SDO On Station Transmitting First Data as Solar Science Payloads Open Today

by Ken Kremer on March 24, 2010

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Video Caption: EVE rediscovered the Van Allen Radiation Belt. These EVE data highlight where the energetic protons are in the inner Van Allen radiation belt. The red dots indicate the highest concentration of protons (lower altitude), and the blue-violet dots represents very little detection of particles (higher altitude of GEO). Visualization by Chris Jeppesen.

Following several precise propulsion burns to circularize its orbit, NASA’s Solar Dynamics Observatory (SDO) has arrived “On Station” and multiple tasks critical to check out of the science instruments are in progress this week, according to Dean Pesnell. Pesnell is the SDO project scientist from NASA’s Goddard Spaceflight Center which built the spacecraft and manages the nearly $1 Billion mission for NASA.

“We reached our final orbit on March 16, 2010”, Pesnell told me in an interview. “The SDO spacecraft is working great and all systems are behaving as expected”. SDO was launched on Feb. 11, 2010 from Cape Canaveral Air Force Station aboard an Atlas V rocket.

Blast off on Feb 11 of mighty Atlas V rocket and SDO from Pad 41 at Cape Canaveral as viewed from the KSC press site. Credit: Ken Kremer

The revolutionary science mission has been dubbed the “crown jewel” of NASA’s Solar Exploration research fleet, joining the twin STEREO spacecraft and SOHO. SDO is equipped with three science instruments (HMI, AIA, and EVE) to explore the Sun and its complex interior mechanisms in unprecedented detail.

Although the doors to the solar science payload will be opened starting just today (March 24), SDO has already managed to transmit its “first data”, Pesnell explained. This bonus science data from Earth’s radiation belt was unexpected he said. The first solar light data will come after the science instruments are fully activated.

SDO Instruments

“One detector in EVE was responding to the protons in the inner Van Allen radiation belt. We spent several orbits going through that part of space and EVE was able to produce a map of the radiation belt,” said Pesnell.

“The amount of proton data was not expected as we were not supposed to spend as much time in the belts as we did. By spending a few extra days in the inner belt the MEGS-P radiometer was able to measure a more complete picture of the radiation belt. It may be the only measurement of the proton fluxes in the inner radiation belt during the extremely low solar activity of the current solar minimum,” added Pesnell.

Check out of the science payload is moving ahead swiftly as planned. “The SDO instruments are working through their initial steps to turning them completely on”, Pesnell explained. A key activity was to “bake out” the instruments to remove any remaining harmful contaminants that could threaten to degrade the quality of the science data.

“CCD decontamination heaters had been turned on for several weeks to allow the instruments to outgas any residual contamination”, according to Pesnell. “During the first 40 days of the mission the instruments kept their CCDs hot with heaters. This prevents water vapor from condensing onto the surfaces of the CCDs while forcing water vapor out of the interior of the instruments. Two instruments, HMI and EVE, have turned off their decontamination heaters while AIA will turn them off next week. Those heaters are being turned off to allow the CCD’s to cool to their normal operating temperatures of about minus 100 C”.

“HMI will open their payload door Wednesday and begin checking out the instrument. EVE is cooling their CCDs getting ready to open their doors on Thursday. AIA will open their doors on Saturday”.

Pesnell mentioned that the SDO team expects to show off the initial data at a telecom in mid-April. “The science data should start to flow in early May, fully calibrated data will show up later. We will discuss the data at the SPD/AAS meeting in Miami, FL at the end of May”.

Van Allen Radiation Belts

SDO will collect a staggering 1.5 terabytes of data per day, equivalent to 380 full length movies per day on a 24/7 basis. “The data will be continuously beamed back to newly built receivers on Earth. We have no onboard recorders since nothing is available to handle such a huge data volume,” said Pesnell. “SDO will transmit 50 times more science data than any other mission in NASA history”.

Test data have already been transmitted via the spacecraft antenna to the receiving station on the ground in New Mexico, confirming that the vital communications systems are operating perfectly.

SDO’s measurements of the Sun’s interior, magnetic field and hot plasma of the solar corona will allow scientists to determine how violent solar events are created which then cause ‘space weather’ that ultimately affects every aspect of life here on Earth. The goal is create better predictions of ‘space weather’ in order to provide early warning to valuable satellites and astronauts operating in space, and to prevent disruption to navigation systems and failures in the power grid.

Rocket firing to raise SDO to its final orbit on March 16, 2010. click to enlarge

SDO was launched into a geosynchronous transfer orbit with an apogee altitude (farthest point from Earth) of 36,000 km (22,000 miles) and a perigee altitude (closest point to Earth) of 2500 km (1600 miles). Over the next 34 days the propulsion module was used to raise the perigee altitude to 36,000 km, with a few small burns to push both apogee and perigee to geosynchronous.

“SDO is in an inclined geosynchronous orbit at the longitude of New Mexico. The inclination of 28 degrees is the natural orbit when launched from Kennedy Space Center. Changing the inclination of an orbit requires a lot of fuel, so this orbit was less expensive than a geostationary orbit,” said Pesnell. This orbit will keep the observatory in constant view of the two newly constructed 18-meter dishes around the clock so that not a single bit of data should be lost.

Nancy Atkinson and Ken Kremer covered the Feb 11, 2010 SDO launch on site at KSC for Universe Today

Read SDO launch report by Nancy Atkinson here.

Read earlier SDO reports by Ken Kremer below, including from on site at the Atlas launch pad

NASA Sun Probe rolled to Pad; 10 hours to Blast off

NASA’s Solar Crown Jewel Bolted atop Atlas Rocket

NASA advanced Solar Observatory nearing February launch; will send IMAX like movies daily

Learn more at the NASA SDO Website

SDO soars to space from the Kennedy Space Center atop Atlas V rocket on Feb 11, 2010 as I observed from the KSC Press Site. Credit: Ken Kremer

Artist's concept of the Solar Dynamics Observatory in Orbit


Dr. Ken Kremer is a speaker, scientist, freelance science journalist (Princeton, NJ) and photographer whose articles, space exploration images and Mars mosaics have appeared in magazines, books, websites and calanders including Astronomy Picture of the Day, NBC, BBC,, Spaceflight Now and the covers of Aviation Week & Space Technology, Spaceflight and the Explorers Club magazines. Ken has presented at numerous educational institutions, civic & religious organizations, museums and astronomy clubs. Ken has reported first hand from the Kennedy Space Center, Cape Canaveral and NASA Wallops on over 40 launches including 8 shuttle launches. He lectures on both Human and Robotic spaceflight -

Hon. Salacious B. Crumb March 26, 2010 at 9:26 PM

Sorry. The last paragraph should read;

One final comment. Ian will say this has nothing to do with SDO. We all know it does, because if we were to take the EU/PC point of view, then we are WRONGLY interpreting what SDO is actually observing. (Also remember the spallation in flares of 7Li. Can SDO find evidence of this in flares?)

Hon. Salacious B. Crumb March 26, 2010 at 11:20 PM

As for Jean statement that “A big majority (60-80%?) of the universe’s baryons are found in the intra-cluster medium of rich clusters and in the WHIM (warm-hot intergalactic medium).”

I was really hoping that Ian would have said that… (Same spider, wrong fly! :))

Values quoted are usually stated as 40%-50%, and the value is only assumed via computer simulations. There is much debate on the nature of this plasma – properly called collision less plasma. Much of it is thought to be remnants of the Big Big, and these baryons are studies under baryongenesis.

Most of this collisionless kind is just sitting in space, and is not connected to any organised electric or magnetic field. It varies enormously in anisotropic temperature, electron temperature and ion differences. This stuff makes up the vast majority of your WHIM (c.95%). What is interesting is that gravity or shocks acts on these collision less plasma, which like in galaxy clusters, is literally drawn into activity. Activity is based over long time periods and various epochs like just after the big bang or when the galaxy cluster were forming, etc. I.e. It is epoch dependant. (As the universe expands the less likely will the WHIM will be important.)

Of course, much of this is speculation, as the only evidence is by soft X-rays along filaments and in active galaxy nuclei and only active galaxy clusters. There is no true observational evidence of the quantity of collisionless plasma nor can it be formally observed – only because it doesn’t show itself. (it is about equally ubiquitous as dark matter or dark energy – and we are yet to find that too!)

Then there is the observed “active plasma” which 99% lies inside stars. This is based mostly on the high density in stellar cores compared to the galactic and intergalactic medium.

Actually, the EU/PC view should read;

“”…99% of the visible universe is LIKELY in the plasma state””

Also, my statement should read;

“99% of the visible universe is LIKELY in the plasma state, but nearly all of THE OBSERVABLE PLASMA is inside stars, and it occupies a volume that is merely a tiny fraction of the universe.

Actually another statement that astounds me is;

“As the nucleon mass is nearly 2000 times the mass of an electron, then all atoms and molecules contain at least as many nucleons as electrons, baryons account for more than 99.5% of the total mass of all the chemical elements observed in the Universe.”

Jon Hanford March 27, 2010 at 9:41 AM

“The intergalactic medium is full(sic) ionized.(ref)”

I wasn’t sure if the source (Zweibel) was referring to the IGM in galaxy clusters or space in general. Rereading of the ref, he mentions this twice, and clearly is talking about the entire IGM. I guess he is not familiar with work over many decades on the distribution of NEUTRAL hydrogen observed both locally around and between galaxies and at the most distant regions of the universe. Might want to read up on the “Lyman-alpha forest” ( ).

“In astronomical spectroscopy, the Lyman alpha forest is the sum of absorption lines arising from the Lyman alpha transition of the neutral hydrogen in the spectra of distant galaxies and quasars.”
“The Lyman alpha forest is an important probe of the intergalactic medium and can be used to determine the frequency and density of clouds containing neutral hydrogen, as well as their temperature.”
“For quasars at higher redshift the number of lines in the forest is higher, until at a redshift of about 6, there is so much neutral hydrogen in the intergalactic medium that the forest turns into a Gunn-Peterson trough. This shows the end of the reionization of the universe.”

Relatively large amounts of neutral hydrogen can also be found in the local universe, usually (but not always) in proximity to known galaxies. So how is the IGM “fully ionized”?

Jean Tate March 27, 2010 at 1:57 PM

iantresman, and others,

As the study of the IGM progresses, it becomes clear that it is not uniform.

However, the existence of large clouds of unionized (neutral) clouds of hydrogen in the local IGM has been known for decades (google HVC = high velocity clouds, for example), and many of these sorts of things are to be expected (for example, minor and major mergers, and close encounters, esp of gas-rich spirals, should produce tidal streams which include many largely neutral gas clouds, and that’s exactly what’s observed – google Magellanic Stream, for example).

In any case, it seems to me there’s no science involved here, just a kind of trivia quiz.

Jean Tate March 27, 2010 at 4:39 PM

Highly ionized HVCs are highly ionized. They tend to have low HI column densities.

HVCs with high column densities may have relatively high degrees of ionization, or not; this is an interesting area of research.

The extent to which a region of space, part of the ISM or IGM for example, is ionized is really only meaningful in terms of sorts of science questions you’re trying to answer. One of the interesting puzzles is why the dust which seems to be within some of the IGM (and ISM) clouds is so cold, despite the fact that many ionized metal lines are detected (in absorption). The characteristic time scales for mixing can be very long (billions of years), far longer than the mean time between major galaxy interactions (in groups). Very little is known about the WHIM (except that it’s exceedingly tenuous, of very low metallicity, and contains no HI to speak of).

Jon Hanford March 27, 2010 at 5:19 PM

Jean Tate & iantresman,

Thank you for your replies and expansion of several of your comments in response to my question concerning ionization of the IGM. Agreed study of HVCs is an interesting subfield all by itself.

Hon. Salacious B. Crumb March 27, 2010 at 6:07 PM

@ iantresman said;

“Yes, it looks like more recent work may supersede the “fully ionized” source (Soward, 2005) , though he does note that “After about 2E8 years, sources of Lyman continuum radiation appeared which reionized the universe, and have maintained the intergalactic medium as a fully ionized plasma, up to the present day”.

That is why plasma in the universe is also epoch dependant! (Why does EU/PC never mention that tidbit too?)

So factually your favourite little statement needs to be modified to;

“…99% of the visible universe is LIKELY in the current epoch to be in the plasma state”

As for “There is no dispute that most of the mass of cosmic plasma is in stars. And each second, our Sun ejects about million tons of plasma per second (ref), that’s over a trillion tons of plasma per year, over a proportion of the Sun’s multi-billion year life time. And our Sun is just one of 100s of billions of stars in our galaxy doing exactly the same, and our galaxy is just one of 100s of billions, all pouring plasma out into space.”

There is a little problem here. What is happening to that plasma? Are you assuming that this makes the grand galactic magnetic field and is immediately then organised into some sort of ground shaking observable phenomena?

It is the end behaviour of the plasma that you have a problem with (and is likely the core of most PC/EU invalid assumptions) – as most of it becomes just uninteresting and boring collisionless plasma that interacts with nothing but itself!

It all comes back to just one thing – that plasma and electric / magnetic fields are partially influential, by it is all gravitational interaction cause most of the astronomical/ astrophysical phenomena. It is that organisation of all matter that determines any possible future plasma interaction – and not the other way round.

(…sorry, PC/EU, clearly has more than the 4000 holes allegedly in Blackburn, Lancashire.)

Comment: My biggest concern regarding ionisation of the IGM is the idea of “cold plasma” (much of it is really only partially ionised.) Sure it is by broad definition plasma, but it importance in astrophysical / astronomical matter is rather piffling. Hell, you could say a glass of water is said to be ionised, but is it “plasma”, “cold plasma” or just “ordinary matter”?
Really, it is as I eluded to before, it is mostly tedious semantics and playing with lexical definitions. PC/EU will always fail, not because it is right or wrong, it is its proponents do not define clearly what they mean – and worst it is deliberately done just to aim for the high ground. I.e. spallation being stated as fusion-based nucleosynthesis, when it is clearly not.
To PC/EU proponents it is a game, to the rest of us it is frankly irrelevant.

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