SDO Almost Ready to Go!

Disclaimer: This week/TweetUp has been super fun so far, and also super busy, so I’m more sleep deprived than normal. Any rambliness/wrongness besides what is normal… apologies in advance.

As part of the Kennedy Space Center #SDOisGO TweetUp event, we attended the Guest Mission Briefing for the Solar Dynamics Observatory. (The wha? This!) Since I couldn’t share some of the interesting tidbits inside the signal-less room, here’s a bit of what I picked up! Elizabeth Citrin, project manager for SDO at Goddard, gave a pictorial overview of much of the assembly. The 15-foot tall, three ton spacecraft was carefully put together and integrated (while all held their breath that it would fit!) after the three science instruments had been developed by their home institutions. We also watched a cool launch simulation video, which is also on YouTube:


Dean Pesnell, project scientist gave a great talk highlighting the science goals and instruments of SDO. And I have to really commend him for that. I complain at times that not enough scientists know how to give public talks, but he nailed it, even when his video simulations didn’t work. So bravo for that! I already touched on much of the science that he discussed in my last post, but I did not yet talk about the specifics of the HMI, or Helioseismic and Magnetic Imager. Pesnell showed us some example dopplergrams, which will help probe the interior of the sun. A dopplergram shows the line-of-sight velocities across the surface of the sun, so you can see individual regions moving in and out. This is done by measuring the Doppler shift of a spectral line of iron with a resolution on the disk of the sun of 1 arcsecond. (1 arcsec = 1/3600 degrees, and the sun is about half a degree across in the sky!) So, that’s technically impressive, and it gives us information about the dynamics underneath the sun’s surface. The measurements will be so accurate that you can “see” sunspots on the opposite side of the sun! (That is, you can detect the motion pattern even while the sunspots are rotated away.) THAT is pretty amazing. The instrument simultaneously measures the polarization or orientation, of the light at these wavelengths, which is determined by the magnetic field orientation. The spectral lines themselves are “split” into two by magnetic fields, so this measures their strength, as well. With the HMI, we can “see” invisible magnetic fields and peer into the sun. This is a really exciting instrument and a step up from previous technology onboard SOHO.

As I predicted, I’m getting a bit rambly… but that’s ok. The last two talks were by Stephen Francois, launch services program manager, and Vernon Thorpe, program manager for United Launch Alliance. These focused more on the rocket systems, with which I am much less familiar. For example, I did not know that Launch Services works with each NASA mission to find the best rocket for its journey. The Atlas V was chosen for SDO back in 2004 because of its larger size and high orbit. The Atlas design goes back 53 years and is probably most famous for lifting astronaut John Glenn into orbit for his Mercury flight. I am pretty excited to see the 191-foot rocket takeoff tomorrow from what will probably be a VIP vantage point. The first stage will burn for 4 minutes, then switch to the Centaur second stage for 11 minutes. Then, it will switch into “coast” mode for 87 minutes until it reaches somewhere over the east coast of Australia. Then, a three minute burn is needed to push the spacecraft into an elliptical orbit with apogee (furthest point) at geosynchronous orbit. The next two months will be spent commissioning the spacecraft and moving it to it’s circular, geosynchronous orbit above New Mexico. And then will come the science!

That’s all for now… be sure to tune in to NASA TV for the 10:26am launch! I’m sure I’ll be back with a little more about EVE (my other favorite SDO instrument), the launch itself, and the TweetUp people and events!

UPDATE: It launched successfully on the second attempt!

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