Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ancient Desert Markings Imaged From Orbit

20.02.2004


Proba image of the Nasca plain
Credit: ESA


The Pan-American Highway runs through the Nasca Lines

Credits: AP Photo/John Moore


Visible from ESA’s Proba spacecraft 600 kilometres away in space are the largest of the many Nasca Lines; ancient desert markings now at risk from human encroachment as well as flood events feared to be increasing in frequency.

Designated a World Heritage Site in 1994, the Lines are a mixture of animal figures and long straight lines etched across an area of about 70 km by 30 km on the Nasca plain, between the Andes and Pacific Coast at the southern end of Peru. The oldest lines date from around 400 BC and went on being created for perhaps a thousand years.
They were made simply enough, by moving dark surface stones to expose pale sand beneath. However their intended purpose remains a mystery. It has variously been proposed they were created as pathways for religious processions and ceremonies, an astronomical observatory or a guide to underground water resources.


The Nasca Lines have been preserved down the centuries by extreme local dryness and a lack of erosion mechanisms, but are now coming increasingly under threat: it is estimated the last 30 years saw greater erosion and degradation of the site than the previous thousand years before them.

In this image, acquired by the Compact High Resolution Imaging Spectrometer (CHRIS) instrument aboard Proba on 26 September 2003, the 18.6 metre resolution is too low to make out the animal figures although the straight Nasca Lines can be seen faintly. Clearest of the straight markings is actually the Pan-American Highway, built right through the region – seen as a dark marking starting at the irrigated fields beside the Ingenio River, running from near the image top to the bottom right hand corner. Associated dirt track roads are also visible amidst the Nasca Lines.

Clearly shown in the Proba image is another cause of damage to the Lines: deposits left by mudslides after heavy rains in the Andean Mountains. These events are believed to be connected to the El Niño phenomenon in the Pacific Ocean – first named by Peruvian fishermen hundreds of years ago – and one concern is they are becoming more frequent due to climate change.

A team from Edinburgh University and remote sensing company Vexcel UK has been using data from another ESA spacecraft to measure damage to the Nasca Lines, with their results due to be published in the May Issue of the International Journal of Remote Sensing.

Their work involves combining radar images from the Synthetic Aperture Radar (SAR) instrument aboard ERS-2. Instead of measuring reflected light, SAR makes images from backscattered radar signals that chart surface roughness.

Nicholas Walker of Vexcel UK explained: "Although the instrument lacks sufficient resolution to unambiguously distinguish individual lines and shapes, by combining two satellite images using a technique known as SAR interferometric coherence it is possible to detect erosion and changes to the surface at the scale of centimetres".

The image shown combines two scenes acquired by ERS-2 in 1997 and 1999. The bright areas show where there has been very little terrain change in the interval, while darker regions show where de-correlation has occurred, highlighting possible sites where erosion may be taking place.

"Some de-correlation comes simply from the geometry of the area as seen by the instrument in space, with low coherence around areas overshadowed by Andean foothills to the east of the Nasca plain," said Iain Woodhouse of Edinburgh University. "The second major loss is seen in the river valleys, due primarily to agricultural activity taking place during the two-year period.

"The third is changes in the surface of the plain due to run-off and human activity. The dark lines crossing the plain are roads and tracks serving local communities and the power line, as well as the Pan American Highway, the only surfaced road in this region of Peru."

The de-correlation observed is most likely caused by vehicles displacing stones along these tracks and the sides of the Pan-American Highway. The de-correlation from the run-off is distinct from this as it follows the characteristic drainage patterns down from the foothills.

"Interferometric coherence seems to provide an effective means for monitoring these two major sources of risk to the integrity of the markings," Woodhouse concluded. "We are developing the technique to include more sensors and data of higher spatial resolution, so as to encourage the establishment of a long term and frequent monitoring programme supporting conservation efforts in the area."

Frédéric Le Gall | ESA
Further information:
http://www.esa.int/export/esaSA/SEMO0R1PGQD_earth_0.html

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

What the world's tiniest 'monster truck' reveals

23.08.2017 | Life Sciences

Treating arthritis with algae

23.08.2017 | Life Sciences

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>