitry on the satellite
causing it to wobble and produce antenna pointing fluctuations in coverage
on the ground. A backup system was turned on and the satellite resumed
operation the same day. The Intelsat-K and the Anik E1 and E2 satellites
are of the same satellite design. The crucial difference however, is that
the Intelsat Corporation specifically modifies its satellites to survive
electrostatic disturbances including solar storms and cosmic rays. This
allowed the Intelsat-K satellite to recover quickly following the storms
that disabled the unmodified Anik satellites.
During a period of intense solar activity, this satellite suffered severe
damage to its solar panels which led to satellite failure on March 25,
- February 8, 1986 - After a large 18-hour magnetic storm, the satellite's
electromagnetic torquing coils were upset by the Earth's changing magnetic
field, and position errors were generated instead of being automatically
corrected by the onboard attitude system. Thrusters had to me manually
used by ground controllers to maintain the satellite's orientation.
- On February 22, 1994 the satellite suffered a 60-minute telemetry outage
because of an electrostatic discharge.
This Japanese geostationary meteorology satellite experienced electrostatic
discharges in January and July 1991 which caused the Visible-Infrared
Spin Scan Radiometer to enter an unscheduled gain setting.
- Between March-June 1987, this satellite experienced 5 deep dielectric
charging events that resulted in low-level logic anomalies.
Experienced 33 electrostatic discharges that led to anomalous phantom
commands between May 1986 and June 1990, and that affected the attitude
- On March 15, 1985 this satellite lost power, attitude control and gyros
soon after launch which forced controllers to employ manual station-keeping,
but on June 1, 1986 an electrostatic discharge caused loss of Earth lock
and the satellite was designated an orbital 'spare'.
June 2, 1973 the satellite failed because a high-energy discharge caused
by spacecraft charging from a magnetic storm had caused a sudden power
failure. This event caused a joint NASA Air Force investigation of spacecraft
charging to evaluate and understand its causes.
Relay Test Satellite (DRTS)
- On October 28, 2003 at 18:42 UT just after a powerful X17 solar flare,
the satellite entered 'safety mode' and shut down all non-critical operations.
The satellite was recovered on November 7, 2003.
September 29, 1989, a powerful X-ray flare caused power panel and star
tracker upsets on NASA's Magellan spacecraft enroute to Venus.
- On December 20, 1998 the spacecraft was just beginning a crucial 20-minute
burn of its thruster to ease it gently into orbit around the asteroid
Eros. The thrusters were turned on by the satellite following a pre-recorded
set of instructions, but suddenly the spacecraft aborted its firing. For
27 hours, the satellite refused to speak to Earth until ground controllers
finally got a weak reply from it. They quickly uploaded commands for NEAR
to take as many pictures as it could as it hurled past Eros. Why had the
carefully planned rocket firing gone awry in mid-execution? By June 1999
engineers had run numerous tests using identical computers and software,
but were unable to reproduce the glitch. A similar thruster firing had
to be commanded exactly on January 3, 1999 so that NEAR could return for
a second orbit insertion try in February 14, 2000. This time there was