Hubble’s View: PLCK G004.5-19.5

The name of this galaxy cluster is PLCK G004.5-19.5.  You may not think the name is very creative, but it did remind me of a paper:  Strong Lensing Analysis of PLCK G004.5-19.5, a Planck-Discovered Cluster Hosting a Radio Relic at z=0.52.  Thanks Hubble it was very useful.

Heh, I remember the paper because of a happy coincidence.  About a week ago I happened to be doing some housekeeping on this computer and that was one of the files – and I didn’t delete it.

ESA — This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster PLCK G004.5-19.5. It was discovered by the ESA Planck satellite through the Sunyaev-Zel’dovich effect — the distortion of the cosmic microwave background radiation in the direction of the galaxy cluster by high-energy electrons in the intracluster gas. The large galaxy at the center is the brightest galaxy in the cluster, and above it a thin, curved gravitational lens arc is visible. This arc is caused by the gravitational forces of the cluster bending the path of light from stars and galaxies behind it, in a similar way to how a glass lens bends light.

Several stars are visible in front of the cluster — recognizable by their diffraction spikes — but aside from these, all other visible objects are distant galaxies. Their light has become redshifted by the expansion of space, making them appear redder than they actually are. By measuring the amount of redshift, we know that it took more than 5 billion years for the light from this galaxy cluster to reach us. The light of the galaxies in the background had to travel even longer than that, making this image an extremely old window into the far reaches of the universe.

This image was taken by Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) as part of an observing program called RELICS (Reionization Lensing Cluster Survey). RELICS imaged 41 massive galaxy clusters with the aim of finding the brightest distant galaxies for the forthcoming NASA James Webb Space Telescope to study.

Credit: ESA/Hubble & NASA, RELICS; Acknowledgement: D. Coe et al.
Text: European Space Agency

Martian Sunrise by Oppy

A few days ago I mentioned that the Mars Exploration Rover Opportunity (Oppy) is reaching another milestone, that of 5000 days on Mars and still returning science. Go Oppy!!

The image above is the Sun rising on day 4,999 or 15 February, clicking the image should open a larger version in a new window.

Here’s the caption — NASA’s Mars Exploration Rover Opportunity recorded the dawn of the rover’s 4,999th Martian day, or sol, with its Panoramic Camera (Pancam) on Feb. 15, 2018, yielding this processed, approximately true-color scene.

The view looks across Endeavour Crater, which is about 14 miles (22 kilometers) in diameter, from the inner slope of the crater’s western rim. Opportunity has driven a little over 28.02 miles (45.1 kilometers) since it landed in the Meridiani Planum region of Mars in January, 2004, for what was planned as a 90-sol mission. A sol lasts about 40 minutes longer than an Earth day.

This view combines three separate Pancam exposures taken through filters centered on wavelengths of 601 microns (red), 535 microns (green) and 482 microns (blue). It was processed at Texas A&M University to correct for some of the oversaturation and glare, though it still includes some artifacts from pointing a camera with a dusty lens at the Sun. The processing includes radiometric correction, interpolation to fill in gaps in the data caused by saturation due to Sun’s brightness, and warping the red and blue images to undo the effects of time passing between each of the exposures through different filters.

Image: NASA/JPL-Caltech/Cornell/Arizona State Univ./Texas A&M

Space Radiation on Earth

So from the Van Allen Belts we turn to cosmic rays. How do we study them? ESA is up to the task.

I can’t wait until this is finished and returning data. Great stuff.

Image: GSI Helmholtzzentrum für Schwerionenforschung GmbH/Jan Michael Hosan 2018

ESA – The constant ‘rain’ of radiation in space includes cosmic rays, which, despite the name ‘ray’, comprises highly energetic particles arriving from beyond the Solar System. These rays are considered the main health hazard for astronauts conducting future exploration missions to the Moon, Mars and beyond.

This bad stuff can also play havoc with sensitive spacecraft electronics, corrupting data, damaging circuits and degrading microchips.

There are many different kinds of cosmic rays, and they can have very different effects on spacecraft and their occupants, depending on the types of particles, the particles’ energies and the duration of the exposure.

A new international accelerator, the Facility for Antiproton and Ion Research (FAIR), now under construction near Darmstadt, Germany, at the existing GSI Helmholtz Centre for Heavy Ion Research (GSI), will provide particle beams like the ones that exist in space and make them available to scientists for studies that will be used to make spacecraft more robust and help humans survive the rigours of spaceflight.

For example, researchers will be able to investigate how cells and human DNA are altered or damaged by exposure to cosmic radiation and how well microchips stand up to the extreme conditions in space.

FAIR’s central element will be a new accelerator ring with a circumference of 1100 m, capable of accelerating protons to near-light speeds. The existing GSI accelerators will repurposed to serve as pre-accelerators for the new FAIR facility.

This image shows the high-tech equipment that generates the particles, which are then injected into the GSI and FAIR accelerator systems.

On 14 February 2018, ESA and FAIR inked a cooperation agreement that will build on an existing framework of cooperation between the Agency and GSI, and see the two cooperate in the fields of radiation biology, electronic components, materials research, shielding materials and instrument calibration.

The agreement also includes cooperation in technology and software development and in joint activities in areas such as innovation management.

ESO’s Studentship Programme

Great opportunity!

ESO — ESO’s Studentship programme provides a valuable opportunity for astronomers of the future to gain experience at the most productive ground-based astronomical observatory in the world. PhD students work alongside senior astronomers and engineers in a creative, collaborative and truly international environment, in which their careers are encouraged to blossom.

Van Allen Belts

I saw somewhere the SpaceX launch couldn’t possibly have deployed the Tesla Roadster because of the Van Allen Belts. What? Well I suppose they are having a laugh, but there is a lot of less than accurate information on the internet about the belts (and a lot of other things).

Here is an excellent overview of the Van Allen Belts, thanks to Fraser Cain.

Perseverance Valley on Mars

Perseverance Valley on Mars as seen from the Mars Exploration Rover Opportunity! I can hardly believe the rover has been on Mars for a bit over 11 years landing in January 2004 and it is still delivering science. Amazing.


This late-afternoon view from the front Hazard Avoidance Camera on NASA’s Mars Exploration Rover Opportunity shows a pattern of rock stripes on the ground, a surprise to scientists on the rover team. Approaching the 5,000th Martian day or sol, of what was planned as a 90-sol mission, Opportunity is still providing new discoveries.

This image was taken inside “Perseverance Valley,” on the inboard slope of the western rim of Endeavour Crater, on Sol 4958 (Jan. 4, 2018). Both this view and one taken the same sol by the rover’s Navigation Camera look downhill toward the northeast from about one-third of the way down the valley, which extends about the length of two football fields from the crest of the rim toward the crater floor.

The lighting, with the Sun at a low angle, emphasizes the ground texture, shaped into stripes defined by rock fragments. The stripes are aligned with the downhill direction. The rock to the upper right of the rover’s robotic arm is about 2 inches (5 centimeters) wide and about 3 feet (1 meter) from the centerline of the rover’s two front wheels.

This striped pattern resembles features seen on Earth, including on Hawaii’s Mauna Kea, that are formed by cycles of freezing and thawing of ground moistened by melting ice or snow. There, fine-grained fraction of the soil expands as it freezes, and this lifts the rock fragments up and to the sides. If such a process formed this pattern in Perseverance Valley, those conditions might have been present locally during a period within the past few million years when Mars’ spin axis was at a greater tilt than it is now, and some of the water ice now at the poles was redistributed to lower latitudes. Other hypotheses for how these features formed are also under consideration, including high-velocity slope winds.

NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover Project for NASA’s Science Mission Directorate, Washington.

For more information about Opportunity, Visit and

Image Credit:NASA/JPL-Caltech