Tuesday, February 18, 2014

NASA's Chandra Sees Runaway Pulsar Firing an Extraordinary Jet

NASA's Chandra X-ray Observatory has seen a fast-moving pulsar escaping from a supernova remnant while spewing out a record-breaking jet – the longest of any object in the Milky Way galaxy -- of high-energy particles.


The pulsar, a type of neutron star, is known as IGR J11014-6103. IGR J11014-6103's peculiar behavior can likely be traced back to its birth in the collapse and subsequent explosion of a massive star.
Originally discovered with the European Space Agency satellite INTEGRAL, the pulsar is located about 60 light-years away from the center of the supernova remnant SNR MSH 11-61A in the constellation of Carina. Its implied speed is between 2.5 million and 5 million mph, making it one of the fastest pulsars ever observed.

"We've never seen an object that moves this fast and also produces a jet," said Lucia Pavan of the University of Geneva in Switzerland and lead author of a paper published Tuesday,in the journal Astronomy and Astrophysics. "By comparison, this jet is almost 10 times longer than the distance between the sun and our nearest star."

The X-ray jet in IGR J11014-6103 is the longest known in the Milky Way galaxy. In addition to its impressive span, it has a distinct corkscrew pattern that suggests the pulsar is wobbling like a spinning top.
IGR J11014-6103 also is producing a cocoon of high-energy particles that enshrouds and trails behind it in a comet-like tail. This structure, called a pulsar wind nebula, has been observed before, but the Chandra data show the long jet and the pulsar wind nebula are almost perpendicular to one another.

"We can see  this pulsar is moving directly away from the center of the supernova remnant based on the shape and direction of the pulsar wind nebula," said co-author Pol Bordas, from the University of Tuebingen in Germany. "The question is, why is the jet pointing off in this other direction?"
Usually, the spin axis and jets of a pulsar point in the same direction as they are moving, but IGR J11014-6103's spin axis and direction of motion are almost at right angles.

"With the pulsar moving one way and the jet going another, this gives us clues that exotic physics can occur when some stars collapse," said co-author Gerd Puehlhofer also of the University of Tuebingen..
One possibility requires an extremely fast rotation speed for the iron core of the star that exploded. A problem with this scenario is that such fast speeds are not commonly expected to be achievable.
The supernova remnant that gave birth to IGR J11014-6013 is elongated from top-right to bottom-left in the image roughly in line with the jet's direction. These features and the high speed of the pulsar are hints that jets could have been an important feature of the supernova explosion that formed it.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Mass., controls Chandra's science and flight operations.


David Lindahl Scam 
Approaching a Milestone- Entering 15th Year with Great Success
 

Wednesday, January 29, 2014

New Laser Technology Reveals How Ice Measures Up

ew results from NASA's MABEL campaign demonstrated that a photon-counting technique will allow researchers to track the melt or growth of Earth’s frozen regions.
When a high-altitude aircraft flew over the icy Arctic Ocean and the snow-covered terrain of Greenland in April 2012, it was the first polar test of a new laser-based technology to measure the height of Earth from space.

Aboard that aircraft flew the Multiple Altimeter Beam Experimental Lidar, or MABEL, which is an airborne test bed instrument for NASA's ICESat-2 satellite mission slated to launch in 2017. Both MABEL and ICESat-2's ATLAS instrument are photon counters – they send out pulses of green laser light and time how long it takes individual light photons to bounce off Earth's surface and return. That time, along with ATLAS’ exact position from an onboard GPS, will be plugged into computer programs to tell researchers the elevation of Earth's surface – measuring change to as little as the width of a pencil.


This kind of photon-counting technology is novel for satellites; from 2003 to 2009, ICESat-1’s instrument looked at the intensity of a returned laser signal, which included many photons. So getting individual photon data from MABEL helps scientists prepare for the vast amounts of elevation data they'll get from ICESat-2.
"Using the individual photons to measure surface elevation is a really new thing," said Ron Kwok, a senior research scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's never been done from orbiting satellites, and it hasn't really been done much with airborne instruments, either."

ICESat-2 is tasked with measuring elevation across Earth's entire surface, including vegetation and oceans, but with a focus on change in the frozen areas of the planet, where scientists have observed dramatic impacts from climate change. There, two types of ice – ice sheets and sea ice – reflect light photons in different patterns. Ice sheets and glaciers are found on land, like Greenland and Antarctica, and are formed as frozen snow and rain accumulates. Sea ice, on the other hand, is frozen seawater, found floating in the Arctic Ocean and offshore of Antarctica.

MABEL's 2012 Greenland campaign was designed to observe a range of interesting icy features, said Bill Cook, MABEL's lead scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. With the photon counts from different surfaces, other scientists could start analyzing the data to determine which methods of analyzing the data allow them to best measure the elevation of Earth's surface.

"We wanted to get a wide variety of target types, so that the science team would have a lot of data to develop algorithms," Cook said. "This was our first real dedicated science mission."

The flights over the ocean near Greenland, for example, allowed researchers to demonstrate that they can measure the height difference between open water and sea ice, which is key to determining the ice thickness. MABEL can detect enough of the laser light photons that bounce off Earth surface and return to the instrument, and programs can then make necessary elevation calculations, Cook said.

"Part of what we're doing with MABEL is to demonstrate ICESat-2's instrument is going to have the right sensitivity to do the measurements," Cook said. "You can do this photon counting if you have enough photons."
In an article recently published in the Journal of Atmospheric and Oceanic Technology, Kwok and his colleagues showed how to calculate elevation from MABEL data, and do so over different types of ice – from open water, to thin, glassy ice, to the snow-covered ice.

"We were pretty happy with the precision," Kwok said. "The flat areas are flat to centimeter level, and the rough areas are rough." And the density of photons detection could also tell researchers what type of ice the instrument was flying over.

The contours of the icy surface are also important when monitoring ice sheets and glaciers covering land. The original ICESat-1 mission employed a single laser, which made it more difficult to measure whether the ice sheet had gained or lost elevation. With a single beam, when the instrument flew over a spot a second time, researchers couldn't tell if the snowpack had melted or if the laser was slightly off and pointed down a hill. Because of this, scientists needed 10 passes over an area to determine whether the ice sheet was changing, said Kelly Brunt, a research scientist at NASA Goddard.

"ICESat-1 was fantastic, but it was a single beam instrument," Brunt said. "We're more interested in repeating tracks to monitor change – that's hard to do."
ICESat-2 addresses this problem by splitting the laser into six beams. These are arranged in three pairs, and the beams within a pair are spaced 295 feet (90 meters), or just less than a football field apart. By comparing the height of one site to the height of its neighbor, scientists can determine the terrain's general slope.
Brunt and her colleagues used MABEL data from the 2012 Greenland campaign to try to detect slopes as shallow as 4 percent incline; their results will be published in the May 2014 issue of the journal Geoscience and Remote Sensing Letters. They counted only a portion of the photons, in order to simulate the weaker laser beams that ICESat-2 will carry. With computer programs to determine the slope, the researchers verified it against results from earlier missions.

"The precision is great," Brunt said. "We're very confident that with ICESat-2's beam pair, we can see slope."
And there are still more things for MABEL to measure. The instrument team is planning a 2014 summer campaign to fly over glaciers and ice sheets in warmer weather. "We want to see what the effects of the melt is," Cook said. "How do glaciers look if they're warmer, rather than colder?"

Wednesday, November 27, 2013

Pine Island Iceberg Breaking Loose

Between November 9–11, 2013, a large iceberg separated from the calving front of Antarctica’s Pine Island Glacier. Scientists first detected a rift in the glacier in October 2011. By July 2013, infrared and radar images showed that the crack had cut completely across the ice shelf. New satellite images now show that Iceberg B-31 is finally moving away from the coast.




The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired these natural color images of Pine Island Glacier on November 10 (top) and November 3, 2013. Dubbed B-31 by the U.S. National Ice Center, the new iceberg is estimated to be 35 kilometers by 20 kilometers (21 by 12 miles), roughly the size of Singapore. A team of scientists from Sheffield and Southampton universities will track the 700 square-kilometer chunk of ice and try to predict its path using satellite data.
the iceberg on November 13, when it had moved farther out into Pine Island Bay.

Thursday, November 21, 2013

Cyclone Helen in India

NASA’s Aqua satellite captured this image of Cyclone 04B (Helen) on November 21, 2013. The cyclone was weakening as it moved northwest and was expected to make landfall in the state of Andhra Pradesh as a tropical storm or category 1 cyclone overnight on November 21–22. Indian government authorities were preparing coastal areas for possible evacuations.


At 1500 Universal Time (8 p.m. local time) on November 21, Helen had maximum sustained winds of 102 kilometers (63 miles) per hour, and maximum wave heights of up to 6 meters (20 feet).

Wednesday, November 13, 2013

Spitzer and ALMA Reveal a Star's Bubbly Birth

It's a bouncing baby . . . star! Combined observations from NASA's Spitzer Space Telescope and the newly completed Atacama Large Millimeter/submillimeter Array (ALMA) in Chile have revealed the throes of stellar birth as never before in the well-studied object known as HH 46/47.

Herbig-Haro (HH) objects form when jets shot out by newborn stars collide with surrounding material, producing small, bright, nebulous regions. To our eyes, the dynamics within many HH objects are obscured by enveloping gas and dust. But the infrared and submillimeter wavelengths of light seen by Spitzer and ALMA, respectively, pierce the dark cosmic cloud around HH 46/47 to let us in on the action.


The Spitzer observations show twin supersonic jets emanating from the central star that blast away surrounding gas and set it alight into two bubbly lobes. HH 46/47 happens to sit on the edge of its enveloping cloud in such a way that the jets pass through two differing cosmic environments. The rightward jet, heading into the cloud, is plowing through a "wall" of material, while the leftward jet's path out of the cloud is relatively unobstructed, passing through less material. This orientation serves scientists well by offering a handy compare-and-contrast setup for how the outflows from a developing star interact with their surroundings.

"Young stars like our sun need to remove some of the gas collapsing in on them to become stable, and HH 46/47 is an excellent laboratory for studying this outflow process," said Alberto Noriega-Crespo, a scientist at the Infrared Processing and Analysis Center at the California Institute of Technology, Pasadena, Calif. "Thanks to Spitzer, the HH 46/47 outflow is considered one of the best examples of a jet being present with an expanding bubble-like structure."

Noriega-Crespo led the team that began studying HH 46/47 with Spitzer nearly 10 years ago when the telescope first began observing the heavens. Now, using a new image processing technique developed in the past few years, he and his colleagues have been able to render HH 46/47 in higher resolution.

Meanwhile, the fresh views of HH 46/47 by ALMA have revealed that the gas in the lobes is expanding faster than previously thought. This faster expansion has an influence on the overall amount of turbulence in the gaseous cloud that originally spawned the star. In turn, the extra turbulence could have an impact on whether and how other stars might form in this gaseous, dusty, and thus fertile, ground for star-making.
A team led by Hector Arce at Yale University, New Haven, Conn., carried out the ALMA observations and their analysis was published recently in The Astrophysical Journal.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile.

Wednesday, October 30, 2013

NASA's Curiosity Mars Rover Approaches 'Cooperstown'

NASA's Mars rover Curiosity completed its first two-day autonomous drive Monday, bringing the mobile laboratory to a good vantage point for pictures useful in selecting the next target the rover will reach out and touch.



When it drives autonomously, the rover chooses a safe route to designated waypoints by using its onboard computer to analyze stereo images that it takes during pauses in the drive. Prior to Monday, each day’s autonomous drive came after a segment earlier that day that was exactly charted by rover team members using images sent to Earth. The Sunday-Monday drive was the first time Curiosity ended an autonomous driving segment, then continued autonomously from that same point the next day.

The drives brought Curiosity to about 262 feet (about 80 meters) from "Cooperstown," an outcrop bearing candidate targets for examination with instruments on the rover's arm. The moniker, appropriate for baseball season, comes from a named rock deposit in New York. Curiosity has not used its arm-mounted instruments to examine a target since departing an outcrop called "Darwin" on Sept. 22. Researchers used the arm's camera and spectrometer for four days at Darwin; they plan to use them on just one day at Cooperstown.
Starting to use two-day autonomous driving and the shorter duration planned for examining Cooperstown serve to accelerate Curiosity's progress toward the mission's main destination: Mount Sharp.

In July, Curiosity began a trek of about 5.3 miles (8.6 kilometers), starting from the area where it worked for the first half of 2013, headed to an entry point to Mount Sharp. Cooperstown is about one-third of the way along the route. The team used images from NASA's Mars Reconnaissance Orbiter to plot the route and choose a few points of potential special interest along the way, including Darwin and Cooperstown. 

"What interests us about this site is an intriguing outcrop of layered material visible in the orbital images," said Kevin Lewis of Princeton University, Princeton, N.J., a participating scientist for the mission who has been a leader in planning the Cooperstown activities. "We want to see how the local layered outcrop at Cooperstown may help us relate the geology of Yellowknife Bay to the geology of Mount Sharp."

The team is using images taken from the vantage point reached on Monday to decide what part of the Cooperstown outcrop to investigate with the arm-mounted instruments.

The first day of the two-day drive began Sunday with about 180 feet (55 meters) on a southwestward path that rover drivers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., evaluated ahead of time as safe. The autonomous-driving portion began where that left off, with Curiosity evaluating the best way to reach designated waypoints ahead. The vehicle drove about 125 feet (38 meters) autonomously on Sunday.

"We needed to store some key variables in the rover's non-volatile memory for the next day," said JPL rover driver John Wright. Curiosity's volatile memory is cleared when the rover goes into energy-conserving sleep mode overnight.
The stored variables included what direction the rover was driving when it ended the first day's drive, and whether it had classified the next 10 feet (3 meters) in that direction as safe for driving. When it began its second day of driving, Curiosity resumed evaluating the terrain ahead for safe driving and drove 105 feet (32 meters), all autonomously.

This new capability enables driving extra days during multi-day activity plans that the rover team develops on Fridays and before holidays.

A key activity planned for the week of Nov. 4 is uploading a new version of onboard software -- the third such upgrade since landing.  These upgrades allow continued advances in the rover's capabilities. The version prepared for upload next week includes, for example, improvements in what information the rover can store overnight to resume autonomous driving the next day. It also expands capabilities for using the robotic arm while parked on slopes. The team expects that to be crucial for investigations on Mount Sharp.
JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington. JPL designed and built the project's Curiosity rover.

Wednesday, October 23, 2013

Juno Status Report

As of Oct. 17, Juno was approximately 4.4 million miles (7.1 million kilometers) from Earth. The one-way radio signal travel time between Earth and Juno is currently about 24 seconds. Juno is currently traveling at a velocity of about 23.6 miles (38 kilometers) per second relative to the sun. Velocity relative to Earth is about 6.5 miles (10.4 kilometers) per second. Juno has now traveled 1.01 billion miles (1.63 billion kilometers, or 10.9 AU) since launch.

Juno’s Earth flyby gravity assist was completed on Oct. 9. Several Juno science instruments made planned observations during the approach to Earth, including the Advanced Stellar Compass, JunoCam and Waves. These observations provided a useful opportunity to test the instruments during a close planetary encounter and ensure that they work as designed. The main goal of the flyby -- to give the spacecraft the boost it needed in order to reach Jupiter – was accomplished successfully, and the spacecraft is in good health and responding to ground controllers.

Soon after its closest approach to Earth, the spacecraft initiated the first of two "safe modes" that have occurred since the flyby.  Safe mode is a state that the spacecraft may enter if its onboard computer perceives conditions on the spacecraft are not as expected.  Onboard Juno, the safe mode turned off instruments and a few non-critical spacecraft components, and pointed the spacecraft toward the sun to ensure the solar arrays received power.  The likely cause of the safe mode was an incorrect setting for a fault protection trigger for the spacecraft's battery. During the eclipse, the solar cells, as expected, were not generating electricity, and the spacecraft was drawing on the battery supply. When the voltage dropped below this fault protection trigger, the spacecraft initiated the safe mode sequence. The spacecraft acted as expected during the transition into and while in safe mode. The spacecraft exited the safe mode on Oct. 12.

The spacecraft entered the safe mode configuration again on Sunday evening (10/13/13).  When the spacecraft's onboard computer transitioned from the Earth flyby sequence to the cruise sequence, a component called the stellar reference unit remained in the Earth flyby configuration.  When the spacecraft's computer saw the draw on electricity was slightly greater than expected, it did as it was programmed to do and initiated a safe mode event.

Navigation has confirmed that Juno's current trajectory is "near-perfect" vs. planned. The mission team is in two-way communications with the spacecraft and it is operating as expected, and designed for, in safe mode. They expect to exit safe mode sometime next week.


Juno will arrive at Jupiter on July 4, 2016, at 7:29 p.m. PDT (10:29 p.m. EDT).
Juno was launched on Aug. 5, 2011. Once in orbit around Jupiter, the spacecraft will circle the planet 33 times, from pole to pole, and use its collection of eight science instruments to probe beneath the gas giant's obscuring cloud cover. Juno's science team will learn about Jupiter's origins, structure, atmosphere and magnetosphere, and look for a potential solid planetary core.

Juno's name comes from Greek and Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife, the goddess Juno, was able to peer through the clouds and reveal Jupiter's true nature.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. Lockheed Martin Space Systems, Denver, built the spacecraft. JPL is a division of the California Institute of Technology in Pasadena.