This turbulent celestial palette of purple and yellow shows a bubble of gas named NGC 3199, blown by a star known as WR18 (Wolf-Rayet 18).
Wolf-Rayet stars are massive, powerful, and energetic stars that are just about reaching the end of their lives. They flood their surroundings with thick, intense, fast-moving winds that push and sweep at the material found there, carving out weird and wonderful shapes as they do so. These winds can create strong shockwaves when they collide with the comparatively cool interstellar medium, causing them to heat up anything in their vicinity. This process can heat material to such high temperatures that it is capable of emitting X-rays, a type of radiation emitted only by highly energetic phenomena in the Universe.
This is what has happened in the case of NGC 3199. Although this kind of scenario has been seen before, it is still relatively rare; only three other Wolf-Rayet bubbles have been seen to emit X-rays (NGC 2359, NGC 6888, and S308). WR18 is thought to be a star with especially powerful winds; once it has run out of material to fuel these substantial winds it will explode violently as a supernova, creating a final breath-taking blast as it ends its stellar life.
This image was taken by the European Photon Imaging Camera (EPIC) on ESA’s XMM-Newton X-ray space observatory, and marks different patches of gas in different colours. The incredibly hot, diffuse, X-ray-emitting gas within the Wolf-Rayet bubble is shown in blue, while a bright arc that is visible in the optical part of the spectrum is traced out in shades of yellow-green (oxygen emission) and red (sulphur emission).
This blue and yellow-green component forms an optical nebula – a glowing cloud of dust and ionised gases – that stretches out towards the western end of the X-ray bubble (in this image, North is to the upper left). This lopsided arc caused astronomers to previously identify WR18 as a so-called runaway star moving far faster than expected in relation to its surroundings, but more recent studies have shown that the observed X-ray emission does not support this idea. Instead, the shape of NGC 3199 is thought to be due to variations in the chemistry of the bubble’s surroundings, and the initial configuration of the interstellar medium around WR18.
Explore this object in ESASky.
Mount Makalu in the Himalayas is pictured in this Copernicus Sentinel-2B image from 9 December 2017.
At 8485 m high, Makalu is the fifth highest mountain in the world. The iconic pyramid-shaped mountain can be seen just to the right of the centre of the image. It is situated on the border between Nepal and China, about 19 km southeast of Mount Everest, which is in the top left of the image.
Because of the mountain’s knife-edge ridges and its remote position, which leaves it exposed to the elements, it is viewed by many as one of the world’s most difficult mountains to climb.
Nevertheless, Swedish explorer, mountaineer and climate campaigner, Carina Ahlqvist, led a climb this year to raise awareness of climate change and to support ESA’s Climate Change Initiative. During the expedition, scientists collected measurements to help validate data from the Copernicus Sentinel-1 radar mission that are used to study natural hazards such as rock falls and landslides in mountainous regions. The team also surveyed the Barun glacier, which lies at the base of Makalu, to help understand its history and therefore the past climate in this region.
Unfortunately, Carina was struck with snow blindness and had to be evacuated just 300 m from Makalu’s summit. She is now safe and well and the data collected during the expedition are being used to further understand the dynamics of this remote region and how it is being affected by climate change.
This image is also featured on the Earth from Space video programme.
This micro-pulsed plasma thruster has been designed for propulsion of miniature CubeSats; its first firing is seen here. The thruster works by pulsing a lightning-like electric arc between two electrodes. This vaporizes the thruster propellant into charged plasma, which is then accelerated in the electromagnetic field set up between the electrodes.
Developed for ESA by Mars Space Ltd and Clyde Space of the UK with Southampton University, this 2 Watt, 42 Newton-second impulse plasma thruster has been qualified for space, with more than a million firing pulses demonstrated during testing.
It has been designed for a range of uses, including drag compensation in low orbits, orbit maintenance, formation flying and small orbit transfers. The thruster could also serve as a CubeSat deorbiting device, gradually reducing orbital altitude until atmospheric re-entry is achieved.
About the size of a DVD reader, the thruster weighs just 280 grams including its propellant load and drive electronics.
Space agencies of Europe, assemble!
Last week, ESA, the German Aerospace Center (DLR) and French space agency CNES joined forces to run a special parabolic flight campaign entirely dedicated to life science experiments. Between 4 and 7 June, eight experiments were run in three different levels of partial gravity, another first for a parabolic flight campaign.
During our more common zero-gravity parabolic flights, research teams are subjected to 20-second bursts of weightlessness during which they run experiments ranging from life sciences, to technology demonstrations, to material physics. Results offer an indication of how various mechanisms work without gravity and are compared to results on the ground. But what happens at varying degrees of weightlessness?
To help fill in the graph, scientists were offered a unique opportunity to run experiments at one-quarter, one-half, and three-quarters gravity. The aim is to better understand biological dependence on gravity. Ultimately, if humans are to embark on long-term spaceflight and live on the Moon and Mars, we need to determine the levels of gravity in which humans can live and work.
One experiment investigated the effects of partial gravity on brain function. Previous studies have shown that short exposure to microgravity increased neurocognitive functions due to increased blood flow to the brain. However, longer-term spaceflight, in which increased blood flow to the brain is more permanent, showed negative effects on cognition. In this campaign, studying the phenomenon in partial gravity is helping scientists better understand where we draw the line for optimal performance.
Another team subjected baby plant roots to doses of partial gravity and monitored root growth using lasers to investigate how the roots manage to stay “grounded” in the absence of gravity. We know plants adapt to weightlessness rather quickly, but researchers still need a clearer picture of what’s happening on a cellular level. Extra-terrestrial farming is vital to human survival off-planet, and adapting agriculture to altered gravity is an important step to making this possible. For a full list of experiments, see here.
Parabolic flights are one of a few ways to recreate microgravity conditions on Earth, but how is this achieved? The A310 Zero-G aircraft, operated by Novespace in Bordeaux, France, repeatedly performs a special manoeuvre. After pulling up sharply to 50 degrees, the pilots reduce the thrust and pitch of the airplane to cancel air-drag and lift. This places the plane on a parabolic flight path, exactly as if it has been thrown upwards and released. It then essentially falls over the top of the parabola, creating 20 seconds of 0g. When it reaches 50 degrees nose-down, the plane then pulls out of the descent to normal flight.
To achieve partial gravity, the angle at which the plane pulls up and pulls out is shallower, and the pilots carefully cancel out only part of the lift. This creates about 25 seconds of one-quarter gravity, or 35 seconds of half-gravity, or 50 seconds of three-quarters gravity. The manoeuvre is performed every three minutes for a total of 31 times per flight. Watch a tour of the Zero-G aircraft here.
In addition to this unique collaboration between ESA, DLR, and CNES, the partial gravity parabolic flight campaign also featured a special guest experiment by NASA and pilot-turned-ESA-astronaut Thomas Pesquet.
"It was a real privilege to work on this unique campaign, not only because of the constructive collaboration with my colleagues from DLR and CNES, but also to provide such an interesting suite of experiments with rare and much-needed data,” said Neil Melville, Coordinator of Parabolic flight and Drop Tower campaigns. He is pictured on the left, alongside Katrin Stang of DLR (middle) and Sébastien Rouquette of CNES (right).
“We are certainly looking forward to the results the science teams will publish once their analyses are completed, and hope to perform a similar campaign in the future."
ESA conducts 0g parabolic flight campaigns twice per year for microgravity research. Learn more here.
One of the main activities in recent weeks for the BepiColombo team at Europe’s Spaceport in Kourou has been the installation of multi-layered insulation foils and sewing of high-temperature blankets on the Mercury Planetary Orbiter.
The insulation is to protect the spacecraft from the extreme thermal conditions that will be experienced in Mercury orbit.
While conventional multi-layered insulation appears gold-coloured, the upper layer of the module’s striking white high-temperature blanket provides the focus of this image.
The white blankets are made from quartz fibres. Because the fabric is not electrically conductive, to control the build-up of electrostatic charge on the surface of the spacecraft, conducting threads have been woven through the outer layer every 10 cm. The edges of the outer blanket are hand-sewn together once installed on the module, as seen in this image.
The face of the spacecraft the engineer is working on is the panel that will always look at Mercury’s surface and as such many of the science instruments are focused here. This includes the orbiter’s cameras and spectrometers, a laser altimeter and particle analyser.
The panel also has fixtures to connect the module to the Transfer Module during the cruise to Mercury.
The face of the spacecraft pointing to the left in this orientation is the spacecraft radiator, which will eventually be fitted with ‘fins’ designed to reflect heat directionally, allowing the spacecraft to fly at low altitude over the hot surface of the planet. Heat generated by spacecraft subsystems and payload components, as well as heat that comes from the Sun and Mercury and ‘leaks’ through the blankets into the spacecraft, will be conducted to the radiator by heat pipes and ultimately radiated into space.
The oval shapes correlate to star trackers, used for navigation, while a spectrometer is connected with ground support equipment towards the top. At the back of this face, the magnetometer boom can be seen folded against the spacecraft – it has now also been fitted with multi-layered insulation.
For more images of the launch preparations at Kourou visit the BepiColombo image gallery.
This sparkling Picture of the Week features a massive galaxy cluster named RXC J0232.2-4420. This image was taken by Hubble’s Advanced Camera for Surveys and Wide-Field Camera 3 as part of an observing programme 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/ESA/CSA James Webb Space Telescope (JWST) to study.
The enormous gravitational influence of such clusters distorts the space around them in such a way that they can be used as giant cosmic lenses that magnify distant background galaxies. Studying some of the earliest galaxies in the Universe will tell us more about our cosmic origins.
RXC J0232.2-4420 also featured in a study that focused on galaxy clusters that are especially luminous sources of X-rays . The study searched for diffuse light around the brightest galaxies in the clusters, among the most massive galaxies in the Universe. This diffuse light comes from intergalactic stars strung out between the constituent galaxies of the cluster and the aim of the study was to explore various theories for the origins of these stars. One theory is that that may have been stripped from their host galaxies during mergers and interactions.
To hunt for threatening asteroids, astronomers use traditional telescopes with narrow fields of view – it’s a slow, tedious process.
ESA is developing new ‘flyeye’ telescopes to conduct automated nightly sky surveys.
Up to four Flyeye Telescopes will be located worldwide. Together with sightings from European and international astronomers, Flyeye data will be sent to the International Astronomical Union (IAU)’s Minor Planet Center (USA), the world’s central clearing house for all asteroid sightings.
ESA asteroid experts work with other space agencies and European civil protection authorities to devise mitigation measures. ESA also supports asteroid warning and risk assessment activities at the United Nations, in cooperation with experts from the IAU and worldwide.
Week In Images
11 - 15 June 2018