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The Countdown, Episode 15 – Sailing on Sunlight, “Goldilocks” Redefined, Supernova Outburst, Columbia‘s Worms, Spring on Mars


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[The text below is a modified transcript of this video.]

5) Sailing on Sunlight

NASA plans to launch a giant solar sail in 2014. It’s the largest sail ever created and will cover 1200 square meters; about the area of your average olympic swimming pool.

The sail, dubbed Sunjammer after a sci-fi short by Arthur C. Clarke, will be propelled along by nothing more than light. Photons from the sun will push on the sail, creating a miniscule force of 0.01 newtons. That’s a force equal to the weight of a sugar packet.

But in space you don’t need much to get moving and the sail’s final destination is nearly three million kilometers away at Lagrange point L1. This is where the gravity of the earth and the sun cancel each other out. Here, Sunjammer and future solar sails could keep watch for solar flares and objects headed towards earth.

The big advantage of solar sails like Sunjammer is they don’t have to carry their own fuel and so they can be much lighter and could travel much farther than propellant-based spacecraft. With a big boost from the Sun, NASA engineers envision giant space sails traveling beyond our solar system and even to nearby stars.

4) Supernova Outburst

Can we predict when a star is about to explode?

Scientists hope to answer that question by looking at SN 2010 mc, a type IIn supernova. These supernovae occur when a star eight to 50 times more massive than our sun collapses and then explodes. But 40 days before this particular star blew up, it spat out a chunk of mass one-hundredth the size of our sun.

Compared to the star’s total lifespan, which was about 10 million years, the 40 days between the mass expulsion and the supernova is the blink of an eye. Researchers at the Palomar Transient Factory, the ground-based astronomical survey that made the discovery, say there’s a 99 percent chance the two events are related.

By studying the exact process behind the mass outburst, the astronomers hope to predict supernovae before they begin.

The study is published in the February 7 edition of Nature.

3) Goldilocks Redefined

The habitable zone is the region around a star where it’s not too hot, and not too cold–for life to thrive. For liquid water, it’s just right, hence the nickname the “Goldilocks Zone.” But Goldilocks just got a little pickier. Scientists have redefined the region qualifying as habitable.

The new standards are based on updated information about how water and carbon dioxide are absorbed in a planet’s atmosphere. These conditions affect whether or not liquid water can exist, and thus support life, on a planet’s surface.

The new model isn’t perfect: Earth itself is teetering at the very edge of the new zone. But obviously we’re not freezing or boiling to death—the model doesn’t take into account Earth’s clouds, which reflect sunlight and help to keep our climate stable.

So, who knows, the new boundaries could be missing other habitable worlds as well.

2) Columbia’s Worms

Last week marked the 10th anniversary of NASA’s Columbia shuttle disaster, which killed all seven astronauts onboard. But did you know there were actually some survivors of the accident?

A few days after the crash, scientists discovered canisters in the wreckage filled with thousands and thousands of roundworms.

As you might remember, Columbia broke down during re-entry into the earth’s atmosphere. But the worms, called c. elegans, were stored in an insulated canister tucked inside one of the shuttle’s compartments. Because several layers of material shielded the nematodes, they didn’t hit the ground with the same intensity as other objects on Columbia. This is what saved them from destruction.

The roundworms were one of 80 experiments taken to space on the shuttle. Along with c. elegans, the mission also carried insects, spiders, fish and silk worms.

The offspring of the surviving worms have since been a part of several space explorations and the subject of various studies and experiments

1) Spring on Mars

Spring on Mars isn’t exactly the same as on Earth. Instead of ice melting into water, Mars has dry ice evaporating into thin air.

During the Martian winter, carbon dioxide freezes into a cap two feet thick, covering the sand dunes on the planet’s north pole. As the temperature heats up in the spring, the solid carbon dioxide, also known as dry ice, transforms into a gas in a process called sublimation. This springtime activity creates patterns of light ice and dark sand, clearly visible in images from NASA’s Mars Reconnaissance Orbiter.

So what exactly is going on? First, the frozen layer cracks open to show the sand. Then dry ice on the underside of the layer sublimates, builds up pressure, and bursts through the top, carrying sand with it. This scratches grooves into the dunes and sprays sand into fan-like shapes on top of the ice.

Mars may or may not have life—but it still has plenty of action.

- Portions of the script above written by Sophie Bushwick, Eric R. Olson & Isha Soni

About the Author: Eric is the resident video producer and an associate editor at Scientific American. He graduated from the University of Washington with a B.S. in biochemistry and New York University with an M.A. in science journalism. His work has also appeared on the websites of Nature, Nature Medicine, Popular Science and The New York Times among many others. Follow on Twitter @EricROlson.

The views expressed are those of the author and are not necessarily those of Scientific American.





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