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Earth Matters

November Puzzler

November 26th, 2019 by Kasha Patel

Every month on Earth Matters, we offer a puzzling satellite image. The November 2019 puzzler is above. Your challenge is to use the comments section to tell us what we are looking at, where it is, and why it is interesting.

November 2019 puzzler is above. Your challenge is to use the comments section to tell us what we are looking at, where it is, and why it is interesting.

How to answer. You can use a few words or several paragraphs. You might simply tell us the location. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure feature in the image. If you think something is interesting or noteworthy, tell us about it.

The prize. We can’t offer prize money or a trip to Mars, but we can promise you credit and glory. Well, maybe just credit. Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. After we post the answer, we will acknowledge the first person to correctly identify the image at the bottom of this blog post. We also may recognize readers who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have shaped the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you would like to recognize, please mention that as well.

Recent winners. If you’ve won the puzzler in the past few months or if you work in geospatial imaging, please hold your answer for at least a day to give less experienced readers a chance.

Releasing Comments. Savvy readers have solved some puzzlers after a few minutes. To give more people a chance, we may wait 24 to 48 hours before posting comments.

Good luck!

See our A Burial Site Fit for an Emperor Image of the Day for the answer.

What Do Satellites Tell Us About Trees?

June 2nd, 2017 by Pola Lem

Tropical forests, such as those in Gabon, Africa, are an important reservoir of carbon. (Photography courtesy of Sassan Saatchi, NASA/JPL-Caltech.)

Old-growth forests are vital because they capture large amounts of carbon and provide homes to hundreds of species. In the Eastern United States, trees in these minimally disturbed ecosystems tend to be more than 120 years old.

Can satellites help pinpoint this “old-growth” and quantify its value? That was the question Joan Maloof posed to a group of researchers during a talk at NASA Goddard Space Flight Center in May 2017. As head of the Old-Growth Forest Network and a professor at Salisbury University, Maloof aims to identify stands of old-growth forests for conservation. A large part of her job involves explaining why these areas are important—something satellite data can help show.

As it turns out, satellites have already told us much about trees. A 2012 story from NASA Earth Observatory described some of the remote sensing methods researchers use:

Scientists have used a variety of methods to survey the world’s forests and their biomass. […] With satellites, they have collected regional and global measurements of the “greenness” of the land surface and assessed the presence or absence of vegetation, while looking for signals to distinguish trees from shrubs from ground cover.

In January 2017, a paper in Science Advances tracked intact forest landscapes between 2000 and 2013. (Intact forest landscapes were defined as areas larger than 500 square kilometers with no signs of human activity in Landsat imagery). This new research underscores the importance of such landscapes. The study’s authors identified several key findings:

  • Dividing up forest landscapes with roads and development can hinder their ability to store carbon
  • Forest wildlands (forests least affected by human activity) have the highest conservation value
  • Large forest wildlands store more carbon than small forest wildlands; they are at risk of deforestation
  • The global extent of intact forests declined by 7 percent 2000 and 2013.

For more information on trees and satellites, check out the NASA Earth Observatory feature, “Seeing Forests for the Trees and the Carbon:  Mapping the World’s Forests in Three Dimensions.”

Bigger isn’t necessarily better—at least where satellites are concerned. Modern “CubeSat” satellites are smaller and more numerous than ever.

The CubeSat takes its name from its dimensions; it is made up of multiples of 10×10×11 centimeter cubic units. A basic CubeSat weighs roughly 3 pounds (1.3 kilograms) and looks a good deal like a portable speaker.

Image by NASA Ames.

BACK TO THEIR ROOTS

Early satellites started out small, too. Launched in 1957, Sputnik weighed around 184 pounds (83 kilograms). America’s first satellite, Explorer I, weighed just under 31 lbs (14 kg). Then, as the desire for more sensors grew, so did the size of satellites. The first American weather satellite, TIROS I, was a hefty 270 lbs (122 kg). But recent years have seen a reversal of this trend.

Explorer I. Image by NASA.

Like modern cell phones, satellites have benefited from more compact and more powerful computing technology. (A 1980s cell phone was an expensive, brick-sized gadget that could only place phone calls and store a couple dozen numbers.) Satellites, too, have sprouted new cameras and sensors. Take the IPEX CubeSat developed by NASA’s Jet Propulsion Laboratory (45 seconds into the video below); it can track features like forest fires, volcanic eruptions, and algae blooms.

THE UPSIDES OF BEING SMALL

A satellite today can be a “hitchhiker,” aboard a larger mission, as the video below mentions. Or, a CubeSat can be launched from the International Space Station.

Because they are smaller, CubeSats tend to cost less, so research organizations can deploy more of them. That means more spatial coverage for monitoring the Earth. Where researchers once relied on two or three larger satellites to keep an eye on weather over the Pacific Ocean, now, handfuls of smaller satellites can help with the job.

NASA is not the only organization that builds CubeSats. The space agency has delivered little satellites made by private companies, college students, and even grade school students.

To learn more, watch the video below. Or read more here.