This presentation reviews the effects of space weather on satellites and gives tips and tricks of how to better design them

1. Space Environmental
Hazards
Effects of Space
Weather
Meidad Pariente

2. Space Environment Effects on
Satellites – Short Brief
• The environment in space has
significant effect on satellites. The
discussion below highlights the
principal effects experienced by
satellites.
• Satellite Charging/ Deep Charging
• Satellite Discharging
• Hardware damage
• Electric problems

3. Satellite Charging
• Satellite charging is a variation in
the electrostatic potential of a
satellite with respect to the
surrounding low density plasma
around the satellite or to another
part of the satellite.
• The extent of the charging depends
on both design and orbit.
• The two primary mechanisms

4. Deep Charging
• Deep charging of a satellite occurs
when cosmic ray particles pass
through a satellite and ionize atoms
within, through collisions.
• Some of these particles are solar in
origin, but the majority are galactic
and with no preference to time or
light conditions.
• They do show some dependence on

5. Satellite Discharging
• The satellites most vulnerable to
charging/discharging are those
located at geosynchronous altitude.
Discharges as high as 20,000 volts
(V) have been experienced.
• Satellites in geosynchronous orbits
typically move both in and out of
the upper regions of the Van Allen
Radiation Belts and the Earth's

6. Hardware Damage
• Sudden electrostatic discharge
(high current or arc) can cause
hardware damage, such as:
• Blown fuses or exploded transistors,
capacitors and other electronic
components
• Vaporized metal parts
• Structural damage
• Breakdown of thermal coatings

7. Electric Problems
• These discharges can result in
electrical or electronic problems,
such as:
• False commands
• On/Off circuit switching
• Memory changes
• Solar cell degradation
• Degradation of optical sensors

8. Particle Collision
• High energy solar flare particles and
galactic cosmic rays can cause
direct damage to the surface of a
satellite. The damage can include
vaporization of surface materials
and structural damage. These
particles can also enter star or
horizon sensors and mimic
reference points.

9. Space Environmental
Hazards
Anomalies Space
Weather

10. Sun Index
• Two of the most used space weather
index are
• Smoothed Sunspot Number (SSN)
Geomagnetic Planetary Geomagnetic „Acrivity‟
• Solar „Acrivity‟ K Index (Kp) or
SSNA Index (Ap)Level Kp Ap Level
>250 Extreme 7-9 >100 Severe Storm
150-250 Very High 6 50-99 Major Storm
80-150 High 5 30-49 Minor Storm
40-80 Moderate 4 16-29 Active
20-40 Low 3 8-15 Unsettled
0-20 Very Low 0-2 0-7 Quiet

11. Geomagnetic Disturbances
• The disturbance of the geomagnetic
field may be measured by an a
magnetometer.
• Several magnetometer data from
dozens of observatories in one minute
intervals are potentially available.
• The data is tracked in „real-time‟ and
allows to monitor the current state of
the geomagnetic conditions.

12. Spacequake – A Magnetic Shock
wave

13. Kp and NOAA G-scale
Kp Index NOAA Space
Weather Scale
Geomagnetic
Storm Level
Kp <= 4 G0
Kp = 5 G1
Kp = 6 G2
Kp = 7 G3
Kp = storm Weather Prediction Center
Kp of 0 to 4 is below
8
NOAA Space G4

14. NOAA Space Weather Scale for
Geomangetic Storm
Physic Average
Sc Descri al Frequency
Effect to Spacecraft Operations
ale ptor Measur (1 cycle = 11
e years)
may experience extensive surface 4 per cycle
Extrem
G5 charging, problems with orientation, Kp=9 (4 days per
e
uplink/downlink and tracking satellites. cycle)
may experience surface charging and 100 per cycle
G4 Severe tracking problems, corrections may be Kp=8 (60 days per
needed for orientation problems cycle)
surface charging may occur on
satellite components, drag may 200 per cycle
G3 Strong increase on low-Earth-orbit satellites, Kp=7 (130 days per
and corrections may be needed for cycle)
orientation problems.
corrective actions to orientation may

15. NOAA Space Weather Scale for
Solar Radiation Storm Average
Sc Descr Physical Frequency
Effect to Spacecraft Operations
ale iptor Measure (1 cycle = 11
years)
Flux Number of
Level of storm events
>=10Me when Kp level
Solar Radiation Storm
V was met;
particles (number of
(ions) storm days)
satellites may be rendered useless, memory
impacts can cause loss of control, may cause
Extre Fewer than 1
S5 serious noise in image data, star-trackers may 105
me per cycle
be unable to locate sources; permanent
damage to solar panels possible.
may experience memory device problems and
noise on imaging systems; star-tracker 3 per cycle
S4 Severe 104
problems may cause orientation problems, and
solar panel efficiency can be degraded

16. Geomagnetic Activity
vs
Number of Recorded Anomalies
(April 2010)

17. Space Environmental
Hazards
The Systems
Engineer POV

18. Designing a Robust satellite –
Good Engineering Practice
• Environmental Testing is not
enough !
• Glitches, Faulty hardware and
computer mishaps due to
environmental conditions must be
considered and anticipated.
• Satellites should be fully automatic
for as long as possible (no less than
48 hours)

19. Designing a Robust satellite – Tips
and Tricks
• Check, check and than double check
your system logic for dead ends.
• If you have such a single point
failure it will surly occur, hence
protect the satellites with timeouts
• Whenever possible perform sanity
checks, especially regarding crucial
data
• Critical system parameters should

20. Hardware Protection
• Exterior surface of satellite is
exposed to charging and
overcharging, especially when using
ion thrusters, hence protection
measured should be implemented
on the outer surface as well
• Listen to weather reports ! When a
storm is approaching shut down all
redundant units, and keep only

21. The Galaxy-15 Case Study
• 5/4/2010 – Contact with Galaxy-15 Lost
• Galaxy-15 team was unable to switch the
payload off, hence causing interference to other
satellites, enforcing evasive maneuvers and
exposed to claims.
• 23/10/2010 – Satellite reboot after battery
drain
• Satellite enters safe mode after six months of
eastward drift
• Currently – at 121ºW (originally 133ºW and
drifted until 93ºW) used as a relay station for
GPS signals

22. Conclusions
• Anomaly trend proved to be correlated
with geomagnetic activity.
• Most of current satellite designs proved
to be resilient to experienced
geomagnetic activity.
• Still catastophric events happen during
peak events.
• Galaxy 15 events to be investigated to
carefully verify repeatabilty.