SDO Launch Coming Soon! – Feb 3rd


The Solar Dynamics Observatory (SDO) is the next robotic scientific mission NASA will launch. Currently it is scheduled to launch from Cape Canaveral’s SLC-41 on an Atlas 5 rocket on February 3, 2010 with a one hour launch window (10:53-11:53 a.m. Eastern Time). The mission will nominally last for 5 years. After the success of the SOHO, STEREO, and TRACE missions, having another active solar observatory will be an incredible leap in capability for solar science.

And what a leap! SDO will have the fastest time resolution ever flown for solar imaging: 8 full disk images covering 8 different wavelengths every 10 seconds. This means SDO will generate an absolutely phenomenal amount of data. One major challenge for missions in orbit is finding a way to transmit large amounts of data to the ground. Often, spaceborne instruments are capable of generating much more data, but must choose to produce less so that the data storage and transmission requirements are met.

SDO’s solution to this issue is to place the observatory in a geosynchronous orbit over the White Sands ground terminal in Las Cruces, New Mexico. Geosynchronous orbits are special because the satellite orbits the Earth at the same rate that the Earth itself is rotating. These are the orbits used by the satellites that monitor weather, or provide your satellite TV. In this case, the geosynchronous orbit will allow SDO to have very long continuous communications directly with the ground. Direct link to the ground allows for transmission of more data per second than using data relay satellites. So this orbit absolutely maximizes the transmission rate for SDO.

Why does SDO need so much data? Well, because the mission is designed to perform very precise helioseismology measurements. Seismology, the study of how waves travel through an object, is used on Earth to study tectonic disturbances such as earthquakes and volcanos. For large, deep earthquakes, seismic measurements of such disturbances tell geologists much about the inner structure of the Earth. By using SDO to watch waves travel across the surface of the Sun, helioseismologists hope to gain similar knowledge of what is occuring deep below the Sun’s surface.

In fact, observations made from the ground have already demonstrated the feasibility of such science. But ground based solar observatories have significant disadvantages over orbiting spacecraft. For example, SDO will only experience nighttime twice each year, with each being about 3 weeks long. This means the rest of the year SDO will have non-stop viewing of the Sun, giving solar scientists an unprecedented dataset just as we start a new solar cycle.

In addition, SDO hopes to uncover much more about the solar magnetic cycle. After the long solar minimum we have just experienced, it is evident that our understanding of the Sun’s intrinsic magnetic field is still in its infancy. SDO’s monitoring of the Sun’s complex magnetic structure will give us an opportunity to better understand how it interacts internally and with the rest of the solar system; from sunspots, prominences, and coronal mass ejections from the Sun’s surface to solar wind and auroras experienced here on Earth.

I’m so excited to see what new science this observatory unlocks! Of course it still has to go through that last big leap to get it into orbit. Let’s just hope the rocket doesn’t blow up!


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