Astronomy

A 19th-century thought experiment that was once thought to defy the laws of thermodynamics has now been realised to make molecules accumulate on one side of a U-bend

Citizen scientists discovered a star speeding through the Milky Way. Now, astronomers are trying to track down its origins.

The post Dwarf Star Caught Speeding; Could Escape the Galaxy appeared first on Sky & Telescope.

Scientists have started building a space medicine biobank as humans look to the moon and beyond.

The Moon is a tough place to survive, and not just for humans. The wild temperature extremes between day and night make it extremely difficult to build reliable machinery that will continue to operate. But an engineering team from Nagoya University in Japan have developed an energy-efficient new way to control Loop Heat Pipes (LHP) to safely cool lunar rovers. This will extend their lifespan, keeping them running for extended lunar exploration missions.

How do you keep a rover insulated well enough to survive the frozen lunar nights, without cooking it during the day? A team of engineers led by Dr Masahito Nishikawara of Nagoya University may have found an answer. By combining a loop heat pipe (LHP) with an electrohydrodynamic pump (EHP), they have created a mechanism to cool machinery efficiently in the vacuum of space, but in a form which can also be turned off at night. Crucially, it is so efficient that it uses practically no power at all.

The Moon is an extraordinarily harsh environment for machinery. Aside from the highly abrasive regolith, which sticks to everything and is found everywhere, the Moon has no atmosphere and a very slow rotational period. This means that days and nights on the moon last 14 Earth days each, and reach extreme temperatures. With no atmosphere to insulate and transport heat around the Moon, night-time temperatures can drop all the way down to -173º Celsius, while the unfiltered heat from the Sun causes daytime temperatures to climb as high as 127º Celsius.

It is very difficult to design complex machinery to work reliably under such conditions. The long nights mean that the energy harvested from solar panels needs to be stored in very large batteries, but batteries do not cope well with low temperatures. They can be electrically warmed, but heaters need a constant flow of electricity, draining the batteries. Alternatively, a machine can be heavily insulated to keep it functional when idle, but this leads to overheating when it is active, and when the Sun rises.

Overheating can damage batteries, but it’s equally bad for electronic components. Active cooling systems are the traditional answer. They work similarly to the radiator in a car by pumping coolant through a large radiator, but these require power to run. This is a problem when you need your batteries to last 14 days before the next recharge. Passive systems, such as LHPs, are effective and don’t require power, but they run continuously, even when you would prefer heating.

“Heat-switch technology that can switch between daytime heat dissipation and nighttime insulation is essential for long-term lunar exploration,” said lead researcher Masahito Nishikawara. “During the day, the lunar rover is active, and the electronic equipment generates heat. Since there is no air in space, the heat generated by the electronics must be actively cooled and dissipated. On the other hand, during extremely cold nights, electronics must be insulated from the outside environment so that they don’t get too cold.”

LHPs can be thought of as a cross between the machinery of a refrigerator or air conditioner, and the heat pipes in modern laptop computers. Like a refrigerator, a liquid refrigerant is allowed to absorb heat which causes it to vaporise. The vapour then passes through a radiator, which cools it back to ambient temperatures. This turns it back into a liquid, and the cycle repeats. The phase changes, from liquid to gas and back, allow the refrigerant to transfer heat very efficiently. Heat pipes, by contrast, use capillary action to move a liquid between a heat source (such as your computer’s CPU or graphics accelerator) and a radiator. LHPs combine the capillary transport action of a heat pipe with the phase changes of a refrigeration unit.

LHPs have been used in space before, where they have been equipped with valves to block the flow of refrigerant when cooling is not needed. However, these valves significantly reduce the system’s cooling efficiency. Nishikawara’s innovation is to replace the valves with an Electrohydrodynamic pump. EHPs are low-powered pumps which work by inducing electric currents in a fluid, and then using the resulting magnetic field to apply force to the fluid. This has the advantage of not intruding into the plumbing of the system, which means there is no interference with flow when it isn’t active.

Nishikawara’s team have added low-powered EHPs to an LHP to act as a very efficient valve: When they need to turn cooling off, the EHP is activated to create a small opposing force that stops the flow of refrigerant, while sipping only a tiny amount of power.

“This groundbreaking approach not only ensures the rover’s survival in extreme temperatures but also minimizes energy expenditure, a critical consideration in the resource-constrained lunar environment,” Nishikawara said. “It lays the foundation for potential integration into future lunar missions, contributing to the realization of sustained lunar exploration efforts.”

https://www.eurekalert.org/news-releases/1047341

The post A New Way to Survive the Harsh Lunar Night appeared first on Universe Today.

Stellar death need not be the end for orbiting planets, which could see their ice melt as they move closer to the white dwarf that their star evolves into.

Employees are working remotely, and office buildings are standing empty, inspiring some cities to work through the challenges of converting these structures into new apartments

The hyperactive sunspot region responsible for the beautiful auroras earlier in May was still alive and kicking when it rotated away from Earth’s view. Watching from the other side of the Sun, the ESA-led Solar Orbiter mission detected this same region producing the largest solar flare of this solar cycle. By observing the Sun from all sides, ESA missions reveal how active sunspot regions evolve and persist, which will help improve space weather forecasting.

“It would be foolish to declare victory” for abortion rights, one expert says of the recent Supreme Court challenge to medication abortion access

The famous Crab Nebula gets a closeup from the James Webb Space Telescope.

We are living through a terrible time in humanity. Here’s why we tend to stick our heads in the sand and why we need to pull them out, fast

A heat dome is sending temperatures soaring across the U.S. Midwest and East

Students should learn about both the natural world and human-made—or engineered—one we live in

Replacing two 50-car trains with a single 100-car train increases the odds of derailment by 11 percent, according to a new risk analysis

NASA will talk about the delayed return to Earth of Boeing's Starliner capsule during a press conference today (June 18), and you can listen to it live.

Europe’s newest rocket soon launches, taking with it many space missions each with a unique objective, destination and team at home, cheering them on. Whether into Earth orbit to look back and study Earth, peer out to deep space or test important new technologies, Ariane 6’s first flight will showcase the versatility and flexibility of this impressive, heavy-lift launcher. Read on for all about Curium One, then see who else is flying first.

There are so many Russian landmines across Ukraine that removing them could take 700 years. To prioritise areas for de-mining, the Ukrainian government has turned to an artificial intelligence model that can identify the most important regions

There are so many Russian landmines across Ukraine that removing them could take 700 years. To prioritise areas for de-mining, the Ukrainian government has turned to an artificial intelligence model that can identify the most important regions

Astronomers have discovered thousands of exoplanets, revealing entirely new types of worlds that we don’t have in the Solar System. It is enough to start getting a rough sense of what kinds of planets are out there. What’s the big picture?

Jupiter’s Great Red Spot (GRS) is one of the Solar System’s defining features. It’s a massive storm that astronomers have observed since the 1600s. However, its date of formation and longevity are up for debate. Have we been seeing the same phenomenon all this time?

The GRS is a gigantic anti-cyclonic (rotating counter-clockwise) storm that’s larger than Earth. Its wind speeds exceed 400 km/h (250 mp/h). It’s an icon that humans have been observing since at least the 1800s, possibly earlier. Its history, along with how it formed, is a mystery.

Its earliest observations may have been in 1632 when a German Abbott used his telescope to look at Jupiter. 32 years later, another observer reported seeing the GRS moving from east to west. Then, in 1665, Giovanni Cassini examined Jupiter with a telescope and noted the presence of a storm at the same latitude as the GRS. Cassini and other astronomers observed it continuously until 1713 and he named it the Permanent Spot.

Unfortunately, astronomers lost track of the spot. Nobody saw the GRS for 118 years until astronomer S. Schwabe observed a clear structure, roughly oval and at the same latitude as the GRS. Some think of that observation as the first observation of the current GRS and that the storm formed again at the same latitude. But the details fade the further back in time we look. There are also questions about the earlier storm and its relation to the current GRS.

New research in Geophysical Research Letters combined historical records with computer simulations of the GRS to try to understand this chimerical meteorological phenomenon. Its title is “The Origin of Jupiter’s Great Red Spot,” and the lead author is Agustín Sánchez-Lavega. Sánchez-Lavega is a Professor of Physics at the University of the Basque Country in Bilbao, Spain. He’s also head of the Planetary Sciences Group and the Department of Applied Physics at the University.

“Jupiter’s Great Red Spot (GRS) is the largest and longest-lived known vortex of all solar system planets, but its lifetime is debated, and its formation mechanism remains hidden,” the authors write in their paper.

The researchers started with historical sources dating back to the mid-1600s, just after the telescope was invented. They analyzed the size, structure, and movement of both the PS and the GRS. But that’s not a simple task. “The appearance of the GRS and its Hollow throughout the history of Jupiter observations has been highly variable due to changes in size, albedo and contrast with surrounding clouds,” they write.

This figure from the research compares the Permanent Spot (PS) and the current GRS. a, b, and c are drawings by Cassini from 1677, 1690, and 1691, respectively. d is a current 2023 image of the GRS. Image Credit: Sánchez-Lavega et al. 2024.

“From the measurements of sizes and movements we deduced that it is highly unlikely that the current GRS was the PS observed by G. D. Cassini. The PS probably disappeared sometime between the mid-18th and 19th centuries, in which case we can say that the longevity of the Red Spot now exceeds 190 years at least,” said lead author Sánchez-Lavega. The GRS was 39,000 km long in 1879 and has shrunk to 14,000 km since then. It’s also become more rounded.

Four views of Jupiter and its GRS. a is a drawing of the Permanent Spot by G. D. Cassini from 19 January 1672. b is a drawing by S. Swabe from 10 May 1851. It shows the GRS area as a clear oval with limits marked by its Hollow (drawn by a red dashed line). c is a Photograph by A. A. Common from 1879. d is a photograph from Observatory Lick with a yellow filter on 14 October 1890. Each image is an astronomical image of Jupiter with south up and east down. Image Credit: Sánchez-Lavega et al. 2024.

The historical record is valuable, but we have different tools at our disposal now. Space telescopes and spacecraft have studied the GRS in ways that would’ve been unimaginable to Cassini and others. NASA’s Voyager 1 captured our first detailed image of the GRS in 1979, when it was just over 9,000,000 km from Jupiter.

Jupiter’s Great Red Spot as imaged by Voyager 1 in 1979. The intricate wave patterns were unseen until this image. Image Credit: By NASA – http://photojournal.jpl.nasa.gov/catalog/PIA00014, Public Domain, https://commons.wikimedia.org/w/index.php?curid=86812

Since Voyager’s image, the Galileo and Juno spacecraft have both imaged the GRS. Juno, in particular, has given us more detailed images and data on Jupiter and the GRS. It captured images of the planet from only 8,000 km above the surface. Juno takes raw images of the planet with its Junocam, and NASA invites anyone to process the images, leading to artful images of the GRS like the one below.

A different take on Jupiter and its GRS. Image Credit: NASA / SwRI / MSSS / Navaneeth Krishnan S © CC BY

Juno also measured the depth of the GRS, something previous efforts couldn’t achieve. Recently, “various instruments on board the Juno mission in orbit around Jupiter have shown that the GRS is shallow and thin when compared to its horizontal dimension, as vertically it is about 500 km long,” explained Sánchez-Lavega.

Jupiter’s atmosphere contains winds running in opposite directions at different latitudes. North of the GRS, winds blow in a westerly direction and reach speeds of 180 km/h. South of the GRS, the winds flow in the opposite direction at speeds of 150 km/h. These winds generate a powerful wind shear that fosters the vortex.

In their supercomputer simulations, the researchers examined different forces that could produce the GRS in these circumstances. They considered the eruption of a gigantic superstorm like the kind that happens, though rarely, on Saturn. They also examined the phenomenon of smaller vortices created by the wind shear that merged together to form the GRS. Both of those produced anti-cyclonic storms, but their shapes and other properties didn’t match the current GRS.

“From these simulations, we conclude that the super-storm and the mergers mechanisms, although they generate a single anticyclone, are unlikely to have formed the GRS,” the researchers write in their paper.

The authors also point out that if either of these had happened, we should’ve seen them. “We also think that if one of these unusual phenomena had occurred, it or its consequences in the atmosphere must have been observed and reported by the astronomers at the time,” said Sánchez-Lavega.

However, other simulations proved more accurate in reproducing the GRS. Jupiter’s winds are known to have instabilities called the South Tropical Disturbance (STrD). When the researchers performed supercomputer simulations of the STrD, they created an anti-cyclonic storm very similar to the GRS. The STrD captured the different winds in the region and trapped them in an elongated shell like the GRS. “We therefore propose that the GRS generated from a long cell resulting from the STrD, that acquired coherence and compactness as it shrank,” the authors write.

These images from the research show how the GRS formed. a is a drawing by T. E. R. Phillips in 1931–1932 of the STrD. The red arrows indicate the flow direction with the longitude scale indicated. b and c are maps drawn from images taken by the New Horizons spacecraft. The yellow arrows mark position-velocity changes in the STrD. The STrD trapped winds and created a long cell that generated the Great Red Spot. Image Credit: Sánchez-Lavega et al. 2024.

The simulations show that over time, the GRS would rotate more rapidly as it shrank and became more coherent and compact until the elongated cell more closely resembled the current GRS. Since that’s what the GRS appears like now, the researchers settled on this explanation.

That process likely began in the mid-1800s when the GRS was much larger than it is now. That leads to the conclusion that the GRS is only about 150 years old.

The post The Great Red Spot Probably Formed in the Early 1800s appeared first on Universe Today.