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Satellite Images May Help Trace Extreme Poverty

The fight against poverty is getting help from a new direction: up.

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- A nighttime view of Europe and North Africa is seen in a global composite assembled from data acquired by the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite in 2012 and released by NASA Oct. 2, 2014. (VOA)

The fight against poverty is getting help from a new direction: up.

Satellite imagery is helping researchers map areas of extreme poverty. It may help officials identify faster and more accurately when development policies and programs are working, and when they aren’t.

Eliminating extreme poverty by 2030 is the first of the 17 Sustainable Development Goals adopted by the United Nations in 2015.

Experts usually measure poverty by using census data and household surveys. But these tools are expensive, time-consuming and labor-intensive. Countries typically do them only once every several years.

On the other hand, satellites map the entire surface of the globe at high resolution every several days. The imagery is getting better and cheaper as a growing number of public and private satellite networks go into service.

 

satellite images
By column, four different convolutional filters (which identify, from left to right, features corresponding to urban areas, nonurban areas, water, and roads) in the convolutional neural network model used for extracting features. (Source – Sciencemag.org)

 

What satellites see

Researchers have used the brightness of lights in nighttime photos to estimate a region’s economic activity. Others have applied machine learning to identify richer and poorer villages from satellite imagery. Another group sorted wealthy and impoverished villages and neighborhoods based on building density and vegetation cover.

A new study takes the most detailed look to date. Within a single village, it distinguished the poorest individual households from their wealthier neighbors with 62 percent accuracy.

The study focuses on Sauri, a village in rural Kenya that was part of the Millennium Villages Project, a large-scale poverty alleviation experiment. Detailed information on each household’s income and assets was collected in 2005.

In satellite images of the village, researchers measured the size of each dwelling and studied the agricultural land surrounding it.

Not surprisingly, smaller homes generally housed poorer people.

Interestingly, the researchers also found that poorer households tended to have more bare farm fields in September. In this part of Kenya, that usually means farmers are preparing the land for a second crop.

Kenya, girls
Turkana people carry water near Lodwar, in Turkana County, Kenya. VOA

That’s a risky undertaking, said University of Edinburgh geographer and study lead author Gary Watmough, because the late-season rains fail up to half the time in this region.

“Generally, [late-season planting] is only done by the poorer households because it’s a necessity,” he said. “They either don’t have enough land or they need to have that insurance, just in case something else goes wrong.”

Satellite imagery also found poorer households’ fields were growing crops for shorter periods of time.

“When we looked back into our field data, we could see that often poorer households were actually not planting their crops in their own fields as early as others,” Watmough said. “That was because they were contracting themselves out to plant other, wealthier households’ crops first.”

The money they earned went toward buying seeds. But that meant their own crops had less time to grow.

Exciting and a little scary

The study is a big step forward, demonstrating “the potential for satellite data to distinguish between the wealth of you and your neighbor,” said World Bank economist David Newhouse, who was not involved with the research. “Which is scary, a little bit, but also somewhat exciting.”

He suggested that privacy concerns would need to be addressed before it could be scaled up.

Also, the markers of poverty found in this area will not be the same everywhere. The approach would need to be tailored to different locations. And the system’s accuracy — 62 percent — is not great on its own.

“I think the science is pretty far ahead of the practical feasibility,” Newhouse said.

Space, Asteroid bennu
This image captured on Dec. 19, 2018, by a camera on the Osiris-Rex spacecraft shows the asteroid Bennu, top right, about 27 miles (43 kilometers) from the spacecraft, and the Earth and moon, bottom left, more than 70 million miles (110 million kilometers. VOA

It’s probably best not to rely solely on satellite data, experts say. The charity GiveDirectly used satellite images to target donations to people in villages with a high proportion of thatched roofs. These villages were considered worse off than those with more metal roofs.

But people figured it out. Some claimed to live in thatched-roof structures next to their metal-roofed houses in order to qualify for donations.

“This is really a way to use the data, but it’s also an example of how people can quickly game it,” said remote sensing expert Damien Jacques. GiveDirectly has since changed its methods.

There’s power, however, in combining satellite data and on-the-ground surveys.

“Using the two types of data, one that is cheap to collect and very frequently available to complement traditional data that are expensive to collect and not frequent, you can get the best of the two,” Jacques said.

And remote sensing data on its own can be helpful in places surveyors can’t go, such as Yemen or North Korea, or in the wake of disasters.

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But it’s not clear that changes in poverty are visible from space. That’s something Watmough and colleagues will be investigating. They have survey data from Sauri from 2005 and 2008. The next step is to look for differences in the imagery.

“Nobody has ever looked at how poverty has changed over a time period and looked at how a satellite image has changed over that same time period,” he said. (VOA)

Next Story

Asteroids Are Falling On Earth’s Surface Twice As Often: Study

This enhanced impact rate poses a threat for the next mass extinction event.

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Asteroids
This Dec. 29, 1968, photo made available by NASA shows craters on the moon. For the past 290 million years, giant rocks from space have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study. VOA

Giant rocks from space are falling from the sky more than they used to, but don’t worry.

For the past 290 million years, large asteroids have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study in Thursday’s journal Science.

But no need to cast a wary glance up. Asteroids still only smack Earth on average every million or few million years, even with the increased crash rate. NASA’s list of potential big space rock crashes shows no pending major threats. The biggest known risk is a 4,200-foot (1.3-km) wide asteroid with a 99.988 percent chance that it will miss Earth when it whizzes very near here in 861 years.

Tell that to the dinosaurs. Most scientists think dinosaurs and a lot of other species went extinct after a huge space rock crashed into Central America about 65 million years ago.

Earth, Asteroids
Taurids meteor shower lights up the sky. The risk of asteroids hitting the Earth has grown over the years. Wikimedia

“It’s just a game of probabilities,” said study lead author Sara Mazrouei, a University of Toronto planetary scientist. “These events are still rare and far between that I’m not too worried about it.”

Mazrouei and colleagues in the United Kingdom and United States compiled a list of impact craters on Earth and the moon that were larger than 12 miles (20 km) wide and came up with the dates of them. It takes a space rock that’s half a mile (800 meters) wide to create holes that big.

The team counted 29 craters that were no older than 290 million years and nine between 291 million years and 650 million years old.

But we can see relatively few big craters on Earth because the planet is more than 70 percent ocean and past glaciers smoothed out some holes, said University of Toronto planetary scientist Rebecca Ghent, a study co-author.

Earth, Asteroids
These rocks were rare survivors from a very different time on Earth. Pixabay

Extrapolating for what can’t be seen brings the total to about 260 space crashes on Earth in the last 290 million years. Adding in other factors, the science team determined that the current space crash rate is 2.6 times more than the previous 700 million years.

Craters older than 650 million years are mostly wiped off on Earth by glacial forces so the scientists used impact craters on the nearby moon as a stand-in for holes between 650 million and 1 billion years old. The moon is a good guide for estimating Earth crashes, because it is close enough to be in the same bombardment path and its craters last longer.

Mixed reactions

So what happened nearly 300 million years ago?

“Perhaps an asteroid family was broken up in the asteroid belt,” Mazrouei speculated. The space rocks then headed toward the Earth and moon, and the planet got slightly more because it is a bigger target and it has higher gravity, Ghent said.

Oldest known asteroid family
An asteroid family. Wikimedia

Outside scientists are split about the research. Jay Melosh at Purdue said he found the number of craters too small to come to a reasonable conclusion, but Harvard’s Avi Loeb said the case was convincing.

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Humans might not have emerged without mass extinctions from space rocks about 250 million and 65 million years ago, Loeb said in an email, adding, “but this enhanced impact rate poses a threat for the next mass extinction event, which we should watch for and attempt to avoid with the aid of technology.”

“This demonstrates how arbitrary and fragile human life is,” Loeb wrote. (VOA)