Solar Dynamics Observatory

The Solar Dynamics Observatory (SDO) is a NASA mission which has been observing the Sun since 2010.[4] Launched on 11 February 2010, the observatory is part of the Living With a Star (LWS) program.[5]

Solar Dynamics Observatory
Solar Dynamics Observatory satellite
NamesSDO
Mission typeSolar research[1]
OperatorNASA GSFC[2]
COSPAR ID2010-005A
SATCAT no.36395
Websitehttp://sdo.gsfc.nasa.gov
Mission duration5 years (planned)
13 years, 8 months, 14 days (elapsed)
Spacecraft properties
Spacecraft typeSolar Dynamics Observatory
ManufacturerGoddard Space Flight Center
Launch mass3,100 kg (6,800 lb)
Dry mass1,700 kg (3,700 lb)
Payload mass290 kg (640 lb)
Start of mission
Launch date11 February 2010, 15:23:00 UTC
RocketAtlas V 401
Launch siteCape Canaveral, SLC-41
ContractorUnited Launch Alliance
Orbital parameters
Reference systemGeocentric orbit[3]
RegimeGeosynchronous orbit
Longitude102° West

Solar Dynamics Observatory patch  

The goal of the LWS program is to develop the scientific understanding necessary to effectively address those aspects of the connected Sun–Earth system directly affecting life on Earth and its society. The goal of the SDO is to understand the influence of the Sun on the Earth and near-Earth space by studying the solar atmosphere on small scales of space and time and in many wavelengths simultaneously. SDO has been investigating 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.[6]

General

The SDO spacecraft was developed at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and launched on 11 February 2010, from Cape Canaveral Air Force Station (CCAFS). The primary mission lasted five years and three months, with expendables expected to last at least ten years.[7] Some consider SDO to be a follow-on mission to the Solar and Heliospheric Observatory (SOHO).[8]

SDO is a three-axis stabilized spacecraft, with two solar arrays, and two high-gain antennas, in an inclined geosynchronous orbit around Earth.

The spacecraft includes three instruments:

Data which is collected by the craft is made available as soon as possible, after it is received.[9]

As of February 2020, SDO is expected to remain operational until 2030.[10]

Instruments

Helioseismic and Magnetic Imager (HMI)
Comparison of HMI Continuum images immediately after an eclipse, and then after the sensor has re-warmed.

The Helioseismic and Magnetic Imager (HMI), led from Stanford University in Stanford, California, studies solar variability and characterizes the Sun's interior and the various components of magnetic activity. HMI takes high-resolution measurements of the longitudinal and vector magnetic field over the entire visible solar disk thus extending the capabilities of SOHO's MDI instrument.[11]

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.[12]

Extreme Ultraviolet Variability Experiment (EVE)

The Extreme Ultraviolet Variability Experiment (EVE) measures the Sun's extreme ultraviolet irradiance with improved spectral resolution, "temporal cadence", accuracy, and precision over preceding measurements made by TIMED SEE, SOHO, and SORCE 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.[13]

The Sun's output of energetic extreme ultraviolet photons is primarily what heats the Earth's upper atmosphere and creates the ionosphere. Solar EUV radiation output undergoes constant changes, both moment to moment and over the Sun's 11-year solar cycle, and these changes are important to understand because they have a significant impact on atmospheric heating, satellite drag, and communications system degradation, including disruption of the Global Positioning System.[14]

The EVE instrument package was built by the University of Colorado Boulder's Laboratory for Atmospheric and Space Physics (LASP), with Dr. Tom Woods as principal investigator,[7] and was delivered to NASA Goddard Space Flight Center on 7 September 2007.[15] The instrument provides improvements of up to 70% in spectral resolution measurements in the wavelengths below 30 nm, and a 30% improvement in "time cadence" by taking measurements every 10 seconds over a 100% duty cycle.[14]

Atmospheric Imaging Assembly (AIA)

The Atmospheric Imaging Assembly (AIA), led from the Lockheed Martin Solar and Astrophysics Laboratory (LMSAL), provides continuous full-disk observations of the solar chromosphere and corona in seven extreme ultraviolet (EUV) channels, spanning a temperature range from approximately 20,000 Kelvin to in excess of 20 million Kelvin. The 12-second cadence of the image stream with 4096 by 4096 pixel images at 0.6 arcsec/pixel provides unprecedented views of the various phenomena that occur within the evolving solar outer atmosphere.

The AIA science investigation is led by LMSAL, which also operates the instrument and – jointly with Stanford University – runs the Joint Science Operations Center from which all of the data are served to the worldwide scientific community, as well as the general public. LMSAL designed the overall instrumentation and led its development and integration. The four telescopes providing the individual light feeds for the instrument were designed and built at the Smithsonian Astrophysical Observatory (SAO).[16] Since beginning its operational phase on 1 May 2010, AIA has operated successfully with unprecedented EUV image quality.

AIA wavelength channelSource [17]Region of solar atmosphereCharacteristic
temperature
White light (450 nm)continuumPhotosphere5000 K
170 nmcontinuumTemperature minimum, photosphere5000 K
160 nmC IV + continuumTransition region and upper photosphere105 and 5000 K
33.5 nmFe XVIActive region corona2.5×106 K
30.4 nmHe IIChromosphere and transition region50,000 K
21.1 nmFe XIVActive region corona2×106 K
19.3 nmFe XII, XXIVCorona and hot flare plasma1.2×106 and 2x107 K
17.1 nmFe IXQuiet corona, upper transition region6.3×105 K
13.1 nmFe VIII, XX, XXIIIFlaring regions4×105, 107 and 1.6×107 K
9.4 nmFe XVIIIFlaring regions6.3×106 K

Photographs of the Sun in these various regions of the spectrum can be seen at NASA's SDO Data website.[18] Images and movies of the Sun seen on any day of the mission, including within the last half-hour, can be found at The Sun Today.

Communications

SDO down-links science data (K-band) from its two onboard high-gain antennas, and telemetry (S-band) from its two onboard omnidirectional antennas. The ground station consists of two dedicated (redundant) 18-meter radio antennas in White Sands Missile Range, New Mexico, constructed specifically for SDO. Mission controllers operate the spacecraft remotely from the Mission Operations Center at NASA 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), and the craft generates approximately 1.5 Terabytes of data per day (equivalent to downloading around 500,000 songs).[7]

Launch
AttemptPlannedResultTurnaroundReasonDecision pointWeather go (%)Notes
110 Feb 2010, 3:26:00 pmScrubbed—Weather (high winds) [19]10 Feb 2010, 4:22 pm ​(T-3:59, immediately after T-4:00 hold)40% [20]window 10:26 to 11:26 EST, attempts made at 10:26, 10:56 and 11:26 EST
211 Feb 2010, 3:23:00 pmSuccess0 days, 23 hours, 57 minutes60% [20]Window: 10:23 to 11:23 EST

NASA's Launch Services Program at Kennedy Space Center managed the payload integration and launch.[21] The SDO launched from Cape Canaveral Space Launch Complex 41 (SLC-41), utilizing an Atlas V-401 rocket with a RD-180 powered Common Core Booster, which has been developed to meet the Evolved Expendable Launch Vehicle (EELV) program requirements.[22]

Orbit
Animation of Solar Dynamics Observatory's trajectory from 11 February 2010 to 11 April 2010
  Solar Dynamics Observatory ·   Earth

After launch, the spacecraft was placed into an orbit around the Earth with an initial perigee of about 2,500 km (1,600 mi). SDO then underwent a series of orbit-raising maneuvers which adjusted its orbit until the spacecraft reached its planned circular, geosynchronous orbit at an altitude of 35,789 km (22,238 mi), at 102° West longitude, inclined at 28.5°.[23] This orbit was chosen to allow 24/7 communications to/from the fixed ground station, and to minimise solar eclipses to about an hour a day for only a few weeks a year.

Sun dog phenomenon

Moments after launch, SDO's Atlas V rocket penetrated a cirrus cloud which created visible shock waves in the sky and destroyed the alignment of ice crystals that were forming a sun dog visible to onlookers.[24]

Mission mascot - Camilla

Camilla Corona is a rubber chicken (similar to a children's toy), and is the mission mascot for SDO. It 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.[25] Camilla also assists in cross-informing the public about other NASA missions and space related projects. Camilla Corona SDO uses social media to interact with fans.

  • SDO: Year 5
  • Camilla Corona SDO
    Camilla Corona SDO
  • SDO 3-D schematic
    SDO 3-D schematic
  • SDO Instruments
    SDO Instruments
  • SDO ready to be placed on Atlas rocket for launch.
    SDO ready to be placed on Atlas rocket for launch.
  • An animation showing the deployment of SDO.
  • First light image from the SDO showing a prominence eruption.
    First light image from the SDO showing a prominence eruption.
  • An image of the 2012 transit of Venus taken by SDO.
    An image of the 2012 transit of Venus taken by SDO.
  • This movie opens with a full-disk view of the Sun in visible wavelengths. Then the filters are applied to small pie-shaped wedges of the Sun.
  • SDO has now captured nearly seven years worth of ultra-high resolution solar footage. This time lapse shows that full run from two of SDO's instruments.

Stamps
The United States Post office announced on 15 January 2021, that they would be releasing a series of stamps highlighting images of the Sun captured by NASA's Solar Dynamics Observatory.

NASA's images of the Sun's dynamic and dazzling beauty have captivated the attention of millions. In 2021, the U.S. Postal Service is showcasing the Sun's many faces with a series of Sun Science forever stamps that show images of solar activity captured by NASA's Solar Dynamics Observatory (SDO). "I have been a stamp collector all my life and I can't wait to see NASA science highlighted in this way", said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate (SMD) in Washington, D.C. "I feel that the natural world around us is as beautiful as art, and it is inspiring to be able to share the import and excitement of studying the Sun with people around the country".[26]

The 20-stamp set features ten images that celebrate the science behind NASA's ongoing exploration of our nearest star. The images display common events on the Sun, such as solar flares, sunspots and coronal loops. SDO has kept a constant eye on the Sun for over a decade. Outfitted with equipment to capture images of the Sun in multiple wavelengths of visible, ultraviolet, and extreme ultraviolet light, SDO has gathered hundreds of millions of images during its tenure to help scientists learn about how our star works and how its constantly churning magnetic fields create the solar activity we see.[26]

That solar activity can drive space weather closer to Earth that can interfere with technology and radio communications in space. In addition to this immediate relevancy to our high-tech daily lives, the study of the Sun and its influence on the planets and space surrounding it – a field of research known as heliophysics – holds profound implications for the understanding of our Solar System and the thousands of solar systems that have been discovered beyond our own. As our closest star, the Sun is the only nearby star that humans are able to study in great detail, making it a vital source of data.[26]

See also

References
  1. "SDO Our Eye on the Sun" (PDF). NASA. Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  2. Dean Pesnell; Kevin Addison (5 February 2010). "Solar Dynamics Observatory: SDO Specifications". NASA. Archived from the original on 30 January 2010. Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  3. "SDO 2010-005A". N2YO. 24 January 2015. Retrieved 25 January 2015.
  4. Bourkland, Kristin L.; Liu, Kuo-Chia (25 July 2011). Verification of the Solar Dynamics Observatory High Gain Antenna Pointing Algorithm Using Flight Data (Report). American Institute of Aeronautics and Astronautics. hdl:2060/20110015278.
  5. Justin Ray. "Mission Status Center: Atlas V SDO". Spaceflight Now. Retrieved 13 February 2010.
  6. Dean Pesnell; Kevin Addison (5 February 2010). "Solar Dynamics Observatory: About The SDO Mission". NASA. Archived from the original on 30 June 2007. Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  7. "Solar Dynamics Observatory — Our Eye on the Sky" (PDF). NASA. 1 February 2010. Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  8. "Solar and Heliospheric Observatory Homepage". NASA /ESA. 9 February 2010. Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  9. "Solar Dynamics Observatory — Exploring the Sun in High Definition" (PDF). NASA. Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  10. Johnson-Groh, Mara (11 February 2020). "Ten Things We've Learned About the Sun From NASA's SDO This Decade". NASA. Retrieved 13 March 2020. Public Domain This article incorporates text from this source, which is in the public domain.
  11. Dean Pesnell; Kevin Addison (5 February 2010). "Solar Dynamics Observatory: SDO Instruments". NASA. Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  12. Solar Physics Research Group. "Helioseismic and Magnetic Imager Investigation". Stanford University. Retrieved 13 February 2010.
  13. "SDO – EVE-Extreme ultraviolet Variability Experiment". Laboratory for Atmospheric and Space Physics (LASP). 27 May 2010. Archived from the original on 16 July 2011. Retrieved 12 March 2020.
  14. Woods, Tom (12 September 2007). "Extreme Ultraviolet Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO) | Analogy on How the SDO EVE Measurements of the Solar Extreme Ultraviolet Irradiance will be Greatly Improved" (PDF). Laboratory for Atmospheric and Space Physics (LASP). Archived from the original (PDF) on 16 July 2011. Retrieved 22 September 2011.
  15. Rani Gran (7 September 2009). "First Solar Dynamic Observatory (SDO) Instrument Arrives at NASA Goddard Space Flight Center". NASA. Retrieved 17 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  16. "AIA – Atmospheric Imaging Assembly". Lockheed Martin. 3 February 2010. Retrieved 14 February 2010.
  17. "Atmospheric Imaging Assembly – Descriptions and Manuals of Instruments, Data, and Software Packages". Lockheed Martin. Retrieved 27 June 2012.
  18. "Solar Dynamics Observatory". Goddard Space Flight Center. NASA. Retrieved 13 March 2020. Public Domain This article incorporates text from this source, which is in the public domain.
  19. Dunn, Marcia. "Stiff wind delays NASA launch of solar observatory". The Associated Press. Retrieved 10 February 2010.
  20. "AFD-070716-027" (PDF). United States Airforce, 45th Weather Squadron. Archived from the original (PDF) on 13 June 2011. Retrieved 7 February 2010.
  21. "A New Eye on the Sun" (Press release). NASA. Archived from the original on 19 June 2010. Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  22. "SDO Launch Services Program" (PDF). Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  23. Wilson, Jim (11 February 2010). "Solar Dynamics Observatory". Retrieved 13 February 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  24. Phillips, Tony (11 February 2011). "SDO Sundog Mystery". NASA. Retrieved 13 March 2020. Public Domain This article incorporates text from this source, which is in the public domain.
  25. "Solar Dynamics Observatory". sdo.gsfc.nasa.gov. Archived from the original on 19 October 2011. Retrieved 3 May 2018. Public Domain This article incorporates text from this source, which is in the public domain.
  26. "The U.S. Postal Service to Issue NASA Sun Science Forever Stamps". NASA. 15 January 2021. Retrieved 19 January 2021. Public Domain This article incorporates text from this source, which is in the public domain.
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