Dark Matter and Particle Acceleration in Near Space

NASA / JAXA - CALET logo.

Nov. 9, 2015

Peering into darkness can strike fear into the hearts of some, but a new space telescope will soon peer into the darkness of “near space” (within a few thousand light years of Earth). Scientists are using the telescope to seek answers related to the field of high-energy astrophysics.

The CALorimetric Electron Telescope (CALET) investigation will rely on the instrument to track the trajectory of cosmic ray particles and measure their charge and energy. The instrument is optimized for measuring electrons and gamma rays, which may contain the signature of dark matter or nearby sources of high-energy particle acceleration.

“The investigation is part of an international effort (involving Japan, Italy and USA) to understand the mechanisms of particle acceleration and propagation of cosmic rays in the galaxy, to identify their sources of acceleration, their elemental composition as a function of energy, and possibly to unveil the nature of dark matter,” said CALET principal investigator Dr. Shoji Torii.

Image above: The HTV5 CALorimetric Electron Telescope (CALET) Flight Crew Interface Test (FCIT). CALET will search for signatures of dark matter and provide the highest energy direct measurements of the cosmic ray electron spectrum. Image Credit: JAXA.

“We know that dark matter makes up about a quarter of the mass-energy of the universe, but we can’t see it optically and don’t know what it is,” said Dr. John Wefel, and CALET co-principal investigator for the US team. “If CALET can see an unambiguous signature of dark matter, it could potentially produce a new understanding of the nature of dark matter.”

Right now, scientists are much more certain what dark matter is not, rather than what it is. This research may help scientists identify dark matter and fit it, more accurately, into standard models of the universe.

CALET launched aboard the Japan Aerospace Exploration Agency (JAXA) H-II Transfer Vehicle “Kounotori” (HTV-5) in August 2015 and was placed on the International Space Station’s Japanese Experiment Module - Exposed Facility just days after its arrival.

Image above: The CALorimetric Electron Telescope (CALET) is transferred from the exposed pallet to the Kibo's exposed facility. Image Credit: NASA.

The instrument is a charged particle telescope designed to measure electrons, protons, nuclei and gamma rays. Unlike the telescopes that are used to pinpoint stars and planets in the night sky, CALET operates in a scanning mode. As it looks upward, it records each cosmic ray event that enters its field of view and triggers its detectors to take measurements of the cosmic ray. These measurements are recorded on the space station and sent to a ground station where they are fed into computers running analysis codes that allow scientists to reconstruct each event.

From the resulting measurements, scientists must then separate electrons from the protons, gamma rays and the higher Z elements (chemical elements with >1 proton in the nucleus). They then sort the particles by energy to extend the existing data to higher energies and search for signatures of new astrophysics processes and phenomena like dark matter and nearby particle acceleration to study cosmic ray propagation in the galaxy.

“The major theoretical model attributes dark matter to weakly interacting massive particles (WIMPs), whose nature is predicted by various high energy physics models,” said Torii. “In these models, a WIMP would be its own antiparticle and, when two of them get together, they annihilate, producing known particles like electron/positron pairs, proton/anti-proton pairs, and gamma rays.”

CALET location on the space station. Image Credit: NASA

Searching for excess annihilation products (i.e. electrons and gamma rays) is one way to try to identify a dark matter candidate and this is where CALET helps scientists. CALET joins another ISS investigation searching for excess annihilation products, the Alpha Magenetic Spectrometer or AMS, which is looking at positrons and antiprotons to identify dark matter.

“Dark matter is still a puzzle,” said Torii. “By measuring with good energy resolution the spectrum of high energy cosmic electrons and photons, CALET may make a discovery or exclude existing models.”

“Seeing an appropriate signature in the electron spectrum and/or gamma rays would be extremely important since this would set the mass scale (weight) for the dark matter particles, which would in turn allow theorists to better determine new physics associated with the WIMP,” said Torii, adding that it is possible that a signature may be found that is not indicative of dark matter, but rather indicates a nearby source of charged particle acceleration.

Image above: The Japan Aerospace Exploration Agency (JAXA) Kounotori H-II Transfer Vehicle (HTV-5) is seen berthed to the International Space Station. The external CALET experiment, which will search for signatures of dark matter, is seen being extracted from the unpressurized section by the station's robotic arm, Canadarm2. An aurora over the Earth limb is visible in the background. Image Credit: NASA.

“The latter would be [a] huge achievement since no individual sources have ever been positively identified,” said Torii. “Such objects seem to be able to accelerate particles to energies far higher than we can achieve on Earth using the largest machines and we want to learn how nature does this, with possible applications here on Earth.”

Understanding the location of these sources as well as particle propagation (the time particles spend, and distance traveled, wandering around the galaxy) means scientists can infer the shape of the cosmic ray spectrum at the source. Gaining a better understanding of how cosmic rays originate and the mechanisms of particle acceleration and propagation is important to space travel and for understanding the radiation environment in space and on Earth.

“Basically, CALET is after new information about how our little corner of the universe works,” said Torii, who added that the investigation underscores the importance of the space station as a platform for performing investigations and for successful international collaboration.

Relate article:

CALET aboard the ISS Kibo Started the First Direct Electron Observation:
http://orbiterchspacenews.blogspot.ch/2015/10/calet-aboard-iss-kibo-started-first.html

Related links:

(JAXA) H-II Transfer Vehicle “Kounotori” (HTV-5): http://www.nasa.gov/mission_pages/station/research/news/htv5_launch

Japanese Experiment Module - Exposed Facility (Kibo): http://www.nasa.gov/mission_pages/station/research/experiments/JEM-EF.html

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

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

Dark Energy and Dark Matter: http://www.nasa.gov/subject/6891/dark-energy-and-dark-matter/

Images (mentioned), Tex, Credits: NASA/JSC/International Space Station Program Science Office/Andrea Dunn/Kristine Rainey.

Best regards, Orbiter.ch

Four Months after Pluto Flyby, NASA’s New Horizons Yields Wealth of Discovery

NASA - New Horizons Mission logo.

Nov. 9, 2015

Pluto hazy atmosphere seen by New Horizons spacecraft. Image Credits:  NASA/JHUAPL/SwRI.

From possible ice volcanoes to twirling moons, NASA’s New Horizons science team is discussing more than 50 exciting discoveries about Pluto at this week’s 47th Annual Meeting of the American Astronomical Society’s Division for Planetary Sciences in National Harbor, Maryland.

“The New Horizons mission has taken what we thought we knew about Pluto and turned it upside down,” said Jim Green, director of planetary science at NASA Headquarters in Washington. “It's why we explore -- to satisfy our innate curiosity and answer deeper questions about how we got here and what lies beyond the next horizon."

For one such discovery, New Horizons geologists combined images of Pluto’s surface to make 3-D maps that indicate two of Pluto’s most distinctive mountains could be cryovolcanoes -- ice volcanoes that may have been active in the recent geological past.

“It’s hard to imagine how rapidly our view of Pluto and its moons are evolving as new data stream in each week. As the discoveries pour in from those data, Pluto is becoming a star of the solar system,” said mission Principal Investigator Alan Stern of the Southwest Research Institute in Boulder, Colorado. “Moreover, I’d wager that for most planetary scientists, any one or two of our latest major findings on one world would be considered astounding. To have them all is simply incredible.”

Image above: Using New Horizons images of Pluto’s surface to make 3-D topographic maps, scientists discovered that two of Pluto’s mountains, informally named Wright Mons and Piccard Mons, could be ice volcanoes. The color depicts changes in elevation, blue indicating lower terrain and brown showing higher elevation. Green terrains are at intermediate heights. Image Credits: NASA/JHUAPL/SwRI.

The two cryovolcano candidates are large features measuring tens of miles or kilometers across and several miles or kilometers high.

“These are big mountains with a large hole in their summit, and on Earth that generally means one thing -- a volcano,” said Oliver White, New Horizons postdoctoral researcher at NASA’s Ames Research Center in Moffett Field, California. “If they are volcanic, then the summit depression would likely have formed via collapse as material is erupted from underneath. The strange hummocky texture of the mountain flanks may represent volcanic flows of some sort that have traveled down from the summit region and onto the plains beyond, but why they are hummocky, and what they are made of, we don't yet know.” 

While their appearance is similar to volcanoes on Earth that spew molten rock, ice volcanoes on Pluto are expected to emit a somewhat melted slurry of substances such as water ice, nitrogen, ammonia, or methane. If Pluto proves to have volcanoes, it will provide an important new clue to its geologic and atmospheric evolution.

“After all, nothing like this has been seen in the deep outer solar system,” said Jeffrey Moore, New Horizons Geology, Geophysics and Imaging team leader, at Ames.

Pluto’s Long History of Geologic Activity

Pluto’s surface varies in age -- from ancient, to intermediate, to relatively young --according to another new finding from New Horizons.

To determine the age of a surface area of the planet, scientists count crater impacts. The more crater impacts, the older the region likely is. Crater counts of surface areas on Pluto indicate that it has surface regions dating to just after the formation of the planets of our solar system, about four billion years ago.

But there also is a vast area that was, in geological terms, born yesterday -- meaning it may have formed within the past 10 million years. This area, informally named Sputnik Planum, appears on the left side of Pluto’s “heart” and is completely crater-free in all images received, so far.

New data from crater counts reveal the presence of intermediate, or “middle-aged,” terrains on Pluto, as well. This suggests Sputnik Planum is not an anomaly -- that Pluto has been geologically active throughout much of its more than 4-billion-year history.

“We’ve mapped more than a thousand craters on Pluto, which vary greatly in size and appearance,” said postdoctoral researcher Kelsi Singer, of the Southwest Research Institute (SwRI) in Boulder, Colorado. “Among other things, I expect cratering studies like these to give us important new insights into how this part of the solar system formed.”

Image above: Locations of more than 1,000 craters mapped on Pluto by NASA’s New Horizons mission indicate a wide range of surface ages, which likely means Pluto has been geologically active throughout its history. Image Credits: NASA/JHUAPL/SwRI.

Building Blocks of the Solar System

Crater counts are giving the New Horizons team insight into the structure of the Kuiper Belt itself. The dearth of smaller craters across Pluto and its large moon Charon indicate the Kuiper Belt, which is an unexplored outer region of our solar system, likely had fewer smaller objects than some models had predicted.

This leads New Horizons scientists to doubt a longstanding model that all Kuiper Belt objects formed by accumulating much smaller objects --less than a mile wide. The absence of small craters on Pluto and Charon support other models theorizing that Kuiper Belt objects tens of miles across may have formed directly, at their current -- or close to current -- size.   

In fact, the evidence that many Kuiper Belt objects could have been “born large” has scientists excited that New Horizons’ next potential target -- the 30-mile-wide (40-50 kilometer wide) KBO named 2014 MU69 -- which may offer the first detailed look at just such a pristine, ancient building block of the solar system.

Pluto’s Spinning, Merged Moons

The New Horizons mission also is shedding new light on Pluto’s fascinating system of moons, and their unusual properties. For example, nearly every other moon in the solar system -- including Earth’s moon -- is in synchronous rotation, keeping one face toward the planet. This is not the case for Pluto’s small moons.

Pluto’s small lunar satellites are spinning much faster, with Hydra -- its most distant moon -- rotating an unprecedented 89 times during a single lap around the planet. Scientists believe these spin rates may be variable because Charon exerts a strong torque that prevents each small moon from settling down into synchronous rotation.

Another oddity of Pluto’s moons: scientists expected the satellites would wobble, but not to such a degree.

Pluto's Spinning Moons

Video above: Most inner moons in the solar system keep one face pointed toward their central planet; this animation shows that certainly isn’t the case with the small moons of Pluto, which behave like spinning tops. Pluto is shown at center with, in order from closest to farthest orbit, its moons Charon, Styx, Nix, Kerberos and Hydra. Video Credits: NASA/JHUAPL/SwRI/M. Showalter.

Pluto’s moons behave like spinning tops,” said co-investigator Mark Showalter of the SETI Institute in Mountain View, California.

Images of Pluto’s four smallest satellites also indicate several of them could be the results of mergers of two or more moons.

Image above: Data from NASA's New Horizons mission indicates that at least two -- and possibly all four -- of Pluto’s small moons may be the result of mergers between still smaller moons. If this discovery is borne out with further analysis, it could provide important new clues to the formation of the Pluto system. Image Credits: NASA/JHUAPL/SwRI.

“We suspect from this that Pluto had more moons in the past, in the aftermath of the big impact that also created Charon,” said Showalter.

To view more images and graphics being presented by New Horizons scientists at the 47th Annual Meeting of the American Astronomical Society’s Division for Planetary Sciences, visit:

http://pluto.jhuapl.edu/News-Center/Press-Conferences/November-9-2015.php

For more information on NASA’s New Horizons mission, including fact sheets, videos and images, visit: http://www.nasa.gov/newhorizons

Images (mentioned), Video (mentioned), Text, Credits: NASA/Dwayne Brown/Laurie Cantillo/Johns Hopkins University Applied Physics Laboratory/Mike Buckley/Karen Northon.

Best regards, Orbiter.ch

Epimetheus Above the Rings

NASA - Cassini International logo.

Nov. 9, 2015

Although Epimetheus appears to be lurking above the rings here, it's actually just an illusion resulting from the viewing angle. In reality, Epimetheus and the rings both orbit in Saturn's equatorial plane.

Inner moons and rings orbit very near the equatorial plane of each of the four giant planets in our solar system, but more distant moons can have orbits wildly out of the equatorial plane. It has been theorized that the highly inclined orbits of the outer, distant moons are remnants of the random directions from which they approached the planets they orbit.

This view looks toward the unilluminated side of the rings from about -0.3 degrees below the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 26, 2015.

The view was obtained at a distance of approximately 500,000 miles (800,000 kilometers) from Epimetheus and at a Sun-Epimetheus-spacecraft, or phase, angle of 62 degrees. Image scale is 3 miles (5 kilometers) per pixel.

Cassini Spacecraft Animation

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov or http://www.nasa.gov/cassini . The Cassini imaging team homepage is at http://ciclops.org and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Image, Video, Text, Credits: NASA/JPL-Caltech/Space Science Institute/ESA/Tony Greicius.

Best regards, Orbiter.ch

Layers and Fractures in Ophir Chasma, Mars

NASA - Mars Reconnaissance Orbiter (MRO) logo.

Nov. 9, 2015

Ophir Chasma forms the northern portion of the vast Mars canyon system Valles Marineris, and this image, acquired on Aug. 10, 2015, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter, features a small part of its wall and floor.

The wall rock shows many sedimentary layers and the floor is covered with wind-blown ridges, which are intermediate in size between sand ripples and sand dunes. Rocks protruding on the floor could be volcanic intrusions of once-molten magma that pushed aside the surrounding sedimentary layers and “froze” in place.

Images like this can help geologists study the formation mechanisms of large tectonic systems like Valles Marineris. (The word “tectonics” does not mean the same thing as “plate tectonics.” Tectonics simply refers to large stresses and strains in a planet’s crust. Plate tectonics is the main type of tectonics that Earth has; Mars does not have plate tectonics).

The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project and Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington.

More information and image from High Resolution Imaging Science Experiment (HiRISE): http://www.uahirise.org/

For more information about NASA's Mars Reconnaissance Orbiter (MRO), visit: http://www.nasa.gov/mission_pages/MRO/main/index.html

Image, Text, Credits: NASA/JPL/University of Arizona/Caption: Kirby Runyon/Sarah Loff.

Greetings, Orbiter.ch

SDO Sees Active Region Outbursts

NASA - Solar Dynamics Observatory (SDO) patch.

Nov. 9, 2015

SDO Sees Active Region Outbursts

This close-up video by NASA’s Solar Dynamics Observatory shows an active region near the right-hand edge of the sun’s disk, which erupted with at least a dozen minor events over a 30-hour period from Nov. 3-5, 2015. 

As competing magnetic forces grappled with each other, tongues of solar material lashed out from the sun’s surface and several small flares erupted --seen as white flashes in this extreme ultraviolet wavelength of 304 angstroms. Though the sun’s extreme ultraviolet light is invisible to our eyes, the wavelength is colorized here in red.

For more information about Solar Dynamics Observatory (SDO), visit: http://www.nasa.gov/mission_pages/sdo/main/index.html

Image, Video, Text, Credits: NASA/SDO/Goddard Space Flight Center/Steele Hill/Sarah Frazier/Rob Garner.

Greetings, Orbiter.ch

Galileo satellites set for year-long Einstein experiment

ESA - Galileo logo.

9 November 2015

Europe’s fifth and sixth Galileo satellites – subject to complex salvage manoeuvres following their launch last year into incorrect orbits – will help to perform an ambitious year-long test of Einstein’s most famous theory.

Galileos 5 and 6 were launched together by a Soyuz rocket on 22 August 2014. But the faulty upper stage stranded them in elongated orbits that blocked their use for navigation.

Galileo for relativity test

ESA’s specialists moved into action and oversaw a demanding set of manoeuvres to raise the low points of their orbits and make them more circular.

“The satellites can now reliably operate their navigation payloads continuously, and the European Commission, with the support of ESA, is assessing their eventual operational use,” explains ESA’s senior satnav advisor Javier Ventura-Traveset.

“In the meantime, the satellites have accidentally become extremely useful scientifically, as tools to test Einstein’s General Theory of Relativity by measuring more accurately than ever before the way that gravity affects the passing of time.”

Albert Einstein

Although the satellites’ orbits have been adjusted, they remain elliptical, with each satellite climbing and falling some 8500 km twice per day.

It is those regular shifts in height, and therefore gravity levels, that are valuable to researchers. 

Albert Einstein predicted a century ago that time would pass more slowly close to a massive object. It has been verified experimentally, most significantly in 1976 when a hydrogen maser atomic clock on Gravity Probe A was launched 10 000 km into space, confirming the prediction to within 140 parts in a million.

Corrected Galileo orbits

Atomic clocks on navigation satellites have to take into account they run faster in orbit than on the ground – a few tenths of a microsecond per day, which would give us navigation errors of around 10 km per day.

“Now, for the first time since Gravity Probe A, we have the opportunity to improve the precision and confirm Einstein’s theory to a higher degree,” comments Javier. 

“This increased precision is of great interest because it will test several alternative theories of gravity.”

Galileo maser clock

This new effort takes advantage of the passive hydrogen maser atomic clock aboard each Galileo, the elongated orbits creating varying time dilation, and the continuous monitoring thanks to the global network of ground stations.

“Moreover, while the Gravity Probe A experiment involved a single orbit of Earth, we will be able to monitor hundreds of orbits over the course of a year,” explains Javier.

“This opens up the prospect of gradually refining our measurements by identifying and removing errors. Eliminating those errors is actually one of the big challenges.

“For that we count on the support of Europe’s best experts in Europe plus precise tracking from the International Global Navigation Satellite System Service, along with tracking to centimetre accuracy by laser.”

Gravity Probe A

The results are expected in about one year, projected to quadruple the accuracy on the Gravity Probe A results.

The two teams devising the experiments are Germany's ZARM Center of Applied Space Technology and Microgravity, and France's Systèmes de Référence Temps-Espace, both specialists in fundamental physics research.

ESA’s forthcoming Atomic Clock Ensemble in Space experiment, planned to fly on the International Space Station in 2017, will go on to test Einstein’s theory down to 2–3 parts per million.

Related articles:

Galileo satellite recovered and transmitting navigation signals:
http://orbiterchspacenews.blogspot.ch/2014/12/galileo-satellite-recovered-and.html

Salvaged Galileo performs its first navigation fix:
http://orbiterchspacenews.blogspot.ch/2014/12/salvaged-galileo-performs-its-first.html


Related links:

Centenary of Einstein's General Theory of Relativity: http://www.light2015.org/Home/CosmicLight/Einstein-Centenary.html

Fifth Colloquium on Scientific and Fundamental Aspects of the Galileo Programme: http://congrexprojects.com/2015-events/15a08/

ZARM Center of Applied Space Technology and Microgravity: https://www.zarm.uni-bremen.de/

Systèmes de Référence Temps Espace – SYRTE: https://syrte.obspm.fr/spip/

International Global Navigation Satellite System Service: https://igscb.jpl.nasa.gov/

International Laser Ranging Service: http://ilrs.gsfc.nasa.gov/satellite_missions/list_of_satellites/goce_general.html

Images, Text, Creedits: ESA/Javier Ventura-Traveset/https://einstein.stanford.edu/SYRTE, Observatoire de Paris/Dr Pacôme Delva/ZARM Center of Applied Space Technology and Microgravity/Dr Sven Hermann.

Best regards, Orbiter.ch

Destination: Venus

ESA - Venus Express Mission patch.

Nov. 9, 2015

On 9 November 2005, 10 years ago today, ESA’s Venus Express spacecraft left Earth and began its 153-day journey to Venus. The craft then spent eight years studying the planet in detail before the mission came to an end in December 2014.

One of the mission aims was to observe the planet’s atmosphere continuously over long periods in a bid to understand its dynamic behaviour.

The atmosphere is the densest of all the terrestrial planets, and is composed almost entirely of carbon dioxide. The planet is also wrapped in a thick layer of cloud made mostly of sulphuric acid. This combination of greenhouse gas and perennial cloud layer led to an enormous greenhouse warming, leaving Venus’ surface extremely hot – just over 450ºC – and hidden from our eyes.

Although winds on the planet’s surface move very slowly, at a few kilometres per hour, the atmospheric density at this altitude is so great that they exert greater force than much faster winds would on Earth.

Winds at the 65 km-high cloud-tops, however, are a different story altogether. The higher-altitude winds whizz around at up to 400 km/h, some 60 times faster than the rotation of the planet itself. This causes some especially dynamic and fast-moving effects in the planet’s upper atmosphere, one of the most prominent being its ‘polar vortices’.

The polar vortices arise because there is more sunlight at lower latitudes. As gas at low latitudes heats it rises, and moves towards the poles, where cooler air sinks. The air converging on the pole accelerates sideways and spirals downwards, like water swirling around a plug hole.

 In the centre of the polar vortex, sinking air pushes the clouds lower down by several kilometres, to altitudes where the atmospheric temperature is higher. The central ‘eye of the vortex’ can therefore be clearly seen by mapping thermal-infrared light, which shows the cloud-top temperature: the clouds at the core of the vortex are at a higher temperature, indicated by yellow tones, than the surrounding region, and therefore stand out clearly in these images.

Venus Express has shown that the polar vortices of Venus are among the most variable in the Solar System. This series of images of Venus’ south pole was taken with the VIRTIS instrument from February 2007 (top left) to April 2008 (bottom right).

ESA’s Venus Express spacecraft

The shape of this vortex core, which typically measures 2000–3000 km across, changes dramatically as it is buffeted by turbulent winds. It can resemble an ‘S’, a figure-of-eight, a spiral, an eye, and more, quickly morphing from one day to the next.

Each of the images in this frame is roughly 4000 km across.

For more information about Venus Express, visit: http://www.esa.int/Our_Activities/Space_Science/Venus_Express

Images, Text, Credits: ESA/VIRTIS-Venus Express/INAF-IAPS/LESIA-Obs. Paris/G. Piccioni.

Greetings, Orbiter.ch