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1. Space Environment
Lecture 13 – Space Weather
Part 2
Professor Hugh Lewis
SESA3038 Space Environment

2. Overview of lecture 13
• In this lecture we remind ourselves of the three main components of space
weather and then we take a brief look at their effects on some of the
spacecraft sent to observe the Sun or to monitor space weather:
– The solar array degradation of SOHO and GOES spacecraft
– Image/sensor noise in SOHO instruments
• We also, very briefly, look at the impacts on humans and on ground-based
infrastructure
– Effects of energetic particle radiation on humans was covered in week 1
• Finally, we consider some of the challenges associated with space weather
forecasting, monitoring and understanding its impacts
Space Environment – Space Weather

3. What is space weather? Space Environment – Space Weather
There are three main components of
space weather:
• Solar Flares
• Solar Energetic Particles
• Coronal Mass Ejections
Where the trajectory of solar activity intersects
with the orbit of Earth there can be detrimental
effects*
Space Weather Preparedness Strategy

4. Impact on space systems Space Environment – Space Weather
Satellite charging/discharging
Variation in electrostatic potential of a satellite
with respect to the surrounding low-density
plasma, or to a different satellite component.
• GEO satellites most vulnerable
• 20,000 V discharges recorded
• Hardware damage:
• Electronics, structure, thermal coatings
• Electrical/electronic problems:
• False commands, on/off circuit switching,
memory changes, solar cell degradation,
optical sensor degradation

5. Impact on space systems Space Environment – Space Weather
Solar array degradation (e.g. GOES):
Flare events of 1989: resulted in an additional 5-10% loss of solar array output at EOL (Marvin &
Gomey, J. Spacecraft, Vol. 28, No. 6, p. 713, 1991)

6. Impact on space systems Space Environment – Space Weather
Solar array
degradation (e.g.
SOHO):
(Overbeek, & Olive, "SOHO, 13
years since launch and still
going strong," 32nd AAS
Guidance and Control
Conference, Breckenridge, CO,
USA, Jan. 31.- Feb. 4, 2009,
AAS 09-032)

7. Impact on space systems Space Environment – Space Weather
Sensor backgrounds & damage (e.g. SOHO):

8. Impact on space systems Space Environment – Space Weather
Single Event
Upsets (e.g.
SOHO):
(From minutes of the 35th
SOHO SWT Meeting, Goddard
Space Flight Center, USA, 24
March 2003)

9. Energy flow Space Environment – Space Weather

10. Impact on humans Space Environment – Space Weather
Geomagnetic storm (G5)
• No impact (visible aurora at low
latitudes)
Solar radiation storm (R5)
• Unavoidable high radiation hazard
to astronauts on EVA
• Radiation risk to passengers and
crew in high-flying aircraft at high
latitudes

11. Impact on industry Space Environment – Space Weather

12. Challenges of space weather events Space Environment – Space Weather
• Forecasting:
• Understanding of physical processes
• Warning time:
• Minutes to days
• Understanding the impacts:
• Complex systems
• Monitoring:
• Earth-based & space-based systems
• Observation of the Sun
• Observation of the Earth’s atmosphere

13. Overview of lectures 12 and 13
• In these lectures we explained what is meant by space weather and
introduced its three main components:
– Solar flares
– Solar energetic particles
– Coronal Mass Ejections
• We established the three NOAA space weather scales used to measure the
magnitude and impacts of space weather:
– Geomagnetic storm scale
– Solar radiation storm scale
– Radio blackout storm scale
• We also looked at examples of the impacts on some spacecraft and briefly
covered impacts on humans and ground-based infrastructure
• Finally, we consider some of the challenges associated with space weather
forecasting, monitoring and understanding its impacts
Space Environment – Space Weather