ILWS Workshop, Ubatuba, Brazil, October 2009 The Solar Dynamics Observatory:Waiting for a Launch Solar Cycle 24 W. Dean Pesnell NASA, Goddard Space Flight

ILWS Workshop, Ubatuba, Brazil, October 2009

The Solar Dynamics The Solar Dynamics Observatory:Waiting for Observatory:Waiting for a a

LaunchLaunch Solar Cycle 24 Solar Cycle 24

W. Dean PesnellNASA, Goddard Space Flight Center

SDO Project Scientist

and the SDO Team


The Sun TodayThe Sun Today

EIT Fe XII 195 Å (roughly 1.5 million K)

As we move thru solar minimum the large loops have faded and the coronal holes at the poles and equator are the featured presentation.

At this time in the solar cycle our Space Weather is dominated by the high-speed streams coming from the now-fading equatorial coronal holes.

The shape, location, and magnetic field of coronal holes may help us predict future solar activity.

2009/10/09 01:13

ILWS Workshop, Ubatuba, Brazil, October 2009SIP Workshop, October 2008

Space Weather Covers Many Research Space Weather Covers Many Research AreasAreas


Solar Wind & Magnetic Field

X-rays, EUV, UV, &

Visible

SDO Provides Information About TwoSDO Provides Information About Two


Solar Dynamics Solar Dynamics ObservatoryObservatory

The Solar Dynamics Observatory (SDO) is the first Living With a Star mission. It will study the Sun’s magnetic field, the interior of the Sun, and changes in solar activity. It is designed to be our solar observatory for Solar Cycle 24.

•The primary goal of the SDO mission is to understand, driving towards a predictive capability, the solar variations that influence life on Earth and humanity’s technological systems by determining:

–How the Sun’s magnetic field is generated and structured

–How this stored magnetic energy is converted and released into the heliosphere and geospace in the form of solar wind, energetic particles, and variations in the solar irradiance.


The SDO SpacecraftThe SDO Spacecraft

The total mass of the spacecraft at launch is 3200 kg (payload 270 kg; fuel 1400 kg).

Its overall length along the sun-pointing axis is 4.5 m, and each side is 2.22 m.

The span of the extended solar panels is 6.25 m.

Total available power is 1450 W from 6.5 m2 of solar arrays (efficiency of 16%).

The high-gain antennas rotate once each orbit to follow the Earth.

Launch is planned on an Atlas V EELV

SDO will be placed into an inclined geosynchronous orbit ~36,000 km (21,000 mi) over New Mexico for a 5-year mission


Helioseismic & Magnetic Helioseismic & Magnetic Imager (HMI)Imager (HMI)

• Built at Stanford University and Lockheed Martin in Palo Alto, CA

• Uses bi-refringent materials as spectral filter• Two 4096 x 4096 CCDs• 72,000 Images each day become

– 1800 Dopplergrams each day• Oscillations• Local Analysis• Internal velocities

– 1800 Longitudinal magnetograms daily– 150 Vector magnetograms daily

HMI and AIA will use six 4096 x 4096 CCDs built by e2v in England.


HMI DopplergramsHMI Dopplergrams


QuickTime™ and aGIF decompressor

are needed to see this picture.

Global HelioseismologyGlobal HelioseismologyWaves on a sphere are described by the spherical harmonics, familiar from quantum mechanics.

Here are some examples. The projected brightness change is plotted for a pulsation velocity of 100 km/s, rotation velocity of 5 km/s, and an inclination of 80º.


Virgo

Global HelioseismologyGlobal HelioseismologyComparing the measured low-l frequencies with those from a model gives a better 1-D model of the Sun and stars:

Waves sound speed temperature + hydrostatic eq. density

This yields a spherical model.


Virgo

Global HelioseismologyGlobal HelioseismologyComparing the measured low-l frequencies with those from a model gives a better 1-D model of the Sun:

Waves sound speed temperature + hydrostatic eq. density

This yields a spherical model.

But that is

so 20th century!

But that is

so 20th century!


An Ultrasound of the SunAn Ultrasound of the SunHelioseismology compares how sound travels between different parts of the Sun to see into and through the Sun.

Right: Farside images show the active regions that launched the

largest flares ever measured. We can see them on our side at top,

behind the Sun two weeks later in the middle and visible from Earth

two weeks later at the bottom.

Earthside

Farside

Above: Bands of faster rotating material (jet streams) appear to determine when and where sunspots appear (GONG and MDI).


Seeing Magnetic FieldsSeeing Magnetic Fields

SOHO/MDI January 14, 2004

Below: Magnetic mage of the Sun from SOHO/MDI shows active regions as light and dark points.

P

Upper right: One ‘day’ in the life of the Sun’s magnetic field (January 2004.) Lines join the same active regions in different views.

Lower right: Three sunspot cycles of the Sun’s magnetic field (Solar Cycles 21, 22, and 23.) SC2

1 2223


EUV Variability ExperimentEUV Variability Experiment• EVE is the Extreme ultraviolet Variability

Experiment• Built by the Laboratory for Atmospheric

and Space Physics at the University of Colorado in Boulder, CO

• EVE uses gratings to disperse the light• Data will include

– Spectral irradiance of the Sun• Wavelength coverage 0.1-105 nm

and Lyman • Full spectrum every 10 s

– Space weather indices from photodiodes

– Information needed to drive models of the ionosphere

– Cause of this radiation– Effects on planetary atmospheres


EVE Data & ResearchEVE Data & Research• One spectrum every 10 seconds is the

primary product• Driver of real-time models of the upper

atmosphere of the Earth and other planets• Identify sources of EUV irradiance (with AIA)• Predict the future of EUV irradiance (with

HMI)

Below (left): Example EVE spectrum. Some of the lines are identified and where the lines are formed in the solar atmosphere is noted at the top.

(right) Absorption of radiation as it enters the Earth’s atmosphere. Red areas are altitudes that do not absorb a wavelength, black means complete absorption. The layers of the atmosphere are also listed. All of the radiation measured by EVE is absorbed above 75 km, most above 100 km.

EVE


Atmospheric Imaging Atmospheric Imaging AssemblyAssembly

• AIA is the Atmospheric Imaging Assembly• Built at Lockheed Martin Solar and Astrophysics

Laboratory in Palo Alto, CA• Four telescopes with cascaded multi-layer interference

filters to select the required wavelength– Filters are at 94, 131, 171, 193, 211, 304, 335, 1600,

1700, and 4500 Å– 4096 x 4096 CCD

• Data will include– Images of the Sun in 10 wavelengths

• Coronal lines• Chromospheric lines• An image every 10 seconds

– Guide telescope for pointing SDO


AIA TelescopesAIA Telescopes

AIA will resolve features in coronal loops that could be caused by either density or temperature.

AIA observes the coronal plasma over a wide and continuous temperature range with 1.2 arc second spatial resolution and at a 10 second cadence.

A set of Iron (Fe) lines minimizes abundance effects and gives a temperature coverage spanning the lower corona. He II 304 and C IV 1600 lines extend the temperature coverage to the Transition Region and Chromosphere. UV continuum (1700 Å) and white light continuum (4500 Å) complete the set.

He II 304

Fe XVIII 94

UV, WL,

Fe IX/X 171

Fe XIV 211

Fe XII 193

Fe XVI 335

Fe XX/

XXIII 131


AIA DataAIA Data

Fe XV 284

He II 304Fe IX/X 171

Fe XII/XXIV 195

X


AIA ImagesAIA Images• Images of the Sun in 10 bandpasses covering a temperature range of 50,000 K to 3 million K

• Images of the corona and chromosphere

• Eight images every 10 seconds

• 70,000 images a day!

• Each must be scaled in size, rotated, registered to solar center, and calibrated

• Analysis difficulties change with the solar cycle; distinguishing features at min., loops and flares at max.

Six days in December 2006


SDO Data RateSDO Data Rate

• SDO will send an extraordinary amount of data to the ground

• 150 Mbps 24/7 for 5-10 years

• About the same as 500,000 iTunes downloads each day

• Our job is to enable people to search this data and find their study objects

• Data served from http://hmi.stanford.edu


SDO on Ransome TableSDO on Ransome TableSDO became an observatory in January 2008 when the instruments were installed on the spacecraft bus.

Since then the observatory has passed all of the environmental tests (vibration, acoustics, thermal, EMI/EMC) and a series of comprehensive performance tests.

We are in now Florida waiting for launch.

SDO is ready for launch!

HGA


SummarySummary1. Solar activity waxes and wanes with the solar cycle. As the

Sun changes so does its ability to affect spacecraft and society.

2. We are in a golden age of solar physics, with many spacecraft and ground-based solar observatories. NASA has an operational interest in solar physics whenever it flies satellites and astronauts in space.

3. SDO will provide an enormous amount of information about the Sun.

4. SDO is ready for its launch date of February 2010.

5. We would like to thank Solar Cycle 24 for waiting for SDO.


Friend Little SDO on Facebook to follow the Adventures of Camilla the Rubber Chicken as she watches over SDO


• W. Dean Pesnell: [email protected]

• http://sdo.gsfc.nasa.gov

Documents

ILWS Workshop, Ubatuba, Brazil, October 2009 The Solar Dynamics Observatory:Waiting for a Launch Solar Cycle 24 W. Dean Pesnell NASA, Goddard Space Flight