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SDO Mission Blog

This is the Solar Dynamics Observatory Mission blog. It will consist of mission status, news, and event updates.

SDO will perform an EVE cruciform maneuver today. From 1700-2152 UTC (1:00 p.m.-5:52 p.m. ET), SDO will rock up and down and back and forth as a calibration maneuver. During this time the AIA and HMI images may be blurred or blank.
SDO will perform momentum management maneuver #26 today from 1945-2000 UTC (3:45-4:00 p.m. ET) today. Science data is not returned during the maneuver.
We are starting the July maneuver season. Today is the HMI roll maneuver from 1500-2000 UTC (11 am ET to 4 pm ET). During the roll the Sun will appear to flip in the NRT data. This data is used to maintain the calibration of HMI and to study how round the Sun is.
Earlier the week we received our conjunction report that lists satellites that will pass close to SDO. Our inclined geosynchronous orbit means there aren't a lot of satellites near SDO, but every couple of months one will come within 20 km (12 mi) of our spacecraft. This week saw the return of Telstar 401 to our list (see the picture at left.) Telstar 401 is a large telecommunications satellite that failed January 11, 1997, and has since drifted around the geostationary belt of satellites. This is not a small satellite, the solar panels stretch about 60 ft across. It's good to know the other satellite is around, but it would be better if was moved to a graveyard orbit well outside of the geostationary belt.

It is possible that Telstar 401 failed because of the activity created by a coronal mass ejection that rose off the Sun on January 6, 1997. (The gray picture at left shows what the CME looked like at 1850 UTC on that date.) The CME is the white arc moving down from the occulting disk. It is called a halo CME because we see it as a ring around the Sun, which means it is heading straight towards Earth!

The impact of the CME was not very dramatic when it reached Earth a few days later. But the energies of the radiation belt protons and electrons were increased enough that they caused an electronic component to arc and fail. There were several attempts to revive Telstar 401, but it was eventually declared a loss.

According to the Union of Concerned Scientists, there are almost 500 satellites currently operating in geosynchronous orbits about the Earth. Most of them are in the geostationary belt that allows them to appear stationary in the sky. There are about 100 defunct satellites in graveyard orbits further away from the Sun. But it is the failed satellites and spent boosters that blunder along and show up on the SDO conjunction report every month or so.

Telstar 401, a true ghost of space weather!

Today at 2234 UTC (6:34 pm ET) is the summer solstice for 2016. It's also a full moon today, the first time the summer solstice and full moon have coincided since 1967. Enjoy the longest daytime of the year and a bright night as well. Maybe we could celebrate the brightest day of the year?

Today I would like to share another picture from the May 9, 2016, Mercury transit. This is a composite created by Monica Bobra at Stanford University. It's an excellent view of the transit from 2nd contact to 3rd contact, with an image every 20 minutes. Creating these composites takes a good bit of art. You can't just add the images together as that blurs the background image of the Sun. You have to take cutouts around the planet and reinsert them in a selected background image.

It turns out that MDI on SOHO was turned on for the transit. Bobra did the same analysis to produce this image from MDI. The data near 2nd contact is not available.

You can see the paths of Mercury are slightly different in the two images. The MDI path is closer to the solar equator and tilted at an angle to the path in the HMI image. These differences are caused by the different viewpoints of the transit from the two spacecraft. Similar differences are what were measured to determine the size of the astronomical unit (AU) during the Venus transits of the 1700 and 1800's.

Thanks, Monica!

The HMI operators restarted HMI and science data is flowing. 

Many thanks to the LMSAL team! 

 HMI has thrown an error. The HMI operations team is working to bring the instrument back online. No data will be available until the instrument is fixed.
On Wednesday, June 1, 2016, the EVE calibration rocket flew high above the New Mexican desert. The instruments all returned good data and the payload was recovered for another flight in a couple of years.

Congratulations to the EVE team for re-flying the payload after last year's lunch problems. Thanks to the Wallops flight crew and the White Sands Missile Range personnel who actually do the launch and recovery.

On May 9, 2016, Mercury passed directly between the Sun and Earth, making a transit of the Sun. Mercury transits happen about 13 times each century. NASA’s SDO studies the sun 24/7 and captured the entire nine-hour event. This composite image of Mercury’s journey across the Sun was created with visible-light images from HMI on SDO. Image courtesy of NASA/SDO, the HMI Science Team, and Genna Duberstein.

It's always nice to see stories using SDO images on the web. It was pretty cloudy on the East Coast of the United States on Monday and a cloud-free satellite feed is a great backup. Here are a few examples where SDO images were used to share the Mercury transit to the world.

SDO will now return to its regularly scheduled observations of the Sun — in better than UltraHD!

I am glad so many people could watch the Mercury transit yesterday, with SDO and from the ground. People around the world were watching the transit along with SDO! Here is my favorite view of the transit. An AIA 193 movie of Mercury passing over a small but active prominence as it moves off the disk of the Sun. The mp4 movies of the transit will be archived at, so you can look at the phases and wavelengths you missed the first time.

Many thanks to the people at Stanford University who got up at 3:00 am PT to start the scripts to provide the SDO data. My thanks also to the people at the Goddard Space Flight Center who worked all morning to keep the data flowing and help with the network configuration.

Now I can relax and start looking forward to the next transit of Mercury on November 11, 2019. But first you should watch for the Great American Eclipse, a total eclipse of the Sun on August 21, 2017. The path of totality of this eclipse spans the continental US, so it can be seen by almost everyone in the USA who can drive a few hundred miles or less. SDO won't see this eclipse and I will just be another person jostling for position at some place along the path!

Mercury has moved off the Sun but can still be seen against the corona.