Space Weather and Space Exploration

1
Space Weather and Space Exploration

• Dr. David H. Hathaway
• NASA/MSFC
• National Space Science and Technology Center
• 2006 July 20

2
Outline

• Space Weather
• What is it and why should we care?
• The Solar Wind
• The Solar Eruptions
• Flares, Prominence Eruptions, Coronal Mass
  Ejections
• The Solar Activity Cycle
• Magnetic Fields
• The Key to Understanding Solar Activity
• Space Weather Related Missions
• Conclusions

3
Space Weather
4
Effects on Satellites
Over 4500 spacecraft anomalies or malfunctions
have been attributed to the space radiation
environment.
5
Effects on Humans
Energetic particles from solar flares can be
hazardous to astronauts beyond the protection of
Earths magnetosphere. Passengers on
trans-Atlantic flights receive the equivalent of
several chest X-rays on each flight during solar
maximum.
6
The Solar Wind
The solar wind streams off of the Sun at speeds
of 400-800 km/s (1-2 Million MPH). The wind
expands through the solar system and doesnt stop
until it reaches the interstellar medium at a
surface about twice as far out as Pluto.
7
Solar ActivityFlares
8
Solar ActivityProminence Eruptions
9
Solar ActivityCoronal Mass Ejections
10
All Together Now The Bastille Day Event 2000
11
Sunspots
Sunspots are cooler, darker regions on the solar
surface where intense magnetic fields emerge from
the deep interior
12
The 11-year Sunspot Cycle
Schwabe, 1844
Each cycle has its own special characteristics
maximum amplitude, length, shape, etc.
13
The Maunder Minimum
During the Maunder Minimum (1645-1715) solar
activity seemed to cease entirely. Predicting the
size of future cycles is extremely important for
satellite (and Space Station) operations.
14
Magnetism is the Key
The Solar Spectrum
The Zeeman Effect
15
Magnetic Fields are Behind all Solar Activity
16
Hales Polarity Law
Hale, 1924
The polarity of the preceding spots in the
northern hemisphere is opposite to the polarity
of the preceding spots in the southern
hemisphere. The polarities reverse from one cycle
to the next.
17
The Suns Magnetic Cycle
18
Polar Field Reversal at Cycle Maximum
Babcock, 1959
The polarity of the polar magnetic fields
reverses at about the time of the solar activity
maximum. (Result of Joys Law Hales Law
Meridional Flow Flux Cancellation across the
equator?)
19
Dikpati Charbonneau Dynamo
20
Magnetic Field and Solar Flares
Flares are likely to occur when the magnetic
field along the neutral line between opposite
polarity regions is sheared or twisted from the
direction given by the potential field. Vector
Magnetograms are needed to determine the presence
of this magnetic shear.
21
Correlations with CMEs
Red gt CME Blue gt no CME
22
Magnetic Models for CMEs
23
Current Missions
Ulysses (ESA/NASA 1990)
SOHO(ESA/NASA 1995)
TRACE (NASA 1998)
RHESSI (NASA 2002)
24
Future Missions
STEREO (NASA -2006/08)
Solar Dynamics Observatory (NASA -2008/04)
Solar-B (Japan/US/UK 2006/09)
25
Conclusions

• Space Weather must be understood and reliably
  predicted for safe and successful space
  exploration
• Additional scientific research is needed to do
  this

http//solarscience.msfc.nasa.gov/