samedi 11 avril 2015

CERN - LHC: Preparations for collisions at 13 TeV












CERN - European Organization for Nuclear Research logo.

11 April 2015

On Sunday proton beams circulated in the Large Hadron Collider (LHC) for the first time after a 2-year period of maintenance and upgrades to the machine. From the CERN Control Centre, LHC operators and systems experts kept the beams at their injection energy of 450 gigaelectronvolts (GeV), far below the target energy of 6.5 teraelectronvolts (TeV) per beam. Now the operators are testing the accelerator's subsystems and optimizing key beam parameters in preparation for increasing the beam intensity and ramping up the energy.


Image above: LHC operators will spend the coming weeks testing and checking all of the accelerator's many subsystems from the CERN Control Centre (Image: Maximilien Brice/CERN).

Only when the machine is sufficiently tuned – and the team declares "Stable Beams" with the beams in collision at the new energy of 6.5 TeV per beam – will the physics data taking begin. This work will take many weeks.

"Beams at injection energy are a useful way of checking that all is running as it should," says LHC operator Ronaldus SuykerBuyk. "For example, we use these low-intensity beams to make sure that our beam-diagnostic equipment is working properly and is well calibrated.”

The team will spend most of the time from now until collisions checking and rechecking a whole wealth of subsystems on the LHC. For example, the Machine Protection subsystem ensures that the LHC is protected from its own beams. It includes the beam dump, beam interlock system, collimators, and beam-energy tracking devices. 'Loss maps' tell the team where the beam is losing particles along the ring. Then there's Beam Instrumentation, which includes position monitors, beam-loss monitors and synchrotron-light monitors among other devices. Not to mention the radiofrequency, vacuum, beam-optics and injection systems, which all need to be tested and double-checked over the coming weeks.


Image above: A wealth of subsystems monitor the quality of beams in the LHC (Image: Maximilien Brice/CERN).

Despite the LHC's complexity, increasing the beam energy is a simple enough process: ramp up the current in the magnets and allow the radiofrequency system to increase the energy of the beams. The current in all the magnets (and hence the magnetic field seen by the beam) is carefully increased as the beam energy rises. The main dipoles provide the necessary centripetal force to bend the beams around the ring. Other magnets such as the quadrupoles have to carefully track along with the increasing dipole field.

"The machine is behaving as expected at 450 GeV," says Mike Lamont of the LHC operations team. "We are now circulating a single bunch of protons, and using it to test our many subsystems. The bunch currently contains about 5 billion protons. When the LHC is ready, we will increase this number to the nominal bunch population of about 120 billion protons per bunch, and focus on fine-tuning the machine for collisions."

For now the team is taking a softly, softly approach, planning on injecting only three bunches of protons at nominal intensity for the first collision attempts, which are expected in the coming weeks.

First successful beam at record energy of 6.5 TeV


Image above: "LHC page 1" shows the status of the LHC last night. The black line shows the beam energy increasing to 6.5 TeV (Image:LHC/CERN).

Last night the Operations team for the Large Hadron Collider (LHC) successfully circulated a beam at 6.5 teralectronvolts (TeV) - one of many steps before the accelerator will deliver collisions at four interaction points within the ALICE, ATLAS, CMS and LHCb detectors.

The image above shows "LHC page 1"- the status of the accelerator between 10.45pm and 1am last night. The lines on the graph show the intensity of Beam 1 (blue) and Beam 2 (red) as the team injects the beams into the accelerator. The black line shows the energy for Beam 2, which begins to increase at around 12.35am from its injection energy of 450 GeV and ramps to 6.5 TeV (shown as 6500 gigaelectronvolts at the top left of the screen).

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.

Related links:

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

ALICE experiments: http://home.web.cern.ch/about/experiments/alice

ATLAS experiments: http://home.web.cern.ch/about/experiments/atlas

CMS experiments: http://home.web.cern.ch/about/experiments/cms

LHCb experiments: http://home.web.cern.ch/about/experiments/lhcb

For more information about the European Organization for Nuclear Research (CERN), visit: http://home.web.cern.ch/

Images (mentioned), Text, Credits: CERN/Cian O'Luanaigh.

Best regards, Orbiter.ch

vendredi 10 avril 2015

The TRMM Rainfall Mission Comes to an End after 17 Years












NASA / JAXA - Tropical Rainfall Measuring Mission (TRMM) patch.

April 10, 2015

In 1997 when the Tropical Rainfall Measuring Mission, or TRMM, was launched, its mission was scheduled to last just a few years. Now, 17 years later, the TRMM mission has come to an end. NASA and the Japan Aerospace Exploration Agency (JAXA) stopped TRMM’s science operations and data collection on April 8 after the spacecraft depleted its fuel reserves.

TRMM observed rainfall rates over the tropics and subtropics, where two-thirds of the world’s rainfall occurs. TRMM carried the first precipitation radar flown in space, which returned data that were made into 3-D imagery, enabling scientists to see the internal structure of storms for the first time.

video
TRMM Mission Ends

Video above: TRMM Project Scientist Scott Braun looks back over the legacy of the Tropical Rainfall Measuring Mission and a few of the scientific milestones it has helped to achieve. Image Credit: NASA.

TRMM also carried a microwave imager, a state-of-the-art instrument that had the highest resolution images of rainfall at the time. Together with three other sensors – the Visible and Infrared Scanner (VIRS), the Lightning Imaging Sensor (LIS), and the Clouds and the Earth’s Radiant Energy System (CERES) instrument – scientists used TRMM data to explore weather events, climate, and Earth’s water cycle.

The cutting-edge TRMM instruments arrived in orbit at the right time to take advantage of the explosion of computing power and major advances in data-sharing.

"In the early 1990s, sharing data consisted of nine-track data tapes in the mail," said research meteorologist George Huffman at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "By the time you got to the 2000s, it became possible to actually share data online. Once we got that piece in place, people were asking, 'Oh, can you send me that data?' Eventually they wanted to see it all the time."

Scientists at Goddard originally intended TRMM's data to be used purely for precipitation research, but before long, people and organizations outside NASA were using it for a variety of purposes.

"The data were being heavily used for tropical cyclone monitoring and forecasting," said TRMM Project Scientist Scott Braun at Goddard. "It was being used for flood detection and monitoring. It was also used for drought monitoring, disease monitoring — where diseases are most prevalent in areas of heavy precipitation and flooding."



Image above: This artist rendering shows the TRMM satellite orbiting over a hurricane's eyewall. Image Credit: NASA.

The scientific community considered TRMM’s data so critical to research and many practical applications that in 2001, at the end of TRMM's primary mission, NASA wanted to extend the mission for as long as possible.

TRMM's original flight altitude was optimized for the precipitation radar. To obtain precipitation profiles through the depth of the lower atmosphere and to concentrate the measurements in the tropics, the orbit was confined to 35 degrees north to 35 degrees south latitude at an altitude of 350 km (217.5 miles). At this altitude, Earth's atmosphere is still sufficiently dense to cause drag on the spacecraft, slowing it down, which progressively lowers its altitude.

"In the early years of its mission, TRMM was burning through fuel quickly," said Eric Moyer, Goddard Earth Science Operations manager. "By design, TRMM carried fuel and had a controlled burn scheduled every few weeks to increase its speed and maintain altitude."

To extend TRMM's mission life, NASA boosted the spacecraft's orbit altitude to 402.5 km (about 250 miles) in 2001. Earth’s atmosphere thins as it stretches out toward space, so a spacecraft at higher altitudes experiences less drag (that slows it down) and consumes less fuel to maintain its orbit. At this altitude, the radar would still return strong, research quality data. This maneuver extended TRMM's life four more years, and after review in 2005, NASA again extended the mission life until the satellite ran out of fuel.

TRMM's 17 years in orbit allowed the mission to grow and evolve, Huffman said.

The original goal was to provide monthly averages of rainfall over Earth's surface divided into large grid boxes, roughly 500 km (about 310 miles) square. TRMM eventually generated rainfall estimates at a higher resolution and in near-real time, every three hours.

"And it's just the same old instruments," Huffman said. "What that demonstrates is that the capability was already there. We just had to work back through the rest of the system to make it happen, starting with the thought, 'Oh gosh, we could do this.'"

Huffman and his team combined TRMM data with precipitation data from several other microwave imaging satellites in orbit, many of them weather satellites. Together with significant advances in data management they created the new TRMM product.


Image above: TRMM observes the 3-D rain structure of Hurricane Katrina on Aug. 28, 2005, including the red spikes known as hot towers that appear where the storm is most intense. The center tower is located on the hurricane's eyewall. Image Credit: NASA.

Now, TRMM has reached the end of its life. Battery issues complicated the operation of the spacecraft over the past year, so Braun and the mission operations team had to make decisions about how to ration what power remains. In March 2014, they decided to turn off the VIRS instruments to extend the battery life. In July 2014, the spacecraft ran out of fuel that kept it at its boosted operational altitude and TRMM slowly began to drift down, while still collecting data. The remaining fuel, initially reserved to avoid collisions with other satellites or space debris, was depleted in early March 2015.

Observations of hurricanes and precipitation from space will not end after TRMM. The Global Precipitation Measurement (GPM) mission's Core Observatory, launched in February 2014, succeeds and improves upon the TRMM project. Both missions are joint projects of NASA and JAXA.

Since TRMM's launch, many other space programs, including those in Europe and Japan, have launched precipitation measurement satellites containing microwave radiometers that measure radiated energy from rainfall and snowfall. The GPM mission harnesses the combined scope of these spacecraft and uses the GPM Core Observatory to standardize the measurements from the individual satellites. Together, they are combined into uniform data sets that are made available online. Just as with TRMM's data, anyone in the world can access the repository.

In addition to the moderate and heavy rainfall that TRMM was capable of observing in the tropics, GPM also observes light rain and falling snow. Its orbit passes above a larger portion of the world. TRMM’s orbit covered the latitude ranging from 35 degrees north to 35 degrees south, which is as far north as Cape Hatteras, North Carolina, and as far south as Buenos Aires, Argentina, but GPM’s coverage of latitude from 65 degrees north to 65 degrees south stretches nearly to the Arctic and Antarctic Circles.

The information these missions can provide is critical to people around the world. The data provided by precipitation-related satellite missions can save lives in cases such as landslides and tropical cyclones. They also help improve climate models, which help predict what our planet may be like years into the future.

Updates on the re-entry of the TRMM spacecraft will be posted to the mission website: http://trmm.gsfc.nasa.gov/

Related Links:

Precipitation Measurement Missions Website: http://pmm.nasa.gov/

GPM Website: http://www.nasa.gov/gpm

Read more about Hurricane Katrina here: http://www.nasa.gov/mission_pages/hurricanes/archives/2005/h2005_katrina.html

Images (mentioned), Video (mentioned), Text, Credits: NASA/J.D. Harrington/Goddard Space Flight Center/Ashley Morrow.

Greetings, Orbiter.ch

Rosetta - GIADA investigates comet’s “fluffy” dust grains












ESA - Rosetta Mission patch.

10 April 2015

In a recent paper published in the Astrophysical Journal Letters, the GIADA team present their findings on the properties of dust particles from Comet 67P/Churyumov-Gerasimenko. This blog post has been prepared with inputs from lead author Marco Fulle, and GIADA principal investigator Alessandra Rotundi.

GIADA, the Grain Impact Analyser and Dust Accumulator, is designed to capture dust particles in the coma of Comet 67P/Churyumov–Gerasimenko as Rosetta flies around it. The characteristic properties of the dust grains can be used to infer the history of the material being ejected from comet.


Image above: The location of GIADA marked on the Rosetta spacecraft. Image courtesy Alessandra Rotundi.

The latest study focuses on the dust particles collected between 1 August 2014 and 14 January 2015. The GIADA team find that the dust particles impacting on their detectors can be separated into two families: ‘compact’ particles with sizes in the range 0.03–1 mm, and somewhat larger ‘fluffy aggregates’ with sizes between 0.2 and 2.5 mm.

The individual compact particles have a bulk density of 800–3000 kg/m3, consistent with a variety of minerals or mixtures of minerals. On the other hand, the larger aggregates are made up of many sub-micron sized grains with void spaces in between, resulting in fluffy, highly porous structures that are mostly empty space. These aggregates are associated with the fluffy particles seen by Rosetta’s COSIMA instrument.

Indeed, the fluffy particles have effective densities of less than 1 kg/m3, literally lighter than air (at sea-level), and which Marco likens to the equivalent density of a dandelion seed head in a vacuum.

During the study period, a total of 193 compact particles were detected, impacting the GIADA detectors at an average speed of 3 m/s. A total of 853 detections of fluffy particles were made, the great majority associated with 45 dust ‘showers’. Roughly 2–3 of these showers were seen by GIADA each week, lasting anywhere between 0.1 to 30 seconds. A typical shower might be broken up into a handful of sub-showers as well, lasting from 10 milliseconds up to a second.


Image above: The fluffy particles are likened to the equivalent density of a dandelion seed head in a vacuum. Image: Greg Hume - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

While more fluffy particles were detected than compact ones, their size distribution reveals that they only contribute a minor fraction of the total mass of dust being lost by the comet.

Also, importantly, most of the fluffy particles were detected hitting GIADA at less than 1 m/s. Because the escape speed of both types of dust particles from the surface of Comet 67P/C-G should be the same, the fluffy aggregates must be decelerated somehow. The scientists believe that this is happening due to Rosetta itself.

Measurements made by Rosetta’s RPC-LAP instrument show that the spacecraft is negatively charged at between –5 and –10 volts due to a variety of effects associated with the plasma environment of the comet and with solar UV photons hitting the spacecraft. This negative potential acts to decelerate approaching dust particles, which are also negatively charged.

Marco explains: “Both the spacecraft and the dust particles are negatively charged, so there is a repulsive force between them. The amount of deceleration experienced by any particle is related to its charge and mass, with the maximum amount of charge held by the dust particle determined by its geometry.

“For example, the fluffy aggregates can collect about 20 times more charge than compact particles of equivalent radius. These fluffy particles will be slowed down more, and could even be stopped or repelled by the spacecraft if their charge-to-mass ratio is large enough.


Image above: This image was taken by Rosetta’s NAVCAM at about 385 km from the comet centre and shows the comet's dust streaming out into space. The image measures 34 km across. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0.

“In addition, the more charge collected by a fluffy dust particle, the larger the internal disruptive forces are, and so the greater chance it will become unstable closer to the spacecraft, leading to its fragmentation before arriving at GIADA.”

Thus, the denser compact particles are not greatly impacted by this effect, while the fluffy aggregates are slowed down and disrupted creating the showers and sub-showers seen by GIADA. The smaller fragments arrive at the spacecraft at speeds as low as a few centimetres per second and may further collapse into rubble piles, as seen in the COSIMA images.

Density is a critical parameter differentiating these two families of particles, and it is likely that they have quite different histories. By comparing the GIADA results with laboratory measurements, the scientists believe that the denser compact grains represent materials that underwent significant processing in the environment surrounding the new born Sun, before being accreted by Comet 67P/C-G as it formed in the outer Solar System.

The low-density fluffy particles, however, are thought to be primitive material linked to interstellar dust, material that pre-dates the birth of the Sun and escaped any processing before being accreted by the comet during its formation.

More detailed information can be found in the paper, which can be accessed here: http://iopscience.iop.org/2041-8205/802/1/L12

Related link:

Rosetta watches comet shed its dusty coat: http://orbiterchspacenews.blogspot.ch/2015/01/rosetta-watches-comet-shed-its-dusty.html

For more information about Rosetta mission, visit: http://www.esa.int/Our_Activities/Space_Science/Rosetta

Images (mentioned), Text, Credit: European Space Agency (ESA).

Greetings, Orbiter.ch

Heart of the black auroras revealed by Cluster







ESA - Cluster Mission logo.

09 April 2015

Most people have heard of auroras - more commonly known as the Northern and Southern Lights - but, except on rare occasions, such as the recent widespread apparition on 17 March, they are not usually visible outside the polar regions. Less familiar are phenomena known as black auroras, dark patches which often subdivide the glowing curtains of red and green light.

For almost 15 years, ESA's four Cluster satellites have been orbiting Earth, sending back data on electrical fields, magnetic fields and particle populations as they sweep above the region of space where these colourful curtains of light are created.

Aurora over Icelandic lake. Image Credit: C. Gauna

For almost 15 years, ESA's four Cluster satellites have been orbiting Earth, sending back data on electrical fields, magnetic fields and particle populations as they sweep above the region of space where these colourful curtains of light are created.

By flying in close formation through Earth's magnetosphere – the invisible magnetic bubble that surrounds our planet - the quartet has gathered a treasure trove of multi-point observations which help to cast light on the physical processes taking place in auroral nurseries and the secrets of how the dark "cavities" in the shimmering auroras are created.

Auroras are known to be generated by beams of electrons which are accelerated along Earth's magnetic field lines. The fast-moving electrons collide with atoms in the ionosphere at altitudes of between 100 to 600 km. This interaction with oxygen atoms results in a green or, more rarely, red glow in the night sky, while nitrogen atoms yield blue and purple colours.

Whereas bright auroras are created by electrons plunging downward into the ionosphere, neighbouring black auroras are caused by electrons escaping from the ionosphere - like a kind of anti-aurora. However, until now, scientists have been struggling to explain the relationship between the two auroral types.

The first observations of the dynamical behaviour of black auroras were made by the four Cluster spacecraft and reported back in 2001. This study revealed that the electron population of the ionosphere becomes more and more depleted in these dark regions.

Now scientists from the UK and Sweden have used the huge archive of Cluster data to develop the first accurate model of electric fields and currents at the heart of the black auroras. Their new paper, published in the Journal of Geophysical Research - Space Physics, accounts for the observed evacuation of electrons from the ionosphere to the magnetosphere and explains the dynamic behaviour of the black aurora.

video
Black aurora near Tromsø. Video Credit: courtesy of Michael Kosch

The scientific collaboration came about as a result of a series of three week-long workshops hosted by the International Space Science Institute (ISSI), which were led by Andrew Wright, a researcher at the School of Mathematics and Statistics in University of St Andrews and a co-author of the paper.

"The ISSI, which is partly funded by ESA, provides a unique facility for scientists to meet and discuss a common research interest, and it was instrumental in bringing us together. Our research resulted directly from our team participating in these workshops," said Wright.

The first step in the diagnosis of the black auroras' creation was made by Tomas Karlsson, a researcher in the Department of Space and Plasma Physics at the Royal Institute of Technology in Stockholm, Sweden, and a co-author of the paper.

"I have been studying the Cluster data archive over many years because the four spacecraft provide multipoint measurements when they fly through a region of near-Earth space," said Karlsson. "This makes it possible to analyse how physical properties evolve over time.

"On a few occasions, particularly on 18 February 2004, I noticed a weird combination of electrical and magnetic field measurements that were different from normal, and I wanted to understand the physics behind the data. On each occasion, the Cluster spacecraft were flying over the night-time auroral region.

"I presented the data at a workshop held by the International Space Science Institute in Bern, Switzerland, in 2012. This led to a collaboration with team leader Andrew Wright and with Alex Russell, who agreed to try to model the Cluster measurements."

By concentrating on data collected by the Electric Field and Wave (EFW) and Fluxgate Magnetometer (FGM) instruments on the four Cluster spacecraft, the two UK scientists were able to generate a computer model that explained the unusual readings.

"We found strong evidence of a two-way interaction between the ionosphere and the magnetosphere," said Alexander Russell, a post-doctoral Research Fellow in the Department of Mathematics, University of Dundee, UK, and lead author of the paper in JGR – Space Physics.

"Auroral arcs are created by electric currents. The beam of electrons shooting down towards Earth along magnetic field lines is actually an electric current aligned with Earth's magnetic field. It is called an upward, field-aligned current because the negatively charged electrons are moving downward. [1]

"On the other hand, when a downward magnetospheric current meets the ionosphere, electrons are driven upwards and 'sucked' from the ionosphere, creating a black aurora. However, when the electron density in the ionosphere drops markedly the black aurora becomes less intense.

"This evacuation of the ionosphere is essential in shaping the black auroras. The process is much more important on Earth's nightside than on the dayside because sunlight creates new electrons which fill the 'hole'.

"Our model demonstrates how this two-way electrodynamic coupling between the magnetosphere and ionosphere works. This is made possible by a horizontal drift of ions in the ionosphere, known as the Pedersen current, which closes the current system."

The main feature of the model is a field-aligned current system comprising a narrow region of downward current sandwiched between two much broader - and much weaker - upward currents. If the downward current intensifies, it can cause a large number of electrons to move upward into the magnetosphere, thus depleting the ionosphere and creating a density cavity.

Cluster's Constellation satellites. Image Credit: ESA

"In our paper we think of the currents flowing into the ionosphere as being carried by waves which propagate along magnetic field lines," said Andrew Wright. "This a key feature of our theory. The depleted density and electrical conductivity in a black aurora substantially modify the wave reflected from the ionosphere, producing signatures in the magnetosphere like the unusual Cluster observations.

"For the first time we are able to reproduce the phenomenon of the black aurora and in particular what happens at its heart, where strong electric fields are present. We hope that this will lead to a better understanding of the interaction between the upper atmosphere and the space environment."

"This is a very nice example of how theorists and experimenters can make much greater progress when they work together instead of separately," said Tomas Karlssson.

"The paper presents a major improvement of the existing magnetosphere-ionosphere coupling model," said Philippe Escoubet, ESA's Cluster project scientist.

"The modelling of the ionosphere's physical state is of prime importance in our modern technological society. For example, GPS signals can be modified by changes in electron content in the ionosphere, so that their navigational and timing accuracy are significantly reduced. Improved modelling of the ionosphere is necessary to make the necessary corrections.

"Aircraft flying over the North Pole rely on radar and radio signals which can also be affected by changes in the ionosphere, so this is not just an academic exercise."

[1] According to convention, negatively charged electrons flow downward, from the magnetosphere to the ionosphere, in an upward field-aligned current. Electrons flow upward, from the ionosphere to the magnetosphere, in a downward field-aligned current.

More information:

"Magnetospheric signatures of ionospheric density cavities observed by Cluster" by A.J.B. Russell, T. Karlsson and A.N. Wright is published in Journal of Geophysical Research - Space Physics, issue 120, April 2015.

Cluster is a constellation of four spacecraft flying in formation around Earth. It is the first space mission able to study, in three dimensions, the natural physical processes occurring within and in the near vicinity of the Earth's magnetosphere. Launched in 2000, it is composed of four identical spacecraft orbiting the Earth in a pyramidal configuration, along a nominal polar orbit of 4 × 19.6 Earth radii (1 Earth radius = 6380 km). Cluster's payload consists of state-of-the-art plasma instrumentation to measure electric and magnetic fields over wide frequency ranges, and key physical parameters characterising electrons and ions from energies of near 0 eV to a few MeV. The science operations are coordinated by the Joint Science Operations Centre (JSOC) at the Rutherford Appleton Laboratory, United Kingdom, and implemented by ESA's European Space Operations Centre (ESOC), in Darmstadt, Germany.

The Cluster Science Data System is a set of nationally distributed data centres, which generate and maintain selected data sets for the experiments most closely associated with each centre.

The Cluster Science Archive is the depository of processed and validated Cluster data, raw data, processing software, calibration data, documentation and other value-added products. All of the Cluster data are public domain.

The International Space Science Institute (ISSI) is an Institute of Advanced Studies based in Bern, Switzerland. The institute's work is interdisciplinary, focusing on the study of the Solar System, but also encompassing planetary sciences, astrophysics, cosmology, astrobiology, and the Earth sciences. One of its main activities is the interpretation of experimental data collected by space research missions. Founded in 1995, ISSI is a non-profit organization and a foundation under Swiss law. ISSI operations are supported by grants from the European Space Agency, the Swiss Confederation, the Swiss National Science Foundation (SNF), the University of Bern and the Space Research Institute (IKI).

Related Publications:

Russell, A. J. B., Karlsson, T., and Wright, A. N. (2015): http://sci.esa.int/cluster/55765-russell-karlsson-and-wright-2015/

See Also:

Cluster quartet probes the secrets of the black aurora: http://sci.esa.int/cluster/29100-cluster-quartet-probes-the-secrets-of-the-black-aurora/

Related Link:

International Space Science Institute (ISSI): http://www.issibern.ch/

For more information about Cluster mission, visit: http://sci.esa.int/cluster/

Images (mentioned), Video (mentioned), Text, Credit: European Space Agency (ESA).

Best regards, Orbiter.ch

Galileo satellites well on way to working orbit












ESA - Galileo Programme logo.

10 April 2015

Their systems performing well, Europe’s recently launched Galileo navigation satellites have carried out a set of manoeuvres that will take them down to their working positions in orbit.

On 27 March, the seventh and eighth Galileo satellites were launched together on a Soyuz launcher into a circular 23 522 km altitude orbit.

Galileo satellite

This was about 300 km above their final orbit. As is standard for nearly all space missions, the satellites themselves are then tasked to manoeuvre themselves precisely into their set positions using their onboard thrusters.

This is especially important for navigation satellites like Galileo, where the precision of their orbits is an essential element of their functioning.

User receivers on the ground derive their position from the time it takes for navigation signals from space to reach them – so just as the Galileo satellites’ onboard atomic clocks are kept accurate down to a few billionths of a second, their orbital position must be known to a matter of centimetres.

Galileo lift-off

The two Galileo satellites have performed all their ‘LEOP’ manoeuvres, called this because they are overseen by their Launch and Early Operations Phase (LEOP) team, based in the Toulouse site of French space agency CNES.

These manoeuvrings began as soon as the automatic initialisation sequence of the satellites was completed. A joint team of ESA and CNES personnel oversaw the LEOP process from CNES Toulouse. 

They spent the morning of 28 March ensuring that the two satellites’ solar arrays deployed correctly and then pointed towards the Sun – so they could switch from relying on their onboard batteries to limitless solar power.

Next came the gradual switch-on of the satellites’ various systems, checking everything was working as planned after the launch.

Controlling Galileo

Their thrusters were fired at precisely timed intervals, for a few minutes at a time. Each manoeuvre is followed up by detailed orbital determinations, to make sure that the satellites have followed their planned trajectories.

Once the two satellites received a clean bill of health then control was passed to Galileo’s Oberpfaffenhofen-based Control Centre (run by SpaceOpal, a joint venture by DLR Gesellschaft für Raumfahrtanwendungen (GfR) and Telespazio) to prepare for their final In-Orbit Testing (IOT) in two phases: commissioning for the host satellite platforms, and then for their navigation and search and rescue payloads.

Galileo satellite in orbit

Platform commissioning is now taking place, while the satellites are drifting in their orbits to reach their final positions.

The Galileo satellites’ navigation and the search and rescue payloads will be switched on in few weeks and will begin detailed in-orbit testing, masterminded from ESA’s Redu centre in Belgium, which is equipped with a 20-m antenna for high-resolution acquisition of the navigation signals.

The hosting of Galileo’s LEOP team alternates between CNES in Toulouse and ESA’s ESOC control centre in Darmstadt, Germany. So the early operations of the next pair of Galileo satellites will be masterminded from ESOC – their launch is scheduled for September.

Related links:

Early operations: http://www.esa.int/Our_Activities/Navigation/The_future_-_Galileo/Launching_Galileo/Early_operations2

In-orbit testing: http://www.esa.int/Our_Activities/Navigation/The_future_-_Galileo/Launching_Galileo/In-orbit_testing2

Joint ESA/CNES team will lead initial Galileo operations: http://www.esa.int/Our_Activities/Navigation/The_future_-_Galileo/Launching_Galileo/Joint_ESA_CNES_team_will_lead_initial_Galileo_operations

Team of teams: http://www.esa.int/ESA_Multimedia/Images/2014/09/Team_of_teams

Imaes, Text, Credits. ESA/P. Carril/CNES/ARIANESPACE-Service Optique CSG, S. Martin.

Greetings, Orbiter.ch

jeudi 9 avril 2015

NASA Study Finds Small Solar Eruptions Can Have Profound Effects On Unprotected Planets












NASA / ESA - SOHO Mission patch.

April 9, 2015

While no one yet knows what's needed to build a habitable planet, it's clear that the interplay between the sun and Earth is crucial for making our planet livable – a balance between a sun that provides energy and a planet that can protect itself from the harshest solar emissions. Our sun steadily emits light, energy and a constant flow of particles called the solar wind that bathes the planets as it travels out into space. Larger eruptions of solar material, called coronal mass ejections, or CMEs, occur too, which can disrupt the atmosphere around a planet. On Earth, some of the impact of these CMEs is deflected by a natural magnetic bubble called the magnetosphere.

But some planets, such as Venus, don't have protective magnetospheres and this can be bad news. On Dec. 19, 2006, the sun ejected a small, slow-moving puff of solar material. Four days later, this sluggish CME was nevertheless powerful enough to rip away dramatic amounts of oxygen out of Venus' atmosphere and send it out into space, where it was lost forever.

Learning just why a small CME had such a strong impact may have profound consequences for understanding what makes a planet hospitable for life. These results appear in the Journal of Geophysical Research on April 9, 2015.


Animation above: A relatively small puff of solar material can be seen escaping the sun on the upper left of this movie from ESA and NASA's SOHO on Dec. 19, 2006. This slow ejection was nevertheless powerful enough to cause Venus to lose dramatic amounts of oxygen from its atmosphere four days later. Image Credit: ESA/NASA/SOHO/Helioviewer.

"What if Earth didn't have that protective magnetosphere?" said Glyn Collinson, first author on the paper at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Is a magnetosphere a prerequisite for a planet to support life? The jury is still out on that, but we examine such questions by looking at planets without magnetospheres, like Venus."

Collinson's work began with data from the European Space Agency, or ESA's, Venus Express, which arrived at Venus in 2006 and carried out an eight-year mission. Studying data from its first year, Collinson noted that on Dec. 23, 2006, Venus' atmosphere leaked oxygen at one of the highest densities ever seen. At the same time the particles were escaping, the data also showed something unusual was happening in the constant solar wind passing by the planet.

To learn more, Collinson worked with Lan Jian, a space scientist at NASA Goddard who specializes in identifying events in the solar wind. Using data from Venus Express, Jian pieced together what had hit the planet. It looked like a CME, so she then looked at observations from the joint ESA and NASA Solar and Heliospheric Observatory. They identifed a weak CME on Dec. 19 that was a likely candidate for the one they spotted four days later near Venus. By measuring the time it took to reach Venus, they established that it was moving at about 200 miles per second – which is extremely slow by CME standards, about the same speed as the solar wind itself.

What Happened to Venus?

Image above: Shareable graphic of Venus: http://www.nasa.gov/content/goddard/what-happened-to-venus/. Image Credit: NASA.

Scientists divide CMEs into two broad categories: those fast enough to drive a shock wave in front of them as they barrel away from the sun, and those that move more slowly, like a fog rolling in. Fast CMEs have been observed at other planets and are known to affect atmospheric escape, but no one has previously observed what a slow one could do.

"The sun coughed out a CME that was fairly unimpressive," said Collinson. "But the planet reacted as if it had been hit by something massive. It turns out it's like the difference between putting a lobster in boiling water, versus putting it in cold water and heating it up slowly. Either way it doesn't go well for the lobster."

Similarly, the effects of the small CME built up over time, ripping off part of Venus's atmosphere and pulling it out into space. This observation doesn't prove that every small CME would have such an effect, but makes it clear that such a thing is possible. That, in turn, suggests that without a magnetosphere a planet's atmosphere is intensely vulnerable to space weather events from the sun.

Venus is a particularly inhospitable planet: It is 10 times hotter than Earth with an atmosphere so thick that the longest any spacecraft has survived on its surface before being crushed is a little over two hours. Perhaps such vulnerabilities to the sun's storms contributed to this environment. Regardless, understanding exactly what effect the lack of a magnetosphere has on a planet like Venus can help us understand more about the habitability of other planets we spot outside our solar system.

The researchers examined their data further to see if they could determine what mechanism was driving off the atmosphere. The incoming CME had clearly pushed in the front nose – the bow shock – of the atmosphere around Venus. The scientists also observed waves within the bow shock that were 100 times more powerful than what's normally present.

"It's kind of like what you'd see in front of a rock in a storm as a wave passes by," said Collinson. "The space in front of Venus became very turbid."

SOHO observing the Sun. Image Credits: NASA/ESA

The team developed three possibilities for the mechanism that drove the oxygen into space. First, even a slow CME increases the pressure of the solar wind, which may have disrupted the normal flow of the atmosphere around the planet from front to back, instead forcing it out into space. A second possibility is that the magnetic fields traveling with the CME changed the magnetic fields that are normally induced around Venus by the solar wind to a configuration that can cause atmospheric outflow. Or, third, the waves inside Venus' bowshock may have carried off particles as they moved.

Collinson says he will continue to look through the collected eight years of Venus Express data for more information, but he points out that seeing a CME near another planet is a lucky finding. Near Earth, we have several spacecraft that can observe a CME leaving the sun and its effects closer to Earth, but it's difficult to track such things near other planets.

This was a rare sighting of a CME that provides a crucial insight into a planet so foreign to our own – and in turn into Earth. The more we learn about other worlds, the more we learn about the very history of our own home planet, and what made it so habitable for life to begin with.

Related link:

Helioviewer.org - Solar and heliospheric image visualization: http://www.helioviewer.org/

For more information about SOHO mission, visit: http://www.nasa.gov/mission_pages/soho/ and http://soho.esac.esa.int/

Animation (mentioned), Images (mentioned), Text, Credits: NASA's Goddard Space Flight
Center/Karen C. Fox.

Best regards, Orbiter.ch

Hubble Space Telescope Turns 25














NASA - Hubble Space Telescope patch / ESA - Hubble Space Telescope patch.

April 9, 2015

NASA's Hubble Space Telescope is a quarter-century old this month. Though only projected to be in service for 10 years when it launched aboard space shuttle Discovery on April 24, 1990, from Kennedy Space Center in Florida, the unique telescope is still a technological marvel 25 years later.

Orbiting 350 miles above the Earth and traveling at 17,500 miles per hour (5 miles per second), Hubble continues to reach back into time to capture stunning images of the universe and our own Milky Way Galaxy with its 100-inch-wide primary mirror. The telescope is credited with confirming the existence of black holes and discovering millions of galaxies and the birthplace of stars, relaying images almost too mind-boggling to comprehend.


Image above: NASA's Hubble Space Telescope is suspended in space by Discovery's Remote Manipulator System following the deployment of part of its solar panels and antennae on April 25, 1990. Image Credit: NASA.

Most recently, Hubble's observations suggest the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter's largest moon. The subterranean ocean may contain more water than all of the water on Earth's surface.

"This discovery marks a significant milestone, highlighting what only Hubble can accomplish," said John Grunsfeld, associate administrator of NASA's Science Mission Directorate at NASA Headquarters in Washington. "In its 25 years in orbit, Hubble has made many scientific discoveries in our own solar system."

Former astronaut Grunsfeld made several trips to upgrade Hubble. He performed a total of eight spacewalks during Servicing Missions 3A, 3B and 4.


Image above: A horizontal view of the launch of the STS-31 mission April 24, 1990. Onboard space shuttle Discovery are the crew of five veteran astronauts and the Hubble Space Telescope. Official launch time was 8:33:51 a.m. EDT. The crew included astronauts Loren Shriver, Charles Bolden Jr., Bruce McCandless, II, Kathryn Sullivan and Steven Hawley. Image Credit: NASA.

In January 2011, the Wide Field Camera 3 on the Hubble Space Telescope found what was thought at the time to be the most distant object ever seen in the universe. The object's light traveled 13.2 billion years to reach Hubble, roughly 150 million years longer than the previous record holder. The very dim and tiny object is a compact galaxy of blue stars that existed 480 million years after the big bang.

Frank Cepollina, who has been with NASA for 52 years, was the project manager for the Hubble Space Telescope servicing missions. He was in the Launch Control Center firing room at Kennedy for all five Hubble servicing missions.

Cepollina is a huge supporter of satellite servicing and currently is project manager for satellite servicing at NASA's Goddard Space Flight Center in Greenbelt, Maryland. He credits Lymon Spitzer, a theoretical physicist and astronomer, and Joe Purcell, a noted physicist, for first suggesting that large telescopes should be built serviceable and modular, so that science instruments and components could be changed out and problems fixed.

NASA's Marshall Space Flight Center in Huntsville, Alabama, led the design, development and construction efforts of the large space telescope. Two primary contractors built Hubble. Lockheed Missiles and Space Company of Sunnyvale, California, produced the protective outer shroud and the spacecraft systems, and Perkin-Elmer Corp. in Danbury, Connecticut, developed the optical system and guidance sensors. Lockheed also assembled and tested the finished product.

Hubble's journey to space began when it arrived at Kennedy in October 1989 on a U.S. Air Force C-5A transport jet from the Lockheed Martin facility in California. Hubble was transported to the Vertical Processing Facility (VPF), where prelaunch preparations were performed. The Payload Hazardous Servicing Facility also was used for offline processing of Hubble science instruments.


Image above: The famous Pillars of Creation, revealing a sharper and wider view of the structures in this visible-light image. Astronomers combined several Hubble exposures to assemble the wider view. The towering pillars are about 5 light-years tall. The dark, finger-like feature at bottom right may be a smaller version of the giant pillars. Image Credit: NASA.

"You couldn't ask for a more customer-friendly center than Kennedy," Cepollina said. "We had, on average, 200 to 300 people at the center through processing and launch, including Kennedy, Goddard, Marshall, and support contractors."

Bob Webster, NASA payload manager at the time, noted that Hubble arrived in a very unique shipping container built by the U.S. Air Force for military surveillance satellites.  Hubble was transported to the pad using Kennedy's payload canister.

Webster recalled several very unusual events that occurred during processing.

The VPF was operated as a class 100k clean work area (less than 100,000 particles larger than 0.5 micrometers in size). The requirement for Hubble's sensitive instruments and lens was less than 20k. The payload processing team worked diligently to maintain the VPF at cleanliness levels between 2k and 5k. The Hubble Space Telescope Program brought with it an array of ground support equipment to test the telescope. Webster said two science instruments were installed in the telescope in the VPF.

"Normally, vertical payloads were transported to the pad before the shuttle," Webster said. "We took Hubble to the pad late in the flow to minimize its time at the pad."


Image above: NASA's Hubble Space Telescope is lifted into the vertical position in the Vertical Processing Facility at Kennedy Space Center on Oct. 10, 1989. Image Credit: NASA.

The hypergolic fuel was loaded into Discovery and then Hubble was delivered to the pad and prepared for installation in the payload bay using the payload changeout room (PCR). But, hundreds of midges, a kind of small fly, had hatched and settled on the payload bay doors, resulting in an unknown number of them getting into the PCR.

Webster said the PCR doors were quickly closed and an environmental team was called in to devise a system to remove the flies. Several lighted traps with small vacuum devices and dry ice were placed throughout the clean room to collect the tiny insects, a process that took about two days.

When the PCR was clear, the eight-hour process began to install and secure the nearly 44-foot-long Hubble in the shuttle payload bay for its trip to space. Precise measurements of the bay and the telescope had been taken in advance to ensure the clearances.

On launch day April 10, pilot Charlie Bolden, now the NASA Administrator, flipped the switches on the shuttle's auxiliary power units (APU) and the launch team realized something was wrong. The flight was delayed two weeks while the faulty APU was changed out.

In a process that had never been planned for, the payload team removed Hubble's batteries inside the payload bay and took them to the Space Shuttle Main Engine Facility in the Vehicle Assembly Building to keep them charged. A few days before launch, the batteries were reinstalled.

"Finally seeing it launch and then deployed was an exciting experience for the entire payload processing team," Webster said. "I enjoyed working with the people on the Hubble team. I felt very proud and lucky to have this opportunity."

Before retiring from NASA in 2000, Webster worked as a division chief in the Space Station Processing Facility, planning for International Space Station segment arrival and processing.


Image above: The Crab Nebula is a six-light-year-wide remnant of a star's supernova explosion. Japanese and Chinese astronomers recorded this violent event nearly 1,000 years ago in 1054, as did, almost certainly, Native Americans. A rapidly spinning neutron star, the dense, crushed core of the exploded star, embedded in the center of the nebula powers the eerie interior bluish glow. Image Credit: NASA.

Hubble was serviced the first time in 1993 to correct a blurred lens, and four more times to upgrade or replace several of the telescope's sensitive instruments. Each servicing mission increased Hubble's ability to reach further and further back in time and improved the clarity of the images. Each time, the space shuttle would bring back Hubble parts and equipment to be refurbished and reused.

"That first servicing mission produced the picture that everybody's seen, called the Eagle Nebula," Cepollina said. "The mission essentially was written around re-establishing the dream."

Cepollina said there were significant societal implications through the course of the servicing program (20 years), from developing the technology to polish the optics on Hubble, which were anywhere from a dime to a quarter size in diameter, to the spherical accuracy needed to be able to correct the light coming into the telescope. The secret was an instrument called COSTAR, which had within it these corrective optics.

COSTAR also represented a great improvement in photolithography, a key process for improving transistor density on a chip. Making microchips is a function of being able to photolithographically create the individual transistors on the head of a pin. The sharper the lines, which are one one-thousandth of the diameter of a human hair, the more transistors can be placed on a pin. More transistors increases the density of the chip, which increases computational ability and memory.

"One example: today's technology has 260,000 times more processing power (i.e. the iPhone) than the original lunar landing vehicle," Cepollina said. "It was a huge leap forward."

On the second servicing mission, the Space Telescope Imaging Spectrograph (STIS) was installed on Hubble. Using its imaging spectrograph, STIS confirmed the existence of black holes.

"One of the very first observations was the M84 galaxy, which indicated there were black holes," Cepollina said. "Because of this instrument, we now know there's a black hole in the center of almost every major galaxy in the universe that we can observe."

STIS also provided a technological push in the medical field, specifically in mammography. This instrument flew a detector that was being developed by the University of Kentucky Medical School. The school sent it to NASA to see if it could be improved upon for use on the STIS instrument. The detectors on that instrument became one of the key elements for the stereotactic breast cancer detection system.

"We did, and handed that technology back to them," Cepollina said. "A year before we launched the STIS instrument to orbit, there were more than 1,000 of these Stereoscopic Imaging breast biopsy machines in hospitals and doctor's offices around the country."

The tools developed to service Hubble were battery-operated systems, some with embedded microprocessors inside of them. Astronauts trained to use these tools. They learned how to program in the amount of speed, torque, turns and direction they wanted to accomplish the tasks.

"All they had to do was crank in the numbers, squeeze the trigger and they would get the right number of RPMs, right number of turns, right speed, clockwise or counter-clockwise motion, and out would come the bolt, or in would go the bolt," Cepollina said.

"That is automation. That is microprocessors. That was a path to robotics."

Another example was the shuttle's robotic arm used to capture Hubble for servicing and then releasing it back into orbit.

"There are two major surgical robotic systems that are in operation today from which we learned and from which they learned from NASA," Cepollina said.

The first is a machine called da Vinci, from a company called Intuitive Surgical, used to perform surgery. Another is the neuro-Arm, a Canadian-built surgical system, used to perform brain surgery on tumors. This surgical robot also can remove tumors that are growing near the central nervous system.

video
Hubble over Earth sunrise. Video Credits: NASA/ESA

"Today there are more than 3,000 da Vinci machines. I recently learned that Intuitive Surgical is using the robot to remove gall bladders," Cepollina said. "Just imagine what the medical field and robotic surgery will be like in 10 years."

What's next on the horizon after Hubble?

Cepollina is studying the possibility of a 1,000-inch telescope, one with modular systems that could be built on the ground in pieces and carried on NASA's Space Launch System, with an Orion crew that could assemble it with robot arms and send it into its final orbit.

"Let's get out there and try something new. Let's get back to the basics of dreaming a dream. Even though we think it may be impossible, something may happen that makes reality click. Although the dream may be impossible, maybe the results will still be startling," Cepollina said.

For more information about Hubble Space Telescope, visit: http://www.spacetelescope.org and http://hubblesite.org

Images (mentioned), Video (mentioned), Text, Credits: NASA's John F. Kennedy Space Center, By Linda Herridge.

Best regards, Orbiter.ch

Our Sun Came Late to the Milky Way’s Star-Birth Party












NASA - Hubble Space Telescope patch.

April 9, 2015

In one of the most comprehensive multi-observatory galaxy surveys yet, astronomers find that galaxies like our Milky Way underwent a stellar “baby boom,” churning out stars at a prodigious rate, about 30 times faster than today.

Our sun, however, is a late “boomer.” The Milky Way’s star-birthing frenzy peaked 10 billion years ago, but our sun was late for the party, not forming until roughly 5 billion years ago. By that time the star formation rate in our galaxy had plunged to a trickle.


Image above: Artist's view of night sky from a hypothetical planet within a young Milky Way-like galaxy 10 billion years ago, the sky are ablaze with star birth. Pink clouds of gas harbor newborn stars, and bluish-white, young star clusters litter the landscape. Image Credit: NASA/ESA/Z. Levay (STScI).

Missing the party, however, may not have been so bad. The sun’s late appearance may actually have fostered the growth of our solar system’s planets. Elements heavier than hydrogen and helium were more abundant later in the star-forming boom as more massive stars ended their lives early and enriched the galaxy with material that served as the building blocks of planets and even life on Earth.

Astronomers don’t have baby pictures of our Milky Way’s formative years to trace the history of stellar growth so they studied galaxies similar in mass to our Milky Way, found in deep surveys of the universe. The farther into the universe astronomers look, the further back in time they are seeing, because starlight from long ago is just arriving at Earth now. From those surveys, stretching back in time more than 10 billion years, researchers assembled an album of images containing nearly 2,000 snapshots of Milky Way-like galaxies.

The new census provides the most complete picture yet of how galaxies like the Milky Way grew over the past 10 billion years into today’s majestic spiral galaxies. The multi-wavelength study spans ultraviolet to far-infrared light, combining observations from NASA’s Hubble and Spitzer space telescopes, the European Space Agency’s Herschel Space Observatory, and ground-based telescopes, including the Magellan Baade Telescope at the Las Campanas Observatory in Chile.

“This study allows us to see what the Milky Way may have looked like in the past,” said Casey Papovich of Texas A&M University in College Station, lead author on the paper that describes the study’s results. “It shows that these galaxies underwent a big change in the mass of its stars over the past 10 billion years, bulking up by a factor of 10, which confirms theories about their growth. And most of that stellar-mass growth happened within the first 5 billion years of their birth.”


Image above: These six Hubble snapshots show how galaxies similar in mass to our Milky Way evolved over time. Milky Way-like galaxies grow larger in size and in stellar mass over billions of years. Image Credit: NASA/ESA/C. Papovich (Texas A&M)/H. Ferguson (STScI)/S. Fabe.

The new analysis reinforces earlier research which showed that Milky Way-like galaxies began as small clumps of stars. The galaxies swallowed large amounts of gas that ignited a firestorm of star birth.

The study reveals a strong correlation between the galaxies’ star formation and growth in stellar mass. So, when the galaxies slow down making stars, their growth decreases as well. “I think the evidence suggests that we can account for the majority of the buildup of a Milky Way-like galaxy through its star formation,” Papovich said. “When we calculate the star-formation rate of a Milky Way-like galaxy in the past and add up all the stars it would have produced, it is pretty consistent with the mass growth we expected. To me, that means we’re able to understand the growth of the ‘average’ galaxy with the mass of a Milky Way galaxy.”

The astronomers selected the Milky Way-like progenitors by sifting through more than 24,000 galaxies in the entire catalogs of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), taken with Hubble, and the FourStar Galaxy Evolution Survey (ZFOURGE), made with the Magellan telescope.

They used the ZFOURGE, CANDELS, and Spitzer near-infrared data to study the galaxy stellar masses. The Hubble images from the CANDELS survey also provided structural information about galaxy sizes and how they evolved. Far-infrared light observations from Spitzer and Herschel helped the astronomers trace the star-formation rate.

The team’s results will appear in the April 9 issue of The Astrophysical Journal.

For images and more information about the Hubble Space Telescope, visit: http://www.nasa.gov/hubble or http://hubblesite.org/news/2015/11

For more information about Hubble Space Telescope, visit: http://www.spacetelescope.org and http://hubblesite.org

Images (mentioned), Text, Credits: NASA/Space Telescope Science Institute/Donna Weaver.

Greetings, Orbiter.ch

mercredi 8 avril 2015

MAVEN Completes 1,000 Orbits around Mars












NASA - MAVEN Mission logo.

April 8, 2015

MAVEN completed 1,000 orbits around the Red Planet on April 6, four-and-a-half months into its one-year primary mission.

MAVEN is in its science mapping orbit and has been taking data since the start of its primary mission on Nov. 16, 2014. The furthest point in the spacecraft’s elliptical orbit has been 6,500 kilometers (4,039 miles) and the closest 130 kilometers (81 miles) above the Martian surface.

“The spacecraft and instruments continue to work well, and we’re building up a picture of the structure and composition of the upper atmosphere, of the processes that control its behavior, and of how loss of gas to space occurs,” said Bruce Jakosky, MAVEN’s principal investigator from the University of Colorado's Laboratory for Atmospheric and Space Physics in Boulder.

MAVEN was launched to Mars on Nov. 18, 2013, from Cape Canaveral Air Force Station in Florida. The spacecraft successfully entered Mars’ orbit on Sept. 21, 2014.


Image above: This artist's concept shows NASA’s MAVEN mission, the first mission devoted to understanding the Martian upper atmosphere, completed 1,000 orbits around the Red Planet on April 6, 2015. Image Credit: NASA/Goddard.

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission is the first mission devoted to understanding the Martian upper atmosphere. The goal of MAVEN is to determine the role that loss of atmospheric gas to space played in changing the Martian climate through time. MAVEN is studying the entire region from the top of the upper atmosphere all the way down to the lower atmosphere so that the connections between these regions can be understood.

Recently, MAVEN observed two unexpected phenomena in the Martian atmosphere: an unexplained high-altitude dust cloud and aurora that reaches deep into the Martian atmosphere.

“MAVEN is already producing wonderful science results,” said Rich Burns, MAVEN project manager at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “We are all eager to see what this mission has to teach us about the Martian atmosphere past and present.”

MAVEN’s principal investigator is based at the University of Colorado’s Laboratory for Atmospheric and Space Physics, Boulder. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. The University of California at Berkeley’s Space Sciences Laboratory also provided four science instruments for the mission. NASA’s Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, as well as the Electra telecommunications relay hardware and operations.

For more information about MAVEN mission, visit: http://www.nasa.gov/mission_pages/maven/main/index.html

Image (mentioned), Text, Credits: NASA’s Goddard Space Flight Center/Nancy Neal Jones.

Cheers, Orbiter.ch

SESAME passes an important milestone at CERN












CERN - European Organization for Nuclear Research logo.

8 April 2015


Image above: An engineer tests the installation of a vacuum chamber for SESAME, at CERN's magnet-testing facility SM18 (Image: Maximilien Brice/CERN).

The SESAME project has reached an important milestone: the first complete cell of this accelerator for the Middle East has been assembled and successfully tested at CERN.

SESAME is a synchrotron light source under construction in Jordan. It will allow researchers from the region to investigate the properties of innovative materials, biological processes and cultural artefacts. SESAME is a unique joint venture that brings together scientists from its Members: Bahrain, Cyprus, Egypt, Iran, Israel, Jordan, Pakistan, the Palestinian Authority and Turkey. Not only is SESAME an important scientific project, it is also helping to build bridges between diverse cultures in a part of the world that usually hits the headlines for its conflicts.


Image above: A sextupole assembled in Cyprus and Pakistan based on CERN/SESAME design (Image: Maximilien Brice/CERN).

CERN has been a strong partner to SESAME, providing technical expertise for the design and procurement of accelerator components. In particular, CERN is responsible for the magnets of the SESAME storage ring and their powering scheme, under a project largely funded by the European Commission (FP7 CESSAMag: http://cern.ch/cessamag).      

Within this project, CERN has been collaborating with SESAME to design, test and characterize the components of the magnetic system, which is now in production. The main contracts have been split among different companies in Cyprus, France, Israel, Italy, Spain, Switzerland, Turkey and the UK, with additional in-kind support (material and personnel) from Iran, Pakistan and Turkey.

The test carried out at CERN together with colleagues from SESAME aimed at assembling a full periodic cell of the machine, one of the 16 which make up the regular structure of the ring. Besides the magnets themselves, this involved also the girder support structure as well as the vacuum chamber for the beam.


Image above: Engineers test the installation of a vacuum chamber for SESAME at the CERN magnet-testing facility SM18 (Image: Maximilien Brice/CERN).

“We already knew that the various individual elements fulfil and even exceed the specifications,” says Attilio Milanese, the CERN engineer in charge of the magnets, who is well satisfied since “this test now confirms that all the subsystems work harmoniously together”.

The magnet production is now in full swing. After acceptance tests, these components will be shipped in batches to SESAME by the end of the year, where installation and commissioning of the main synchrotron is planned for 2016.

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.

Related links:

The SESAME project: http://www.sesame.org.jo/sesame/

For more information about the European Organization for Nuclear Research (CERN), visit: http://home.web.cern.ch/

Images (mentioned), Text, Credits: CERN/Cian O'Luanaigh.

Best regards, Orbiter.ch

Seasonal, Year-Long Cycles Seen on the Sun











NASA logo.

April 8, 2015

Our sun is constantly changing. It goes through cycles of activity – swinging between times of relative calm and times when frequent explosions on its surface can fling light, particles and energy out into space. This activity cycle peaks approximately every 11 years. New research shows evidence of a shorter time cycle as well, with activity waxing and waning over the course of about 330 days.

Understanding when to expect such bursts of solar activity is crucial to successfully forecast the sun's eruptions, which can drive solar storms at Earth. These space weather events can interfere with satellite electronics, GPS navigation, and radio communications. The quasi-annual variations in space weather seem to be driven by changes in bands of strong magnetic field that are present in each solar hemisphere, said researchers in a paper published on April 7, 2015, in Nature Communications.


Image above: Bands of magnetized solar material march toward the sun's equator. The way the bands in each hemisphere interact leads to a 330-day cycle of waxing and waning activity on the sun that can be as strong as the more well-studied 11-year solar cycle. Image Credit: S. McIntosh.

What we’re looking at here is a massive driver of solar storms,” said Scott McIntosh, lead author of the paper and director of the High Altitude Observatory of the National Center for Atmospheric Research in Boulder, Colorado. “By better understanding how these activity bands form in the sun and cause these seasonal instabilities, we can greatly improve forecasts of space weather.”

The new study is one of several by the research team to examine what creates the magnetic bands and how they influence solar cycles. McIntosh and his co-authors detected the bands by drawing on a host of NASA satellites and ground-based observatories that observe the sun and its output -- from the constant flow of particles in the solar wind to large explosions such as solar flares or giant eruptions of solar material called coronal mass ejections, or CMEs.

The scientists note that the changes in the magnetic field in the bands gives rise to a 330-day activity cycle on the sun that is observable but has often been downplayed and overlooked when trying to seek the cause of the sun's longer, 11-year cycle.

"People have not paid much attention to this nearly-annual cycle," said McIntosh. "But it's such a driver of space weather that we really do need to focus on it. Cycles over this time frame are observed in all sorts of output from the sun: the sun’s radiance, the solar wind, solar flares, CMEs."

Magnetic band interaction can also help explain a puzzle first discovered in the 1960s: Why does the number of powerful solar flares and CMEs peak a year or more after the maximum number of sunspots? This lag is known as the Gnevyshev Gap, after the Soviet scientist who first noticed the pattern. The answer appears to also depend on two activity bands. Having one band located in each solar hemisphere provides an opportunity for them to mix -- magnetic field from one band effectively leaking into the other -- creating more unstable active regions on the sun and leading to more flares and CMEs. In other papers, scientists have shown that this process happens only after the sunspot maximum.

In doing their analysis on band interaction the scientists noticed that the bands themselves undergo strong quasi-annual variations, taking place separately in both the northern and southern hemispheres. Those quasi-annual variations in magnetism could be almost as large in magnitude as those of the more familiar, approximately 11-year solar cycle, giving rise to the appearance of stormy seasons.

“The activity bands on the sun have very slow-moving waves that can expand and warp,” said Robert Leamon, co-author on the paper at Montana State University in Bozeman and NASA Headquarters in Washington. “Sometimes this results in magnetic field leaking from one band to the other. In other cases, the warp drags magnetic field from deep in the solar interior and pushes it toward the surface.”

The surges of magnetic fuel from the sun’s interior can catastrophically destabilize the existing corona, the sun’s outermost atmosphere. They are a driving force behind the most intense solar storms.


Image above: A dark, snaking line across the lower half of the sun in this images from Feb. 10, 2015, shows a filament of solar material hovering above the sun's surface. Filaments can float sedately for days before disappearing. Sometimes they also erupt out into space, releasing solar material in a shower that either rains back down or escapes out into space, becoming a moving cloud known as a coronal mass ejection, or CME. Image Credit: NASA/SDO.

Researchers can turn to advanced computer simulations and focused observations to learn more about the influence of these bands on solar activity. McIntosh suggested that this could be assisted by a proposed network of satellites observing the sun, much as the global networks of satellites around Earth has significantly advanced terrestrial weather models since the 1960s.

“If you understand what the patterns of solar activity are telling you, you’ll know whether we’re in a stormy phase or quiet phase in each hemisphere,” McIntosh said. “If we can combine these pieces of observational information with modeling efforts, then space weather forecast skill can go through the roof.”

The research was funded by NASA and the National Science Foundation, which is NCAR’s sponsor.

For more information on the sun's magnetic activity bands:
http://www.nasa.gov/content/goddard/researchers-discover-new-clues-to-determining-the-solar-cycle/

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Karen C. Fox.

Greetings, Orbiter.ch