Orbiter.ch Space News

mercredi 2 mai 2018

CryoSat Reveals Retreat of Pantagonian Glaciers

ESA - CryoSat Mission logo.

2 May 2018

While ESA’s CryoSat continues to provide clear insight into how much sea ice is being lost and how the Antarctic and Greenlandic ice sheets are changing, the mission has again surpassed its original scope by revealing exactly how mountain glaciers are also succumbing to change.

Glaciers all over the globe are retreating – and for the last 15 years, glacial ice has been the main cause of sea-level rise.

Glaciers in decline

Apart from Antarctica, Patagonia is home to the biggest glaciers in the southern hemisphere, but some are retreating faster than anywhere else in the world.

This is because the weather is relatively warm and these glaciers typically terminate in fjords and lakes, exacerbating surface melting and causing them to flow faster and lose ice as icebergs at their margins.

There is a clear need to monitor and understand glacial dynamics, not only in Patagonia but globally.

However, with around 200 000 glaciers worldwide coupled with their remote rugged terrain, maintaining local monitoring systems is extremely difficult.

Turning to space, satellite radar altimeters have been mapping ice loss from the large sheets for the last 25 years, but the footprint of this type of instrument is generally too coarse to monitor the smaller mountain glaciers.

Fortunately, a new way of processing CryoSat data now makes it possible to map these glaciers in fine detail.

Swath processing

Noel Gourmelen from the University of Edinburgh said, “The technique of swath processing differs from conventional radar altimetry. Using CryoSat’s novel interferometric mode, we see how the radar wave front interacts with the surface.

“We can then extract a whole swath of elevations rather than single elevation points. This is revolutionising the use of CryoSat over complex icy terrains, yielding more detail than we ever thought possible.”

A paper published recently in Remote Sensing of Environment describes how this technique has been used to reveal complex patterns in the changing height of glaciers in Patagonia.

Luca Foresta, also from the University of Edinburgh, explained, “We’ve used CryoSat to discover that between 2011 and 2017 there was widespread thinning, particularly in the northern part of the ice fields.

“For example, the Jorge Montt glacier, which flows down to the ocean, retreated 2.5 km and lost about 2.2 Gt of ice a year, and the Upsala glacier, which terminates at a lake, lost 2.68 Gt a year.

“In contrast, however, Pio XI, the largest glacier in South America, advanced and gained mass at a rate of about 0.67 Gt a year.”

Over the six-year period, the Patagonian ice fields overall lost mass at a rate of over 21 Gt a year, which is equivalent to adding 0.06 mm to sea level. It is also a 24% increase compared to the amount of ice lost between 2000 and 2014.

ESA's ice mission

This paper coincides with the release of a similar new CryoSat swath dataset over Greenland. In addition to the six billion or so measurements gathered over six years, researchers are also using this dataset to generate a digital elevation model of the Greenland ice sheet and a new map of thinning rates.

Flora Weissgerber from the University of Edinburgh said, “Thanks to CryoSat’s interferometric capabilities and swath processing, we have managed to compute the elevation and elevation change across the Greenland ice sheet.

“This unique high-resolution dataset should enable better modelling and increased understanding of how much ice is being lost from Greenland.”

ESA’s Mark Drinkwater noted, “This approach opens a window to what could be possible as a matter of routine in the future with the Polar Ice and Snow Topography mission, which is currently a candidate mission studied as part of the Copernicus Expansion.”

Related links:

CryoSat: http://www.esa.int/Our_Activities/Observing_the_Earth/CryoSat

Access CryoSat data: https://earth.esa.int/web/guest/missions/esa-operational-eo-missions/cryosat

CryoTop Evolution: https://cryotop-evolution.org/

CryoSat swath elevation dataset: https://cryotop-evolution.org/page/datasets/

University of Edinburgh–School of Geosciences: http://www.ed.ac.uk/geosciences

Support to Science Element: http://due.esrin.esa.int/stse/

Images, Text, Credits: ESA/Planetary Visions/AOES Medialab.

Greetings, Orbiter.ch

mardi 1 mai 2018

Blue Origin - New Shepard Mission 8

Blue Origin logo.

May 1, 2018

New Shepard Mission 8 launch

New Shepard flew again for the eighth time on April 29, 2018, from Blue Origin’s West Texas Launch Site. Known as Mission 8 (M8), the mission featured a reflight of the vehicle flown on Mission 7.

The Crew Capsule reached an apogee of 351,000 feet (66 miles, 107 kilometers) – the altitude we’ve been targeting for operations. For the second time, Blue Origin’s test dummy “Mannequin Skywalker” flew to space conducting astronaut telemetry and science studies.

Replay of New Shepard Mission 8 Livestream

The flight also carried research payloads for NASA, the German Aerospace Center (DLR), and commercial customers.

These payloads represent a range of users, from NASA’s Johnson Space Center to a small commercial communications firm, as well as our first European customers, funded by the German national space agency, DLR. Each of the payloads has been outfitted with a custom Blue Origin Payload Locker to provide structural, power, and data interfaces throughout the flight.

Suborbital Flight Experiment Monitor-2 (SFEM-2)
NASA Johnson Space Center (Houston, Texas)

NASA’s Suborbital Flight Experiment Monitor-2, or SFEM-2, was designed to characterize payload test environments in support of the NASA Flight Opportunities program and other payload initiatives. The sensor suite collects cabin environmental data (CO2, pressure, acceleration, acoustics) and also tests components for future flights on NASA’s Orion capsule.

Schmitt Space Communicator (SC-1x)
Solstar (Santa Fe, NM), developed with private funding

The Schmitt Space Communicator, named after Solstar advisor and Apollo 17 astronaut Harrison “Jack” Schmitt, is a technology demo to test the concept of providing commercial Wi-Fi access to in-space users. This flight test is being conducted with support from NASA’s Flight Opportunities Program.

Daphnia
University of Bayreuth with ZARM (The Center of Applied Space Technology and Microgravity at the University of Bremen) and funding from German space agency, DLR

The Daphnia experiment investigates the effects of microgravity on gene expression and the cytoskeleton of daphnia water fleas. This small invertebrate species is popular in design of future bioregenerative life support systems for human space exploration.

EQUIPAGE
Otto von Guericke University (Magdeburg, Germany) with ZARM (The Center of Applied Space Technology and Microgravity at the University of Bremen) and funding from German space agency, DLR

EQUIPAGE studies the motion of macroscopic rod shaped grains to validate physics models of these systems under microgravity conditions. Such “granular gases” allow researchers to study a unique state far from equilibrium and not possible in normal Earth environments.

EUPHORIE
University of Duisburg-Essen with ZARM (The Center of Applied Space Technology and Microgravity at the University of Bremen) and funding from German space agency, DLR

EUPHORIE uses a laser to examine the phenomenon of photophoresis, the interaction of light on solid particles suspended in a gas. As the laser heats one side of such particles, it warms nearby gas molecules and accelerates the particle towards its cooler side. This research has applications to the study of early solar system evolution and meteorite formation.

Blue Origin first stage landing

For more information about Blue Origin, visit: https://www.blueorigin.com/

Images, Video, Text, Credit: Blue Origin.

Greetings, Orbiter.ch

Dragon Packed with NASA Science Experiments for Saturday Return

ISS - Expedition 55 Mission patch.

May 1, 2018

Image above: The SpaceX Dragon resupply ship was gripped by the Canadarm2 robotic arm on April 27, 2018 in preparation for its detachment from the Harmony module and its release back to Earth for splashdown and retrieval in the Pacific Ocean. Image Credit: NASA.

The SpaceX Dragon resupply ship is packed with International Space Station hardware and scientific samples ready for return to Earth on Saturday. Meanwhile, the Expedition 55 crew members continued maintenance of the orbital lab and space research operations.

Dragon’s departure was pushed back from Wednesday after SpaceX personnel observed high sea states in the Pacific Ocean splashdown zone southwest of Long Beach, California. Its remotely controlled release from the Canadarm2 is now scheduled for Saturday at 9:30 a.m. EDT with live NASA TV coverage beginning at 9 a.m. Dragon’s splashdown is targeted at about 3 p.m. but will not be seen on NASA TV.

Image above: Flying over North Pacific Ocean, seen by EarthCam on ISS, speed: 27'514 Km/h, altitude: 406,23 Km, image captured by Roland Berga (on Earth in Switzerland) from International Space Station (ISS) using ISS-HD Live application with EarthCam's from ISS on May 1, 2018 at 14:06 UTC.

Mice living on the station have been transferred to specialized habitats in Dragon. They will be studied on Earth to observe how their bones and muscles have changed during their stay in microgravity. Other critical biological samples preserved in science freezers, such as plants, insects and human tissue, have also been transferred into Dragon for retrieval and analysis.

The astronauts and cosmonauts living on the space station exercise every day to maintain strong bones and muscles on orbit. One of the workout machines, the Advanced Resistance Exercise Device (ARED), got a tune up today amid the Dragon close out activities. Flight Engineer Drew Feustel greased the ARED’s rails and rollers and inspected its x-axis rotation points.

Related links:

NASA TV: https://www.nasa.gov/multimedia/nasatv/index.html

Advanced Resistance Exercise Device (ARED): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=973

Expedition 55: https://www.nasa.gov/mission_pages/station/expeditions/expedition55/index.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Text, Credits: NASA/Mark Garcia/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.ch

Space Station Science Highlights: Week of April 23, 2018

ISS - Expedition 55 Mission patch.

May 1, 2018

The Expedition 55 crew members were busy this week as they began prep work for a mid-May spacewalk in addition to many hours of scientific operations aboard the International Space Station.

Image above: The Great Lakes, as captured by NASA astronaut Ricky Arnold during a day pass. Image Credit: NASA.

Here is a look at some of the science that happened this week aboard your orbiting laboratory:

Investigation to monitor upper atmosphere continues commissioning phase

Thunderstorms in Earth’s upper atmosphere remain something of a mystery. The European Space Agency (ESA) Atmosphere-Space Interactions Monitor (ASIM) is a collection of optical cameras, photometers and a large X- and gamma-ray detector mounted on the outside of ESA’s Columbus Module on the station. For at least two years, it will observe thunderstorm-generated electrical discharges in the upper atmosphere – the stratosphere and mesosphere – up to the ionosphere, the edge of space. This Earth observation facility enables study of severe thunderstorms and their role in the Earth’s atmosphere and climate.

Since its arrival on SpaceX CRS-14, ASIM has been in the commissioning phase. Once this period ends, ASIM will enter a two-year operation phase.

New plant biology investigation initiated in Veggie facility

Future long-duration missions into the solar system will require a fresh food supply to supplement crew diets, which means growing crops in space. A new plant biology investigation, Veggie PONDS, began in the Veggie facility this week. Veggie PONDS uses a newly developed, passive nutrient delivery system to cultivate lettuce and mizuna greens which are to be harvested and consumed on orbit, with samples returned to Earth for analysis.

Animation above: Veggie PONDS was installed and its first run was initiated this week, as seen above. Animation Credit: NASA.

Once the installation was complete, crew members filled the modules with water, some of which are clear, so that the surface tension behavior could be observed.

Other plant biology investigations aboard the station include Veg-03, Plant Gravity Perception, and a recent addition to the lab, the Advanced Plant Habitat.

Crew dons sensor to track sleep and wake habits

In addition to studying alternative lighting options to improve sleeping habits in space, researchers are also examining changes in in circadian rhythms in humans during long-term spaceflight. The Circadian Rhythms investigation provides important insight into adaptations of the human autonomic nervous system in space over time, helps to improve physical exercise plans, rest- and work shifts and fosters adequate workplace illumination during future spaceflight.

Animation above: The crew removed a card containing experiment cubes from the TangoLab-1 facility this week. The TangoLab-1 locker is a reconfigurable general research facility designed for microgravity research and development and pilot manufacturing aboard the space station. Animation Credit: NASA.

This week, JAXA astronaut Norishige Kanai donned the Thermolab Double sensor, a wearable sensor, and then removed it 36 hours later.

Other work was done on these investigations: Crew Earth Observations, Mouse Stress Defense, CASIS PCG-9, HDEV, CIR, DOSIS-3D, Meteor, AstroPi, MERLIN, ACME E-FIELD Flames, Space Pup, ACE-T-9, Food Acceptability, SCAN Testbed, Metabolic Tracking, MISSE-FF, VESSEL-ID, NR-Module 66, Made in Space Fiber Optics, and SPHERES.

Space to Ground: Color of the Sun: 04/27/2018

lundi 30 avril 2018

The 2018 data-taking run at the LHC has begun

CERN - European Organization for Nuclear Research logo.

30 Apr 2018

Image above: A collision event recorded by LHCb on 28 April, following the formal start of this year’s data taking (Image: LHCb/CERN).

On Saturday, 28 April 2018, the operators of the Large Hadron Collider (LHC) successfully injected 1200 bunches of protons into the machine and collided them. This formally marks the beginning of the LHC’s 2018 physics season. The start of the physics run comes a few days ahead of schedule, continuing the LHC’s impressive re-awakening since the end of its annual winter hibernation just over a month ago. In early April, a small number of bunches were injected into the ring to deliver test collisions inside the four large LHC experiments. These experiments – ALICE, ATLAS, CMS and LHCb – have now begun their data collection in earnest, which they will use to continue measuring the properties of the Standard Model of particle physics and search for any chinks in its armour.

The Standard Model provides the best explanation of the properties of all known particles and three forces that govern them: the electromagnetic force, the weak force and the strong force. But we know that this model does not give us the complete picture of our universe. For one, it only addresses 5% of the contents of the universe: the remaining 95% is thought to be made of dark matter and dark energy, and the Standard Model has no answers for these mysteries. It also does not provide any way of integrating gravity with the three other forces.

Particle physicists working on the LHC experiments seek explanations to fill this gap in two principle ways. Firstly, they do so by taking a close look at various phenomena predicted by the Standard Model and looking for subtle differences between prediction and measurement. In addition, they search for previously unobserved phenomena and particles. Both types of searches for physics beyond the Standard Model require huge quantities of data in order to filter a potential signal from the expected background processes. The LHC experiments will therefore hope that the LHC continues its annual tradition of outdoing its previous year’s data volume.

Image above: An event recorded by ATLAS earlier in April, from some of the first collisions of the year with three proton bunches circulating in the LHC (Image: ATLAS/CERN).

ATLAS and CMS, the two “general-purpose” detectors, will continue to probe the properties of the Higgs boson that they discovered in July 2012. This particle is the newest tool in the utility belt used by particle physicists to explore the properties of nature. Since its discovery, physicists have studied its behaviour and interactions with other particles, which have so far shown good agreement with the Standard Model. Searches will also continue for supersymmetric partners of the familiar bosons and fermions that are predicted to exist by a family of theories known as supersymmetry, which might provide us with a candidate for a dark-matter particle. ATLAS, CMS and LHCb are also searching for hints of dark matter through other means, and will add the forthcoming trove of data to their stockpiles as they advance their explorations.

Image above: An event recorded by CMS earlier in April, from some of the first collisions of the year with three proton bunches circulating in the LHC (Image: CMS/CERN).

Among other searches, LHCb will continue to seek a solution to the problem of matter-antimatter asymmetry, as the Standard Model cannot adequately explain the observed abundance of matter in the universe. When matter was formed in the Big Bang, there should have been an equal amount of antimatter accompanying it; each matter-antimatter pair should then have annihilated upon contact, leaving us with a universe without stars or human beings to observe them.

ALICE, the LHC’s heavy-ion specialist, focuses on collisions of lead nuclei in order to study the strong interaction and the quark-gluon plasma, a state of matter that is believed to have prevailed in the very early universe. However, ALICE will also record proton-proton collisions to continue its investigation of the properties of collision events that contain a large number of particles produced at the same time and to serve as a baseline with which to compare lead-lead collisions.

Image above: An event recorded by ALICE earlier in April, from some of the first collisions of the year with three proton bunches circulating in the LHC (Image: ALICE/CERN).

The LHC operators will keep ramping up the number of bunches, aiming to hit 2556 bunches in total. This will help them achieve their target of 60 inverse femtobarns (fb^-1) of proton-proton collisions this year delivered to both ATLAS and CMS, 20% more than the 50 fb ^-1 achieved in 2017. In simple terms, each inverse femtobarn can correspond to up to 100 million million (10¹⁴) individual collisions between protons. The proton-proton run will be followed by the first heavy-ion run since 2016; the LHC will inject and collide lead nuclei at the end of the year.

This is the last year with collisions before the LHC enters a period of hibernation until spring 2021, known as Long Shutdown 2, during which the machine and the experiments will be upgraded. All four experiments will therefore hope to maximise their data-collection efficiency to keep themselves occupied with many analyses and new results over the two-year shutdown, using high-quality data collected this year.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

Read more about the start of the LHC's 2018 physics run:

ATLAS starts new year of data-taking: https://atlas.cern/updates/atlas-news/atlas-starts-new-year-data-taking

Start of 2018 data taking period [LHCb]: http://lhcb-public.web.cern.ch/lhcb-public/#2018SB

Related links:

Large Hadron Collider (LHC): https://home.cern/topics/large-hadron-collider

ALICE: https://home.cern/about/experiments/alice

ATLAS: https://home.cern/about/experiments/atlas

CMS: https://home.cern/about/experiments/cms

LHCb: https://home.cern/about/experiments/lhcb

Standard Model of particle physics: https://home.cern/about/physics/standard-model

Dark matter: https://home.cern/about/physics/dark-matter

Matter-antimatter asymmetry: https://home.cern/topics/antimatter

Higgs boson that they discovered in July 2012: https://home.cern/topics/higgs-boson

For more information about European Organization for Nuclear Research (CERN), Visit: https://home.cern/

Images (mentioned), Text, Credits: CERN/Achintya Rao.

Best regards, Orbiter.ch

Twin Spacecraft to Weigh in on Earth's Changing Water

NASA & DLR - GRACE Mission patch.

April 30, 2018

A pair of new spacecraft that will observe our planet’s ever-changing water cycle, ice sheets, and crust is in final preparations for a California launch no earlier than Saturday, May 19. The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission, a partnership between NASA and the German Research Centre for Geosciences (GFZ), will take over where the first GRACE mission left off when it completed its 15-year mission in 2017.

GRACE-FO will continue monitoring monthly changes in the distribution of mass within and among Earth’s atmosphere, oceans, land and ice sheets, as well as within the solid Earth itself. These data will provide unique insights into Earth’s changing climate, Earth system processes and even the impacts of some human activities, and will have far-reaching benefits to society, such as improving water resource management.

“Water is critical to every aspect of life on Earth – for health, for agriculture, for maintaining our way of living,” said Michael Watkins, GRACE-FO science lead and director of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “You can’t manage it well until you can measure it. GRACE-FO provides a unique way to measure water in many of its phases, allowing us to manage water resources more effectively.”

Image above: Illustration of the NASA's Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) spacecraft, which will track changes in the distribution of Earth’s mass, providing insights into climate, Earth system processes and the impacts of some human activities. GRACE-FO is a partnership between NASA and the German Research Centre for Geosciences. Image Credits: NASA/JPL-Caltech.

Like GRACE, GRACE-FO will use an innovative technique to observe something that can’t be seen directly from space. It uses the weight of water to measure its movement – even water hidden far below Earth’s surface. GRACE-FO will do this by very precisely measuring the changes in the shape of Earth’s gravity field caused by the movement of massive amounts of water, ice, and solid Earth.

“When water is underground, it’s impossible to directly observe from space. There’s no picture you can take or radar you can bounce off the surface to measure changes in that deep water,” said Watkins. “But it has mass, and GRACE-FO is almost the only way we have of observing it on large scales. Similarly, tracking changes in the total mass of the polar ice sheets is also very difficult, but GRACE-FO essentially puts a ‘scale’ under them to track their changes over time.”

Image above: At the Harris facility at Vandenberg Air Force Base in California, one of the twin GRACE-FO satellites is integrated with the multi-satellite dispenser structure that will be used to deploy the satellites during launch. Image Credit: Airbus.

A Legacy of Discoveries

GRACE-FO will extend the GRACE data record an additional five years and expand its legacy of scientific achievements. GRACE chronicled the ongoing loss of mass from the Greenland and Antarctic ice sheets and mountain glaciers. That wealth of data shed light on the key processes, short-term variability, and long-term trends that impact sea level rise, helping to improve sea level projections. The estimates of total water storage on land derived from GRACE data, from groundwater changes in deep aquifers to changes in soil moisture and surface water, are giving water managers new tools to measure the impact of droughts and monitor and forecast floods.

GRACE data also have been used to infer changes in deep ocean currents, a driving force in Earth’s climate. Its atmospheric temperature profile data, derived from measurements of how signals from the constellation of GPS satellites were bent as they traveled through the atmosphere and received by antennas on the GRACE satellites, have contributed to U.S. and European weather forecast products. GRACE data have even been used to measure changes within the solid Earth itself, including the response of Earth’s crust to the retreat of glaciers since the last Ice Age, and the impact of large earthquakes.

According to Frank Webb, GRACE-FO project scientist at JPL, the new mission will provide invaluable observations of long-term climate-related mass changes.

“The only way to know for sure whether observed multi-year trends represent long-term changes in mass balance is to extend the length of the observations,” Webb said.

An Orbiting Cat and Mouse

Like its predecessors, the two identical GRACE-FO satellites will function as a single instrument. The satellites orbit Earth about 137 miles (220 kilometers) apart, at an initial altitude of about 305 miles (490 kilometers). Each satellite continually sends microwave signals to the other to accurately measure changes in the distance between them. As they fly over a massive Earth feature, such as a mountain range or underground aquifer, the gravitational pull of that feature tugs on the satellites, changing the distance separating them. By tracking changes in their separation distance with incredible accuracy - to less than the thickness of a human hair - the satellites are able to map these regional gravity changes.

A global positioning system receiver is used to track each spacecraft’s position relative to Earth’s surface, and onboard accelerometers record non-gravitational forces on the spacecraft, such as atmospheric drag and solar radiation. These data are combined to produce monthly maps of the regional changes in global gravity and corresponding near-surface mass variations, which primarily reflect changes in the distribution of water mass in Earth’s atmosphere, oceans, land and ice sheets.

In addition, GRACE-FO will test an experimental Laser Ranging Interferometer, an instrument that could increase the precision of measurements between the two spacecraft, by a factor of 10 or more, for future missions similar to GRACE. The interferometer, developed by a German/American instrument team, will be the first in-space demonstration of laser interferometry between satellites.

“The Laser Ranging Interferometer is an excellent example of a great partnership,” said Frank Flechtner, GFZ’s GRACE-FO project manager. “I’m looking forward to analyzing these innovative inter-satellite ranging data and their impact on gravity field modeling.”

GRACE-FO will be launched into orbit with five Iridium NEXT communications satellites on a commercially procured SpaceX Falcon 9 rocket from Vandenberg Air Force Base in California. This unique “rideshare” launch will first deploy GRACE-FO, then the Falcon 9 second stage will continue to a higher orbit to deploy the Iridium satellites.

GRACE-FO continues a successful partnership between NASA and Germany’s GFZ, with participation by the German Aerospace Center (DLR). JPL manages the mission for NASA’s Science Mission Directorate in Washington.

For more information on GRACE-FO, visit: https://www.nasa.gov/gracefo

Images (mentioned), Text, Credits: NASA/Steve Cole/Karen Northon/JPL/Alan Buis.

Greetings, Orbiter.ch

Old Data, New Tricks: Fresh Results from NASA’s Galileo Spacecraft 20 Years On

NASA - Galileo Mission patch.

April 30, 2018

Image above: Hubble Space Telescope has caught Jupiter's moon Ganymede playing a game of "peek-a-boo." In this crisp Hubble image, Ganymede is shown just before it ducks behind the giant planet. This color image was made from three images taken on April 9, 2007, with the Wide Field Planetary Camera 2 in red, green, and blue filters. The image shows Jupiter and Ganymede in close to natural colors. Image Credits: NASA, ESA and E. Karkoschka (University of Arizona).

Far across the solar system, from where Earth appears merely as a pale blue dot, NASA’s Galileo spacecraft spent eight years orbiting Jupiter. During that time, the hearty spacecraft — slightly larger than a full-grown giraffe — sent back spates of discoveries on the gas giant’s moons, including the observation of a magnetic environment around Ganymede that was distinct from Jupiter’s own magnetic field. The mission ended in 2003, but newly resurrected data from Galileo’s first flyby of Ganymede is yielding new insights about the moon’s environment — which is unlike any other in the solar system.

“We are now coming back over 20 years later to take a new look at some of the data that was never published and finish the story,” said Glyn Collinson, lead author of a recent paper about Ganymede's magnetosphere at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We found there’s a whole piece no one knew about.”

The new results showed a stormy scene: particles blasted off the moon’s icy surface as a result of incoming plasma rain, and strong flows of plasma pushed between Jupiter and Ganymede due to an explosive magnetic event occurring between the two bodies’ magnetic environments. Scientists think these observations could be key to unlocking the secrets of the moon, such as why Ganymede’s auroras are so bright.

Image above: This image of Ganymede, one of Jupiter's moons and the largest moon in our solar system, was taken by NASA's Galileo spacecraft. Image Credit: NASA.

In 1996, shortly after arriving at Jupiter, Galileo made a surprising discovery: Ganymede had its own magnetic field. While most planets in our solar system, including Earth, have magnetic environments — known as magnetospheres — no one expected a moon to have one.

Between 1996 and 2000, Galileo made six targeted flybys of Ganymede, with multiple instruments collecting data on the moon’s magnetosphere. These included the spacecraft's Plasma Subsystem, or PLS, which measured the density, temperature and direction of the plasma — excited, electrically charged gas — flowing through the environment around Galileo. New results, recently published in the journal Geophysical Research Letters, reveal interesting details about the magnetosphere's unique structure.

We know that Earth’s magnetosphere — in addition to helping make compasses work and causing auroras — is key to in sustaining life on our planet, because it helps protect our planet from radiation coming from space. Some scientists think Earth’s magnetosphere was also essential for the initial development of life, as this harmful radiation can erode our atmosphere. Studying magnetospheres throughout the solar system not only helps scientists learn about the physical processes affecting this magnetic environment around Earth, it helps us understand the atmospheres around other potentially habitable worlds, both in our own solar system and beyond.

Image above: This infographic describes Ganymede's magnetosphere. Image Credits: NASA's Goddard Space Flight Center/Mary Pat Hrybyk-Keith.

Ganymede’s magnetosphere offers the chance to explore a unique magnetic environment located within the much larger magnetosphere of Jupiter. Nestled there, it’s protected from the solar wind, making its shape different from other magnetospheres in the solar system. Typically, magnetospheres are shaped by the pressure of supersonic solar wind particles flowing past them. But at Ganymede, the relatively slower-moving plasma around Jupiter sculpts the moon's magnetosphere into a long horn-like shape that stretches ahead of the moon in the direction of its orbit.

Flying past Ganymede, Galileo was continually pummeled by high-energy particles — a battering the moon is also familiar with. Plasma particles accelerated by the Jovian magnetosphere, continually rain down on Ganymede’s poles, where the magnetic field channels them toward the surface. The new analysis of Galileo PLS data showed plasma being blasted off the moon’s icy surface due to the incoming plasma rain.

“There are these particles flying out from the polar regions, and they can tell us something about Ganymede’s atmosphere, which is very thin,” said Bill Paterson, a co-author of the study at NASA Goddard, who served on the Galileo PLS team during the mission. “It can also tell us about how Ganymede’s auroras form.”

Jupiter's Magnetosphere

Video above: This visualization shows a simplified model of Jupiter’s magnetosphere, designed to illustrate the scale, and basic features of the structure and impacts of the magnetic axis (cyan arrow) offset from the planetary rotation axis (blue arrow). The semi-transparent gray mesh in the distance represents the boundary of the magnetosphere. Video Credits: NASA's Scientific Visualization Studio/JPL NAIF.

Ganymede has auroras, or northern and southern lights, just like Earth does. However, unlike our planet, the particles causing Ganymede’s auroras come from the plasma surrounding Jupiter, not the solar wind. When analyzing the data, the scientists noticed that during its first Ganymede flyby, Galileo fortuitously crossed right over Ganymede’s auroral regions, as evidenced by the ions it observed raining down onto the surface of the moon’s polar cap. By comparing the location where the falling ions were observed with data from Hubble, the scientists were able to pin down the precise location of the auroral zone, which will help them solve mysteries, such as what causes the auroras.

Image above: In this illustration, the moon Ganymede orbits the giant planet Jupiter. Ganymede is depicted with auroras, which were observed by NASA’s Hubble Space Telescope. Image Credits: NASA/ESA.

As it cruised around Jupiter, Galileo also happened to fly right through an explosive event caused by the tangling and snapping of magnetic field lines. This event, called magnetic reconnection, occurs in magnetospheres across our solar system. For the first time, Galileo observed strong flows of plasma pushed between Jupiter and Ganymede due to a magnetic reconnection event occurring between the two magnetospheres. It’s thought that this plasma pump is responsible for making Ganymede’s auroras unusually bright.

Future study of the PLS data from that encounter may yet provide new insights related to subsurface oceans previously determined to exist within the moon using data from both Galileo and the Hubble Space Telescope.

The research was funded by NASA’s Solar System Workings program and the Galileo mission managed by NASA’s Jet Propulsion Laboratory in Pasadena, California, for the agency’s Science Mission Directorate in Washington.

Related Links:

Learn more about NASA’s Galileo mission: https://www.jpl.nasa.gov/missions/galileo/

"NASA’s Hubble Observations Suggest Underground Ocean on Jupiter's Largest Moon" (March 12, 2015): http://orbiterchspacenews.blogspot.ch/2015/03/hubble-observations-suggest-underground.html

Images (mentioned), Video, Text, Credits: NASA/Rob Garner/Goddard Space Flight Center, by Mara Johnson-Groh.

Greetings, Orbiter.ch