SDO Project Science Team 1

The Science of SDOThe Science of SDO

SDO Project Science Team 2

Sensing the Sun from SpaceSensing the Sun from Space High-resolution Spectroscopy for Helioseismology and Magnetic Fields

Observe ripples and polarization properties on the surface of the Sun

Sound waves require long strings of continuous data to interpret—satellites may have no day/night cycle

Convection zone velocities and magnetic fields require high spatial resolution

Coronal Imaging Observe bright plasma in the corona at ultraviolet wavelengths —can’t be seen from ground

Temperatures of the plasma range from 50,000 K to >3 million K

High spatial resolution to see the detailed interaction of the magnetic field and the plasma

High time resolution is required to see how those features develop

Spectral Irradiance Measure the total energy in narrow wavelength bands

Measure from space to avoid the twinkling and absorption of atmosphere

Essential for models of the ionosphere

Coronagraphs Light scattered from the corona and solar wind

Track material as it exits the Sun and moves through the solar system

Energetic Particles and Fields Point measurements from many platforms to resolve structure

SDO Project Science Team 3

The SDO MissionThe SDO MissionNASA/LWS Cornerstone Solar MissionNASA/LWS Cornerstone Solar Mission NASA and three Instrument Teams are building SDO

NASA/ Goddard Space Flight Center: build spacecraft, integrate the instruments, provide launch and mission operations

Lockheed Martin & Stanford University: AIA & HMI

LASP/University of Colorado: EVE

Launch is planned for August 2008 on an Atlas V EELV from Cape Canaveral

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

Data downlink rate is 150 Mbps, 24 hours/day, 7 days/week (1 CD of data every 36 seconds)

Data is sent to the instrument teams and served to the public from there

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.

Atlas V carries Rainbow 1 into orbit, July 2003.

SDO Project Science Team 4

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.

AIA (1 of 4 telescopes)

EVE (looking at CCD radiator and front)

HMI (looking down from top)

High-gain antennas (1 of 2)

SDO Project Science Team 5

SDO OperationsSDO Operations Mission operations for SDO are at NASA's Goddard Space Flight Center near

Washington, DC. Communications with the spacecraft are via two radio dishes at NASA's site in the White

Sands Missile Range in New Mexico. The main tasks of the controllers are to keep SDO pointing at the Sun, maintain its

inclined geosynchronous orbit, and keep the data flowing. A scientific team, led by NASA and instrument project scientists, plans and executes

programs of observations with SDO’s 3 instruments suites, and analyzes the data. Unique Operations Mode

Few observing modes: turn it on and let the data flow! Raw images are sent to the ground for processing Data is made available soon after downlink; people can use the data in near-real-time Campaigns and collaborations are coordinated where convenient, but the data is always

available

TDRSS antennae in White Sands Missile Range

SDO Project Science Team 6

Helioseismic & Magnetic ImagerHelioseismic & Magnetic Imager

HMI is the Helioseismic and Magnetic Imager

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

Two 4096 x 4096 CCDs Instrument is designed to observe

polarized light to measure the magnetic field

Data will include Doppler velocities

Oscillations Local Analysis

Longitudinal magnetograms Vector magnetograms

SDO Project Science Team 7

HMI Data & ResearchHMI Data & Research

Helioseismology and magnetic field

A high-resolution instrument with high data return

Constrains the convection zone and the interior of Sun

Motions responsible for the solar dynamo are seen

Far-side imaging (see the other side of the Sun)

Longitudinal magnetic field shows the strength of B

Vector magnetic field shows strength and direction of B

The velocities under a sunspot show that material moves toward the spot near the surface and away from the spot lower down. It is important to see small details to study this problem.

Right: Farside images show the active regions that launched the largest flares ever measured. We can see them on our side at top, continuing around the Sun in the middle and re-appearing at the bottom. The middle view is two weeks after the top and the bottom two weeks later.

SDO Project Science Team 8

Atmospheric Imaging AssemblyAtmospheric Imaging Assembly

AIA is the Atmospheric Imaging Assembly

Built at Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, CA

Four telescopes with 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 at each wavelength every 8 seconds

Guide telescope for pointing SDO

SDO Project Science Team 9

AIA Data & ResearchAIA Data & Research

Images of the Sun in eight bandpasses that cover the temperature range 50,000 K to 3 million K

Images of the corona and chromosphere

The dissipation and redistribution of magnetic field

Coronal seismology, understand the magnetic field by the waves generated along a coronal loop

Combined with the magnetic field of HMI, models of the magnetic field throughout the corona

Magnetic field model for September 23, 2004; created from magnetogram data. White lines are loops connecting one part of the Sun to another; green lines are “open”, they do not connect back to the Sun’s surface.

AIA will combine their images with the HMI vector magnetograms to build more accurate models.

SDO Project Science Team 10

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

Data will include Spectral irradiance of the Sun

Wavelength coverage 0.1-105 nm Photodiodes to give activity indices Full spectrum every 20 s

Information needed to drive models of the ionosphere

Cause of this radiation Effects on planetary atmospheres

SDO Project Science Team 11

EVE Data & ResearchEVE Data & Research

One spectrum every 20 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 spectrum from EVE. The elements emitting some of the lines 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.

SDO Project Science Team 12

SDO Project Science Team 13

EVE CutawayEVE Cutaway

SDO Project Science Team 14

SummarySummary

To understand the Sun we must have data that is high-resolution in space (many To understand the Sun we must have data that is high-resolution in space (many pixels), high-resolution in time (many samples), and cover the entire Sun (full-disk)pixels), high-resolution in time (many samples), and cover the entire Sun (full-disk)

Velocities and magnetic field in the photosphereVelocities and magnetic field in the photosphere Extrapolate the field measurements into the chromosphere and coronaExtrapolate the field measurements into the chromosphere and corona High time resolution is needed to study the motions in the coronaHigh time resolution is needed to study the motions in the corona

Space-based measurements can see the ultraviolet radiation that is related to the Space-based measurements can see the ultraviolet radiation that is related to the solar magnetic field but that is absorbed by the atmospheresolar magnetic field but that is absorbed by the atmosphere

Plasma motion and temperature in the coronaPlasma motion and temperature in the corona This radiation creates the ionospheres of the Earth and other planetsThis radiation creates the ionospheres of the Earth and other planets

Space-based instruments do not have the day-night cycle of ground-based Space-based instruments do not have the day-night cycle of ground-based instrumentsinstruments

Helioseismology studies are more accurateHelioseismology studies are more accurate Changes can be tracked with shorter intervals of timeChanges can be tracked with shorter intervals of time

SDO carries three instruments to help us understand and forecast solar activitySDO carries three instruments to help us understand and forecast solar activity HMI: Helioseismology and Magnetic ImagerHMI: Helioseismology and Magnetic Imager AIA: Atmospheric Imaging AssemblyAIA: Atmospheric Imaging Assembly EVE: EUV Variability ExperimentEVE: EUV Variability Experiment

SDO has a large data rate and an open data policySDO has a large data rate and an open data policy Data is made available soon after downlinkData is made available soon after downlink

SDO will allow us to understand and to better forecast solar activitySDO will allow us to understand and to better forecast solar activity

SDO Project Science Team 15

Imaging the Sun’s Far SideImaging the Sun’s Far Side

SDO Project Science Team 16

New Farside Imaging ResultsNew Farside Imaging Results

SDO Project Science Team 17

MDI Solar Polar FieldsMDI Solar Polar Fields

SDO Project Science Team 18

Synoptic Magnetic FieldsSynoptic Magnetic FieldsCycles 21-23Cycles 21-23