The 22 March is World Water Day, which focuses on the importance of freshwater. The Sustainable Development Goals of the United Nations aim to achieve a better and more sustainable future. Goal number 6 focuses on ensuring the availability and sustainable management of water for all by 2030.
This image, captured on 31 October 2018 by the Copernicus Sentinel-2A satellite, takes us over Lake Chad at the southern edge of the Sahara, where water supplies are dwindling.
The rapid decline of the lake’s waters in just 34 years is clear to see in this comparison with an image acquired on 6 November 1984 by the US Landsat 5 satellite.
Once one of Africa’s largest lakes, Lake Chad has shrunk by around 90% since the 1960s. This receding water is down to a reduction of precipitation, induced by climate change, as well as development of modern irrigation systems for agriculture and the increasing human demand for freshwater.
Straddling the border of Chad, Niger, Cameroon and Nigeria, the lake is a major source of freshwater for millions of people in the area. It is also a source for irrigation, fishing and it was once rich in biodiversity.
As the lake continues to dry up, many farmers and herders move towards greener areas or move to larger cities to seek alternative work. Several attempts have been made to replenish these shrinking waters, however little progress has been achieved.
The borders of the lake’s body are only partly visible in the most-recent image – as the majority of the shoreline is swamp and marsh. The Chari River, visible snaking its way towards Lake Chad at the bottom of the image, provides over 90% of the lake’s waters. It flows from the Central African Republic following the Cameroon border from N'Djamena, where it joins with its main tributary the Logone River.
The demand for water is growing inexorably. Access to water is vital – not only for drinking, but also for agriculture, energy and sanitation. By providing measurements of water quality and detecting changes, the Copernicus Sentinel-2 mission can support the sustainable management of water resources.
These images are also featured on the Earth from Space video programme.
Saturn is famous for its bright, glorious rings but in this picture, taken during Saturn's 2009 equinox, the rings are cast in a different light as sunlight hits the rings edge-on.
The equinox is a point in a planet's orbit where the Sun shines directly overhead at the equator. It occurs twice per orbit and on Earth it happens in March and September. At the equinox, day and night are almost equal and the Sun rises due east and sets due west. This year, for northern hemisphere dwellers, the spring equinox occurs on 20 March.
Further afield, the international Cassini mission captured a Saturnian equinox for the first time on 12 August 2009. Saturn's equinoxes occur approximately every 15 Earth years and the next one will take place on 6 May 2025.
When Saturn's equinox is viewed from Earth, the rings are seen edge-on and appear as a thin line – sometimes giving the illusion they’ve disappeared. In this image however, Cassini had a vantage point of 20 degrees above the ring plane, and viewed the planet from a distance of 847,000 kilometres. Its wide angle camera took 75 exposures over eight hours, which were then aligned and combined to create this mosaic.
As the Sun is striking the rings straight on, rather than illuminating them from above or below, the shadows cast by the rings onto the planet are compressed into a single narrow band on the planet.
The rings also appear darker than usual. This can cause out-of-plane structures to look brighter than normal and then cast shadows across the rings. These Saturnian shadow puppets only appear a few months before and after the equinox. The shadows that Cassini saw revealed new ‘mountains’ in the rings, and also discovered previously hidden moonlets. Radial markings known as spokes are also visible on the B ring on the right side of the image.
Several moons are also visible in the mosaic: Janus (lower left), Epimetheus (middle bottom), Pandora (just outside the rings on the right), and Atlas (inside the thin F ring on the right).
Cassini explored the Saturn system for 13 years. It is a cooperative project of NASA, ESA and Italy’s ASI space agency. This image was first published in September 2009; read the full caption for more information and imaging details.
Captured on 22 January 2019 by the Copernicus Sentinel-2B satellite, this true-colour image shows Thailand’s most populous city Bangkok, and its ‘Green Lung’ Bang Kachao.
The UN International Day of Forests is held annually on 21 March. It raises awareness of the importance of all types of forest and the vital role they play in some of the biggest challenges we face today, such as addressing climate change, eliminating hunger and keeping urban and rural communities sustainable. As the global population is expected to climb to 8.5 billion by 2030, forests are more important than ever.
This year, the International Day of Forests put a particular focus on education, but also on making cities a greener, healthier and happier place to live. In cities, trees can help many urban challenges. They act as air filters by removing pollutants, reduce noise pollution, offer shade and provide an oasis of calm in an otherwise busy urban environment, for example.
While Bangkok, which is home to over eight million people, is an example of ongoing efforts being made to increase green spaces to improve city life, it also has a much-valued green haven, which can be seen in the centre of the image.
This horseshoe or lung-shaped, green oasis is Bang Kachao and is in the middle of the bustling city.
Rich in gardens, mangroves and agricultural fields, the 2000 hectares of land is a significant contrast to the vastness of the city’s urban sprawl. Fighting Bangkok’s traffic and air pollution, Bang Kachao’s lush green forest provides the dense city, and the surrounding Samutprakan province, with a flow of fresh air.
The government-protected oasis of green is wrapped around the Chao Phraya River, which is seen flowing through the city of Bangkok before emptying into the Gulf of Thailand.
Copernicus Sentinel-2 allows urban growth to be monitored accurately, providing essential information to urban planners and decision-makers, and is a prime mission for monitoring the health of the world’s vegetation.
This fluorescent work of art captures the beauty of biofilms, or the growth of microbes on rocks. In this microscopic image, Sphingomonas desiccabilis is growing on basalt.
It is one of three microbes chosen for the BioRock experiment, run by a research team from the University of Edinburgh in the UK, that will test how altered states of gravity affect biofilm formation on the International Space Station.
Microbes are able to weather down a rock from which they can extract ions. This natural process enables biomining, in which useful metals are extracted from rock ores.
Already a common practice on Earth, biomining will eventually take place on the Moon, Mars and asteroids as we expand our understanding and exploration of the Solar System. In the meantime, microbes will be used for many other processes that involve microbial growth on rocks, such as making soil.
In preparation for the experiment, researchers performed a “dry run” on Earth ahead of BioRock’s launch to the Space Station aboard a Space-X cargo resupply mission in July.
Cells of one of three organisms that will be used for BioRock were inoculated and dried on a sample of basalt, then given ‘food’ to restore cell growth. The biofilm was left to grow for three weeks at 20°C, then preserved and stored at 4-6°C for one month. Researchers finally observed the sample under a fluorescent microscope to assess its performance.
And it performed beautifully. A patch of biofilm is visible to the right of the central cavity, which is the basalt’s natural porosity.
The results of the dry run show that the experimental conditions for BioRock, from the choice of the organism to the storage temperature and timing, are appropriate. This experiment also gave researchers the first clues as to what would be most interesting to focus on when samples return from space.
Using post-flight data, researchers will map out how altered states of gravity affect the rock and microbe system as a whole. The results hope to shine light on extraterrestial biomining technologies and life support systems involving microbes for longer duration spaceflight.
Biomining in space can also increase the efficiency of the process on Earth and could even reduce our reliance on precious Earth resources.
Captured by the Copernicus Sentinel-3 mission, this image shows Cyclone Idai on 13 March 2019 west of Madagascar and heading for Mozambique. Here, the width of the storm is around 800–1000 km, but does not include the whole extent of Idai. The storm went on to cause widespread destruction in Mozambique, Malawi and Zimbabwe. With thousands of people losing their lives, and houses, roads and croplands submerged, the International Charter Space and Major Disasters and the Copernicus Emergency Mapping Service were triggered to supply maps of flooded areas based on satellite data to help emergency response efforts.
The platform destined to land on the Red Planet as part of the next ExoMars mission has arrived in Europe for final assembly and testing – and been given a name.
An announcement was made by the Russian State Space Corporation Roscosmos of its new name: ‘Kazachok’.
Kazachok left Russia after being carefully packed to meet planetary protection requirements, making sure to not bring terrestrial biological contamination to Mars. It was shipped to Turin, Italy, on an Antonov plane along with ground support equipment and other structural elements.
Captured just yesterday, 19 March, at 17:11 GMT (18:11 CET) by the Copernicus Sentinel-1 mission, this image shows the oil spill from the Grande America vessel. The Italian container ship, carrying 2200 tonnes of heavy fuel, caught fire and sank in the Atlantic, about 300 km off the French coast on 12 March.
Copernicus Sentinel-1 acquired this radar image of the oil slick, the large, dark patch visible in the centre of the image, stretching about 50 km. Marine vessels are identifiable as smaller white points, which could be those assisting in the clean-up process.
Oil is still emerging from the ship now lying at a depth of around 4500 metres. French authorities are trying to reduce the impact of pollution along the coast.
Sentinel-1 is a two-satellite constellation built for the European Commission’s Copernicus environmental monitoring programme. The identical satellites each carry an advanced radar instrument that can ‘see’ through the dark and through clouds.
Satellite radar is particularly useful for monitoring the progression of oil spills because the presence of oil on the sea surface dampens down wave motion. Since radar basically measures surface texture, oil slicks show up well – as black smears on a grey background.
An X-ray view of the centre of our Milky Way galaxy, where the supermassive black hole Sagittarius A* is hosted. This image, obtained with ESA’s XMM-Newton space observatory, shows the temperature of the X-ray emitting gas in this turbulent region, with cooler regions shown in red and hotter regions in green and blue.
The bright area at the middle of the image identifies the vicinity of Sagittarius A*. The yellow-orange features streaming above and below the centre are two colossal ‘chimneys’, extending hundreds of light-years each, that funnel material from the Galactic centre into two huge cosmic bubbles.
This view combines data collected in the following energy bands: 1.5–2.6 keV (shown in red); 2.35– 2.56 keV (shown in green); 2.7–2.97 keV band (shown in blue). The many white patches, large and small, are artifacts where unrelated, bright, point-like X-ray sources have been removed from the image.
More information: Giant ‘chimneys’ vent X-rays from Milky Way’s core
A test version of the 10.5-m long magnetometer boom built for ESA’s mission to Jupiter, developed by SENER in Spain, seen being tested at ESA’s Test Centre in the Netherlands, its weight borne by balloons.
The flight model will be mounted on the Juice spacecraft – Jupiter Icy Moons Explorer – due to launch in 2022, arriving at Jupiter in 2029. The mission will spend at least three years making detailed observations of the giant gaseous planet Jupiter and three of its largest moons: Ganymede, Callisto and Europa.
The Juice spacecraft will carry the most powerful remote sensing, geophysical, and in situ payload complement ever flown to the outer Solar System. Its payload consists of 10 state-of-the-art instruments.
This includes a magnetometer instrument that the boom will project clear of the main body of the spacecraft, allowing it to make measurements clear of any magnetic interference. Its goal is to measure Jupiter’s magnetic field, its interaction with the internal magnetic field of Ganymede, and to study subsurface oceans of the icy moons.
The deployment of this qualification model boom has been performed before and after simulated launch vibration on Test Centre shaker tables to ensure it will deploy correctly in space. Since the boom will deploy in weightlessness, three helium balloons were used to help bear its weight in terrestrial gravity.
This fuzzy orb of light is a giant elliptical galaxy filled with an incredible 200 billion stars. Unlike spiral galaxies, which have a well-defined structure and boast picturesque spiral arms, elliptical galaxies appear fairly smooth and featureless. This is likely why this galaxy, named Messier 49, was discovered by French astronomer Charles Messier in 1771. At a distance of 56 million light-years, and measuring 157 000 light-years across, M49 was the first member of the Virgo Cluster of galaxies to be discovered, and it is more luminous than any other galaxy at its distance or nearer.
Elliptical galaxies tend to contain a larger portion of older stars than spiral galaxies and also lack young blue stars. Messier 49 itself is very yellow, which indicates that the stars within it are mostly older and redder than the Sun. In fact, the last major episode of star formation was about six billion years ago — before the Sun was even born!
Messier 49 is also rich in globular clusters; it hosts about 6000, a number that dwarfs the 150 found in and around the Milky Way. On average, these clusters are 10 billion years old. Messier 49 is also known to host a supermassive black hole at its centre with the mass of more than 500 million Suns, identifiable by the X-rays pouring out from the heart of the galaxy (as this Hubble image comprises infrared observations, these X-rays are not visible here).
Week in images
18 - 22 March 2019