NASA ER-2: Melt ponds shine in MABEL laser altimeter flight images

Engineers installed a new camera system on MABEL for its summer 2014 campaign, so scientists could better understand what it measured during flights. 

A key goal of the Alaska-based campaign was to measure glacial melt ponds like this one, photographed July 16. 

Credit: NASA

Even from 65,000 feet above Earth, aquamarine melt ponds in the Arctic stand out against the white sea ice and ice sheets. These ponds form every summer, as snow that built up on the ice melts, creating crystal clear pools.

On July 16 and July 17, NASA's ER-2 aircraft flew above Alaskan glaciers and to the North Pole, carrying an instrument called the Multiple Altimeter Beam Experimental Lidar (MABEL).

MABEL is a laser altimeter, measuring the elevation of glaciers, mountains, forests and other topography below.

Scientists will use those measurements to design analysis software, or algorithms, for the upcoming Ice, Cloud and land Elevation Satellite-2 (ICESat-2) mission.

The 2014 MABEL campaign continued through July and was launched, in part, to capture melt ponds and other features of summer ice.

After nine science flights out of Fairbanks, Alaska, the ER-2 and MABEL returned to California on Aug. 1, gathering additional data along the way.

For this campaign, engineers added a new camera system to allow the team to match the MABEL measurements with a visual glimpse of the ground.

The digital camera takes a picture every 3 seconds, each frame capturing an area about 2.5 by 1.5 kilometers (1.6 by 0.9 miles).

Some of these first images downloaded were just what the MABEL team wanted to see, said Thorsten Markus, ICESat-2 project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

They want to understand how the MABEL data collected over a melt pond differs from data collected over open water, ice and more, and the images indicate there will be good measurements to analyze.

From the ER-2’s cruising altitude of 65,000 feet, the camera system snaps images of an area about 2.5 by 1.5 kilometers (1.6 by 0.9 miles). 

These melt ponds, formed by snowmelt on Alaskan glaciers, can range in size and shape. 

Credit: NASA

"We have clear open water, then we see melt ponds and then we see open water again," Markus said of a shot taken on the way to the North Pole.

"For algorithm development, this is perfect."

On a July 17 flight to the North Pole and back, the ER-2 aircraft carrying the MABEL instrument flew over fractured sea ice, dotted with melt ponds and marked by ridges formed by the dynamic ice. 

Credit: NASA

NASA LRO: Interactive mosaic of the Moon's North Pole

A new interactive mosaic from NASA's Lunar Reconnaissance Orbiter (LRO) covers the north pole of the moon from 60 to 90 degrees north latitude at a resolution of 6-1/2 feet (2 meters) per pixel. 

Close-ups of Thales crater (right side) zoom in to reveal increasing levels of detail. 

Credit: NASA /GSFC /Arizona State University

Scientists, using cameras aboard NASA's Lunar Reconnaissance Orbiter (LRO), have created the largest high resolution mosaic of our moon's north polar region.

The six-and-a-half feet (two-meters)-per-pixel images cover an area equal to more than one-quarter of the United States.

Web viewers can zoom in and out, and pan around an area.

Constructed from 10,581 pictures, the mosaic provides enough detail to see textures and subtle shading of the lunar terrain.

Consistent lighting throughout the images makes it easy to compare different regions.

"This unique image is a tremendous resource for scientists and the public alike," said John Keller, LRO project scientist at NASA's Goddard Space Flight Center, Greenbelt, Md.

"It's the latest example of the exciting insights and data products LRO has been providing for nearly five years."

The images making up the mosaic were taken by the two LRO Narrow Angle Cameras, which are part of the instrument suite known as the Lunar Reconnaissance Orbiter Camera (LROC).

The cameras can record a tremendous dynamic range of lit and shadowed areas.

"Creation of this giant mosaic took four years and a huge team effort across the LRO project," said Mark Robinson, principal investigator for the LROC at Arizona State University in Tempe.

"We now have a nearly uniform map to unravel key science questions and find the best landing spots for future exploration."

The entire image measures 931,070 pixels square – nearly 867 billion pixels total.

A complete printout at 300 dots per inch – considered crisp resolution for printed publications, would require a square sheet of paper wider than a professional U.S. football field and almost as long.

If the complete mosaic were processed as a single file, it would require approximately 3.3 terabytes of storage space.

Instead, the processed mosaic was divided into millions of small, compressed files, making it manageable for users to view and navigate around the image using a web browser.

LRO entered lunar orbit in June 2009 equipped with seven instrument suites to map the surface, probe the radiation environment, investigate water and key mineral resources, and gather geological clues about the moon's evolution.

Researchers used additional information about the moon's topography from LRO's Lunar Orbiter Laser Altimeter, as well as gravity information from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission, to assemble the mosaic.

ESA MARS Express: MARS North Pole Fly-by - Video

Data from the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument, MARSIS aboard ESA's Mars Express has been used to create this animation of the Red Planets north pole. The ice cap is about 1000km in diameter (621 miles).

Credit: ESA

Cassini gets new views of Titan's land of lakes

This false-colour mosaic, made from infrared data collected by NASA's Cassini spacecraft, reveals the differences in the composition of surface materials around hydrocarbon lakes at Titan, Saturn's largest moon. 

Credit: NASA/JPL-Caltech/University of Arizona/University of Idaho

With the sun now shining down over the north pole of Saturn's moon Titan, a little luck with the weather, and trajectories that put the spacecraft into optimal viewing positions, NASA's Cassini spacecraft has obtained new pictures of the liquid methane and ethane seas and lakes that reside near Titan's north pole.

The images reveal new clues about how the lakes formed and about Titan's Earth-like "hydrologic" cycle, which involves hydrocarbons rather than water.

While there is one large lake and a few smaller ones near Titan's south pole, almost all of Titan's lakes appear near the moon's north pole.

Cassini scientists have been able to study much of the terrain with radar, which can penetrate beneath Titan's clouds and thick haze.

And until now, Cassini's visual and infrared mapping spectrometer and imaging science subsystem had only been able to capture distant, oblique or partial views of this area.

Several factors combined recently to give these instruments great observing opportunities. Two recent flybys provided better viewing geometry.

Sunlight has begun to pierce the winter darkness that shrouded Titan's north pole at Cassini's arrival in the Saturn system nine years ago.

A thick cap of haze that once hung over the north pole has also dissipated as northern summer approaches. And Titan's beautiful, nearly cloudless, rain-free weather continued during Cassini's flybys this past summer.

The images are mosaics in infrared light based on data obtained during flybys of Titan on July 10, July 26, and Sept. 12, 2013.

The colorised mosaic from the visual and infrared mapping spectrometer, which maps infrared colors onto the visible-color spectrum, reveals differences in the composition of material around the lakes.

The data suggest parts of Titan's lakes and seas may have evaporated and left behind the Titan equivalent of Earth's salt flats.

Only at Titan, the evaporated material is thought to be organic chemicals originally from Titan's haze particles that once dissolved in liquid methane.

They appear orange in this image against the greenish backdrop of Titan's typical bedrock of water ice.

Almost all of the hydrocarbon seas and lakes on the surface of Saturn's moon Titan cluster around the north pole, as can be seen in this mosaic from NASA's Cassini mission. 

This mosaic, made from near-infrared images of Titan obtained by Cassini's imaging science subsystem, shows a view from the north pole (upper middle of mosaic) down to near the equator at the bottom. 

Credit: NASA/JPL-Caltech/SSI/JHUAPL/Univ. of Arizona

"The view from Cassini's visual and infrared mapping spectrometer gives us a holistic view of an area that we'd only seen in bits and pieces before and at a lower resolution," said Jason Barnes, a participating scientist for the instrument at the University of Idaho, Moscow.

"It turns out that Titan's north pole is even more interesting than we thought, with a complex interplay of liquids in lakes and seas and deposits left from the evaporation of past lakes and seas."

MARS MRO Image: North Pole Weather forecasts

In winter a layer of frozen carbon dioxide covers the Martian North Pole. 

Approximately 50 percent of this ice cap falls to the ground as snow. 

This image was taken by NASA's Mars Reconaissance Orbiter (MRO) in 2006. 

Credits: NASA

In the north of the red planet snowfalls occur with great regularity.

Expeditions of Mars rovers into this region could therefore be easily planned.

Snowstorms lashing down at the northern hemisphere of Mars during the icy cold winters may be predicted several weeks in advance, say researchers from the Tohoku University in Sendai (Japan) and the Max Planck Institute for Solar System Research (MPS) in Katlenburg-Lindau (Germany) in their newest publication.

For the first time, the scientists' calculations show a connection between these snowfalls and a special Martian weather phenomenon: fluctuations of pressure, temperature, wind speeds, and directions that in the northern hemisphere propagate in a wave-like manner and occur very regularly.

For missions to the red planet exploring this region with rovers, such weather forecasts would offer the possibility of choosing a route that avoids heavy snow storms.

The Martian polar regions are an icy cold world. Similar to those on Earth they are covered by cohesive ice caps. In winter, when the temperatures drop below -128 degrees Celcius, this layer of ice is mainly supplied by frozen carbon dioxide from the atmosphere.

The ice caps then cover a region reaching south to about 70 degrees northern latitude. Only in the comparably warm Martian summer the carbon dioxide sublimates revealing the planet's eternal ice: a considerably smaller cap of frozen water.

Dr. Paul Hartogh

"Mars' seasonal ice has two different origins", says Dr. Paul Hartogh from the MPS. "A part of the carbon dioxide from the atmosphere condensates directly on the surface – similar to the way a layer of frost forms on Earth in cold, clear weather. Another part freezes in the atmosphere", he adds.

The tiny ice crystals accumulate into clouds and fall to the ground as snow.

In the new study, the researchers were now for the first time able to establish a connection between the occurrence of such ice clouds and a wave-like weather phenomenon characterized by a periodic change of pressure, temperature, wind speed, and -direction.

"This weather phenomenon on Mars is unique", says Dr. Alexander Medvedev from the MPS. Indeed, these so-called planetary waves can also be found in Earth's meteorology.

However, not only are the oscillations in pressure and temperature in the lower atmosphere much weaker here. They also occur much less regularly and their wave characteristics are much less pronounced.

"In the Martian northern hemisphere between fall and spring these waves can be found with astonishing reliability", the physicist adds. They propagate eastward with a uniform period of five to six days. Close to the surface, waves with higher frequencies can also be observed.

ESA Weather Satellites: Antartica Ozone Holes Showing signs of closing

Time-series (1996 to 2012) of total polar ozone mean values over the months of September, October and November as measured by GOME, SCIAMACHY and GOME-2 flown on ERS-2, Envisat and MetOp-A, respectively. Smaller ozone holes are evident during 2002 and 2012. 

The maps were generated using total ozone columns derived with the GODFIT algorithm (BIRA/IASB, RT Solutions Inc.), which has been consistently applied to the three different satellite instruments. 

Credit BIRA/IASB.

Satellites show that the recent ozone hole over Antarctica was the smallest seen in the past decade. Long-term observations also reveal that Earth's ozone has been strengthening following international agreements to protect this vital layer of the atmosphere.

According to the ozone sensor on Europe's MetOp weather satellite, the hole over Antarctica in 2012 was the smallest in the last 10 years.

The instrument continues the long-term monitoring of atmospheric ozone started by its predecessors on the ERS-2 and Envisat satellites.

"The Ozone Layer, which protects the Earth from dangerous levels of uv-radiation, would be fatal to any animal that inhaled it, including humans. It is located approx 24 Kms above the earth's surface and smells faintly of geraniums."

Since the beginning of the 1980s, an ozone hole has developed over Antarctica during the southern spring - September to November - resulting in a decrease in ozone concentration of up to 70%.

Ozone depletion is more extreme in Antarctica than at the North Pole because high wind speeds cause a fast-rotating vortex of cold air, leading to extremely low temperatures. Under these conditions, human-made chlorofluorocarbons - CFCs - have a stronger effect on the ozone, depleting it and creating the infamous hole.

Over the Arctic, the effect is far less pronounced because the northern hemisphere's irregular landmasses and mountains normally prevent the build-up of strong circumpolar winds.

Reduced ozone over the southern hemisphere means that people living there are more exposed to cancer-causing ultraviolet radiation.

International agreements on protecting the ozone layer - particularly the Montreal Protocol - have stopped the increase of CFC concentrations, and a drastic fall has been observed since the mid-1990s.

However, the long lifetimes of CFCs in the atmosphere mean it may take until the middle of this century for the stratosphere's chlorine content to go back to values like those of the 1960s.

The evolution of the ozone layer is affected by the interplay between atmospheric chemistry and dynamics like wind and temperature.

If weather and atmospheric conditions show unusual behaviour, it can result in extreme ozone conditions - such as the record low observed in spring 2011 in the Arctic - or last year's unusually small Antarctic ozone hole.

To understand these complex processes better, scientists rely on a long time series of data derived from observations and on results from numerical simulations based on complex atmospheric models.

Although ozone has been observed over several decades with multiple instruments, combining the existing observations from many different sensors to produce consistent and homogeneous data suitable for scientific analysis is a difficult task.

Within the ESA Climate Change Initiative, harmonised ozone climate data records are generated to document the variability of ozone changes better at different scales in space and time.

With this information, scientists can better estimate the timing of the ozone layer recovery, and in particular the closure of the ozone hole.

The Earth's Magnetic Field Is Wonky

The solution to a long-standing puzzle, why magnetic north sits off the coast of Canada, rather than at the North Pole, may have been found in the strange, lopsided nature of Earth's inner core.

The inner core is a ball of solid iron about 760 miles (1,220 kilometers) wide.

It is surrounded by a liquid outer core (mostly iron and nickel), a rocky, viscous mantle layer and a thin, solid crust.

As the inner core cools, crystallizing iron releases impurities, sending lighter molten material into the liquid outer core.

This upwelling, combined with the Earth's rotation, drives convection, forcing the molten metal into whirling vortices.

These vortices stretch and twist magnetic field lines, creating Earth’s magnetic field. Currently, the center of the field, called an axis, emerges in the Arctic Ocean west of Ellesmere Island, about 300 miles (500 kilometers) from the geographic North Pole.

In the last decade, seismic waves from earthquakes revealed the inner core looks like a navel orange, bulging slightly more on its western half.

Geoscientists recently explainedthe asymmetry by proposing a convective loop: The inner core might be crystallizing on one half and melting on the other.

Peter Olson and Renaud Deguen, geophysicists at Johns Hopkins University, set out to test this theory, called translational instability.

They ran numerical models simulating the forces that generate Earth’s magnetic field, and included a lopsided inner core.

Olson and Deguen found that adding inner-core asymmetry shifted magnetic north away from the center of the Earth, into the cooling hemisphere. Convection was stronger there, as was the magnetic field.

"The lopsided growth of the inner core makes convection in the outer core a little bit lopsided, and that then induces the geomagnetic field to have this lopsided or eccentric character too," Olson stated.

Olson and Deguen's research was detailed online July 1 in the journal Nature Geoscience.

Geophysicist Bruce Buffett said Olson and Deguen’s research is intriguing, but there are still questions about the underlying theory. "It's an interesting result, but we don't know for sure the inner core is translating.

The model does a good job at explaining some but not all of the features of the inner core," said Buffett, a professor at the University of California, Berkeley, who was not involved with the research.

Olson points out that his numerical model offers a real-world proof of the theory. Magnetic particles trapped and aligned in rocks reveal that the magnetic north pole wandered around the Western Hemisphere over the past 10,000 years, and circled the Eastern Hemisphere before that — a result mirrored by the numerical test.

Gathering a longer, more detailed record of the magnetic field's behavior, Olson said, could reveal whether the inner core acts as researchers predict.

"The key question for interesting ideas like translational instability is, 'Can we test it?'" Olson said. "What we're doing is proposing a test, and we think it's a good test because people can go out and look for eccentricity in the rock record and that will either confirm or shoot down this idea."

Excellent views of Mars in night sky

Interesting atmospherics on Mars last night from around midnight to three in the morning (earliest image on left, last image on right).

Credit: Peter Tickner

MARSIS Completes Measurement Campaign Over Martian North Pole

Location of the measurements made by Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) over the planet's North Pole during the recently completed campaign. Copyright: ESA.

The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board Mars Express has recently completed a subsurface sounding campaign over the planet's North Pole.

The campaign was interrupted by the suspension of science observations several times between August and October due to safe modes and to anomalies in the operation of the spacecraft's Solid-State Mass Memory (SSMM) system.

As MARSIS best observes in the dark, which for the North Pole only occurs every few years, it was among the first instruments to resume observations once a partial work-around for the problems had been implemented.

The primary objective of MARSIS is to map the distribution of water and ice in the upper layers of the Martian subsurface.

Using techniques similar to oil prospecting on Earth, the instrument analyses the reflection of radio waves down to a few kilometres in the subsurface; it is able to distinguish between dry, frozen and wet soil.

The polar regions of Mars are of particular interest because climate variations affect the quantities of water ice and dust found in the polar deposits.

The North Pole measurement campaign lasted from June to November 2011, taking place during orbits 9500 to 10 100. The observations extended from the pole out to just beyond 45Â degrees N.

Data acquisition was affected by solar events, as well as the technical problems with the spacecraft.

During the main part of the campaign, around 40 per cent of the available orbits were lost, with roughly a quarter of the losses being attributable to solar activity and three quarters to the suspension of observations.

The velocity of Mars Express at pericentre is extremely high and the fly-overs of the north polar cap lasted only between three and seven minutes per orbit.

The accumulated observing time over ~ 600 orbits was about 3000 minutes. Mars Express therefore spent a total of about two days over the north polar cap in the whole observing season.

About 25 hours were spent acquiring data while the pole was in darkness, and another 25 hours observing the pole while it was in sunlight.

MARSIS can observe the subsurface with maximum sensitivity only when the pole is not illuminated, so the best observations were made between June and September.

The pole was still observable until late November, but by then it was partially illuminated, so the measurements were of lower quality.

The presence of an ionosphere also impacts the MARSIS measurements with MARSIS signals being disturbed or even completely attenuated when free electrons are present in the Martian atmosphere.

There is always an ionosphere on the dayside of the planet, created by solar ultraviolet photons and energetic particles interacting with the thin atmosphere.

It is, therefore, greatly preferably to observe on the nightside, where, in principle, there is no ionosphere. In practice, during periods of high solar activity an active ionosphere can be present on the nightside as well.

Ancient blue stragglers in constellation Cepheus

Mysterious "blue stragglers" are old stars that appear younger than they should be: they burn hot and blue.

Several theories have attempted to explain why they don't show their age, but, until now, scientists have lacked the crucial observations with which to test each hypothesis.

Armed with such observational data, two astronomers from Northwestern University and the University of Wisconsin-Madison report that a mechanism known as mass transfer explains the origins of the blue stragglers.

Essentially, a blue straggler eats up the mass, or outer envelope, of its giant-star companion.

This extra fuel allows the straggler to continue to burn and live longer while the companion star is stripped bare, leaving only its white dwarf core.

The scientists report their evidence in a study to be published by the journal Nature.

The majority of blue stragglers in their study are in binaries: they have a companion star. "It's really the companion star that helped us determine where the blue straggler comes from," said Northwestern astronomer Aaron M. Geller, first author of the study.

"The companion stars orbit at periods of about 1,000 days, and we have evidence that the companions are white dwarfs. Both point directly to an origin from mass transfer."

Geller is the Lindheimer Postdoctoral Fellow in the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and the department of physics and astronomy in Northwestern's Weinberg College of Arts and Sciences. Robert Mathieu, professor of astronomy and chair of the astronomy department at UW-Madison, is co-author of the study.

The astronomers studied the NGC 188 open cluster, which is in the constellation Cepheus, situated in the sky near Polaris, the North Star.

This cluster is one of the most ancient open star clusters, but it features these mysterious young blue stragglers.

The cluster has around 3,000 stars, all about the same age, and has 21 blue stragglers. Geller and Mathieu are the first to use detailed observational data from the WIYN Observatory in Tucson, Ariz., of the blue stragglers in NGC 188.

They used the information to analyze and compare the three main theories of blue straggler formation: collisions between stars, mergers of stars and mass transfer from one star to another. The only one left standing was the theory of mass transfer.

The light from the blue stragglers' companion stars is not actually visible in Geller and Mathieu's observations.

While the companions haven't been seen directly, their effect on the blue stragglers is evident: each companion pulls gravitationally on its blue straggler and creates a "wobble" as it orbits, and this allows astronomers to measure the mass of the companion stars.

The WIYN data show that each companion star is about half the mass of the sun, which is consistent with a white dwarf.

The other two origin theories, collisions and mergers, require the companion stars to be more massive than what is observed.

 In fact, in both scenarios, some of the companion stars could be bright enough to be visible in the WIYN data, which is not the case.

NASA - Venus Rising

This hemispheric view of Venus was created using more than a decade of radar investigations culminating in the 1990-1994 Magellan mission, and is centered on the planet's North Pole.


The Magellan spacecraft imaged more than 98 percent of the planet Venus and a mosaic of the Magellan images (most with illumination from the west) forms the image base.

Gaps in the Magellan coverage were filled with images from the Earth-based Arecibo radar in a region centered roughly on 0 degree latitude and longitude, and with a neutral tone elsewhere (primarily near the south pole).

This composite image was processed to improve contrast and to emphasise small features, and was colour-coded to represent elevation. Gaps in the elevation data from the Magellan radar altimeter were filled with altimetry from the Venera spacecraft and the Pioneer Venus missions.

Image Credit: NASA/JPL/USGS

NASA Radar Finds Ice Deposits at Moon's North Pole

NASA Radar Finds Ice Deposits at Moon's North Pole

Using data from a NASA radar that flew aboard India's Chandrayaan-1 spacecraft, scientists have detected ice deposits near the moon's north pole.

NASA's Mini-SAR instrument, a lightweight, synthetic aperture radar, found more than 40 small craters with water ice.

The craters range in size from 1 to 9 miles (2 to15 km) in diameter. Although the total amount of ice depends on its thickness in each crater, it's estimated there could be at least 1.3 trillion pounds (600 million metric tons) of water ice.

The Mini-SAR has imaged many of the permanently shadowed regions that exist at both poles of the Moons. These dark areas are extremely cold and it has been hypothesized that volatile material, including water ice, could be present in quantity here. The main science object of the Mini-SAR experiment is to map and characterize any deposits that exist.

Mini-SAR is a lightweight (less than 10 kg) imaging radar. It uses the polarisation properties of reflected radio waves to characterise surface properties. Mini-SAR sends pulses of radar that are left-circular polarised.

Typical planetary surfaces reverse the polarisation during the reflection of radio waves, so that normal echoes from Mini-SAR are right circular polarised. The ratio of received power in the same sense transmitted (left circular) to the opposite sense (right circular) is called the circular polarisation ratio (CPR).

Most of the Moon has low CPR, meaning that the reversal of polarisation is the norm, but some targets have high CPR. These include very rough, fresh surfaces (such as a young, fresh crater) and ice, which is transparent to radio energy and multiply scatters the pulses, leading to an enhancement in same sense reflections and hence, high CPR.

CPR is not uniquely diagnostic of either roughness or ice; the science team must take into account the environment of the occurrences of high CPR signal to interpret its cause.