Solar Dynamics Observatory
Encyclopedia
The Solar Dynamics Observatory (SDO) is a NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 mission which will observe the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 for over five years. Launched on February 11, 2010, the observatory is part of the Living With a Star
Living With a Star
Living With a Star is a NASA scientific program to study those aspects of the connected Sun-Earth system that directly affect life and society. LWS is a crosscutting initiative with goals and objectives relevant to NASA's Exploration Initiative, as well as to NASA's Strategic Enterprises...

 (LWS) program. The goal of the LWS program is to develop the scientific understanding necessary to effectively address those aspects of the connected Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

 system that directly affect life and society. SDO's goal is to understand the Sun's influence on Earth and near-Earth space by studying the solar atmosphere on small scales of space and time and in many wavelengths simultaneously. SDO will investigate how the Sun's magnetic field
Stellar magnetic field
A stellar magnetic field is a magnetic field generated by the motion of conductive plasma inside a star. This motion is created through convection, which is a form of energy transport involving the physical movement of material. A localized magnetic field exerts a force on the plasma, effectively...

 is generated and structured, how this stored magnetic energy is converted and released into the heliosphere
Heliosphere
The heliosphere is a bubble in space "blown" into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself...

 and geospace in the form of solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

, energetic particles, and variations in the solar irradiance.

General

The SDO spacecraft was assembled and tested at NASA's Goddard Space Flight Center
Goddard Space Flight Center
The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...

 in Greenbelt, Maryland
Greenbelt, Maryland
Greenbelt is a city in Prince George's County, Maryland, United States. Contained within today's City of Greenbelt is the historic planned community now known locally as "Old Greenbelt" and designated as the Greenbelt Historic District...

, and launched on February 11, 2010, from Cape Canaveral Air Force Station
Cape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...

. The primary mission is scheduled to last five years and three months, with expendables expected to last for ten years. Some consider SDO to be a follow-on mission to the Solar and Heliospheric Observatory
Solar and Heliospheric Observatory
The Solar and Heliospheric Observatory is a spacecraft built by a European industrial consortium led by Matra Marconi Space that was launched on a Lockheed Martin Atlas IIAS launch vehicle on December 2, 1995 to study the Sun, and has discovered over 2100 comets. It began normal operations in May...

 (SOHO).

SDO is a 3-axis stabilized spacecraft, with two solar arrays, and two high-gain antennas. The spacecraft includes three instruments: the Extreme Ultraviolet Variability Experiment (EVE) built in partnership with the University of Colorado at Boulder
University of Colorado at Boulder
The University of Colorado Boulder is a public research university located in Boulder, Colorado...

's Laboratory for Atmospheric and Space Physics
Laboratory for Atmospheric and Space Physics
The Laboratory for Atmospheric and Space Physics is a research organization at the University of Colorado at Boulder. LASP is a research institute with over 100 research scientists ranging in fields from solar influences, to Earth's and other planetary atmospherics processes, space weather, space...

 (LASP), the Helioseismic and Magnetic Imager (HMI) built in partnership with Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...

, and the Atmospheric Imaging Assembly (AIA) built in partnership with the Lockheed Martin Solar & Astrophysics Laboratory. Data which is collected by the craft will be made available as soon as possible, after it is received.

Helioseismic and Magnetic Imager

The Helioseismic
Helioseismology
Helioseismology is the study of the propagation of wave oscillations, particularly acoustic pressure waves, in the Sun. Unlike seismic waves on Earth, solar waves have practically no shear component . Solar pressure waves are believed to be generated by the turbulence in the convection zone near...

 and Magnetic Imager (HMI), led from Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...

 in Stanford, California
Stanford, California
Stanford is a census-designated place in Santa Clara County, California, United States and is the home of Stanford University. The population was 13,809 at the 2010 census....

, studies solar variability and characterizes the Sun's interior and the various components of magnetic activity. HMI produces data to determine the interior sources and mechanisms of solar variability and how the physical processes inside the Sun are related to surface magnetic field and activity. It also produces data to enable estimates of the coronal magnetic field for studies of variability in the extended solar atmosphere. HMI observations will enable establishing the relationships between the internal dynamics and magnetic activity in order to understand solar variability and its effects. HMI will take high-resolution measurements of the longitudinal and vector magnetic field over the entire visible disk thus extending the capabilities of the SOHO
Solar and Heliospheric Observatory
The Solar and Heliospheric Observatory is a spacecraft built by a European industrial consortium led by Matra Marconi Space that was launched on a Lockheed Martin Atlas IIAS launch vehicle on December 2, 1995 to study the Sun, and has discovered over 2100 comets. It began normal operations in May...

's MDI instrument.

Extreme Ultraviolet Variability Experiment

The Extreme Ultraviolet Variability Experiment (EVE), will measure the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

's extreme ultraviolet
Extreme ultraviolet
Extreme Ultraviolet radiation is high-energy ultraviolet radiation, generally defined to be electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths from 120 nm down to 10 nm, and therefore having photons with energies from 10 eV up to 124 eV...

 irradiance with improved spectral resolution
Spectral resolution
The spectral resolution of a spectrograph, or, more generally, of a frequency spectrum, is a measure of its ability to resolve features in the electromagnetic spectrum...

, "temporal cadence", accuracy, and precision over preceding measurements made by TIMED SEE, SOHO
Soho
Soho is an area of the City of Westminster and part of the West End of London. Long established as an entertainment district, for much of the 20th century Soho had a reputation for sex shops as well as night life and film industry. Since the early 1980s, the area has undergone considerable...

, and SORCE
SORCE
The Solar Radiation and Climate Experiment is a NASA-sponsored satellite mission that provides state-of-the-art measurements of incoming X-ray, ultraviolet, visible, near-infrared, and total solar radiation...

 XPS. The instrument incorporates physics-based models in order to further scientific understanding of the relationship between solar EUV variations and magnetic variation changes in the Sun.

The Sun's output of energetic extreme ultraviolet photons is primarily what heats the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

's upper atmosphere and creates the ionosphere
Ionosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...

. Solar EUV radiation output undergoes constant changes, both moment to moment and over the Sun's 11-year solar cycle
Solar cycle
The solar cycle, or the solar magnetic activity cycle, is a periodic change in the amount of irradiation from the Sun that is experienced on Earth. It has a period of about 11 years, and is one component of solar variation, the other being aperiodic fluctuations. Solar variation causes changes in...

, and these changes are important to understand because they have a significant impact on atmospheric heating
Atmospheric physics
Atmospheric physics is the application of physics to the study of the atmosphere. Atmospheric physicists attempt to model Earth's atmosphere and the atmospheres of the other planets using fluid flow equations, chemical models, radiation balancing, and energy transfer processes in the atmosphere...

, satellite drag, and communications system degradation, including disruption of the Global Positioning System
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

.

The EVE instrument package was built by the University of Colorado at Boulder
University of Colorado at Boulder
The University of Colorado Boulder is a public research university located in Boulder, Colorado...

's Laboratory for Atmospheric and Space Physics
Laboratory for Atmospheric and Space Physics
The Laboratory for Atmospheric and Space Physics is a research organization at the University of Colorado at Boulder. LASP is a research institute with over 100 research scientists ranging in fields from solar influences, to Earth's and other planetary atmospherics processes, space weather, space...

, with Dr. Tom Woods as Principal Investigator
Principal investigator
A principal investigator is the lead scientist or engineer for a particular well-defined science project, such as a laboratory study or clinical trial....

, and was delivered to Goddard Space Flight Center
Goddard Space Flight Center
The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...

 on September 7, 2007. The instrument provides improvements of up to 70 percent in spectral resolution measurements in the wavelengths below 30nm, and a 30 percent improvement in "time cadence" by taking measurements every 10 seconds over a 100 percent duty cycle
Duty cycle
In engineering, the duty cycle of a machine or system is the time that it spends in an active state as a fraction of the total time under consideration....

.

Atmospheric Imaging Assembly

The Atmospheric Imaging Assembly (AIA), led from the Lockheed Martin Solar and Astrophysics Laboratory (LMSAL), provides full-disk imaging of the Sun in ten white light
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...

, ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

 and extreme ultraviolet
Extreme ultraviolet
Extreme Ultraviolet radiation is high-energy ultraviolet radiation, generally defined to be electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths from 120 nm down to 10 nm, and therefore having photons with energies from 10 eV up to 124 eV...

 (EUV) band passes at high spatial and temporal resolution. The four telescopes that provided the individual light feeds for the instrument were designed and built at the Smithsonian Astrophysical Observatory
Smithsonian Astrophysical Observatory
The Smithsonian Astrophysical Observatory is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory to form the Harvard-Smithsonian Center for Astrophysics .-History:The SAO was founded in 1890 by...

 (SAO). Unfortunately, after launch it was discovered that there is a speck of dust on the CCD.
AIA Wavelength Channel Region of solar atmosphere Characteristic
Temperature
White Light
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...

 
Photosphere
Photosphere
The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived...

 
5000 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

170 nm  Temperature minimum, photosphere
Photosphere
The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived...

 
5000 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

160 nm  Transition region & photosphere
Photosphere
The photosphere of an astronomical object is the region from which externally received light originates. The term itself is derived from Ancient Greek roots, φῶς, φωτός/phos, photos meaning "light" and σφαῖρα/sphaira meaning "sphere", in reference to the fact that it is a spheric surface perceived...

 
105 & 5000 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

30.4 nm  Chromosphere
Chromosphere
The chromosphere is a thin layer of the Sun's atmosphere just above the photosphere, roughly 2,000 kilometers deep....

 & transition region 
50,000 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

17.1 nm  Quiet corona
Corona
A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...

, upper transition region 
6.3×105 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

19.3 nm  Corona
Corona
A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...

 & hot flare
Solar flare
A solar flare is a sudden brightening observed over the Sun surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy . The flare ejects clouds of electrons, ions, and atoms through the corona into space. These clouds typically reach Earth a day...

  plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

 
1.2×106 & 2x107 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

21.1 nm  Active region corona
Corona
A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...

 
2×106 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

33.5 nm  Active region corona
Corona
A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...

 
2.5×106 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

 9.4 nm  Flaring
Solar flare
A solar flare is a sudden brightening observed over the Sun surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy . The flare ejects clouds of electrons, ions, and atoms through the corona into space. These clouds typically reach Earth a day...

 regions
6.3×106 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

13.1 nm  Flaring
Solar flare
A solar flare is a sudden brightening observed over the Sun surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy . The flare ejects clouds of electrons, ions, and atoms through the corona into space. These clouds typically reach Earth a day...

 regions
4×105, 107 & 1.6×107 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...


Communications

SDO down-links science data (K-band) from its two onboard high-gain antenna
High-gain antenna
A high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...

s, and telemetry (S-band) from its two onboard omnidirectional antenna
Omnidirectional antenna
In radio communication, an omnidirectional antenna is an antenna which radiates radio wave power uniformly in all directions in one plane, with the radiated power decreasing with elevation angle above or below the plane, dropping to zero on the antenna's axis. This radiation pattern is often...

s. The ground station consists of two dedicated (redundant) 18-meter radio antennas in White Sands Missile Range
White Sands Missile Range
White Sands Missile Range is a rocket range of almost in parts of five counties in southern New Mexico. The largest military installation in the United States, WSMR includes the and the WSMR Otera Mesa bombing range...

, New Mexico, constructed specifically for SDO. Mission controllers operate the spacecraft remotely from the Mission Operations Center at NASA's Goddard Space Flight Center. The combined data rate is about 130 Mbit/s (150 Mbit/s with overhead, or 300 Msymbols/s with rate 1/2 convolutional encoding
Convolutional code
In telecommunication, a convolutional code is a type of error-correcting code in which* each m-bit information symbol to be encoded is transformed into an n-bit symbol, where m/n is the code rate and...

), and the craft generates approximately 1.5 terabytes of data per day, beaming back 150 million bits of data every second (equivalent to about 380 full length movies).

Launch

NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

's Launch Services Program
Launch Services Program
Launch Services Program is responsible for NASA oversight of launch operations and countdown management, providing added quality and mission assurance in lieu of the requirement for the launch service provider to obtain a commercial launch license...

 at Kennedy Space Center
Kennedy Space Center
The John F. Kennedy Space Center is the NASA installation that has been the launch site for every United States human space flight since 1968. Although such flights are currently on hiatus, KSC continues to manage and operate unmanned rocket launch facilities for America's civilian space program...

 managed the payload integration and launch. The SDO launched from Cape Canaveral Air Force Station Space Launch Complex 41, utilizing an Atlas V
Atlas V
Atlas V is an active expendable launch system in the Atlas rocket family. Atlas V was formerly operated by Lockheed Martin, and is now operated by the Lockheed Martin-Boeing joint venture United Launch Alliance...

-401 rocket with a RD-180 powered Common Core Booster
Common Core Booster
A modular rocket is a type of multistage rocket which features components that can be interchanged for specific mission requirements. Several such rockets use similar concepts such as unified modules to minimize expenses on manufacturing, transportation and for optimization of support...

, which has been developed to meet the Evolved Expendable Launch Vehicle (EELV) program requirements. On launch the SDO carried a suite of three scientific instruments.

Orbit

After launch, the spacecraft was placed into an orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...

 around the earth with an initial perigee
Perigee
Perigee is the point at which an object makes its closest approach to the Earth.. Often the term is used in a broader sense to define the point in an orbit where the orbiting body is closest to the body it orbits. The opposite is the apogee, the farthest or highest point.The Greek prefix "peri"...

 of about 2500 kilometres (1,553.4 mi). SDO will undergo a series of orbit-raising maneuvers which will adjust its orbit until the spacecraft reaches its planned circular
Circular orbit
A circular orbit is the orbit at a fixed distance around any point by an object rotating around a fixed axis.Below we consider a circular orbit in astrodynamics or celestial mechanics under standard assumptions...

, geosynchronous orbit
Geosynchronous orbit
A geosynchronous orbit is an orbit around the Earth with an orbital period that matches the Earth's sidereal rotation period...

 at an altitude of 36000 kilometres (22,369.4 mi), at 102° W longitude, inclined at 28.5°.

Camilla

Camilla Corona is a rubber chicken (similar to a children's toy), and is the mission mascot for NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

's Solar Dynamics Observatory (SDO). She is part of the Education and public outreach team and assists with various functions to help educate the public, mainly children, about the SDO mission, facts about the sun and space weather
Space weather
Space weather is the concept of changing environmental conditions in near-Earth space or thespace from the Sun's atmosphere to the Earth's atmosphere. It is distinct from the concept ofweather within the Earth's planetary atmosphere...

. Camilla also assists in cross-informing about other NASA missions and space related projects. Camilla Corona SDO uses social media
Social media
The term Social Media refers to the use of web-based and mobile technologies to turn communication into an interactive dialogue. Andreas Kaplan and Michael Haenlein define social media as "a group of Internet-based applications that build on the ideological and technological foundations of Web 2.0,...

 to interact with fans.


External links


Instruments

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