American archaeologist and Egyptologist Sarah Parcak, who teaches at the University of Alabama, is a new age Indiana Jones harnessing the power of satellites to discover archaeological sites. She has now tied up with Archaeological Survey of India (ASI) to use remote sensing to map archaeological sites. Manimugdha S Sharma picks her brain:

What is space archaeology?

It’s a term that describes how archaeologists use diverse remote sensing datasets – from lasers to space-based imaging systems – to map partially to totally invisible ancient features, from small walls to entire cities. Other terms are ‘satellite archaeology’, ‘satellite remote sensing’. You become an archaeologist first.

Why is it needed in India?

India has such an extraordinary and rich heritage, with many thousands of years of occupation. There have been archaeologists using satellites already in India, proving their effectiveness in site detection. They allow sites to be detected rapidly and over large areas, which is an advantage as India’s landscapes are varied and massive. With so many archaeological sites likely to be detected from space, satellites will allow archaeologists to gain an accurate count of sites across India and the modern threats to them, and hopefully some exciting new discoveries.

What’s your project in India about?

We will be launching our free citizen archaeology platform in India later this year. This online platform allows anyone to look at satellite imagery and help us map potential cultural heritage, starting in Gujarat and over time, expanding across India. The data will be shared with ASI without GPS location so that site locations will be protected. We’ll also be offering satellite remote sensing training for ASI and archaeology students at Indian universities, with the goal of training a new generation of archaeologists in advanced mapping. We also hope to work together with ASI to develop new sites for tourism.

What sort of hurdles do space archaeologists face on the ground?

Satellites are among a number of tools available to help archaeologists gain a better understanding of the landscapes around the sites where they work, and a way for them to discover features on sites or even entire sites in time- and cost-efficient ways. Using satellites is a tool, not the means to an end. We ultimately have to do good excavation and survey on the ground, with all the associated hurdles: challenges with limited time, funding, or any restrictions we face.

Is there a risk of false positives in analysing satellite data?

Many satellite sensors capture light reflected off the earth’s surface, recorded in the visible through infrared parts of the light spectrum. Scientists can order and download the satellite data either for free from NASA or from commercial companies for high resolution data. They then process it using off-the-shelf software, using differences in the vegetation, soil, or water content in the imagery to make subtle to otherwise invisible features appear – from small walls or roads to relic river courses or monumental structures. Like any science, there can be false positives – usually about 10% of the time is standard.

Roughly, how much of India’s heritage lies buried?

It is very hard to predict how much of our past is buried. But I do feel confident saying more than 90% of most archaeological sites have not been excavated, and there are millions of archaeological sites across the globe that need to be found. Thus, I would estimate that more than 90% of India’s heritage is buried, the same percentage I would give for any country that contains significant archaeological sites. Several Indus Valley Civilisation sites have suffered artefact loot.

Can your work stop this?

A government cannot protect all the cultural assets within the boundaries of their country without first knowing where they are. Thus, step one is mapping sites, and understanding the potential threats to them from urbanisation, looting, general development, or climate change. The problems are bigger than just looting, and these issues are global. Governments can then prioritise which sites to safeguard or develop for tourism. We will share all the threats we find to India’s heritage sites with ASI and appropriate government authorities. This is about developing good systems of detection first, and then strategising approaches to work with local communities closest to the threatened sites.

Your project is also a citizen oriented venture. How does the common man get involved?

There’s just no way that archaeologists alone can map and locate all the archaeological features. Globalxplorer or GX, is a not-for-profit, focussed on using innovative technologies to empower the world to help map and protect its collective global heritage. The website we run is an online citizen science satellite archaeology platform that allows anyone in the world, aged 5-105, to look at satellite imagery and help us find sites. All the data will be shared with professional archaeologists at the ASI as well as academic specialists. Our goal is to map the world in the next 10 years.