January 2014

Comets are among the most beautiful and least understood nomads of the night sky. To date, half a dozen of these most heavenly of heavenly bodies have been visited by spacecraft in an attempt to unlock their secrets. All these missions have had one thing in common: the high-speed flyby. Like two ships passing in the night (or one ship and one icy dirtball), they screamed past each other at hyper velocity -- providing valuable insight, but fleeting glimpses, into the life of a comet. That is, until Rosetta.

NASA is participating in the European Space Agency's Rosetta mission, whose goal is to observe one such space-bound icy dirt ball from up close -- for months on end. The spacecraft, festooned with 25 instruments between its lander and orbiter (including three from NASA), is programmed to "wake up" from hibernation on Jan. 20. After a check-out period, it will monitor comet 67P/Churyumov-Gerasimenko as it makes its nosedive into, and then climb out of, the inner solar system. Over 16 months, during which old 67P is expected to transform from a small, frozen world into a roiling mass of ice and dust, complete with surface eruptions, mini-earthquakes, basketball-sized, fluffy ice particles and spewing jets of carbon dioxide and cyanide.

"We are going to be in the cometary catbird seat on this one," said Claudia Alexander, project scientist for U.S. Rosetta from NASA's Jet Propulsion Laboratory in Pasadena, Calif.  "To have an extended presence in the neighborhood of a comet as it goes through so many changes should change our perspective on what it is to be a comet."

Since work began on Rosetta back in 1993, scientists and engineers from all over Europe and the United States have been combining their talents to build an orbiter and a lander for this unique expedition.  NASA's contribution includes three of the orbiter's instruments (an ultraviolet spectrometer called Alice; the Microwave Instrument for Rosetta Orbiter; and the Ion and Electron Sensor. NASA is also providing part of the electronics package for an instrument called the Double Focusing Mass Spectrometer, which is part of the Swiss-built Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument. NASA is also providing U.S. science investigators for selected non-U.S. instruments and is involved to a greater or lesser degree in seven of the mission's 25 instruments. NASA's Deep Space Network provides support for ESA's Ground Station Network for spacecraft tracking and navigation.

"All the instruments aboard Rosetta and the Philae lander are designed to work synergistically," said Sam Gulkis of JPL, the principal investigator for the Microwave Instrument for Rosetta Orbiter. "They will all work together to create the most complete picture of a comet to date, telling us how the comet works, what it is made of, and what it can tell us about the origins of the solar system."

The three NASA-supplied instruments are part of the orbiter's scientific payload. Rosetta's Microwave Instrument for Rosetta Orbiter specializes in the thermal properties. The instrument combines a spectrometer and radiometer, so it can sense temperature and identify chemicals located on or near the comet's surface, and even in the dust and ices jetting out from it. The instrument will also see the gaseous activity through the dusty cloud of material.  Rosetta scientists will use it to determine how different materials in the comet change from ice to gas, and to observe how much it changes in temperature as it approaches the sun.

Like the Microwave for Rosetta Orbiter, the Alice instrument contains a spectrometer. But Alice looks at the ultraviolet portion of the spectrum. Alice will analyze gases in the coma and tail and measure the comet’s production rates of water and carbon monoxide and dioxide. It will provide information on the surface composition of the nucleus, and make a potentially key measurement of argon, which will be a big clue about what the temperature was in the primordial solar system when the comet's nucleus originally formed (more than 4.6 billion years ago).

An M5 flare (medium-size) associated with a coronal mass ejection generated a fairly robust radiation storm (May 22-23, 2013). The outburst originated from active region right near the right edge of the Sun. After the eruption, cascades of magnetic loops spun up above the area as the magnetic fields tried to reorganize themselves. When viewed in profile, they put on a marvelous display of solar activity. The images are a combination of two wavelengths of extreme ultraviolet light (at 171 and 304 Angstroms). Credit: NASA's Solar Dynamics Observatory.

Sea water off the east coast of Greenland looked a bit like marbled paper in October 2012. The shifting swirls of white were sea ice, as observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on October 17, 2012. In fact, this ice moved discernibly between October 16 and October 17. Thin, free-drifting ice moves very easily with winds and currents.

Each year, Arctic sea ice grows through the winter, reaching its maximum extent around March. It then melts through the summer, reaching its minimum in September. By October, Arctic waters start freezing again. However, the ice in the image above is more likely a remnant of old ice that migrated down to the coast of Greenland. Sea water is unlikely to start freezing this far south in October.

Along Greenland’s east coast, the Fram Strait serves as an expressway for sea ice moving out of the Arctic Ocean. The movement of ice through the strait used to be offset by the growth of ice in the Beaufort Gyre. Until the late 1990s, ice would persist in the gyre for years, growing thicker and more resistant to melt. Since the start of the twenty-first century, however, ice has been less likely to survive its trip through the southern part of the Beaufort Gyre. As a result, less Arctic sea ice has been able to pile up and form multi-year ice.

With less thick ice there is less Arctic sea ice volume, something the researchers at the Polar Science Center at the University of Washington have modeled from 1979 to 2012. Their results appear in the graph above. The model indicates that ice volume peaks in March through May of each year and reaches its lowest levels from August through October. But while the seasonal timing of the peaks and valleys has remained consistent since 1979, the total sea ice volume has declined.

The thick blue line is the 1979–2000 average, and the lighter blue bands surrounding it are one and two standard deviations from the median. The lines below the blue line are the calculated sea ice volumes for the years since 2000. All of them fall below the median, and almost all of them fall below two standard deviations.

The drop in sea ice volume is consistent with other observed changes in Arctic sea ice. In terms of sea ice extent, the National Snow and Ice Data Center and NASA reported that Arctic sea ice set a record low in September 2012.

The sun emitted a mid-level solar flare, peaking at 5:13 a.m. EST on Jan. 7, 2014. Images of the flare were captured by NASA's Solar Dynamics Observatory and showed that it came from an active region on the sun that currently sports one of the largest sunspots seen in the last 10 years. Sunspots are regions of strong and complex magnetic fields on the sun's surface.

Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel.

To see how this event may impact Earth, please visit NOAA's Space Weather Prediction Center at http://spaceweather.gov, the U.S. government's official source for space weather forecasts, alerts, watches and warnings.

This flare is classified as an M7.2-class flare.

Swirling, stormy clouds may be ever-present on cool celestial orbs called brown dwarfs. New observations from NASA's Spitzer Space Telescope suggest that most brown dwarfs are roiling with one or more planet-size storms akin to Jupiter's "Great Red Spot." "As the brown dwarfs spin on their axis, the alternation of what we think are cloud-free and cloudy regions produces a periodic brightness variation that we can observe," said Stanimir Metchev of the University of Western Ontario, Canada. "These are signs of patchiness in the cloud cover."

In a Spitzer program named "Weather on Other Worlds," astronomers used the infrared space telescope to watch 44 brown dwarfs as they rotated on their axis for up to 20 hours. Previous results had suggested that some brown dwarfs have turbulent weather, so the scientists had expected to see a small fraction vary in brightness over time. However, to their surprise, half of the brown dwarfs showed the variations. When you take into account that half of the objects would be oriented in such a way that their storms would be either hidden or always in view and unchanging, the results indicate that most, if not all, brown dwarfs are racked by storms.

"We needed Spitzer to do this," said Metchev. "Spitzer is in space, above the thermal glow of the Earth's atmosphere, and it has the sensitivity required to see variations in the brown dwarfs' brightness."
The results led to another surprise as well. Some of the brown dwarfs rotated much more slowly than any previously measured, a finding that could not have been possible without Spitzer's long, uninterrupted observations from space. Astronomers had thought that brown dwarfs sped up to very fast rotations when they formed and contracted, and that this rotation didn't wind down with age.

"We don't yet know why these particular brown dwarfs spin so slowly, but several interesting possibilities exist," said Heinze.  "A brown dwarf that rotates slowly may have formed in an unusual way -- or it may even have been slowed down by the gravity of a yet-undiscovered planet in a close orbit around it."

The work may lead to a better understanding of not just brown dwarfs but their "little brothers": the gas-giant planets. Researchers say that studying the weather on brown dwarfs will open new windows onto weather on planets outside our solar system, which are harder to study under the glare of their stars. Brown dwarfs are weather laboratories for planets, and, according to the new results, those laboratories are everywhere.

The International Space Station Program and Orbital Sciences Corporation have decided to postpone the launch of the Antares rocket and its Cygnus cargo craft on the first Orbital commercial resupply mission to the space station to no earlier than Wednesday, Jan. 8 due to the forecast of cold temperatures for Tuesday, Jan. 7 at the launch site at NASA’s Wallops Flight Facility in Virginia.

The forecast for Wednesday also calls for cold temperatures, but the station program and Orbital plan to revisit the weather forecast at the beginning of the week. The main concern with the weather is the cold temperatures coupled with likely precipitation. Orbital says the Antares rocket has a lower limit temperature constraint of 20 degrees Fahrenheit.

Orbital still plans to roll out its Antares rocket to Launch Pad 0A at Wallops on Saturday night because the weather is forecast to be favorable at that time. The launch time for Wednesday, Jan. 8 is 1:32 p.m. Eastern time. NASA TV coverage of launch will begin at 1 p.m.

A launch on Wednesday will result in a grapple of Cygnus by the Expedition 38 crew aboard the station on Sunday, Jan. 12 at 6:02 a.m. NASA TV coverage will begin at 5 a.m. Coverage of the installation of Cygnus on the Earth-facing port of the Harmony module will begin at 7 a.m.

The sun ushered out 2013 and welcomed 2014 with two mid-level flares on Dec. 31, 2013 and Jan. 1, 2014. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel. This disrupts the radio signals for as long as the flare is ongoing, anywhere from minutes to hours.

To see how this event may impact Earth, please visit NOAA's Space Weather Prediction Center at http://spaceweather.gov, the U.S. government's official source for space weather forecasts, alerts, watches and warnings.

The first flare (below) was categorized as an M6.4 and it peaked at 4:58 p.m EST on Dec. 31. The second (above) was categorized as an M9.9 and peaked at 1:52 p.m. EST on Jan. 1. Both flares emerged from the same active region on the sun, AR1936. Imagery of the flares was captured by NASA's Solar Dynamics Observatory, which keeps a constant watch on the sun, collecting new data every 12 seconds.


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