The Copernicus Sentinel-2A satellite takes us over the Petermann Glacier in northwest Greenland in this false-colour image captured on 16 August 2017.
Sentinel-2’s imager can view a given area in different parts of the spectrum, and producing a false-colour image help us to differentiate between targets similar in colour, such as snow and clouds. In this image, clouds are white with a hint of green, while snow and ice appear blue. Bright green areas show vegetation, while black spots are shadows and water.
Petermann is one of the largest glaciers connecting the Greenland ice sheet with the Arctic Ocean. Upon reaching the sea, a number of these large outlet glaciers extend into the water with a floating ‘ice tongue’. Icebergs occasionally break or ‘calve’ off these tongues. In late July, Sentinel-2 caught a 5.5 sq km iceberg calving off the end of Petermann.
Polar scientists are keeping a close watch on a new crack near the centre of the tongue – an usual place for cracks to form – while older cracks continue to grow nearby.
Petermann’s ice flow has accelerated in recent years. Land-based glaciers in Greenland are a major contributor to global sea-level rise and as global temperatures warm, more ice is expected to melt into the oceans. Scientists estimate that if Petermann collapses completely the sea level would rise by about 30 cm.
This image is featured on the Earth from Space video programme.
Although the pictures of the devastation of Hurricane Harvey on Earth leave little to the imagination, seeing it from space confirms the enormous power the hurricane had. Taken by NASA astronaut Randy Bresnik from the International Space Station orbiting Earth at 400 km altitude, Randy commented, “The destructive power beneath the clouds of Hurricane Harvey ruins any thought of the beauty of the cloud formations from above”.
The hurricane hit mainland USA and caused flooding and damage affecting hundreds of thousands of people. The city of Houston was hit with much of its force including NASA’s Johnson Space Center, the main site for astronauts and the International Space Station. Mission control in Houston remained operational despite the centre being closed from August 28 until today – flight controllers slept on site in makeshift beds as entrance to the facility was difficult due to floods.
After record rainfall for five days, the storm passed, leaving many people without homes, water or electricity. ESA has many staff members working at Johnson Space Center including ESA astronauts Luca Parmitano and Andreas Mogensen. People in Houston are now working to rebuild damaged property.
Among the many consequences of the hurricane, was the delay of the departure of NASA’s G5 plane from Houston to collect NASA astronauts Peggy Whitson and Jack Fischer from their landing site after their mission on the International Space Station. An ESA plane was sent to retrieve the two astronauts in Karaganda, Kazakhstan, and brought them back to Cologne, home of ESA’s astronaut centre for a stopover before continuing to USA.
ESA’s Director General Jan Woerner said, “Spaceflight is a global endeavour and partnerships created by the International Space Station extend beyond space back to Earth. Our thoughts go out to everyone affected by Harvey, our American colleagues and their friends and families.”
Gaia, ESA’s billion-star surveyor, is detecting stars and measuring their properties in order to build up the most precise 3D map of the Milky Way. By accurately measuring the motion of each star, astronomers will be able to peer back in time to understand the Milky Way’s history, its evolution and its destiny.
In general, as Gaia registers stars, only data covering the object of interest are transmitted to the ground. However, in the densest regions on the sky there are more stars close to each other than the detection and processing system of Gaia can cope with, which could result in a less complete census in these crowded areas.
To help mitigate this, a scientific selection of high-density regions is made to cover them in a special imaging mode, as illustrated here. These types of observations are carried out routinely every time Gaia scans over these regions.
The image, taken on 7 February 2017, covers part of the Sagittarius I Window (Sgr-I) located only two degrees below the Galactic Centre. Sgr-I has a relatively low amount of interstellar dust along the line of sight from Earth, giving a ‘window’ to stars close to the Galactic Centre.
The stellar density here is an incredible 4.6 million stars per square degree. The image covers about 0.6 square degrees, making it conceivable that there are some 2.8 million stars captured in this image sequence alone.
The image appears in strips, each representing a sky mapper CCD (see this animation of how Gaia’s camera works). The image has been lightly processed to bring out the contrast of the bright stars and darker traces of gas and dust. Zooming in reveals some imaging artifacts relating to the CCDs, including some vertical striping, as well as short bright streaks indicating cosmic rays. Analysis of these images will only start once the effort required by the routine data processing allows.
Gaia’s first catalogue of more than a billion stars, based on the first 14 months of data collection, was released in September 2016. The next release is targeting April 2018, with subsequent releases foreseen for 2020 and 2022.
A group of astronomers at ESA's ESTEC were testing some solar observing equipment on 6 September and serendipitously captured a solar flare, which turned out to be one of the most powerful observed in the last decade.
The image shown here was taken with an iPhone through a special interference H-alpha filter (centred at the wavelength of hydrogen emission) mounted to a small dedicated solar telescope at 13:09:26 GMT. An X9.3 flare was observed to launch from the Sun by space telescopes at 12:02 GMT, meaning that this image was taken as the flare was in the gradual decay phase.
The flare is seen as the white cloudy feature with multiple ribbons towards the bottom right of the image. It appears as a lighter feature against the solar background average because of post-flare energy release visible in hydrogen emission from interconnected magnetic loops. North is up.
ESA’s Large European Acoustic Facility (LEAF) will be on view to visitors at next month’s ESA Open Day in the Netherlands, along with other facilities in the establishment’s Test Centre.
LEAF subjects satellites to the same noise a launcher produces as it takes off and flies through the atmosphere. One wall of the chamber – which stands 11 m wide by 9 m deep and 16.4 m high – is embedded with a set of enormous sound horns. Nitrogen shot through the horns can produce a range of noise up to more than 154 decibels, like standing close to multiple jets taking off.
As a safety feature, LEAF can operate only once all the doors are closed. Steel-reinforced concrete walls safely contain its noise, coated with epoxy resin to reflect noise to produce a uniform sound field within the chamber. The chamber itself is supported on rubber bearing pads to isolate it from its surroundings.
LEAF is an integral part of ESA’s Test Centre at ESTEC in Noordwijk, the Netherlands, a collection of spaceflight simulation facilities under a single roof. Following the recent departure of the last of a batch of 22 Galileo satellites, this year’s Open Day on Sunday 8 October will feature a tour of key Test Centre facilities.
To attend ESA’s Open Day in the Netherlands you have to register; you can do that here.
It's thirty-seven days to launch of the Copernicus Sentinel-5P satellite, and the mission control team at the European Space Operations Centre (ESOC), Darmstadt, Germany, are getting ready to handle any eventuality. Pressure is high, and even though ESOC is celebrating 50 years as Europe’s ‘Gateway to Space’ tomorrow, the launch team are keeping all eyes on Sentinel-5P.
Today's simulation, held in the Main Control Room, covers the engineers' worst nightmare: failure to acquire first signals from the spacecraft in space just after it separates from the rocket. This is vital, as the ground teams must immediately establish contact in order to initiate the procedures that will bring the satellite into its correct position.
To react to the failed contact, the Ground Operations team on console in the control room will conduct a sky search, pointing the ground station antenna, via remote control, at the points in the sky where the satellite could be. This is called ‘targeting in the blind’, transmitting commands to a position in space where the spacecraft is expected to pass.
This is not easy, since the satellite might pass too early or too late over the ground station if it is not on its planned trajectory (due to over- or under-performance of the launching rocket). This delicate phase is conducted with little information, relying on skill, experience and teamwork.
For the team at ESOC on this occasion, the simulation was successful. The ground station antenna 'saw' the satellite (but at a different location than expected) and contact was established.
The whole process will be repeated many times until the Flight Director is satisfied that any eventuality can be met.
Sentinel-5P is set for launch on 13 October from the Plesetsk cosmodrome in Russia.
More on ESOC's 50th anniversary.
Sentinel-5P is unveiled after it's journey to the Plesetsk launch site in Russia where it will be prepared for liftoff.
Soil moisture in Italy during early August 2017 was particularly low in some areas (red). The data were compiled by ESA’s Soil Moisture CCI project, and includes information from active and passive microwave sensors (such as those on the ERS, MetOp, SMOS, Aqua and GCOM-W1 satellite missions). Read more.
Participants in the second edition of ESA's Pangaea geology field training course receive a lesson in surface geology interpretation using orbital images.
Pangaea prepares not only astronauts, but also mission developers to work with European planetary geology field scientists on operational concepts for exploration, operating rovers and the design of sample-return missions. This year’s course concentrates on Earth and planetary geology, interpreting orbital images, planetary protection, lunar geology and impact cratering.
Participants include ESA astronauts Samantha Cristoforetti, Pedro Duque and Matthias Maurer, as well as members of ESA’s exploration strategy and future missions team.
Read more: Sampling the future: Pangaea geology course goes operational
Week in Images
4-8 September 2017