Wednesday, July 20, 2016

EVE Cruciform today

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.

Wednesday, July 13, 2016

Momentum Management Maneuver Today

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.

Wednesday, July 6, 2016

HMI Roll Today

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.

Friday, June 24, 2016

Telstar 401, A Ghost of Space Weather Past

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!

Monday, June 20, 2016

Celebrate the Summer Solstice with Cool Pictures of the Mercury Transit!

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!

Friday, June 10, 2016

HMI has returned to science mode

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.

Friday, June 3, 2016

EVE Calibration Rocket Flies Above New Mexico

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.