Brown hills speckle the eastern part of Australia’s Lake MacKay in this satellite image.
Located on the border of the states of Western Australia and Northern Territory, the salt lake only sees water after seasonal rainfall – if at all. It is classified as an ephemeral lake, meaning it exists only after precipitation. This is not the same as a seasonal lake, which sees water for longer periods.
About half of Australia's rivers drain inland and often end in ephemeral salt lakes.
The greens and blues in this image show desert vegetation or algae, soil moisture and minerals – mainly salt. On some of the brown ‘islands’ and on the shore in the lower right, we can see the east–west sand ridges forming lines in the landscape.
The lake lies at the edge of the Great Sandy Desert, which covers nearly 285 000 sq km. Roads are scarce in the area, and often frequented by four-wheel drive adventurers. Roads include the Canning Stock Route about 300 km to the west of the image, or Tanami Track connecting Australia’s Stuart Highway to the Great Northern Highway around 300 km to the east.
This image, also featured on the Earth from Space video programme, was captured by the Copernicus Sentinel-2B satellite on 15 March.
Although it is still being calibrated following the 7 March launch, the satellite’s main instrument is already delivering images, demonstrating its capability to map Earth’s land, coast and inland water bodies. Once fully operational, the data will be made available to users for a variety of applications, free of charge.
The blue of the Calanda reservoir amid the rugged landscape of northeastern Spain, as seen by ESA’s oldest – and one of its smallest – Earth-observing missions, Proba-1, midway through its 15th year of operations.
Located around 120 km southeast of the city of Zaragoza, and built within a surrounding gorge, the reservoir is used for agricultural irrigation and fishing. The town of Calanda is visible at the top of the image.
Researchers can use Proba-1’s hyperspectral camera to gather data on the reservoir’s water quality and phytoplankton content.
The cubic-metre Proba-1 is the first in ESA’s series of satellites aimed at flight-testing new space technologies. It was launched on 22 October 2001 but is still going strong, having since been reassigned to ESA’s Earth observation duties.
Proba-1’s main hyperspectral CHRIS imager records 15 m-resolution scenes across a programmable selection of up to 62 spectral bands, from a variety of viewing angles. It is supplemented by a 5 m-resolution black-and-white microcamera.
Other innovations include what were then novel gallium-arsenide solar cells, the use of startrackers for gyroless attitude control, one of the first lithium-ion batteries – now the longest such item operating in orbit – and one of ESA’s first ERC32 microprocessors to run Proba-1’s agile computer.
For more background on Proba-1, read this celebration in the ESA Bulletin.
Thanks to scientists, citizen scientists, ground-based imagers and ESA’s magnetic field Swarm mission, this purple streak of light in the night sky has been discovered. Originally thought to be a ‘proton arc’, this strange feature has been called Steve. While there is still a lot to learn about Steve, the electric field instrument carried on the Swarm mission has measured it. Flying through Steve, the temperature 300 km above Earth’s surface jumped by 3000°C and the data revealed a 25 km-wide ribbon of gas flowing westward at about 6 km/s compared to a speed of about 10 m/s either side of the ribbon.
Read full story: When Swarm met Steve
Two Sentinel-1 radar images from 7 and 14 April 2017 were combined to create this interferogram showing the growing crack in Antarctica’s Larsen-C ice shelf.
Polar scientist Anna Hogg said: “We can measure the iceberg crack propagation much more accurately when using the precise surface deformation information from an interferogram like this, rather than the amplitude – or black and white – image alone where the crack may not always be visible.”
When the ice shelf calves this iceberg it will be one of the largest ever recorded – but exactly how long this will take is difficult to predict. The sensitivity of ice shelves to climate change has already been observed on the neighbouring Larsen-A and Larsen-B ice shelves, both of which collapsed in 1995 and 2002, respectively.
These ice shelves are important because they act as buttresses, holding back the ice that flows towards the sea.
The Copernicus Sentinel-1 two-satellite constellation is indispensable for discovering and monitoring events like these because it delivers radar images every six days, even when Antarctica is shrouded in darkness for several months of the year.
After completion of its vibration and acoustic testing in March, the James Webb Space Telescope – JWST – is shown here undergoing a detailed ‘lights out’ inspection in one of NASA’s cleanrooms at the Goddard Space Flight Center.
This is a special type of visual inspection to check for any forms of contamination. Both bright white LEDs and UV lights are used in order to better search for possible contamination, with the lights inside the cleanroom switched off to improve the contrast.
The low lighting means the image had to be taken with a longer than normal exposure time. This makes the technicians appear somewhat ghostly as they moved about the cleanroom during the exposure.
The image shows the segmented and gold-coated primary mirror of the telescope, which has a diameter of about 6.5 m when unfolded. It consists of 18 hexagonal segments, which will work together as one gigantic state-of-the-art mirror.
In order to fit inside the Ariane 5 rocket that will boost it into space, some segments will be folded, which will then open in orbit.
By the end of April, the telescope and the instruments will be shipped from NASA Goddard Space Flight Center in Maryland to Johnson’s Space Center in Texas where, over the course of the summer, it will go through final cryogenic-temperature testing.
JWST is joint project of NASA, ESA and the Canadian Space Agency, and is scheduled for launch in October 2018 from Europe’s Spaceport in Kourou, French Guiana. This image was first published on 15 March via the NASA JWST pages.
The stellar views from the International Space Station are not the only things to take an astronaut’s breath away: devices like this are measuring astronauts’ breath to determine the health of their lungs. ESA astronaut Tim Peake took part in the Airway Monitoring experiment during his Principia mission in 2016.
Developed by researchers at the Karolinska Institutet in Sweden, the experiment draws on a study of airway inflammation that ran on the Station from 2005 to 2008.
The analyser measures the amount of nitric oxide in exhaled air – a signalling molecule produced in the lungs to help regulate blood vessels. Too much nitric oxide suggests inflammation. Causes can be environmental, like dust or pollutants, or biological, such as asthma – at least on Earth, but what happens in space?
Researchers compare measurements from astronauts taken before their flights to those taken in space to understand the effects of weightlessness on airway health. Astronauts in space are essentially fish out of water. Understanding how to track, diagnose and treat lung inflammations is important for their safety.
The experiment began with ESA astronaut Samantha Cristofretti’s 2015 mission and measurements have been gathered by six astronauts. Four more astronauts will conduct the experiment next year.
Retired astrophysicist and former NASA scientist Donald Kessler seen attending the European Conference on Space Debris at ESA in Darmstadt, Germany, on 18 April 2017.
Since 1957, more than 5250 space launches have led to an orbiting population today of more than 23 000 tracked debris objects.
Only about 1200 are working satellites. The remaining are classified as space debris and no longer serve any useful purpose. A large percentage of the routinely tracked objects are fragments from the approximately 290 breakups, explosions and collisions of satellites or rocket bodies that are known to have occurred.
An estimated 750 000 objects larger than 1 cm and a staggering 166 million pieces larger than 1 mm are thought to reside in commercially and scientifically valuable Earth orbits.
Relative orbital speeds of up 56 000 km/h mean that even centimetre-sized debris can seriously damage or disable a working satellite, and collisions with objects larger than 10 cm will lead to catastrophic break-ups, releasing clouds of hazardous debris fragments that will go on to cause further catastrophic collisions, potentially leading to an unstable debris environment in some orbital regions.
This run-away scenario is known as the “Kessler syndrome” because it was first postulated by Don in 1978.
This stunning cosmic pairing of the two very different-looking spiral galaxies NGC 4302 (left) and NGC 4298 (right) was imaged by the NASA/ESA Hubble Space Telescope and released as part of the telescope’s 27th anniversary celebrations.
An image shared by ESA astronaut Thomas Pesquet on his social media channels showing the arrival of a Soyuz spacecraft at the International Space Station. Carrying two new members of the Expedition 51 crew, the Soyuz spacecraft launched from Baikonur Cosmodrome at 09:13 CEST on 20 April 2017 and docked with the Station some six hours later.
Connect with Thomas: http://thomaspesquet.esa.int
Week In Images
17-21 April 2017