Exploration Images
Mars Reconnaissance Orbiter:  Images of Comet C/2013 A1 Siding Spring taken with the HiRISE high resolution camera.

These images were taken of comet C/2013 A1 Siding Spring by NASA’s Mars Reconnaissance Orbiter on Oct. 19, 2014, during the comet’s close flyby of Mars and the spacecraft. Comet Siding Spring is on its first trip this close to the sun from the Oort Cloud at the outer fringe of the solar system. This is the first resolved imaging of the nucleus of a long-period comet.

The High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter acquired images of this comet from a minimum distance of about 86,000 miles (138,000 kilometers), yielding a scale of about 150 yards (138 meters) per pixel. Telescopic observers had modeled the size of the nucleus as about half a mile, or one kilometer, wide. However, the best HiRISE images show only two to three pixels across the brightest feature, probably the nucleus, suggesting a size less than half that estimate.

This composite image shows two versions of each of two of the best HiRISE images of the comet. Shown at top are images with the full dynamic range, showing the nucleus and bright coma near the nucleus. Shown at bottom are versions where the fainter outer coma is brightened, saturating the inner region. The images at left and right were taken about nine minutes apart.

These closest-approach images were made possible due to very precise pointing and slewing of the Mars Reconnaissance Orbiter by engineers at Lockheed Martin in Denver, based on comet position calculations by engineers at NASA’s Jet Propulsion Laboratory, Pasadena, California. HiRISE acquired three images 12 days before closest approach, when the comet was barely detectable above the “noise level” of the images. These early images indicated the comet was not quite at its predicted location. This new viewing angle on the comet was used to update its predicted location and timing at closest approach. Without this update, the comet may have been outside the HiRISE image area in the best images.

Image credit: NASA/JPL-Caltech/University of Arizona

Mars Reconnaissance Orbiter: Images of Comet C/2013 A1 Siding Spring taken with the HiRISE high resolution camera.

These images were taken of comet C/2013 A1 Siding Spring by NASA’s Mars Reconnaissance Orbiter on Oct. 19, 2014, during the comet’s close flyby of Mars and the spacecraft. Comet Siding Spring is on its first trip this close to the sun from the Oort Cloud at the outer fringe of the solar system. This is the first resolved imaging of the nucleus of a long-period comet.

The High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter acquired images of this comet from a minimum distance of about 86,000 miles (138,000 kilometers), yielding a scale of about 150 yards (138 meters) per pixel. Telescopic observers had modeled the size of the nucleus as about half a mile, or one kilometer, wide. However, the best HiRISE images show only two to three pixels across the brightest feature, probably the nucleus, suggesting a size less than half that estimate.

This composite image shows two versions of each of two of the best HiRISE images of the comet. Shown at top are images with the full dynamic range, showing the nucleus and bright coma near the nucleus. Shown at bottom are versions where the fainter outer coma is brightened, saturating the inner region. The images at left and right were taken about nine minutes apart.

These closest-approach images were made possible due to very precise pointing and slewing of the Mars Reconnaissance Orbiter by engineers at Lockheed Martin in Denver, based on comet position calculations by engineers at NASA’s Jet Propulsion Laboratory, Pasadena, California. HiRISE acquired three images 12 days before closest approach, when the comet was barely detectable above the “noise level” of the images. These early images indicated the comet was not quite at its predicted location. This new viewing angle on the comet was used to update its predicted location and timing at closest approach. Without this update, the comet may have been outside the HiRISE image area in the best images.
Image credit: NASA/JPL-Caltech/University of Arizona
Opportunity:  Comet C/2013 A1 Siding Spring from the surface of Mars.  I think this is the same image as the previous post, but cleaned up and captioned. 

Researchers used the panoramic camera (Pancam) on NASA’s Mars Exploration Rover Opportunity to capture this 10-second-exposure view of comet C/2013 A1 Siding Spring as it passed near Mars on Oct. 19, 2014.

This image was taken about two-and-a-half hours before the closest approach of the comet’s nucleus to Mars. The sky was still relatively dark, before Martian dawn. At the time of closest approach, the morning sky was too bright for observation of the comet.

The comet, some nearby stars, and some effects of cosmic rays hitting the camera’s light detector are labeled.

The image has been processed by removal of detector artifacts and slight twilight glow. The duration of the exposure resulted in a 2.5-pixel smear from rotation of Mars.

A Martian dust storm to the west of Opportunity hampered visibility somewhat on Oct. 19, compared to the sky over Opportunity a week earlier.

For more information about comet Siding Spring, see http://mars.nasa.gov/comets/sidingspring/. 

Image Credit:
NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

Opportunity: Comet C/2013 A1 Siding Spring from the surface of Mars. I think this is the same image as the previous post, but cleaned up and captioned.

Researchers used the panoramic camera (Pancam) on NASA’s Mars Exploration Rover Opportunity to capture this 10-second-exposure view of comet C/2013 A1 Siding Spring as it passed near Mars on Oct. 19, 2014.

This image was taken about two-and-a-half hours before the closest approach of the comet’s nucleus to Mars. The sky was still relatively dark, before Martian dawn. At the time of closest approach, the morning sky was too bright for observation of the comet.

The comet, some nearby stars, and some effects of cosmic rays hitting the camera’s light detector are labeled.

The image has been processed by removal of detector artifacts and slight twilight glow. The duration of the exposure resulted in a 2.5-pixel smear from rotation of Mars.

A Martian dust storm to the west of Opportunity hampered visibility somewhat on Oct. 19, compared to the sky over Opportunity a week earlier.

For more information about comet Siding Spring, see http://mars.nasa.gov/comets/sidingspring/.
Image Credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.
Opportunity:  Comet Siding Spring, as seen from the surface of Mars.  Sol 3817 / October 19th 2014.  (The comet is the fuzzy bit near the center of the photo.)

Opportunity: Comet Siding Spring, as seen from the surface of Mars. Sol 3817 / October 19th 2014. (The comet is the fuzzy bit near the center of the photo.)

starstuffblog:

Probing the past

Most reliable remote distance measurement yet

Using the NASA/ESA Hubble Space Telescope astronomers have made what may be the most reliable distance measurement yet of an object that existed in the Universe’s formative years. The galaxy is one of the faintest, smallest and most distant galaxies ever seen and measuring its distance with this accuracy was possible due only to the incredibly detailed mapping of how giant galaxy clusters warp the space-time around them.

Astronomers often use gravitational lensing — the magnifying power of galaxy clusters — to find distant galaxies [1]. However, when it comes to the very early Universe, distance measurements can become inaccurate as the objects are so dim [2]. Now, a team of astronomers has combined a traditional method of distance measurement with some clever reverse engineering to vastly improve accuracy.

The lensing power of the mammoth galaxy cluster Abell 2744, nicknamed Pandora’s Cluster, focussed the light from the faraway galaxy that was being studied, making it appear about ten times brighter than it otherwise would have been, and allowing astronomers to see it. The lensing also produced three magnified images of the same galaxy.

"We were able to spot the galaxy’s multiple gravitationally-lensed images using near-infrared and visible-light photos from Hubble," explained study leader Adi Zitrin of the California Institute of Technology, USA. "But at first we didn’t know how far away it was from Earth."

By analysing the colour of the faraway galaxy the team could estimate its distance. Since the light left the galaxy the Universe’s expansion has stretched its wavelength, shifting its colour towards red in the spectrum, and this colour change can be measured and quantified as a redshift. For this object, the team estimated a redshift of 10, almost a record-breaking value and meaning the light from this object has taken over 13 billion years to reach us. But this is hard to do for faint and distant objects, and the method has some limitations, so can be inaccurate, misleading, and in some unfortunate cases, completely wrong.

To be sure their measurement could be trusted the team took advantage of the multiple images produced by the lens. The angular separations of the three magnified images of the galaxy in the Hubble photos were measured. The astronomers had already characterised the cluster and the distorting effects of the gravitational lens so well that they could tell how far the remote galaxy was behind the lensing cluster. They did this by comparing these angular separations to those of the less distant galaxies lensed by the cluster — the greater the angular separation, the further away the object is.

"This is a demonstration of the power of relativistic optics," remarked team member Tom Broadhurst, from the University of Basque Country & Basque Foundation for Science, Spain. "We now understand these lenses so well that we can use them to measure distances. It is the equivalent of using your camera to focus on an object, and then reading its distance from you on the lens focus ring. Being able to do this kind of reverse engineering at these distances is a huge accomplishment for us."

By combining the traditional analysis of the colours with the reverse engineering of the lens, the team calculated a robust distance measurement. “We are about 95 percent confident that this object is at redshift 10,” said Zitrin. “The lensing takes away any doubt that this might be a heavily reddened, nearby object masquerading as a far more distant object.”

The galaxy appears as a tiny blob only a small fraction of the size of the Milky Way, but it offers a peek back to a time when the Universe was only about 500 million years old, roughly three percent of its current age of 13.8 billion years. Although about ten other galaxy candidates have been uncovered at this early era, astronomers say this newly found object is significantly smaller and fainter than most of those other remote objects.

"This object is a unique example of what is suspected to be an abundant, underlying population of small and faint galaxies at about 500 million years after the Big Bang," explained Zitrin. "The discovery is telling us that galaxies as faint as this one exist, and we should continue looking for them and even fainter objects so that we can understand how galaxies, and the Universe, have evolved over time."

Analysis of the galaxy shows that it measures 850 light-years across and is estimated to have a mass of 40 million times that of the Sun. Tiny when compared to our own galaxy, which spans more than 100 000 light-years. It was also discovered that the galaxy is forming about one star every three years [3]. Although this is only one third of the star formation rate in the Milky Way it is actually pretty prolific for a galaxy this size and shows that the galaxy is rapidly evolving and efficiently forming stars.

"Galaxies such as this one are probably small clumps of matter that are starting to form stars and shine, but they don’t have a defined structure yet. Therefore, it’s possible that we only see one bright clump magnified due to the lensing, and this is one possible reason why it is smaller than typical field galaxies of that time," Zitrin explained.

Astronomers have long debated whether such early galaxies could have provided enough radiation to warm the hydrogen that cooled soon after the Big Bang. This process, called reionisation, made the Universe transparent to light, allowing astronomers to look far back in time without running into a fog of cold hydrogen [4].

"We tend to assume that galaxies ionised the Universe with their ultraviolet light. But we do not see enough galaxies or light that could do that," Zitrin explained. "So we need to look at fainter and fainter galaxies, and the Frontier Fields and galaxy cluster lensing can help us achieve this goal" [5].

The team’s results appeared in the online edition of Astrophysical Journal Letters on 4 September 2014.

Notes

[1] Galaxy clusters are so massive that their gravity deflects light passing through them, distorting the images of the distant objects behind them and sometimes magnifying and brightening them in a phenomenon called gravitational lensing.

[2] Ideally, astronomers use spectroscopy to determine an object’s distance. The further away a galaxy, the more its light has been stretched by the Universe’s expansion and we can precisely measure this effect, called the redshift, spectroscopically. But objects found at this early epoch (including this gravitationally lensed galaxy) are too dim for astronomers to use spectroscopy. For these fainter objects, astronomers have to rely on a less accurate method that estimates their distance based on their colours.

[3] The actual number of stars produced by this galaxy may be more or less than one every three years; this figure really means that the mass of the stars it produces per year on average is the same as a third of the mass of the Sun.

[4] Reionisation is thought to have occurred 200 million to one billion years after the birth of the Universe.

[5] This galaxy was detected as part of the Frontier Fields programme, an ambitious three-year effort that teams Hubble, NASA’s Spitzer Space Telescope and the Chandra X-ray Observatory with massive galaxy clusters to help astronomers probe the early Universe.

starstuffblog:

Probing the past

Most reliable remote distance measurement yet

Using the NASA/ESA Hubble Space Telescope astronomers have made what may be the most reliable distance measurement yet of an object that existed in the Universe’s formative years. The galaxy is one of the faintest, smallest and most distant galaxies ever seen and measuring its distance with this accuracy was possible due only to the incredibly detailed mapping of how giant galaxy clusters warp the space-time around them.

Astronomers often use gravitational lensing — the magnifying power of galaxy clusters — to find distant galaxies [1]. However, when it comes to the very early Universe, distance measurements can become inaccurate as the objects are so dim [2]. Now, a team of astronomers has combined a traditional method of distance measurement with some clever reverse engineering to vastly improve accuracy.

The lensing power of the mammoth galaxy cluster Abell 2744, nicknamed Pandora’s Cluster, focussed the light from the faraway galaxy that was being studied, making it appear about ten times brighter than it otherwise would have been, and allowing astronomers to see it. The lensing also produced three magnified images of the same galaxy.

"We were able to spot the galaxy’s multiple gravitationally-lensed images using near-infrared and visible-light photos from Hubble," explained study leader Adi Zitrin of the California Institute of Technology, USA. "But at first we didn’t know how far away it was from Earth."

By analysing the colour of the faraway galaxy the team could estimate its distance. Since the light left the galaxy the Universe’s expansion has stretched its wavelength, shifting its colour towards red in the spectrum, and this colour change can be measured and quantified as a redshift. For this object, the team estimated a redshift of 10, almost a record-breaking value and meaning the light from this object has taken over 13 billion years to reach us. But this is hard to do for faint and distant objects, and the method has some limitations, so can be inaccurate, misleading, and in some unfortunate cases, completely wrong.

To be sure their measurement could be trusted the team took advantage of the multiple images produced by the lens. The angular separations of the three magnified images of the galaxy in the Hubble photos were measured. The astronomers had already characterised the cluster and the distorting effects of the gravitational lens so well that they could tell how far the remote galaxy was behind the lensing cluster. They did this by comparing these angular separations to those of the less distant galaxies lensed by the cluster — the greater the angular separation, the further away the object is.

"This is a demonstration of the power of relativistic optics," remarked team member Tom Broadhurst, from the University of Basque Country & Basque Foundation for Science, Spain. "We now understand these lenses so well that we can use them to measure distances. It is the equivalent of using your camera to focus on an object, and then reading its distance from you on the lens focus ring. Being able to do this kind of reverse engineering at these distances is a huge accomplishment for us."

By combining the traditional analysis of the colours with the reverse engineering of the lens, the team calculated a robust distance measurement. “We are about 95 percent confident that this object is at redshift 10,” said Zitrin. “The lensing takes away any doubt that this might be a heavily reddened, nearby object masquerading as a far more distant object.”

The galaxy appears as a tiny blob only a small fraction of the size of the Milky Way, but it offers a peek back to a time when the Universe was only about 500 million years old, roughly three percent of its current age of 13.8 billion years. Although about ten other galaxy candidates have been uncovered at this early era, astronomers say this newly found object is significantly smaller and fainter than most of those other remote objects.

"This object is a unique example of what is suspected to be an abundant, underlying population of small and faint galaxies at about 500 million years after the Big Bang," explained Zitrin. "The discovery is telling us that galaxies as faint as this one exist, and we should continue looking for them and even fainter objects so that we can understand how galaxies, and the Universe, have evolved over time."

Analysis of the galaxy shows that it measures 850 light-years across and is estimated to have a mass of 40 million times that of the Sun. Tiny when compared to our own galaxy, which spans more than 100 000 light-years. It was also discovered that the galaxy is forming about one star every three years [3]. Although this is only one third of the star formation rate in the Milky Way it is actually pretty prolific for a galaxy this size and shows that the galaxy is rapidly evolving and efficiently forming stars.

"Galaxies such as this one are probably small clumps of matter that are starting to form stars and shine, but they don’t have a defined structure yet. Therefore, it’s possible that we only see one bright clump magnified due to the lensing, and this is one possible reason why it is smaller than typical field galaxies of that time," Zitrin explained.

Astronomers have long debated whether such early galaxies could have provided enough radiation to warm the hydrogen that cooled soon after the Big Bang. This process, called reionisation, made the Universe transparent to light, allowing astronomers to look far back in time without running into a fog of cold hydrogen [4].

"We tend to assume that galaxies ionised the Universe with their ultraviolet light. But we do not see enough galaxies or light that could do that," Zitrin explained. "So we need to look at fainter and fainter galaxies, and the Frontier Fields and galaxy cluster lensing can help us achieve this goal" [5].

The team’s results appeared in the online edition of Astrophysical Journal Letters on 4 September 2014.

Notes

[1] Galaxy clusters are so massive that their gravity deflects light passing through them, distorting the images of the distant objects behind them and sometimes magnifying and brightening them in a phenomenon called gravitational lensing.

[2] Ideally, astronomers use spectroscopy to determine an object’s distance. The further away a galaxy, the more its light has been stretched by the Universe’s expansion and we can precisely measure this effect, called the redshift, spectroscopically. But objects found at this early epoch (including this gravitationally lensed galaxy) are too dim for astronomers to use spectroscopy. For these fainter objects, astronomers have to rely on a less accurate method that estimates their distance based on their colours.

[3] The actual number of stars produced by this galaxy may be more or less than one every three years; this figure really means that the mass of the stars it produces per year on average is the same as a third of the mass of the Sun.

[4] Reionisation is thought to have occurred 200 million to one billion years after the birth of the Universe.

[5] This galaxy was detected as part of the Frontier Fields programme, an ambitious three-year effort that teams Hubble, NASA’s Spitzer Space Telescope and the Chandra X-ray Observatory with massive galaxy clusters to help astronomers probe the early Universe.

Hubble:  "Turquoise-tinted plumes in the Large Magellanic Cloud"

The brightly glowing plumes seen in this image are reminiscent of an underwater scene, with turquoise-tinted currents and nebulous strands reaching out into the surroundings.
However, this is no ocean. This image actually shows part of the Large Magellanic Cloud (LMC), a small nearby galaxy that orbits our galaxy, the Milky Way, and appears as a blurred blob in our skies. The NASA/ESA Hubble Space Telescope has peeked many times into this galaxy, releasing stunning images of the whirling clouds of gas and sparkling stars (opo9944a, heic1301, potw1408a).
This image shows part of the Tarantula Nebula’s outskirts. This famously beautiful nebula, located within the LMC, is a frequent target for Hubble (heic1206, heic1402). 
In most images of the LMC the colour is completely different to that seen here. This is because, in this new image, a different set of filters was used. The customary R filter, which selects the red light, was replaced by a filter letting through the near-infrared light. In traditional images, the hydrogen gas appears pink because it shines most brightly in the red. Here however, other less prominent emission lines dominate in the blue and green filters.

Credit: ESA/Hubble & NASA Acknowledgement: Josh Barrington
Hubble: "Turquoise-tinted plumes in the Large Magellanic Cloud"

The brightly glowing plumes seen in this image are reminiscent of an underwater scene, with turquoise-tinted currents and nebulous strands reaching out into the surroundings.

However, this is no ocean. This image actually shows part of the Large Magellanic Cloud (LMC), a small nearby galaxy that orbits our galaxy, the Milky Way, and appears as a blurred blob in our skies. The NASA/ESA Hubble Space Telescope has peeked many times into this galaxy, releasing stunning images of the whirling clouds of gas and sparkling stars (opo9944a, heic1301, potw1408a).

This image shows part of the Tarantula Nebula’s outskirts. This famously beautiful nebula, located within the LMC, is a frequent target for Hubble (heic1206, heic1402). 

In most images of the LMC the colour is completely different to that seen here. This is because, in this new image, a different set of filters was used. The customary R filter, which selects the red light, was replaced by a filter letting through the near-infrared light. In traditional images, the hydrogen gas appears pink because it shines most brightly in the red. Here however, other less prominent emission lines dominate in the blue and green filters.

Credit: ESA/Hubble & NASA
Acknowledgement: Josh Barrington

X-37B Orbital Test Vehicle-3 Lands at Vandenberg AFB

The X-37B Orbital Test Vehicle mission 3 (OTV-3), the Air Force’s unmanned, reusable space plane, landed at Vandenberg Air Force Base at 9:24 a.m. Oct. 17 .
Rosetta:  Another selfie, with comet Churyumov-Gerasimenko in the background, a mere 16km away this time.  This was taken on October 7th, with the CIVA camera on the Philae lander, which is scheduled to land on the comet about a month from now.

Rosetta: Another selfie, with comet Churyumov-Gerasimenko in the background, a mere 16km away this time. This was taken on October 7th, with the CIVA camera on the Philae lander, which is scheduled to land on the comet about a month from now.

MESSENGER:  Animated gif of the October 8th 2014 lunar eclipse, taken from orbit around Mercury.  The gif shows both the Earth and the Moon, and you can see the moon fade out as it enters the Earth’s shadow.

MESSENGER: Animated gif of the October 8th 2014 lunar eclipse, taken from orbit around Mercury. The gif shows both the Earth and the Moon, and you can see the moon fade out as it enters the Earth’s shadow.

Lunar Reconnaissance Orbiter:  Photo looking back at the Earth, with Mars as a tiny speck in the background.  Taken May 24th 2014.

Lunar Reconnaissance Orbiter: Photo looking back at the Earth, with Mars as a tiny speck in the background. Taken May 24th 2014.

Mid-level Solar Flare 
NASA’s Solar Dynamics Observatory captured these images of a solar flare on Oct. 2, 2014. The solar flare is the bright flash of light on the right limb of the sun. A burst of solar material erupting out into space can be seen just below it.
 
Read more: 1.usa.gov/1mW8rel

Credit: NASA/Goddard/SDO

Mid-level Solar Flare

NASA’s Solar Dynamics Observatory captured these images of a solar flare on Oct. 2, 2014. The solar flare is the bright flash of light on the right limb of the sun. A burst of solar material erupting out into space can be seen just below it.

Read more: 1.usa.gov/1mW8rel
Credit: NASA/Goddard/SDO