(This post was provided by Caroline Alexander, UCLan, UK)
SDO Mission Overview
The Solar Dynamics Observatory (SDO) is a satellite that was launched into orbit in February 2010.
SDO is a NASA mission to study many aspects of the Sun and its effect on the Earth and solar system. It is part of NASA’s Living With a Star (LWS) program which aims to look at how the Sun affects life and society on Earth. For example, now that the Sun is becoming much more active again, with X-class solar flares, there are concerns over how this will affect modern technology, such as the many satellites (e.g. GPS) that orbit the Earth.
Large solar flares from the Sun have damaged and even destroyed satellites in the past, which is a real concern for our technology dependent society. Understanding the causes of solar flares and improving our ability to predict them is one of the goals which SDO will help us to achieve.
The Extreme UltraViolet (EUV) image of the Sun shown above was taken by SDO on 30th March 2010 and shows gas at different temperatures (red is 60,000 °C; blues and greens are about 1,000,000 °C). Several active regions can be seen with large loops of hot gas tracing out the Sun’s magnetic field. On the solar limb (at the 10 o’clock position) is a huge explosion with gas and twisted magnetic fields reaching high above the solar surface.
Solar physicists around the world are really excited about SDO because of the extremely high spatial resolution it provides (that is the amount of detail we can see on the Sun). SDO takes a full-disk image of the Sun in 8 different wavelength bands (sensitive to different temperatures) every 10 seconds with a spatial resolution of 4096 x 4096 pixels (that is an IMAX cinema quality in terms of clarity and sharpness).
These two images show the same solar active region imaged with the Extreme Ultraviolet Imaging Telescope (EIT) onboard the SoHO satellite (left), compared to an image taken with SDO/AIA (right). The loops in these images are around one million degrees Celsius. You can see that the SDO/AIA image is much clearer and shows the loop detail much better than the SOHO/EIT image. This is because SoHO was launched in 1995 and since then imaging technology has come on in leaps and bounds.
A downside of this fantastic amount of detail is that the images which the satellite beams back are really large. The enormous amount of data that SDO sends down is equivalent to downloading half a million iTunes songs a day! This has presented a new challenge for solar scientists. Storing and distributing so much solar data had never been done before.
SDO Launch and Orbit
The SDO satellite was successfully launched on the 11th of February 2010 from Cape Canaveral in Florida after being delayed for a day due to fears over high winds.
The rocket flight went perfectly with the AtlasV launch vehicle pushing the spacecraft up to an orbit of 22,300 miles above Earth where SDO separated and began moving into its final geosynchronous orbit.
Watch the movie of the SDO launch below.
SDO takes so many images that it needs to send back data continuously. This is why it is in a geosynchronous orbit. This type of orbit means that it stays over the same area on Earth so it can beam its images straight down without having to store them for long periods of time. To cope with this enormous amount of data, NASA built two dedicated radio antennae near Las Cruces in New Mexico to keep the SDO satellite in constant view of the 18 m dishes.
Instruments on SDO
SDO has three instruments:
• AIA – The Atmospheric Imaging Assembly
• HMI – Helioseismic and Magnetic Imager
• EVE – Extreme Ultraviolet Variability Experiment
• The Atmospheric Imaging Assembly (AIA) takes high resolution (very detailed) images of the solar atmosphere in different wavebands, characteristic of different temperatures. It takes an image in each waveband every 10 seconds which allows us to see the very fast moving features in the solar atmosphere.
• The Heliospheric and Magnetic Imager (HMI) maps the Sun’s magnetic field in detail, and also probes beneath the surface using sophisticated techniques of Helioseismology. This instrument allows us to see what the magnetic field is doing on the solar surface which allows us to see how the surface and upper atmosphere are connected.
• The Extreme UV Experiment (EVE) measures fluctuations in the Sun’s radiation. These data will lead to a better understanding of how the Sun’s UV radiation interacts with the Earth’s atmosphere, affecting its chemistry and the Earth’s climate.
SDO was launched in order to find out more about the Sun. In particular it will try to find answers to some of these science questions:
1. What drives the 11 year solar cycle?
2. How do active regions form?
3. How does the magnetic field on the Sun reorganise itself?
4. How does the Sun’s irradiance change over the solar cycle?
5. What can we learn about Coronal Mass Ejections (CME’s) and prominences by studying the magnetic field?
6. Can we predict what the solar wind at Earth will be like based on what we see on the solar surface?
7. Can we predict space weather and how it will affect us?
SDO observations will also be combined with those from other solar spacecraft, Hinode, STEREO, RHESSI, TRACE and SoHO to study the Sun, sunspots, solar flares, Coronal Mass Ejections (CME’s) and how the Sun affects the Earth, for example by disrupting communication and navigation (GPS). Learn more about the solar satellites and observations on the Sun|trek website.
This movie (credit: Dan Brown, UCLan) shows the Sun observed by SDO/AIA in 10 wavebands. Each waveband represents a different temperature. The movie shows data for a whole month and you can see the active regions moving as the Sun spins around.
This other movie (credit: Dan Brown, UCLan) shows an erupting prominence seen by SDO. The three boxes on the left show close ups at three different wavebands to show what the prominence material is doing at different temperatures.
Learn more about SDO
For more information on SDO visit the NASA website at http://sdo.gsfc.nasa.gov/
If Twitter is more your thing then you might want to follow @NASA_SDO mission updates and news.
Little SDO is a Facebook page where you can get the latest news and images from the satellite.
Also check out Camilla SDO on Facebook. This rubber chicken is the mascot for the SDO mission and her page is geared more towards kids and outreach activities. As well as learning about the Sun through SDO, she regularly posts about other NASA topics such as learning to become an astronaut. Also follow Camilla tweeting away on @CamillaSDO for regular mission updates and news.
The University of Central Lancashire is the UK data hub for SDO data.
Follow them on Facebook (SDO at UCLan) or visit http://www.sdo.uclan.ac.uk/ for news and cool pictures.
Caroline is a graduate student at the University of Central Lancashire (UCLan), UK. She grew up in Edinburgh, Scotland, and was fascinated by astronomy. She now works with the SDO team, analysing solar data and trying to understand more about the Sun. Find out more about Caroline and other Solar Guides on the Sun|trek website.