This false-colour Sentinel-2A image captured on 20 August 2015 takes us to the city of Yuma in the United States, in southwestern Arizona.
Visible in the image in scattered greys, Yuma is home to some 90 000 people. Situated along the Colorado River, the Mexican frontier lies just west of it and California lies to the north.
The fence forming the border is visible as a fine and perfectly straight line, running from left to right through the image between the irrigation canal and the irrigated fields west of the city. Just north of the canal, a small square marks a water reservoir for irrigating the fields in this highly arid region.
Founded in 1854, Yuma is the centre of large irrigation districts that converted parts of the desert into rich farmland.
It is considered to be the winter vegetable capital of the US because it has some of the most fertile soil in the country, stemming from sediments deposited by the Colorado River over thousands of years. These lay the foundation for making it the third most productive in the entire US for vegetables. It is also known for wheat – two thirds is exported, mainly to Italy for producing premium pasta.
The false-colour bands render the farmed fields in varying shades of browns and red. The circular features are created by centre-pivot irrigation, while rectangular fields use different irrigation methods that deliver the water along straight lines. The shades of red indicate how sensitive the multispectral instrument on Sentinel-2A is to differences in chlorophyll content, providing key information on vegetation health.
Also visible in the image are the Yuma International Airport just south of town, and parts of the Kofa National Wildlife Refuge to the east, which protects the desert bighorn sheep, while offering hiking and camping in the rugged wilderness.
Sentinel-2A has been in orbit since 23 June 2015 as a polar-orbiting, high-resolution satellite for land monitoring, providing imagery of vegetation, soil and water cover, inland waterways and coastal areas.
This image is also featured on the Earth from Space video programme.
Showcased in this NASA–ESA Hubble Space Telescope image is a young stellar cluster known as R136.
Located in the Tarantula Nebula within the Large Magellanic Cloud, about 170 000 light-years away, the young cluster hosts many extremely massive, hot and luminous stars whose energy is mostly radiated in the ultraviolet. Scientists have combined images taken with the Wide Field Camera 3 (WFC3) on Hubble with the unprecedented ultraviolet spatial resolution of the Space Telescope Imaging Spectrograph (STIS) to identify some of the most massive and brightest stars known.
As well as finding dozens of stars exceeding 50 solar masses, this new study revealed nine very massive stars in the cluster, all more than 100 times more massive as the Sun. The detected stars are not only extremely massive, but also extremely bright. Together, these nine stars outshine the Sun by a factor of 30 million.
Ireland seen from the International Space Station by ESA astronaut Tim Peake.
Tim commented on the picture: "The Emerald Isle looking lush and green from space...Happy St Patrick's day to all down there!"
Tim's six-month mission to the International Space Station is named Principia, after Isaac Newton’s ground-breaking Naturalis Principia Mathematica, which describes the principal laws of motion and gravity.
He is performing more than 30 scientific experiments for ESA and taking part in numerous others from ESA’s international partners.
ESA and the UK Space Agency have partnered to develop many exciting educational activities around the Principia mission, aimed at sparking the interest of young children in science and space.
More about the Principia mission: http://www.esa.int/principia
More photos from Tim on his flickr photostream: https://www.flickr.com/photos/timpeake
ExoMars 2016 lifted off on a Proton-M rocket from Baikonur, Kazakhstan at 09:31 GMT on 14 March 2016.
ExoMars 2016 lifted off on a Proton-M rocket from Baikonur, Kazakhstan at 09:31 GMT on 14 March 2016.
Positioning the Sentinel-1B satellite on the tilting trolley for testing at Europe's Spaceport near Kourou in French Guiana. The satellite will spend the next weeks being tested and prepared for launch, scheduled for 22 April 2016.
Sentinel-2A satellite captured the nations’capital last 25 August 2015.
A prototype 3D-printed antenna being put to work in ESA’s Compact Antenna Test Facility, a shielded chamber for antenna and radio-frequency testing.
“This is the Agency’s first 3D-printed dual-reflector antenna,” explains engineer Maarten van der Vorst, who designed it.
“Incorporating a corrugated feedhorn and two reflectors, it has been printed all-in-one in a polymer, then plated with copper to meet its radio-frequency (RF) performance requirements.
“Designed for future mega-constellation small satellite platforms, it would need further qualification to make it suitable for real space missions, but at this stage we’re most interested in the consequences on RF performance of the low-cost 3D-printing process.”
“Although the surface finish is rougher than for a traditionally manufactured antenna, we’re very happy with the resulting performance,” says antenna test engineer Luis Rolo.
“We have a very good agreement between the measurements and the simulations. Making a simulation based on a complete 3D model of the antenna leads to a significant increase in its accuracy.
“By using this same model to 3D print it in a single piece, any source of assembly misalignments and errors are removed, enabling such excellent results.”
Two different antennas were produced by Swiss company SWISSto12, employing a special copper-plating technique to coat the complex shapes.
“As a next step, we aim at more complex geometries and target higher frequencies,” adds Maarten, a member of ESA’s Electromagnetics & Space Environment Division. “And eventually we want to build space-qualified RF components for Earth observation and science instruments.”
Based at ESA’s ESTEC technical centre in Noordwijk, the Netherlands, the test range is isolated from outside electromagnetic radiation while its inside walls are covered with ‘anechoic’ foam to absorb radio signals, simulating infinite space.
The range is part of ESA’s suite of antenna testing facilities, intended for smaller antennas and subsystems, with larger antennas and entire satellites put to the test in its ‘big brother’, the Hertz chamber.
A close-up of the engineering model of ESA’s International Berthing and Docking Mechanism (IBDM) that will mate spacecraft with an airtight seal. Whereas present docking systems are passive and rely on the spacecraft to push against each other to make the connection, ESA’s new mechanism is active, allowing the spacecraft to meet more gently before it draws them together.
The International Space Station has three types of docking units that are all incompatible: one designed for Russian spacecraft and used by Europe’s ATV space freighter; one for the now-retired US Space Shuttle; and a berthing port for vessels that cannot dock on their own but are first captured by the Station’s robotic arm.
To promote cooperation and allow the next generation of spacecraft to link up, the Station’s partner agencies are creating the International Docking System Standard. This will allow the underlying mechanism to be designed in any way but ensures all spacecraft will be able to connect.
ESA’s IBDM follows the standard to work with a lighter generation of space vehicles. It is identical for both craft – any two vehicles can dock or be berthed. It is the only design that will sense the forces at play during the mating and adapt accordingly, ‘grabbing’ a lighter vessel or absorbing the loads of a heavier vehicle.
Although the connection is defined by the international standard, the mechanism behind the docking ring can be designed in any way, simplifying future cooperation in space.
On the night of 13–14 March 1986, ESA’s Giotto spacecraft flew to within a mere 596 km of Comet Halley, revealing for the first time how a cometary nucleus looks up close.
This montage features six images from the historic flyby, with the first one (top left) taken about three hours before closest approach, from a distance of 766 371 km, and the last (bottom right) taken only 27 s before closest approach, 1917 km from the nucleus. As Giotto closed in, the images showed an extremely dark potato-shaped object of 15 x 7.2 x 7.2 km.
The comet is also known as 1P/Halley, where 1P marks it as the first comet to be identified as periodic. It was Edmond Halley who recognised that comets observed in 1531, 1607 and 1682 had remarkably similar orbital properties and suggested that they might just be the same object, regularly returning to our skies.
In 1705, he forecast that the comet, moving along a very elongated ellipse with a period of about 76 years, would be visible again in 1758. Unfortunately, Halley died before then, but other astronomers did observe the return in 1758 and 1759, confirming his prediction and, with it, the possibility that comets might indeed be periodic.
Further appearances of Comet Halley, in 1835 and 1910, were eagerly awaited and provided insights into the nature of comets, with increasingly more powerful astronomical instrumentation. After the dawn of the space age in the second half of the 20th century, the 1986 return of the comet was welcomed with a fleet of spacecraft.
The Halley Armada included Giotto alongside two probes from the Soviet Union, Vega-1 and Vega-2, and two from Japan, Sakigake and Suisei. NASA’s International Cometary Explorer, which had became the first space mission to approach a comet, passing some 7800 km of Comet 21P/Giacobini–Zinner in 1985, also observed Halley in 1986.
Giotto, named after the Italian painter who, in 1303, depicted the star of Bethlehem as a comet, obtained the closest pictures ever taken of a comet at the time. After Vega-1 and Vega-2 came within 8900 km and 8000 km, respectively, in early March 1986, ESA used their data to guide Giotto even closer.
As scientists analysed the unique images and data from Giotto, they were also thinking ahead, laying the foundations of a future project that would evolve into ESA’s Rosetta mission. Launched in 2004, Rosetta reached Comet 67P/Churyumov–Gerasimenko in 2014, orbiting the comet and deploying the Philae lander.
Rosetta escorted the comet as they passed perihelion – the closest point to the Sun along their orbit – in August 2015, and will continue close-up studies until the end of September 2016, when it will be guided into a controlled impact on the surface.
This week, scientists are celebrating the 30th Anniversary of Giotto’s close encounter with Comet Halley, as well as the continuing investigations by Rosetta, at the 50th ESLAB Symposium “From Giotto to Rosetta,” in Leiden, the Netherlands.
In October of 2013 Hubble kicked off the Frontier Fields programme, a three-year series of observations aiming to produce the deepest ever views of the Universe. The project’s targets comprise six massive galaxy clusters, enormous collections of hundreds or even thousands of galaxies. These structures are the largest gravitationally-bound objects in the cosmos.
One of the Frontier Fields targets is shown in this new image: MACS J0717.5+3745, or MACS J0717 for short. MACS J0717 is located about 5.4 billion light-years away from Earth, in the constellation of Auriga (The Charioteer). It is one of the most complex galaxy clusters known; rather than being a single cluster, it is actually the result of four galaxy clusters colliding.
This image is a combination of observations from the NASA/ESA Hubble Space Telescope (showing the galaxies and stars), the NASA Chandra X-ray Observatory (diffuse emission in blue), and the NRAO Jansky Very Large Array (diffuse emission in pink). The Hubble data were collected as part of the Frontier Fields programme mentioned above.
Together, the three datasets produce a unique new view of MACS J0717. The Hubble data reveal galaxies both within the cluster and far behind it, and the Chandra observations show bright pockets of scorching gas — heated to millions of degrees. The data collected by the Jansky Very Large Array trace the radio emission within the cluster, enormous shock waves — similar to sonic booms — that were triggered by the violent merger.
Single frame enhanced NavCam image taken on 15 March 2016, when Rosetta was about 13 km from the nucleus of Comet 67P/Churyumov-Gerasimenko. The average scale is 1.1 m/pixel and the image measures about 1.1 km across.
The original image and more information is available on the blog: CometWatch 15 March
Week In Images
14-18 March 2016