Black carbon, a short-lived particle, is in perpetual motion across the globe. The Tibetan Plateau's high levels of black carbon likely impact the region's temperature, clouds and monsoon season.

The needle-in-a-haystack object found by Hubble is only 3,200 feet across and a whopping 4.2 billion miles away. The smallest Kuiper Belt Object (KBO) seen previously in reflected light is roughly 30 miles across, or 50 times larger.

This is the first observational evidence for a population of comet-sized bodies in the Kuiper Belt that are being ground down through collisions. The Kuiper Belt is therefore collisionally evolving, meaning that the region's icy content has been modified over the past 4.5 billion years.

The object detected by Hubble is so faint - at 35th magnitude -- it is 100 times dimmer than what the Hubble can see directly.

So then how did the space telescope uncover such a small body?

In a paper published in the December 17th issue of the journal Nature, Hilke Schlichting of the California Institute of Technology in Pasadena, Calif., and her collaborators are reporting that the telltale signature of the small vagabond was extracted from Hubble's pointing data, not by direct imaging.

Hubble has three optical instruments called Fine Guidance Sensors (FGS). The FGSs provide high-precision navigational information to the space observatory's attitude control systems by looking at select guide stars for pointing. The sensors exploit the wavelike nature of light to make precise measurement of the location of stars.

Schlichting and her co-investigators determined that the FGS instruments are so good that they can see the effects of a small object passing in front of a star. This would cause a brief occultation and diffraction signature in the FGS data as the light from the background guide star was bent around the intervening foreground KBO.

They selected 4.5 years of FGS observations for analysis. Hubble spent a total of 12,000 hours during this period looking along a strip of sky within 20 degrees of the solar system's ecliptic plane, where the majority of KBOs should dwell. The team analyzed the FGS observations of 50,000 guide stars in total.

Scouring the huge database, Schlichting and her team found a single 0.3-second-long occultation event. This was only possible because the FGS instruments sample changes in starlight 40 times a second. The duration of the occultation was short largely because of the Earth's orbital motion around the sun.

They assumed the KBO was in a circular orbit and inclined 14 degrees to the ecliptic. The KBO's distance was estimated from the duration of the occultation, and the amount of dimming was used to calculate the size of the object. "I was very thrilled to find this in the data," says Schlichting.

Hubble observations of nearby stars show that a number of them have Kuiper Belt-like disks of icy debris encircling them. These disks are the remnants of planetary formation. The prediction is that over billions of years the debris should collide, grinding the KBO-type objects down to ever smaller pieces that were not part of the original Kuiper Belt population.

The finding is a powerful illustration of the capability of archived Hubble data to produce important new discoveries. In an effort to uncover additional small KBOs, the team plans to analyze the remaining FGS data for nearly the full duration of Hubble operations since its launch in 1990.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc. in Washington, and is an International Year of Astronomy 2009 program partner.

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"The completion of the Demonstration Motor 1 hot-fire test is a substantial advancement in developing the ACM," said LAS Manager Kevin Rivers, of NASA’s Langley Research Center in Hampton, Va. "With an elaborate eight-valve control system that relies on advanced ceramic composites for several key components, the ACM is among the most complex solid rocket systems ever built."

The test performed at ATK’s facility in Elkton, Md., was the sixth in a series of ground tests of Orion’s attitude control motor system. The ACM is charged with keeping the crew module on a controlled flight path after it jettisons, steering it away from the Ares 1 crew launch vehicle in the event of an emergency, and then reorienting the module for parachute deployment.

Having reached this milestone brings Constellation another step closer to flight-ready status and demonstrates progress toward improved flight safety for astronauts, which is at the core of Constellation Program success.

The launch abort system, mounted on top of the Orion crew module, centers around three solid propellant rocket motors: an abort motor, an attitude control motor; and a jettison motor. Successful tests of both the abort and jettison motors were completed in 2008. The attitude control motor consists of a solid propellant gas generator, with eight proportional valves equally spaced around the outside of the 32-inch diameter motor. Together, the valves can exert up to 7,000 pounds of steering force to the vehicle in any direction upon command from the crew module.

"Controllable solid rockets have only recently begun seeing application in spacecraft, and the ACM delivers an order of magnitude greater thrust than any of those systems," said Rivers. "It represents a significant technical advancement in controllable solid propulsion."

Testing wouldn’t be possible without the support and hard work from the ATK, Lockheed Martin and NASA LAS teams.

"There are many dedicated people from across the nation who have worked diligently to overcome technical challenges to make the test happen,” said Rivers. “I am proud of each of them."

The entire launch abort system will be demonstrated during a Pad Abort 1 flight test at the U.S. Army’s White Sands Missile Range (WSMR) in New Mexico in the spring of 2010.

The attitude control motor for the flight test is scheduled to be delivered to WSMR in January, followed by the stacking of the launch abort system.

Langley manages the launch abort system design and development effort with partners and team members from NASA’s Marshall Space Flight Center in Huntsville, Ala. Langley’s Launch Abort System Office performs this function as part of the Orion Project Office located at NASA’s Johnson Space Center in Houston. ATK is under contract with Lockheed Martin, NASA’s prime contractor for Orion, to develop and test the attitude control motor.

A months-long airborne campaign in 2008 gave scientists a new look at how everyday human behaviors in Europe, North America and Asia are affecting the Arctic, the most rapidly changing region on Earth and a major regulator of the planet's climate. The data show human fingerprints all over the Arctic in the form of polluted exhaust from factories and smoke from fires often set by human hands. Observations from the ground have long recorded some of this impact, and satellites in low-earth orbit provide a different view, but scientists had not undertaken a detailed, airborne study of this magnitude in years.

The mission provided a new view of how pollution from industrializing Asian countries influences the Arctic. Ground sensors have long detected the regular, low-altitude movement of polluted air masses from Europe to the Arctic. Because of the colder temperatures in the countries of the pollution's origin, the plumes of carbon dioxide, carbon monoxide and other warming-related gases do not rise high in the atmosphere. On the contrary, pollution from warmer regions in Asia has apparently been moving to altitudes too high for ground instruments to observe well. The airborne instruments provided invaluable measurements of the extent of this pollution, said Daniel Jacob, a Harvard University atmospheric scientist and both mission scientist and co-principal investigator for NASA’s Arctic Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission.

"With Asian pollution, there's a relatively warm ocean immediately downwind of a fairly cold continent, so you have interesting storm tracks that lift pollution and transport it at higher altitudes," Jacob said. "It's certainly a much larger influence on Arctic haze than what had been traditionally ascribed."

Now that researchers have had some time to sift through the data collected, Jacob said the value of these observations is coming in to focus. Major airborne campaigns like this are rare, so almost any study of the Arctic atmosphere in coming years will draw on ARCTAS.

"We're getting to the point where results from ARCTAS are getting into climate models. We’re able to test different models of snow albedoes, and we've been able to introduce some corrections," Jacob said. "From the standpoint of the Asian pollution influence, if you want to claim Asia has a certain influence, you better check it against the ARCTAS results."

While factories, power plants and cars on the highway provide a 365-day-a-year source of pollution, the Arctic flights revealed insights into a more cyclical source of emissions: fires in boreal forests and from agricultural burning as far away as Kazakhstan. In concert with NASA, NOAA sponsored spring flights as part of a field study called Aerosols, Radiation and Cloud Processes affecting Arctic Climate (ARCPAC). These flights observed an unusually active spring fire season. Even if the data collected was somewhat anomalous, scientists say it has provided great insight into fire and smoke influence on the Arctic. In addition, there is some evidence that as the Arctic warms and dries out, there is more fuel for these fires.

"We expected to see pollution. But it turns out there's a seasonal cycle to fires, and there’s a springtime peak and summertime peak," said Chuck Brock, ARCPAC project scientist. "I don't think we appreciated that these fires in Siberia and in southern Russia could be so dominant and important in the Arctic. So, is 2008 representative or is it an unusual year? But every year there is this peak, and every year this smoke gets carried to the Arctic."

Brock said the wealth of data will be important in studying the link between smoke and cloud formation and the repercussions of this link. For instance, could there be an impact on snowmelt -- through aerosol-related warming -- if the spring fire season inches up by even a week or two?

The campaigns also provided the opportunity to create a sharper picture of several specific emission sources of greenhouse gases that find their way to the Arctic. Scientists focused on emissions from the oil and gas industry in Prudhoe Bay, Alaska and the natural methane emissions from the massive wetlands near Hudson Bay in Canada. These are two examples of the many variables that need to be accurately characterized in order for scientists to understand what is driving Arctic warming.

It is the rarity of these measurements that makes them important to future study of the Arctic climate, said Jim Crawford, a research scientist at NASA's Langley Research Center and the ARCTAS program manager during the campaign. The data gathered will allow scientists to better interpret satellite observations and better simulate how industrial pollution and wildfire smoke affect the Arctic.

"For scientists interested in studying the role of changing atmospheric composition on climate, the ARCTAS data will represent the best and often only detailed information available for this poorly characterized region," Crawford said.

Related Links:
› ARCTAS Mission
› NASA's Earth Science Project Office

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