Author(s): Daniel Niesner, Max Wilhelm, Ievgen Levchuk, Andres Osvet, Shreetu Shrestha, Miroslaw Batentschuk, Christoph Brabec, and Thomas FausterThe alignment of spins in an organic-inorganic perovskite semiconductor is directly observed via photoemis…
Full circle: space algae fighting malnutrition in Congo

Looking for food that could be harvested by astronauts far from Earth, researchers focused on spirulina, which has been harvested for food in South America and Africa for centuries. ESA astronaut Samantha Cristoforetti ate the first food containing spirulina in space and now the knowledge is being applied to a pilot project in Congo as a food supplement.
Preparing for long missions far from Earth, astronauts will need to harvest their own food. ESA’s Micro-Ecological Life Support System Alternative team, or MELiSSA, is looking at creating a closed ecosystem that continuously recycles waste into food, oxygen and water.
The moon may be obliterated pieces of Earth reformed
New evidence shows that the once-planet Theia may have been destroyed in the early impact that formed the moon.
A star is evolving on a timescale we can see
A star in the Stingray Nebula has cycled through heating up and cooling down in our lifetimes.
Space for inspiration
Watch the replays from this two-day event exploring the impact of human spaceflight on our world
Direct Measurement of the Density Matrix of a Quantum System
Author(s): G. S. Thekkadath, L. Giner, Y. Chalich, M. J. Horton, J. Banker, and J. S. Lundeen
Researchers have developed a new technique to measure the density matrix—a more general way of characterizing the state of a quantum system than that provided by the wave function.

[Phys. Rev. Lett. 117, 120401] Published Mon Sep 12, 2016
Direct Measurement of the Density Matrix of a Quantum System
Author(s): G. S. Thekkadath, L. Giner, Y. Chalich, M. J. Horton, J. Banker, and J. S. Lundeen
Researchers have developed a new technique to measure the density matrix—a more general way of characterizing the state of a quantum system than that provided by the wave function.

[Phys. Rev. Lett. 117, 120401] Published Mon Sep 12, 2016
Star mapper

Space Science Image of the Week: Explore the sky with this new visualisation using data from ESA’s Hipparcos mission
First Gaia Data Release

Gaia’s first star catalogue will be unveiled on Wednesday, 14 September. Watch livestream from 09:30 GMT / 11:30 CEST
Jeff Bezos debuted a massive rocket plan to take Blue Origin into deep space
The New Glenn will take the previously-suborbital company to dizzying new heights.
Hundreds of black holes congregate surprisingly peacefully in a Milky Way star cluster
The black holes don’t eject each other as expected
Curiosity captures a snapshot of Mars’ past
NASA’s rover captured images of layered rock formations on the “Murray Buttes” region of Mount Sharp last week.
Proba-3: set the controls for the verge of the Sun

By converging in orbit, a pair of small satellites will open a new view on the source of the largest structure in the Solar System: the Sun’s ghostly atmosphere, extending millions of kilometres out into space.
Mars Rover Views Spectacular Layered Rock Formations
The layered geologic past of Mars is revealed in stunning detail in new color images returned by NASA’s Curiosity Mars rover of the “Murray Buttes” region on Mount Sharp.
RapidScat Team Investigating Power System Anomaly
Mission managers are assessing two power system-related anomalies affecting the operation of NASA’s ISS-RapidScat instrument on the International Space Station.
Mars Rover Views Spectacular Layered Rock Formations
The layered geologic past of Mars is revealed in stunning detail in new color images returned by NASA’s Curiosity Mars rover of the “Murray Buttes” region on Mount Sharp.
RapidScat Team Investigating Power System Anomaly
Mission managers are assessing two power system-related anomalies affecting the operation of NASA’s ISS-RapidScat instrument on the International Space Station.
Acoustic Force Density Acting on Inhomogeneous Fluids in Acoustic Fields
Author(s): Jonas T. Karlsen, Per Augustsson, and Henrik BruusThe classical theory of acoustic forces acting on fluids in acoustic fields is extended to inhomogeneous systems with continuous spatial variations of density, compressibility, and viscosity….
Acoustic Force Density Acting on Inhomogeneous Fluids in Acoustic Fields
Author(s): Jonas T. Karlsen, Per Augustsson, and Henrik BruusThe classical theory of acoustic forces acting on fluids in acoustic fields is extended to inhomogeneous systems with continuous spatial variations of density, compressibility, and viscosity….
Week In Images
Our week through the lens: 5-9 September 2016
Rosetta’s descent towards region of active pits

Squeezing out unique scientific observations until the very end, Rosetta’s thrilling mission will culminate with a descent on 30 September towards a region of active pits on the comet’s ‘head’.
Open Science

Follow the EO Open Science 2016 conference via live webstream from ESA’s ESRIN establishment in Italy 12–14 September. Live coverage begins Monday at 9:00 CEST
After a successful launch, OSIRIS-REx is headed for an asteroid encounter
The craft will scoop up a bit of asteroid and bring it back to Earth.
Astronomers find fossil stars from the beginning of the galaxy
A collection of stars from the beginning of our galaxy could shed light on how it formed.
Fantastic four: November’s Galileos reach Europe’s Spaceport

A transatlantic flight delivered four Galileo satellites to French Guiana on Tuesday, in preparation for a shared launch this November by Ariane 5 – the first for Europe’s satnav constellation.
Barents bloom
Earth observation image of the week: a Sentinel-2A image of a plankton bloom in the Barents Sea
‘Enterprise’ Nebulae Seen by Spitzer
Just in time for the 50th anniversary of the TV series “Star Trek,” which first aired September 8th,1966, a new infrared image from NASA’s Spitzer Space Telescope may remind fans of the historic show.
‘Enterprise’ Nebulae Seen by Spitzer
Just in time for the 50th anniversary of the TV series “Star Trek,” which first aired September 8th,1966, a new infrared image from NASA’s Spitzer Space Telescope may remind fans of the historic show.
Signing the SciFi car
Operations image of the week: The Rosetta flight control team add their signatures to the SciFi car
Observation of π^{−} K^{+} and π^{+} K^{−} Atoms
Author(s): B. Adeva et al. (DIRAC Collaboration)
The DIRAC collaboration at CERN reports the first statistically significant observation of an atom formed from a π meson and a K meson.

[Phys. Rev. Lett. 117, 112001] Published Thu Sep 08, 2016
Search for Dark Matter Annihilations towards the Inner Galactic Halo from 10 Years of Observations with H.E.S.S.
Author(s): H. Abdallah et al. (H.E.S.S. Collaboration)An analysis of 10 years of observations of the Galactic center by H.E.S.S. provide the strongest constraints to date on TeV dark matter.[Phys. Rev. Lett. 117, 111301] Published Thu Sep 08, 2016
Search for Dark Matter Annihilations towards the Inner Galactic Halo from 10 Years of Observations with H.E.S.S.
Author(s): H. Abdallah et al. (H.E.S.S. Collaboration)An analysis of 10 years of observations of the Galactic center by H.E.S.S. provide the strongest constraints to date on TeV dark matter.[Phys. Rev. Lett. 117, 111301] Published Thu Sep 08, 2016
Observation of π^{−} K^{+} and π^{+} K^{−} Atoms
Author(s): B. Adeva et al. (DIRAC Collaboration)
The DIRAC collaboration at CERN reports the first statistically significant observation of an atom formed from a π meson and a K meson.

[Phys. Rev. Lett. 117, 112001] Published Thu Sep 08, 2016
Earth from Space

Join us Friday, 9 September, at 10:00 CEST for the ‘Earth from Space’ video programme. This week features the watercolour swirls of a plankton bloom in the Barents Sea
Titan’s Dunes and Other Features Emerge in New Images
New scenes from a frigid alien landscape are coming to light in recent radar images of Saturn’s largest moon, Titan, from NASA’s Cassini spacecraft.
Small Asteroid Flew Safely Past Earth Today
A small asteroid designated 2016 RB1 safely flew past Earth today, Sept. 7, at a distance of about 25,000 miles (just less than 1/10th the distance of Earth to the moon).
Small Asteroid Flew Safely Past Earth Today
A small asteroid designated 2016 RB1 safely flew past Earth today, Sept. 7, at a distance of about 25,000 miles (just less than 1/10th the distance of Earth to the moon).
Chaos in AdS_{2} Holography
Author(s): Kristan JensenA theoretical analysis points at a possible connection between near-conformal two-dimensional gravity and a fermionic quantum mechanical system with applications to condensed matter physics.[Phys. Rev. Lett. 117, 111601] Publis…
Emulating Anyonic Fractional Statistical Behavior in a Superconducting Quantum Circuit
Author(s): Y. P. Zhong, D. Xu, P. Wang, C. Song, Q. J. Guo, W. X. Liu, K. Xu, B. X. Xia, C.-Y. Lu, Siyuan Han, Jian-Wei Pan, and H. Wang
A superconducting circuit is used as a platform to experimentally study the fractional statistics of Abelian anyons.

[Phys. Rev. Lett. 117, 110501] Published Wed Sep 07, 2016
Experimental X-Ray Ghost Imaging
Author(s): Daniele Pelliccia, Alexander Rack, Mario Scheel, Valentina Cantelli, and David M. PaganinThe technique of ghost imaging, which builds up images of objects by combining information from light collected at two detectors, has been demonstrated …
Emulating Anyonic Fractional Statistical Behavior in a Superconducting Quantum Circuit
Author(s): Y. P. Zhong, D. Xu, P. Wang, C. Song, Q. J. Guo, W. X. Liu, K. Xu, B. X. Xia, C.-Y. Lu, Siyuan Han, Jian-Wei Pan, and H. Wang
A superconducting circuit is used as a platform to experimentally study the fractional statistics of Abelian anyons.

[Phys. Rev. Lett. 117, 110501] Published Wed Sep 07, 2016
Fourier-Transform Ghost Imaging with Hard X Rays
Author(s): Hong Yu, Ronghua Lu, Shensheng Han, Honglan Xie, Guohao Du, Tiqiao Xiao, and Daming ZhuThe technique of ghost imaging, which builds up images of objects by combining information from light collected at two detectors, has been demonstrated in…
Symmetric States Requiring System Asymmetry
Author(s): Takashi Nishikawa and Adilson E. Motter
Coupled oscillators in certain networks will—counterintuitively—only move in tandem if each oscillator is different.

[Phys. Rev. Lett. 117, 114101] Published Wed Sep 07, 2016
Chaos in AdS_{2} Holography
Author(s): Kristan JensenA theoretical analysis points at a possible connection between near-conformal two-dimensional gravity and a fermionic quantum mechanical system with applications to condensed matter physics.[Phys. Rev. Lett. 117, 111601] Publis…
‘Star Trek’ stamps mark 50th anniversary of franchise
They can’t get your letters to warp speed, but they are pretty great nonetheless.
Watch NASA launch its new asteroid-sampling robotic mission
OSIRIS-REx is due for an encounter with a near-Earth object in two years.
A cosmic oyster’s pearl
Space Science Image of the Week: This image from the NASA/ESA Hubble Space Telescope shows NGC 1501, a duo resembling a cosmic oyster and its much-coveted pearl
Four steps nearer Mercury
Technology image of the week: all four ion thrusters have been integrated into the BepiColombo mission to the innermost planet
Vega to launch ESA’s wind mission

Today, ESA and Arianespace signed a contract to secure the launch of the Aeolus satellite. With this milestone, a better understanding of Earth’s winds is another step closer.
Comment on ?Towards addressing transient learning challenges in undergraduate physics: an example from electrostatics?
We make some crucial remarks about the recent presentation by Fredlund et al (2015 Eur. J. Phys. 36
[http:// http://dx.doi.org/10.1088/0143-0807/36/5/055002] 055002 ) considering the tutorial problem
raised therein. After working out the velocity of …
Levitating a strip of paper by blowing over it
It is shown that if you blow vigorously over a curved strip of paper, it levitates into the shape of
a catenary. This result quantifies a common classroom demonstration and is a pedagogically useful
addition to other studies of catenaries in an inter…
Comment on ‘Towards addressing transient learning challenges in undergraduate physics: an example from electrostatics’
We make some crucial remarks about the recent presentation by Fredlund et al (2015 Eur. J. Phys. 36
[http:// http://dx.doi.org/10.1088/0143-0807/36/5/055002] 055002 ) considering the tutorial problem
raised therein. After working out the velocity of …
Some physical applications of generalized Lambert functions
In this paper we show two applications for a generalization of the Lambert W function. Explicit
calculations are given for the inverse Langevin function that plays an important role in the study
of paramagnetic materials, and for the dispersion equat…
Stable equilibria of elliptic roly-poly toys
As an instructive (gravitational potential) energy approach, we show that the elliptic roly-poly has
a richer and more useful profile (including the tilted configuration) of stable equilibria than
conventional spherical or cylindrical roly-polys.
The Kronecker product and some of its physical applications
In a typical introductory course on quantum mechanics the student has to face two quite different
operator products. One of them leads to, for example, commutators and the uncertainty principle, and
the other appears when one goes from a one-particle…
Corrigendum: Corrections to classical radiometry and the brightness of stars (2008 Eur. J. Phys. 29 [http://dx.doi.org/10.1088/0143-0807/29/5/023] 1105 )
Description unavailable
Titan’s Dunes and Other Features Emerge in New Images
New scenes from a frigid alien landscape are coming to light in recent radar images of Saturn’s largest moon, Titan, from NASA’s Cassini spacecraft.
Rosetta’s legacy

Tell us how Rosetta has influenced you and there’s a chance to win ESA prizes
Space history
Human spaceflight and robotic exploration image of the week: ESA astronaut Andreas Mogensen and cosmonaut Sergei Volkov unveil a bust of Yuri Gagarin
Detection of 15 dB Squeezed States of Light and their Application for the Absolute Calibration of Photoelectric Quantum Efficiency
Author(s): Henning Vahlbruch, Moritz Mehmet, Karsten Danzmann, and Roman Schnabel
Researchers have created quantum states of light whose noise level has been “squeezed” to a record low.

[Phys. Rev. Lett. 117, 110801] Published Tue Sep 06, 2016
Philae’s final resting place has been found
ESA’s comet lander missed its mark two years ago. Yesterday, its parent craft Rosetta found the probe finally.
Arctic and Space
As the Arctic is developed, how can space help safeguard this fragile environment? Follow the Arctic and Space workshop at the Finnish Meteorological Institute on 6 September. Livestream starts at 06:00 GMT (08:00 CEST)
Philae found!
Rosetta’s Philae lander is revealed in new images of the comet
Philae found!

Less than a month before the end of the mission, Rosetta’s high-resolution camera has revealed the Philae lander wedged into a dark crack on Comet 67P/Churyumov–Gerasimenko.
NASA Approves 2018 Launch of Mars InSight Mission
NASA is moving forward with a spring 2018 launch of its InSight mission to study the deep interior of Mars, following final approval this week by the agency.
Jupiter’s North Pole Unlike Anything Encountered in Solar System
NASA’s Juno spacecraft has sent back the first-ever images of Jupiter’s north pole, taken during the spacecraft’s first flyby of the planet with its instruments switched on.
Jupiter’s North Pole Unlike Anything Encountered in Solar System
NASA’s Juno spacecraft has sent back the first-ever images of Jupiter’s north pole, taken during the spacecraft’s first flyby of the planet with its instruments switched on.
NASA Approves 2018 Launch of Mars InSight Mission
NASA is moving forward with a spring 2018 launch of its InSight mission to study the deep interior of Mars, following final approval this week by the agency.
Week In Images
Our week through the lens: 29 August – 2 September 2016
Juno gets the first-ever view of Jupiter’s North Pole
Some never-before-seen features come to light.
This Twitter lets you know what Hubble is staring at RIGHT NOW
Want to know what Hubble is up to right now? There’s a tweet for that.
The weird, isolated mountain on Ceres is a giant ice volcano
Ceres: a world that just keeps getting weirder and weirder.
Ceres’ Geological Activity, Ice Revealed in New Research
A lonely 3-mile-high (5-kilometer-high) mountain on Ceres is likely volcanic in origin, and the dwarf planet may have a weak, temporary atmosphere.
Ceres’ Geological Activity, Ice Revealed in New Research
A lonely 3-mile-high (5-kilometer-high) mountain on Ceres is likely volcanic in origin, and the dwarf planet may have a weak, temporary atmosphere.
Earth from Space

The ‘Earth from Space’ video programme is back! Join us Friday, 2 September, at 10:00 CEST and discover Argentina’s Upsala Glacier
Mars team
Operations image of the week: ExoMars mission control trains for arriving at the Red Planet
How can we get to Proxima Centauri b?
There’s an exoplanet as close to us as one can get. So how will we get there?
Newly discovered protostar is well placed for studying how massive stars form
What was thought to be an old star is likely a baby star 12,000 light-years from Earth.
Cuddly comet chaser

Technology image of the week: a plush toy version of Rosetta joins a rover in ESA’s Mars Yard – the actual Rosetta spacecraft will soon join the planetary lander club
Intro to EO: sign up today
Sign up for a free online course that provides an introduction to optical satellite Earth observation. The five-week Future Learn course begins on 12 September
Dawn Sets Course for Higher Orbit
After studying Ceres for more than eight months from its low-altitude science orbit, NASA’s Dawn spacecraft will move higher up for different views of the dwarf planet.
Planck: First Stars Formed Later Than We Thought
ESA’s Planck satellite, has revealed that the first stars in the universe started forming later than previous observations of the cosmic microwave background indicated.
Planck: First Stars Formed Later Than We Thought
ESA’s Planck satellite, has revealed that the first stars in the universe started forming later than previous observations of the cosmic microwave background indicated.
Dawn Sets Course for Higher Orbit
After studying Ceres for more than eight months from its low-altitude science orbit, NASA’s Dawn spacecraft will move higher up for different views of the dwarf planet.
Late stars
The first stars were born much later than previously thought, ESA’s Planck reveals
Universal Quantum Computing with Arbitrary Continuous-Variable Encoding
Author(s): Hoi-Kwan Lau and Martin B. PlenioA theoretical scheme is proposed for universal quantum computation using qubits encoded with the parity of two or four continuous variable quantum modes.[Phys. Rev. Lett. 117, 100501] Published Wed Aug 31, 2016
Copernicus Sentinel-1A satellite hit by space particle

ESA engineers have discovered that a solar panel on the Copernicus Sentinel-1A satellite was hit by a millimetre-size particle in orbit on 23 August. Thanks to onboard cameras, ground controllers were able to identify the affected area. So far, there has been no effect on the satellite’s routine operations.
Space for inspiration

Join us for an exploration of human spaceflight in science, industry and everyday life 14–15 September in London, UK
Space recovery USB
Human spaceflight and exploration image of the week: Recovery disk for International Space Station experiment
Galileo’s Ariane 5 arrives at Europe’s Spaceport

The first Ariane 5 rocket modified to carry four Galileo satellites into orbit has arrived at Europe’s Spaceport in French Guiana for a November launch.
The ‘promising’ SETI signal probably isn’t aliens
We haven’t made contact with anything.
Powerful magnetars may give way to small black holes
The strongest magnets in the universe may have a shorter-than-expected shelf life.
An atypical protostar

Space Science Image of the Week: A peculiar, age-defying star as seen by ESA’s Herschel
NASA Team Probes Peculiar Age-Defying Star
For years, astronomers have puzzled over a massive star lodged deep in the Milky Way that shows conflicting signs of being extremely old and extremely young.
NASA Team Probes Peculiar Age-Defying Star
For years, astronomers have puzzled over a massive star lodged deep in the Milky Way that shows conflicting signs of being extremely old and extremely young.
Sentinel-1 provides new insight into Italy’s earthquake
On 24 August, an earthquake struck central Italy, claiming at least 290 lives and causing widespread damage. Satellite images are being used to help emergency aid organisations, while scientists have begun to analyse ground movement.
Gate Tuning of Electronic Phase Transitions in Two-Dimensional NbSe_{2}
Author(s): Xiaoxiang Xi, Helmuth Berger, László Forró, Jie Shan, and Kin Fai Mak
The efficient gate control of electronic phase transitions in the 2D crystalline metal NbSe2 is experimentally demonstrated.

[Phys. Rev. Lett. 117, 106801] Published Mon Aug 29, 2016
First satellite-based wildlife monitoring tool for airports
Wildlife habitats close to airports pose a serious risk to safety at takeoff and landing. Thanks to ESA, a new service lets airports use satellites to identify and manage these areas.
Russian SETI researchers are pursuing a promising signal
It may not be aliens, but something weird was picked up by Russian radio astronomers, who are now digging for answers.
NASA’s Juno Successfully Completes Jupiter Flyby
NASA’s Juno mission successfully executed its first of 36 orbital flybys of Jupiter today.