Tag Archives: city.

Ancient Cambodian City Revealed in Laser Scan


Airborne laser scanning has revealed the remnants of a vast urban structure in the vicinity of Angkor Wat, a famous temple in Cambodia. The study, which will be published soon in the journal PNAS, follows earlier research that showed Angkor Wat to have been one of the world’s most complex preindustrial cities.

Light Detection and Ranging (LIDAR) is making it easier for archaeologists to explore human settlements in tropical vegetation; previous LIDAR work has found evidence of new cities in Central America, in addition to further enhancing the layout of known settlements such as the Mayan city of Caracol.

For the new study, the researchers used a LIDAR setup emitting up to 200,000 laser pulses each second from a helicopter. Amazingly, the entire operation for the data collection spanned just two days in April 2012 for a total 20 hours of flight time, capturing imagery that would have taken many years to assemble from the ground, if at all. The LIDAR analysis also appears to have discovered what could be an older city beside Angkor Wat.

Angkor Wat

A digital recreation of Angkor Wat temple site (top) based on raw LIDAR digital terrain data (bottom). Image courtesy of PNAS.

The study has revealed new canals, temples and still unidentified manmade features, confirming a metropolitan area that housed many thousands of people, much as the Giza Plateau Mapping Project is doing for cities surrounding the Pyramids construction in Egypt.

As LIDAR technology gets cheaper, it will accelerate our understanding of early human settlements from the lingering geographic footprints we left, traces which can be almost as shallow as a footprint itself. As the authors write in their PNAS paper:

LIDAR technology has recently matured to the point where it has become cost-effective for archaeologists with sufficient accuracy and precision to identify archaeological features of only a few centimeters in size.

Image courtesy of sam garza/Wikimedia Commons

This article originally published at MIT Technology Review

Read more: http://mashable.com/2013/06/18/lidar-angkor-wat/

NASA Wants To Establish A Floating Cloud City To Study Venus

While Mars may be all the rage right now, a team of NASA scientists has dreamed up an innovative concept that could eventually see humans permanently occupying Venus’ atmosphere, in a floating cloud city.

Everybody is keen to get humans to Mars; it’s been seen as the next logical step for some time now, mostly because of its Earth-like qualities. Our atmospheric chemistry is closest to Mars out of all the planets in the solar system, and its average temperature isn’t unreasonably cold (-63oC) either. Furthermore, both Earth and Mars have large polar caps that are believed to be predominantly composed of water ice.

But what about Venus, our closest neighbor? Venus is actually remarkably similar to Earth. So much so that it’s often described as Earth’s twin, albeit an evil or fiery one. The two planets are similar in size, mass, density, gravity and composition. So why aren’t we trying to get humans there instead? Well, it’s probably to do with the fact that it’s hellish.

It’s the hottest planet in the solar system, with surface temperatures reaching 465oC (870oF)—plenty hot enough to melt lead. It’s also shrouded in a very dense atmosphere with clouds of toxic sulphuric acid, and its crushing surface pressure is around 90 times that of ours.

So, Venus’ surface is pretty much a no-go zone. But what about taking up residence in its atmosphere? That’s NASA’s thinking anyway, and its Langley Research Center has already started to put forward some interesting ideas for a potential future mission, or five.

Named the High Altitude Venus Operational Concept (HAVOC), the evolutionary program comprises a series of ventures that would kick off by sending a robot into the atmosphere to test the waters, followed by a 30 day crewed, orbital mission. If successful, the next mission would be a crewed, 30-day venture in Venus’ atmosphere, ultimately leading up to humans spending a year in the atmosphere, or maybe even the establishment of a permanent presence in a floating “city.”

What sets this apart from other space missions is the crafts that NASA has dreamed up; helium-filled, solar-powered airships. As described by IEEE, the robotic version would be 31 meters long, whereas the crewed vehicle would be almost 130 meters in length. The top would be decorated with solar panels, a gondola would be built underneath for instruments and, in the manned vehicle, there would be a habitat for humans and an ascent robot that astronauts would use to both enter Venus’ orbit and return to Earth.

The ships would float 50 kilometers (31 miles) above the planet’s surface. Here, there would be only one atmosphere of pressure, and the temperature would be a reasonable 75oC. There would also be ample solar energy to power the crafts, much more than on Mars, and radiation exposure would be around the same as if you were in Canada.

This all sounds great on paper, but there are some serious hurdles that need to be overcome. They need to work out how to deploy the ships, which would have to unravel and fill themselves with gas. They also need to come up with a feasible way to safely get humans to the crafts, and home again. Much more thinking needs to be done, but it’s an exciting idea nonetheless.

[Via NASA, IEEE, Extreme Tech, Phys.org and io9]

Read more: http://www.iflscience.com/space/nasa-wants-establish-floating-cloud-city-study-venus