‘Spectacular’ sights come from solar probe

Solar Dynamics Observatory's first images pose scientific puzzles

This full-disk multiwavelength extreme ultraviolet image of the sun was taken by the new Solar Dynamics Observatory on March 30. False colors trace different gas temperatures. Reds are relatively cool (about 110,000 degrees Fahrenheit); blues and greens are hotter (greater than 1.8 million degrees F).

The first images of the sun beamed home from NASA's newest solar observatory have wowed mission scientists with their extraordinary detail and unexpected findings.

NASA on Wednesday released the first new images from the Solar Dynamics Observatory, a probe launched on Feb. 11 to peer deep into the layers of the sun, monitor solar storms and investigate the mysteries of the sun's inner workings.

"The spacecraft and the instruments are working very well," said Richard Fisher, director of the Heliophysics Division at NASA Headquarters in Washington. "What we've seen is truly, in my view, spectacular." 

The Solar Dynamics Observatory, or SDO, carries three instruments that constantly stare at the sun, generating images that have a resolution 10 times better than high-definition television.

"I believe this is going to be a revolutionary view" of the sun, said Fisher, who likened the new observatory's impact to that of the Hubble Space Telescope.

SDO will be revolutionary to the study of the sun "in the same way Hubble was revolutionary for astrophysics," he told Space.com.

The young solar observatory will also be generating an astounding amount of data.

It will stream the equivalent of half a million songs per day down to a ground station from its geosynchronous orbit. That's about 150 million bits of data per second, 24 hours a day, seven days a week — almost 50 times more science data than any other mission in NASA's history.

Monitoring solar flares, stormsThe simultaneous monitoring of several wavelengths of the sun's light, coupled with the more rapid pace of observations, will give scientists an unprecedentedly detailed view of the features present on the sun. It will also help monitor the solar flares and storms that can impact Earth, as well as shed light on the influence of the sun's magnetic field on the processes that take place within the sun.

"The nice thing about SDO is that we have all of the sun all of the time," said Philip H. Scherrer the principal investigator for SDO's Helioseismic and Magnetic Imager instrument at Stanford University. Already observations of solar features and their evolution is showing that "the magnetic field is really much more dominant than we thought," Fisher said.

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It's also very dynamic: "That magnetic field is never the same twice, it is always changing," said Dean Pesnell, SDO project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

And though the spacecraft is still in its commissioning phase — meaning all of the instruments are being properly calibrated and the probe is entering its final orbit — it has taken images that are already making unexpected revelations.

One particularly interesting observation, Fisher said, shows the evolution of an active region of the sun, also known as a sunspot. The dark spots on the sun's surface are connected to intense magnetic activity. SDO caught this sunspot in decline that didn't look quite how scientists expected it to.

"It's a little bit baffling about what happened," Fisher said.

Tiny changes, huge impact
SDO observed that tiny changes in the magnetic field due to the decline of the sunspot "have a huge impact on the upper solar atmosphere," Fisher said, likening that to a situation on Earth where a lightning bolt in Indiana would cause a hurricane on the East Coast.

The sunspot is associated with a blast of solar material out into space known as a coronal mass ejection, or CME. SDO was able to see the sunspot associated with this CME as well as the waves rippling across the sun's surface associated with it and the flare that caused it.

The CME ejected as much material as is contained in the entire Mississippi River at a speed of about a million miles per hour; the material was accelerated up to that speed in just one second, said Alan Title, the principal investigator of SDO's Atmospheric Imaging Assembly instrument at Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, Calif.

That SDO is already stumping scientists with its findings even though it's not yet in full observing mode (which will happen sometime next month) shows what a useful spacecraft it is, Fisher said.

"The hallmark of a successful science experiment [is] that you don't understand what you've gotten back," he said.

Helping with predictionsSuch solar events aren't just interesting to scientists — they can have a major impact on the Earth by knocking out communication systems, GPS satellites and even electrical grids. Scientists hope that SDO will allow them to make better predictions on when solar flares and CMEs might erupt in Earth's direction.

Solar cells made through oil-and-water 'self-assembly'

Researchers have demonstrated a simple, cheap way to create self-assembling electronic devices using a property crucial to salad dressings.

It uses the fact that oil- and water-based liquids do not mix, forming devices from components that align along the boundary between the two.

The idea joins a raft of approaches toward self-assembly, but lends itself particularly well to small components.

The work is reported in Proceedings of the National Academy of Sciences.

Crucially, it could allow the large-scale assembly of high-quality electronic components on materials of just about any type, in contrast to "inkjet printed" electronics or some previous self-assembly techniques.

Specific gravity

Such efforts have until now exploited the effect of gravity, assembling devices through so-called "sedimentation".

In this approach, "blank" devices are etched with depressions to match precisely-shaped components. Simply dumped into a liquid, the components should settle down into the blank device like sand onto a riverbed, in just the right places.

"That's what we tried for at least two years and we were never able to assemble these components with high yield - gravity wasn't working," said Heiko Jacobs of the University of Minnesota, who led the research.

SELF-ASSEMBLY EXPLAINED The oil/water mix contains a number of individual solar cell elements Each is coated with a "water-loving" molecule on the bottom and a "water-hating" one on top The elements align neatly at the oil/water boundary in a two-dimensional sheet The "blank" solar cell has pre-cut places for the elements and is dipped through the boundary As it is slowly drawn upwards, the elements pop into place

"Then we thought if we could concentrate them into a two-dimensional sheet and then have some kind of conveyor belt-like system we could assemble them with high yields and high speed," he told BBC News.

To do that, the team borrowed an idea familiar to fans of vinaigrette: they built their two-dimensional sheets at the border between oil and water.

They first built a device blank as before, with depressions lined with low-temperature solder, designed for individual solar cell elements.

They then prepared the elements - each a silicon and gold stack a few tens of millionths of a metre across - and put different coatings on each side.

On the silicon side, they put a hydrophobic molecule, one that has a strong tendency to evade contact with water. On the gold side, they put a hydrophilic molecule, which has the converse tendency to seek out water.

By getting the densities of the oil- and water-based parts of the experiment just right, a "sheet" of the elements could be made to "float" between the two, pointing in the right direction thanks to their coatings.

The conveyor belt process is to simply dunk the device blank through the boundary and draw it back slowly; the sheet of elements rides up along behind it, each one popping neatly into place as the solder attracts its gold contact.

The team made a working device comprising 64,000 elements in just three minutes.

Bendy future

Having proved that the concept works, the team is now investigating just how small they can go in terms of individual elements, or how large they can go in finished devices.

The approach should also work for almost any material, stiff or flexible, plastic, metal or semiconductor - a promising fact for future display and imaging applications.

Babak Parviz, a nano-engineering professor at the University of Washington in Seattle, said the technique is a "clear demonstration that self-assembly is applicable across size scales".

"Self-assembly is probably the best method for integrating high-performance materials onto unconventional substrates," he told BBC News.

The method tackles what Dr Parviz said is the most challenging problem - the proper alignment of thousands of parts, each thinner than a human hair. But it also works with the highest-performance materials, he said.

"For example, this method allows one to use single-crystal silicon, which is far superior to other types of silicon for making solar cells."