With the final observation of the distant galaxy cluster Abell 370 – some five billion light-years away – the Frontier Fields program came to an end.
Abell 370 is one of the very first galaxy clusters in which astronomers observed the phenomenon of gravitational lensing, the warping of spacetime by the cluster's gravitational field that distorts the light from galaxies lying far behind it. This manifests as arcs and streaks in the picture, which are the stretched images of background galaxies.
Read more: The final frontier of the Frontier Fields [heic1711]
While one instrument of the NASA/ESA Hubble Space Telescope observed a pair of spiral galaxies for its 27th anniversary last month, another simultaneously observed a nearby patch of the sky to obtain this wide-field view.
These ‘parallel field’ observations increase the telescope’s productivity.
This parallel field shows an area of the sky awash largely with spiral galaxies like our Milky Way. Most of the prominent galaxies look different only because they are tilted at various orientations to our viewpoint – from edge-on to face-on. A few others are interacting or merging.
The image also shows a number of foreground stars in our own galaxy.
More image formats available here.
What is the best way to control a robot from afar as you circle a planet with your mechanised alter ego doing precise work on the surface? ESA is testing human–robot control in space and on Earth as part of a strategy that sees astronauts controlling robots from space.
Last week at ESA’s technical heart in the Netherlands, the Interact Centaur rover was controlled from the Human Robot Interaction Laboratory next door, formerly known as the Telerobotics and Haptics lab. Relying on video feedback, the operator drove the car-sized rover through an obstacle course.
The left hand controls the rover’s movements, while the right-hand controller pictured here moves the robot’s arm and gripper, offering 3D movement such as twisting and gripping.
A triangular brick 3D printed out of simulated moondust using concentrated sunlight. It was produced using a 3D printer table, to bake successive 0.1 mm layers of moondust at 1000°C, to complete a 20 x 10 x 3 cm brick for building in around five hours. As raw material, the test used commercially available simulated lunar soil based on terrestrial volcanic material, processed to mimic the composition and grain sizes of genuine moondust.
The solar furnace at the DLR German Aerospace Center facility in Cologne has two working setups. As a baseline, 147 curved mirrors focus sunlight into a high-temperature beam to melt the soil grains together. But the weather in northern Europe does not always cooperate, so the Sun is sometimes simulated by an array of xenon lamps more typically found in cinema projectors.
The resulting bricks have the equivalent strength of gypsum, and are set to undergo detailed mechanical testing.
ESA is testing human–robot control in space and on Earth as part of a strategy that sees astronauts controlling robots from space.
Last week at ESA’s technical heart in the Netherlands, this Interact Centaur rover was controlled from the Human Robot Interaction Laboratory next door.
Relying on video feedback, the operator drove the car-sized rover through a rock-strewn obstacle course.
ESA’s sensitive tracking antennas at New Norcia, Western Australia, and Malargüe, Argentina (seen here in 2012), are being called in to help gather crucial science data during Cassini’s last months in orbit, dubbed the Grand Finale.
The mission will end on 15 September, when Cassini plunges into Saturn’s atmosphere, bringing to a close one of the most successful exploration endeavours ever (more information).
The craft isn’t exiting meekly, however, and its Grand Finale orbits are proving to be immensely valuable. On 26 April, Cassini made the first-ever daring dive between Saturn and its beautiful and enigmatic ring system.
Starting next week, ESA ground stations will work with NASA’s Deep Space Network to record radio signals transmitted by Cassini across 1.6 billion km during 22 communication ‘passes’.
The recorded signals will serve important new scientific purposes with the strong involvement of European teams.
During its final 22 orbits, the Cassini orbiter is approaching Saturn and its ring so close that the tiny wobbles in Cassini’s orbit can be measured to separate the gravitational contribution of the planet and its main rings. From those gravity measurements, allowing radial velocity changes of the spacecraft as tiny as 0.05 mm/s to be measured, the total mass of Saturn’s ring can be inferred. Scientists will also gain a better understanding of the interior structure of Saturn.
In addition, during certain part of the orbits, the radio signal will be transmitted directly through the rings and Saturn’s upper atmosphere, allowing valuable information on their composition and material distribution to be retrieved.
“We are just now getting into a new mode of radio science, with much more accurate measurements of gravitational effects compared to previous where the effects of ring density on the radio signals were the main topic of study," says Daniel Firre, the service manager at ESA’s mission control centre in Darmstadt, Germany.
The Copernicus Sentinel-2B satellite takes us over part of the western Netherlands on 16 March, with the capital city of Amsterdam at the centre of the image.
Divided among some 90 islands, Amsterdam has more than 100 km of canals. The city lies about 2 m below sea level – in fact, around a third of the country lies below sea level, making it susceptible to floods. Rising sea waters during periods of bad weather – called storm surges – are kept under control by dams, dikes, floodgates and natural sand dunes.
While we can see the North Sea on the left, the water on the right is part of the Markermeer lake. This area was once a saltwater bay called the Zuiderzee, but was closed off by a dam in the 1930s. The bay was drained in stages and land reclaimed, including Flevoland on the right side of the image – one of the world’s largest artificial islands.
Another relatively recent addition to the Dutch landscape is the neighbourhood of IJburg comprising six artificial islands east of Amsterdam. The first residents moved in only 15 years ago.
Satellites like Sentinel-2 can help to monitor urban expansion. For example, in the upper-right corner we see what looks like an artificial island being built – but this structure is not present in satellite imagery from a year ago.
The meticulously planned landscape seen in most of the image breaks for the coastal dunes along the left. These areas are home to dozens of bird species, as well as deer, squirrels, rabbits and foxes. In one protected area, grazing animals including Highland cattle were introduced to the area.
This image is featured on the Earth from Space video programme.
On 4 May 2017, Ariane 5 flight VA236 lifted off from Europe’s Spaceport in French Guiana and delivered two telecom satellites, SGDC and Koreasat-7, into their planned orbits. Flight VA236 was the 92nd Ariane 5 mission.
Read more: Ariane 5's second liftoff this year
Week In Images
1-5 May 2017