# Presentation: 372552

## The Solar Wind:ACE, Ulysses, Genesis, STEREO

- Ruth Skoug
- LASSO Workshop
- July 2008

- Ulysses

**Notes:**
Our research group at LANL involved in NASA missions to study the solar wind.

## The Solar Wind

- In the19th century, associations were made between
- Solar flares (visible)
- Magnetic storms and aurora
- Implies there is something between the Sun and the Earth which transfers solar energy to the Earth (and other planets)
- 1930s – Chapman & Ferraro postulate that geomagnetic storms are caused by solar wind plasma
- But think that the solar wind is intermittent
- Evidence for continuous solar wind from comet tails (1950s)

**Notes:**
1859 Lord Carrington observing sunspots observed a Flare.
Must have been a whopper.  Common flares are not visible.  
17 hours later a magnetic storm was observed - intense, as well as unusual aurora. 
“One swallow does not make a summer”
Lots of attention because we had one in October 2003.
Gradually, associated became clearer - 
Something travels from sun to earth.

## Comet Hale-Bopp 

**Comet Hale-Bopp**
- http://www.solarviews.com/eng/comet.htm
- (Courtesy John Laborde)
- This image of comet Hale-Bopp was taken by John Laborde with his home designed and built, 8.8" f/3.7 Wright Schmidt Camera. The picture was taken at the Tierra Del Sol Observatory site in San Diego County with a 25 minute exposure on Kodak PPF400 film.

## Comet West (1975) 

**Comet West (1975) **
- http://www.solarviews.com/eng/comet.htm
- This photograph was taken by amateur astronomer John Loborde on March 9, 1976. This picture shows two distinct tails. The thin blue plasma tail is made up of gases and the broad white tail is made up of microscopic dust particles. (Courtesy John Laborde)

## Ion tail

- http://www.solarviews.com/eng/comet.htm

- Solar wind pressure.
- Always points away from the sun.
- Ions “picked up” by solar wind.
- Dust tail and hydrogen envelope
- Light pressure.
- Material on lagging orbits.

**Notes:**
Ion tail - Solar Wind - is a highly ionized gas, a plasma.  Every ion has an electric charge.  Electrons carried along to keep neutral.
In the presence of this flowing plasma, charged particles cannot sit still.
They get swept up.
Ion tails always point away from the sun! 
Neutrals don’t see that.
BUT light pressure slowly pushes the dust back.  Particles begin to lag.
(Shuttle orbits at 100 miles in 90 minutes.  Moon orbits at 28 days at 200000 miles.

## The Solar Wind

- 1958: Parker develops a theoretical model of a continuous solar wind
- Corona is so hot that particles are not gravitationally bound
- First direct observation from spacecraft by Mariner 2 (1962)
- Shows a continuous solar wind

- From Neugebauer & Snyder, 1966

**Notes:**
1859 Lord Carrington observing sunspots observed a Flare.
Must have been a whopper.  Common flares are not visible.  
17 hours later a magnetic storm was observed - intense, as well as unusual aurora. 
“One swallow does not make a summer”
Lots of attention because we had one in October 2003.
Gradually, associated became clearer - 
Something travels from sun to earth.

## Eclipse 7/11/1991 From Mauna Kea

_**Eclipse 7/11/1991 From Mauna Kea**_

- http://antwrp.gsfc.nasa.gov/apod/ap990716.html

**Notes:**
Solar wind is the boiled off outer atmosphere of the sun.
Corona - is visible during solar eclipse in white light.
From space, coronagraph cn occult the sun with a disk.
Note Helmut streamers.
Radial feathers of light.  

## The Solar Wind

-  Photosphere:  *the visible sun*.  5800 K
-  Corona: *visible during solar eclipse*.  1,000,000 K
-  Local Interstellar Medium: 10,000 K
-  The corona expands naturally because of
* *High pressure in corona
-  Low pressure in interstellar medium
-  The solar corona expanding into space is called the solar wind
-  Spacecraft have measured solar wind beyond Pluto
-  Voyager 1 & 2 have crossed the “termination shock” and entered the heliosheath

**Notes:**
Start at the sun.
Photosphere - visible surface, 5800 K
Compare: 1400 red-hot iron,  3900 K light bulb filament.
Corona at a million degrees:
	1869 - coronium - a bright green wavelength line not identified
	1940 - shown to be a line of Fe +13 (of 26)
Why a solar wind?  The corona must expand!  But it expands into a near vacuum - so it becomes supersonic. 
Once it has escaped, how far does it travel?

## The Solar Wind

- Flow of ionized plasma from the Sun
- Extension of the solar corona
- ~95% H, 5% He
- Speed range 200–1000 km/s
- average 400 km/s (≈ a million miles/hour!)
- Density: <1–100 particles/cc
- average 7 particles/cc
- Carries a weak magnetic field
- ≈5 nT (≈1/10,000 of Earth’s field)

**Notes:**
Plasma flow out from the sun.
Fast!  4 days from sun to earth (light is 8 minutes).
Big event in October - less than a day!
(Think of the kinetic energy - goes as the speed squared - 
Teenage drivers should know this).
Density - Not Much at 1 AU.
Falls off as 1/r^2 light the intesity of light from a bulb.

Carries a magnetic field with it!
Like a superconductor - the field is locked in.  
Commonly think of rigid fields.  
But the “fluid” is the electric gas.  The field is locked in to it.
If the fluid moves, the field is carried with it.
This it a new idea for you?

## The Solar Wind

- The solar wind varies on many time scales
- Years
- 11 year solar cycle
- Days - hours
- fast streams
- slow streams
- coronal mass ejections (CMEs)
- Hours - seconds
- waves
- shocks
- interactions

**Notes:**
1859 Lord Carrington observing sunspots observed a Flare.
Must have been a whopper.  Common flares are not visible.  
17 hours later a magnetic storm was observed - intense, as well as unusual aurora. 
“One swallow does not make a summer”
Lots of attention because we had one in October 2003.
Gradually, associated became clearer - 
Something travels from sun to earth.

## Spiral magnetic fields:

- http://www-istp.gsfc.nasa.gov/istp/outreach/theretohere.html

- The Garden Sprinkler effect

**Notes:**
This is important - the large scale magnetic field of the sun, extended out into space, is like a spiral.  
The sun itself rotates every 27 days as seen from Earth.
The field remains connected roughly to one point on the sun.
What direction is the flow?  Radial.
Result?  Spiral field.

## Smooth Spiral is only an average.

- Real data ... local interplanetary field measured by a spacecraft shows fluctuations

## Solar Wind Types

- Different origins, composition, speeds, etc.
- Fast solar wind
- > 500 km/s
- From coronal holes
- Major type at the poles
- Slow solar wind
- < 500 km/s
- Major type in the ecliptic
- Coronal mass ejections
- Transient events, can have high or low speed
- Distinguished by shock waves, low temperatures, enhanced alpha particle densities, bi-directional electron beams
- Responsible for most large geomagnetic storms

## Jan 8, 2002

- Feb 3, 2002

- Mar 2, 2002

**SOHO EIT 284 Å**

- EIT images courtesy of the SOHO EIT team
- http://sohowww.nascom.nasa.gov/

- Solar rotation 27 days

**Notes:**
Sun in x-ray wavelengths - sees the 1-2 million degree plasma.
Cooler regions (not emitting in x-ray) are called coronal holes.
Note lack of obvious closed magnetic loops at the sun.
Fast wind apparently comes from these regions.
See speed measured by Genesis.
See structure is repeated - as sun rotates.

## Coronal Mass Ejection

**Notes:**
If coronal holes are steady sources of solar wind,
Coronal Mass ejections are transient explosive blasts of plasma.
(Might not be a surprise that Los Alamos has been expert on these).
This is a sequence from SMM satellite around 1980.
See the Helmut streamer.
See the closed loops grow outward and expand. 
Cavity behind.  Finally, ragged stuff from bright core.
Classic 3 part structure - bright outer loop, cavity, bright core.

How about the ones coming toward us?!?

## Los Alamos Solar Wind Detectors

## Electrostatic Analyzer for Detecting Charged Particles

- (Curved Plate Analyzer)

## Electrostatic Analyzer for Detecting Charged Particles

- (Curved Plate Analyzer)

## Electrostatic Analyzer for Detecting Charged Particles

- (Curved Plate Analyzer)

- Particles with slightly less energy
- Still make it through

- Particles with slightly more energy
- Still make it through

- For a fixed voltage on the analyzer plates, particles are accepted over a range of energies
- ∆E.

## Electrostatic Analyzer for Detecting Charged Particles

- (Curved Plate Analyzer)

- Electrostatic analyzers have an energy-angle skewing.  Detector designers try to minimize this.

## Solar Wind Measurements

- LANL designs and builds electrostatic analyzers to measure ions and electrons
- Have flown on many spacecraft
- Vela, IMP, ISEE, Ulysses, ACE, Genesis
- Collaborations with SNL, JPL

- Ion detector

- Electron detector

## Ion Detectors

_**Ion Detectors**_
- Solar wind ions come from a narrow range of angles.
- Consider the flow direction, and the thermal spread.

- Genesis Ion Monitor (GIM)

## Slide 23

## Electron Detectors

_**Electron Detectors**_
- Solar wind electrons come from all directions in space!

- Ulysses, ACE, Genesis electron monitors

## Slide 25

## ions

- electrons

- Arrow gives spacecraft spin axis, which roughly points to the Sun

## E = Vo/Dgap

- E = Vo/Dgap

*Force on a charge *q* in an electric field* E is*:*
- F = q E

*Acceleration for an object in uniform circular motion **(**v is speed) : *a = v2/R

*Newtons 2nd law:*
- F = ma

- F = qVo/Dgap = mv2/R
*Solve for V**o*
- Vo = (Dgap mv2)/(qR)
- Vo = 2 (Dgap/R)(mv2 /2)/q
-  Energy/Charge!

*Kinetic Energy of motion:*
- Ke = mv2 /2

- Our detectors don’t select particles by *Energy*,
- they select by *Energy/Charge*

## Vo = 2 (Dgap/R)(mv2 /2)/q

- Solar Wind is 95% H+ and 5% He++
- He++ has 4 times the mass of H+
- He++ has 2 times the charge of H+
- If both H+ and He++ move at the same speed v,
- then He++ has *2 times* the Energy/Charge

## Genesis Ion Monitor Data

**Protons   alphas**

- 1     2  3 45 (keV)

## Genesis Ion Monitor Data

## Solar Wind Data

- _Solar Wind Data_

- Proton Density

- He/H Density Ratio

- Proton Temperature

- Solar Wind Speed

- Suprathermal electron “pitch angle” distribution

## Advanced Composition Explorer (ACE)

- Designed to measure elemental, isotopic, and charge state composition of solar system material
- LANL provided plasma instrument
- Launched in August, 1997
- Halo orbit about the L1 point
- Approximately 1 hour upstream of the Earth
- Continuous real-time solar wind monitor

## Advanced Composition Explorer (ACE)

##  ACE provides real time solar wind observations

-  ACE provides real time solar wind observations
-  ~ One hour warning for Earth-directed events

## Unusually high speed solar wind -- October 2003

## Unusually high speed solar wind -- October 2003

##  Suprathermal electrons move through the solar wind

-  Suprathermal electrons move through the solar wind
-  100 – 1000 eV
-  Typically aligned with the magnetic field direction
-  Plot shows “pitch angle”, which is the angle between the magnetic field direction and the particle travel direction

**Notes:**
Red is more particles, blue is fewer.
Each panel is different energy.
Vertical scale is direction relative to the magnetic field at the spacecraft.
Electrons stream away from the sun along the field.

## Electrons at 100 eV - 1000 eV move through

- the solar wind

- Transient Solar Burst:
- Time of arrival is delayed for slower particles

## Genesis – Solar Wind Sample Return

- Place a spacecraft in the solar wind
- Expose ultra-pure materials to collect solar wind (2 years)
- Use LANL ion and electron monitors and logic to characterize solar wind in real time and deploy appropriate collectors
- Return embedded solar wind samples to Earth
- Analyze samples with state-of-the-art laboratory equipment

-  Launched: August, 2001
-  Returned to Earth: Sept 2004

## GENESIS: A NASA DISCOVERY MISSION to:

*Expose nearly 3 m**2** of collector materials to the solar wind*
*And return samples to Earth for analysis *
-  Materials include:
- Ultrapure Si, Ge, CVD diamond, and Al & Au on sapphire.
-  Collectors assembled in a class 10 cleanroom.
-  Analysis of returned samples will be done by mass spectrometry:
- AMS, SIMS, RIMS, and neutron activation analysis.
- Key Measurement objectives:
- 17O/16O, 18O/16O to an accuracy of 0.1%,
- 15N/14N, 13C/12C, noble gas isotope ratios,
- 14C, Li, Be, B composition,
- Other heavier element and
- isotope abundances.

- Photo courtesy JSC, JPL.

**Notes:**
CVD = Chemical Vapor Deposit
SIMS = Secondary Ion Mass Spectrometry
RIMS = Resonant Ion Mass Spectrometry
AMS = Accelerator Mass Spectrometry - ionize the material and accelerater through a foil to eliminate moleculars.

## Launch 			  	August 8, 2001

**Launch ****	****	****	****  ****	****August 8, 2001**
**L1 Orbit Insertion ****	****	****November 16, 2001**
**Begin Solar Wind Collection    ****	****December 3, 2001**

## Genesis Solar Wind Concentrator

- _Genesis Solar Wind Concentrator_

- Increases solar wind fluence by a factor of ~20
- Uses a large electrostatic mirror
- H+ rejection controlled by ion monitor
- Improves measurement of oxygen isotopes
- Unique instrument!
- Designed and built at LANL

## Genesis Autonomous Solar Wind Identification

## Genesis Regime Selection Example

## Ulysses

- First observations of the solar wind out of the ecliptic plane, over the poles of the Sun
- Heliographic latitudes of 0–80 ̊
- Study differences between fast and slow solar wind
- Determine latitudinal and radial dependence of solar wind
- LANL provided plasma instrument
- Launched in 1990
- Observations over a complete solar cycle
- Currently in 3rd solar orbit

- _Ulysses_

## Solar Wind Speed Over the Poles – Ulysses

- [McComas et al., 1998]

## Solar Cycle

## Solar Min vs. Solar Max – Ulysses

- McComas, D. J., et al., 2001

## Solar Min vs. Solar Max – Ulysses

- McComas et al., Geophys. Res. Lett., 27, 2437, 2000

## Solar Cycle

## Solar Cycle

## STEREO

- Solar TErestrial RElations Observatory
- Two nearly identical satellites
- One ahead of Earth in its orbit
- One trailing behind Earth in its orbit

**Notes:**
1859 Lord Carrington observing sunspots observed a Flare.
Must have been a whopper.  Common flares are not visible.  
17 hours later a magnetic storm was observed - intense, as well as unusual aurora. 
“One swallow does not make a summer”
Lots of attention because we had one in October 2003.
Gradually, associated became clearer - 
Something travels from sun to earth.

## STEREO

- Provide the first-ever stereoscopic measurements to study the Sun and the nature of coronal mass ejections (CMEs)
- Scientific Objectives** **
- Understand the causes and mechanisms of CME initiation
- Characterize the propagation of CMEs through the heliosphere
- Discover the mechanisms and sites of energetic particle acceleration in the low corona and the interplanetary medium
- Improve the determination of the structure of the ambient solar wind
- Launched Oct 25, 2006

**Notes:**
1859 Lord Carrington observing sunspots observed a Flare.
Must have been a whopper.  Common flares are not visible.  
17 hours later a magnetic storm was observed - intense, as well as unusual aurora. 
“One swallow does not make a summer”
Lots of attention because we had one in October 2003.
Gradually, associated became clearer - 
Something travels from sun to earth.

## STEREO Instruments

-  Instruments include:
-  coronagraphs (SECCHI)
-  wave detectors (S/WAVES)
-  magnetometers (IMPACT)
-  enegetic particle detectors (IMPACT)
-  plasma detectors (PLASTIC)

## Artist’s conception of STEREO observing a solar flare

## In-situ STEREO science

## In-situ STEREO science

## STEREO sees the Sun

- EUV “light”
- Orange: 304 Å
- Blue: 171 Å
- Yellow: 284 Å
- Green: 195 Å

## STEREO sees a CME

- Jan 24, 2007

## STEREO sees a solar eclipse

## 3D Coronal Hole

## 3D Active Region

## Summary

- Variations in the Sun and the solar wind can have important impacts on humans and technological systems
- LANL has long been, and continues to be, involved in solar wind measurements
- Designing and building instruments
- Science data analysis
- On-board autonomous algorithms
- Science highlights
- Solar wind variations with latitude
- Study of solar wind evolution from multi-point measurements
- Determination of topology from electron measurements
- CME identification & the possibility of forecasting events

##  ACE provides real time solar wind observations

-  ACE provides real time solar wind observations
-  ~ One hour warning for Earth-directed events