Week In Images

This montage of 365 images shows the changing activity of our Sun through the eyes of ESA’s Proba-2 satellite during 2017, along with a partial eclipse for good measure.

The images were taken by the satellite’s SWAP camera, which works at extreme ultraviolet wavelengths to capture the Sun’s hot turbulent atmosphere - the corona, at temperatures of about a million degrees.

In general, the Sun’s 11-year activity cycle continued throughout 2017 towards a minimum, a period when the number of active regions (seen as bright regions in the images) diminish, and coronal holes (seen as darker regions) are larger and more prominent.

Look closely and several images stand out as different. For around a week at the end of April/beginning of May the Sun is not centred in the field-of-view: this is deliberate, indicating ’off-pointing’ observations to study the extended atmosphere.

Perhaps the highlight for many Sun-watchers last year was the total eclipse observed from Oregon to South Carolina in the US on 21 August. From its viewpoint in space, about 800 km above Earth, Proba-2 passed through the Moon’s shadow several times and observed three partial eclipses. One such moment is captured in the montage presented here.
Columbus stripped
Inside the cylindrical modules of the International Space Station is the standard stuff of technology. Wires, cables and pumps form the framework of the one-of-a-kind European Columbus laboratory , seen here in its early days of assembly.

The cornerstone of Europe’s contribution to the Space Station, Columbus is a pressurised laboratory that allows astronauts to work in a comfortable and safe environment.

This year marks the 10th anniversary of Columbus in orbit. In celebration of its remarkable decade, we will revisit the technological and scientific milestones of the lab in feature images, beginning with this one taken during its construction in 2001.

Like its sister nodes Tranquility and Harmony, Columbus’ assembly began in Turin, Italy. The structure, thermal control and life-support equipment, plumbing and external protection were completed by September 2001.

Columbus then moved to the prime contractor in Bremen, Germany for assembly to be completed before being shipped to the US for testing.

Although Columbus is the Station’s smallest laboratory module, it provides the same payload volume, power, data retrieval, vacuum and venting services as the other modules, an achievement made possible thanks to careful planning.

The lab has been supporting sophisticated research in life and physical sciences, space science, Earth observation and technology demonstrations in weightlessness for the past decade.
Sahara snow
The Copernicus Sentinel-2 mission has captured rare snowfall in northwest Algeria, on the edge of the Sahara desert.

Part of the Sahara was covered with snow on 7 January 2018, despite the desert at times being one of the hottest places on Earth. The snow was reported to be up to 40 cm thick in some places. Although temperatures plummet during the night, snowfall is very unusual in the Sahara because the air is so dry. It is only the third time in nearly 40 years that this part of the desert has seen snow.

Most of the snow had melted by the end of the next day, but luckily the Sentinel-2A satellite happened to be in the right place at the right time to record this rare event from space. The image was acquired on 8 January.

While snow is common in the High Atlas Mountains, the image shows that, unusually, snow fell on the lower Saharan Atlas Mountain Range. The image is dominated by the orange-brown dunes and mountains dusted with snow.

The town of El Baydah can be seen towards the bottom left. To the east of El Baydah, a cultivated forest is visible as a red rectangle. The image, which has been processed to display vegetation in red, shows that there is very little flora in the region.

The two Copernicus Sentinel-2 satellites each carry a high-resolution camera that images Earth’s surface in 13 spectral bands. The mission is largely used to track changes in Earth’s land and vegetation, so useful for monitoring desertification.

This image is featured on the Earth from Space video programme.
Heavenly palace
This vivid image shows China’s space station Tiangong-1 - the name means ’heavenly palace’ - and was captured by French astrophotographer Alain Figer on 27 November 2017. It was taken from a ski area in the Hautes-Alpes region of southeast France as the station passed overhead near dusk.

The station is seen at lower right as a white streak, resulting from the exposure of several seconds, just above the summit of the snowy peak of Eyssina (2837 m altitude). Several artefacts in the original have been removed.

Tiangong-1 is 12 m long with a diameter of 3.3 m and had a launch mass of 8506 kg. It has been unoccupied since 2013 and there has been no contact with it since 2016.

The craft is now at about 280 km altitude in an orbit that will inevitably decay some time in March-April 2018, when it is expected to mostly burn up in the atmosphere.

"Owing to the geometry of the orbit, we can already exclude the possibility that any fragments will fall over any spot further north than 43ºN or further south than 43ºS," says Holger Krag, head of ESA’s Space Debris Office.

"This means that reentry may take place over any spot on Earth between these latitudes, which includes several European countries, for example."

"The date, time and geographic footprint can only be predicted with large uncertainties. Even shortly before reentry, only a very large time and geographical window can be estimated."

The station’s mass and construction materials mean there is a possibility that some portions of it will survive and reach the ground.

In the history of spaceflight, no casualties from falling space debris have ever been confirmed.

ESA is hosting a test campaign to follow the reentry, which will be conducted by the Inter Agency Space Debris Coordination Committee, a grouping of the world’s top space agencies including ESA, NASA and the China National Space Administration.

More images

More images from Alain Figer via Flickr

Astrophotography group in Flickr