Coral castaways, peculiar pathogens and space station renovations
Right on cue – here are our favourite science images of the week, chosen by Cosmos art director Robyn Adderly.
Expedition 48 Commander Jeff Williams (shown here) and Flight Engineer Kate Rubins successfully installed the first of two international docking adapters last Friday during a nearly six-hour spacewalk outside the International Space Station.
The docking adapters will allow future commercial spacecraft, in development by Boeing and SpaceX under NASA’s Commercial Crew Program, to dock to the space station.
On 1 September, the pair will again walk in space. This time, they’ll work on the port side of the orbiting complex’s backbone or truss to retract a thermal radiator (part of the station’s cooling system).
They’ll also tighten struts on a solar array joint and install the first of several enhanced high-definition television cameras to monitor activities outside the station, including the comings and goings of visiting cargo and crew vehicles.
More to rainbows than meets the eye
Studying these natural multicoloured arcs of scattered light can be incredibly useful in ways that may not immediately spring to mind. Rainbows can warn of chemical contamination in the atmosphere, help develop more efficient combustion engines and possibly even provide insight into the mechanics of reinforced concrete.
In the European Journal of Physics, Alexander Haußmann of the Institute of Applied Physics at the Technical University of Dresden, Germany, points out these patterns of scattered light can provide considerable clues to the size distribution and shape of raindrops falling during wet weather.
If paired with radar data, this information could be used to quantify the amount of rainwater reaching the ground.
"If our analysis methods are precise enough, we can turn rainbows into optical remote sensing tools to study the physics of rain," he comments.
"Raindrops are not exactly spherical but become deformed into slightly flattened 'hamburger bun' shapes due to air drag as they fall through the sky.
“This has a drastic influence on the appearance of rainbows and makes scattering calculations numerically very demanding."
As well as focusing on the science, Haußmann provided tips for capturing rainbows on camera, which could help impress your followers on Instagram and other popular photo-sharing websites.
"Rainbows are short-lived and special phenomena such as twinned bows are pretty rare, so it's important to always have your camera to hand. “This can be a smartphone or, in my case, an SLR camera with a fisheye lens to capture the full width of a rainbow in a single frame."
Newly discovered 'multicomponent' virus
Scientists have identified a new "multicomponent" virus – one containing different segments of genetic material in separate particles – that can infect animals, according to research published this week in the journal Cell Host & Microbe.
This new pathogen, called Guaico Culex virus (GCXV), was isolated from several species of mosquitoes in Central and South America. GCXV does not appear to infect mammals, according to the researchers.
The team also isolated a related virus – called Jingmen tick virus, or JMTV – from a nonhuman primate.
Further analysis demonstrates that both GCXV and JMTV belong to a highly diverse and newly discovered group of viruses called the Jingmenvirus group. The research suggests that the host range of this virus group is quite diverse and highlights the potential relevance of these viruses to animal and human health.
"Animal viruses typically have all genome segments packaged together into a single viral particle, so only one of those particles is needed to infect a host cell," Jason Ladner of the US Army Medical Research Institute of Infectious Diseases explained.
"But in a multicomponent virus, the genome is divided into multiple pieces, with each one packaged separately into a viral particle. At least one particle of each type is required for cell infection."
Several plant pathogens have this type of organisation, but this study is the first to describe a multicomponent virus that infects animals.
The image above depicts the presence of different viral RNA segments within infected cells.
Plugging away inside massive fuel tank
Welders are captured working inside a large liquid hydrogen tank for NASA's Space Launch System at the Michoud Assembly Facility in New Orleans, plugging holes left after the tank was assembled.
Using frictional heating and forging pressure, friction stir welding produces high-strength bonds virtually free of defects. The process transforms metals from a solid state into a plastic-like state and uses a rotating pin tool to soften, stir and forge a bond between two metal sections to form a uniform welded joint.
At the beginning and end of each weld, holes remain where the rotating pin tool enters and exits the metal.
Six seven-metre-tall barrels and two domed caps were joined to create the qualification test article, which measures an astounding eight metres in diameter and 40 metres long.
An international team of researchers showed that vulnerable coral populations in the eastern tropical Pacific have been completely isolated from the rest of the Pacific Ocean for at least the past two decades.
The researchers used a supercomputer to trace the journeys of billions of coral larvae travelling at the whim of ocean currents over a 14.5-year period. The team discovered that even during extreme environmental events that speed ocean currents, such as the 1997-1998 El Niño, coral larvae could not survive long enough to make the 5,000-kilometre trip from coral reefs in the western and central Pacific to help corals in the east recover from environmental damage.
The severe El Niño in 1997-1998 wiped out a lot of the corals in the eastern Pacific. Corals can recover from events such as this through a combination of the proliferation of survivors and colonisation by larvae brought in sporadically by the currents from nearby unaffected reefs.
But the study's findings, published in Nature Communications this week, show that coral reefs in the far eastern Pacific Ocean, separated from the nearest reefs by more than 5,000 kilometres of open ocean, could be on their own when it comes to recovery from mass mortality events such as that which happened in 1998.
The work also provides evidence that local conservation is essential for the sparse and poorly protected coral reefs of the eastern Pacific Ocean.