Wednesday, March 14, 2018

Happy Pi Day!

Although there isn't a major geomagnetic storm happening today (and none expected tomorrow), here is a lovely picture of the Sun showing a coronal hole. The high-speed plasma streaming out of this coronal hole will probably hit the Earth and create some lovely aurora, but a geomagnetic storm is not expected.

Enjoy Π Day!

Wednesday, February 14, 2018

Station Keeping Maneuver #16 Today

SDO will perform station-keeping maneuver #16 today. The maneuver begins at 22:12 UTC (5:12 pm ET) and lasts until 22:56 UTC (5:56 pm ET). During the maneuver science data may be blurry or unavailable.

Station-keeping maneuvers are performed to keep SDO inside of its box in the geostationary belt. Even though SDO’s orbit is inclined 28° to the equator (where geostationary satellites orbit), we pass through the geostationary belt twice each day. We must stay inside our longitude box to avoid interfering with our neighbors. SK maneuvers happen about twice each year.

Sunday, February 11, 2018

Happy 8th Birthday, SDO!

It was a cold day at Cape Kennedy as SDO rose slowly into the sky. Eight years later, SDO has sent over 260 million images of the Sun to the ground. Over 3000 scientific papers have described how the Sun's magnetic field is created and destroyed. We have a large number of citizen scientists who study our images, especially using HelioViewer.

SDO still produces high quality data of the Sun every day. Even Solar Cycle 24 fades from view, we are watching the polar region magnetic fields grow. Large coronal holes can often be seen in the AIA coronal images. Solar Cycle 25 will soon be visible. SDO is ready!

Monday, January 29, 2018

2018 Maneuvers, Past and Future

SDO ran a number of maneuvers during January 2018. Science data may be unavailable or blurry on days when a maneuver is run. During eclipse season the Earth blocks the Sun for up to 72 minutes each day around 0700 UTC (2:00 am ET). This is also midnight Mountain Time, the timezone of the SDO ground station.
  • 01/03/18: RWA Jitter Test Successful: Instruments reported no blurring in images; ISS performance looked reasonable.
  • 01/17/18: EVE Cruciform Successfully Executed
  • 01/24/18: HMI roll, starting at 1500 UTC (10:00 am ET)
  • 02/10/18: Spring 2018 Eclipse Season Begins
  • 02/14/18: Stationkeeping Maneuver #16 (2234 UTC, 5:34 pm ET)
  • 03/05/18: Spring 2018 Eclipse Season Ends
Above is a movie in AIA 171 Å showing the effects of the EVE Cruciform on January 17, 2018. During the HMI Roll the Sun appears to rotate.

Thursday, January 11, 2018

Server maintenance, January 11, 2018

Today, January 11, 2018 at approx. 1:30 pm the SDO website will undergo server maintenance. The website will still be operational. However, images, movies, and data will not be available for some time.

Wednesday, December 20, 2017

Momentum Management Maneuver #31

SDO will perform Momentum Management Maneuver (Delta-H) #31 between 1919 and 1953 UTC (2:19-2:53 pm ET) today. We will fire the thrusters to bring the reaction wheels to their planned speeds. Science data may be unavailable or blurry during the maneuver.

Monday, November 20, 2017

Why Look at the Sun from Space?

SDO is one of fleet of satellites watching the Sun and recording the data that we use to study the solar magnetic field. The Sun was one of the first objects observed from above the Earth's atmosphere. One reason is the Sun's brightness — it was easy to see in the cameras. A more important reason was the ability to see wavelengths of light that are absorbed by the Earth's atmosphere. Although these wavelengths of light produce the ozone layer, which absorbs another wavelength, and the ionosphere, they are very useful to solar scientists. For example, the total solar irradiance measurements described in a previous post can only be made from a satellite.

What other satellites can you use to study the Sun?

Here are two sources (from many I could list) that can tell you about solar satellites from the dawn of space flight to today.

The first is Solar Satellites by Drs. Brian Dennis and Ryan Milligan. It is a web article on Scholarpedia with a list of 86 solar research satellites starting with the SOLRAD series that had its first launch in 1960. Dennis and Milligan also describe the instruments and observations on more modern satellites.

Another source is Watching the Sun from Space, which is available as a free download from the linked AJP website. This article starts with Skylab and traces the ways we observe the Sun from space. Links are provided for 27 solar missions, with data available for about 21. It also describes some orbits we haven't yet used to observe the Sun but could in the future.

Since the dawn of the Space Age during the decline of Solar Cycle 19, data from solar missions have been crucial in helping us understand the solar magnetic field and solar activity. Solar observatories in space continue to provide useful solar data and will as long as they keep flying and observing the Sun.

SDO should be around to watch Solar Cycle 25.