Month: May 2019

Enlarge / At Vandenberg Air Force Base in 2009, two cranes have raised NASA's Orbiting Carbon Observatory, or OCO, spacecraft to vertical. OCO would later be lifted and attached to the waiting Stage 0 motor of the Taurus XL launch vehicle in the tower. (credit: NASA)

A little more than a decade ago, on February 24, 2009, a Taurus XL rocket launched from Vandenberg Air Force Base in California carrying a NASA satellite designed to measure carbon dioxide levels in the atmosphere. However, the payload never properly separated from the rocket, and due to the extra mass the combined spacecraft and rocket failed to reach orbit.

Two years after this, on March 4, 2011, another Taurus XL rocket launched from Vandenberg, again carrying a science payload for NASA. This Glory satellite would have measured the properties of sulfate and other aerosols in the atmosphere. Again, the payload failed to properly separate from the rocket, and it was a total loss.

Combined, the loss of NASA's Orbiting Carbon Observatory and Glory satellites cost the space agency $700 million. In the years since, the space agency's Launch Services Program and the rocket's manufacturer, Orbital Sciences—which has since been acquired by Northrop Grumman—have been conducting investigations into just what happened.

Enlarge / The flash from the impact of a meteoroid on the eclipsed Moon in early 2019, seen as the dot at top left. (credit: J. M. Madiedo / MIDAS)

On January 19, 2019, a lunar eclipse dazzled observers throughout the Americas (and a sliver of Africa and Europe). After the event, some who had watched it reported seeing a very brief flash.

Two days later as buzz began to build about the eclipse, University of Oxford astronomer Chris Lintott tweeted, "If you have footage of the lunar eclipse at 4.41 GMT check your image carefully...There might have been an impact during the eclipse!" Soon, high-quality still images of the impact began to emerge. Later, some video did as well.

Now, four Spanish scientists have published a detailed analysis of the impact in Monthly Notices of the Royal Astronomical Society that estimates the size of the object, its origin, and the impact it left on the lunar surface. They based their estimates on observations made by five f/10 Schmidt–Cassegrain telescopes in Seville, Spain. Clear weather afforded the telescope an uninterrupted view of the eclipse during the event's totality.

The ideal crystalline structure of graphene is a hexagonal grid. (credit: CORE-Materials / Flickr)

This being Ars, I expect that many readers are familiar with Peltier coolers, which make use of something called the thermoelectric effect and use electrical power to pump heat. The nice thing about the thermoelectric effect is that it works both ways: a temperature difference can generate electrical power. The problem, of course, is that generating electricity this way is about as efficient as a teenager cleaning house.

But if you choose the right materials, it doesn't have to be that way. Recent research shows that it might be possible to convert heat energy to electrical energy with an efficiency in the range of 15-20 percent. If that can actually be realized, it would be a truly incredible advance.

Putting the heat on efficiency

What makes thermoelectric conversion so inefficient? It boils down to how heat and electricity are moved through a material. Heat is carried through a material in two different ways. One route is via the vibrations of atoms—essentially heat is carried by sound waves called phonons. But electrons can also carry heat. In an insulator, the electrons don't travel very far, so heat is only carried by phonons. In an electrical conductor, however, heat transfer is more likely to be dominated by electron motion.

Enlarge (credit: Donna Nash)

When the people of the Wari Empire (predecessors of the Inca) abandoned the southern Andes around 1100 CE, they made sure nobody else could enjoy their former home by destroyed the brewery that, for 400 years, had provided for lavish festivals held at the provincial center of Cerro Baúl.

"They intentionally and deliberately destroyed the site so that it couldn't be used by successor societies when they left," Field Museum Associate Curator & Professor of Anthropology Ryan Williams told Ars Technica. "The brewery itself was burned down at the end, and a great feast accompanied that burning, in which the special ceramic vessels from which the local lords would have been served were smashed into the burning flames."

The smashed pots that were left behind, however, contained clues to the ancient beer recipe that once held an empire together.