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A Group of Suitcase-Sized Satellites Will Transform Hurricane Tracking

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Screenshot from "CYGNSS Overview," NASA Langley Research Center

Earlier this month, NASA launched a constellation of small satellites that will transform hurricane forecasting and enable new insights into storm formation and activity. Called the Cyclone Global Navigation Satellite System (CYGNSS), eight spacecraft, each the size of a carry-on suitcase, are flying over the tropics to measure and map ocean winds. Because of their altitude, heavy rain and storm surges are no obstacles to the satellites, and when hurricanes form, the spacecraft will be able to peer through walls of water into the storm’s core and continue to collect data—something no space-based system has ever done before.

“CYGNSS is a tool that will provide us 24/7 coverage of the tropical cyclone zone. It will improve our knowledge of how hurricanes grow so that we can better prepare and protect people in the path of each hurricane as it comes,” Christine Bonniksen, CYGNSS program executive with the Science Mission Directorate's Earth Science Division at NASA Headquarters, tells mental_floss.

THE RAIN BARRIER HAS BLOCKED OUR VIEW

Over the past several decades, there has been a steady improvement in storm track forecasting—or where storms will hit—and the National Hurricane Center’s error rate is half of what it was 20 years ago. The same cannot be said for storm intensity forecasting—how strong these storms will be. “If you look at the record for their intensity forecast, there has been very, very little improvement in the last 20 years,” said Chris Ruf, the principal investigator on the CYGNSS mission and a scientist at the University of Michigan, Ann Arbor. One of the primary reasons for this is that today’s satellites are unable to measure what’s going on in the inner core of hurricanes. “This has been identified for many years as a primary lacking ingredient in the numerical forecasts that are used by the National Hurricane Center. They wish they had information on the inner core of the storms and they don’t.”

Storm cores have so far been impenetrable because current wind-observing spacecraft cannot see through rain. This is because their on-board instruments emit signals at an 8-millimeter wavelength—about the same size as a large raindrop. When the signals encounter rain, they are simply scattered and absorbed. (Hurricane paths depend on environmental factors outside of the storm, which is why this rain shroud has not been an impediment to predicting where storms will hit.)

Additionally, it takes about three days for current systems to collect data to build a map of global wind speeds and precipitation. This is a big problem if you’re trying to track the rapid intensification of tropical storms and hurricanes, which can happen in a matter of hours. So until now, scientists have had to rely on so-called “Hurricane Hunter” aircraft to fly into the storm to perform wind speed reconnaissance.

THE CYGNSS SOLUTION

CYGNSS changes all of this by using GPS satellite signals, which were designed to penetrate heavy rains. GPS operates at a 19-centimeter wavelength—more than long enough to avoid rain interaction. When GPS satellite signals hit the ocean, they reflect back into space and are received by CYGNSS observatories. Think about the way the Moon reflects on a placid lake: When the lake is calm, the Moon's image is sharp. When the wind blows, the water roughens and the image diffuses. CYGNSS relies on a similar principle, reading the clarity of the GPS signals to reveal the characteristics of the wind. It measures the strength of the GPS signal as it scatters off the ocean surface to determine wind speed.

The eight CYGNSS observatory spacecraft operate evenly in a single orbital plane around the Earth. Each satellite has a payload called a Delay Doppler Mapping Instrument, a GPS receiver capable of tracking four different GPS signals simultaneously. Two antennas look down at reflected GPS signal and take measurements of the diffuse scattering, and from those derive the wind speed and activity. Meanwhile, one antenna looks up and receives a direct GPS satellite signal for geolocation. In essence, each 65-pound satellite is doing the work of four Hurricane Hunter airplanes. Collectively, CYGNSS is like a squadron of 32 such planes flying continuously over the tropics taking simultaneous measurements.

The system gives a total refresh of the entire tropical wind distribution map every seven hours, even under heavy precipitation. In a hurricane or tropical storm—including in areas with the highest wind speeds and the most powerful surges—CYGNSS can immediately answer questions about the storm size, intensity, and the reach of its strong winds. Moreover, because the satellite constellation has such expansive coverage of the Earth, it can collect massive amounts of data on the entire storm environment. There are three different data downlink points around the world, and the data can be downloaded from the satellites within the hour—an unprecedented timeframe.

HOW THE LAUNCH WENT DOWN

CYGNSS launched on the morning of December 15, 2016 from Cape Canaveral with the help of a Pegasus rocket, an air launch system. The rocket was mounted to the bottom of an L-1011 airplane called Stargazer that took off from a runway, just like any other plane you’ve ever seen. At 39,000 feet above the Atlantic Ocean, the plane released the Pegasus rocket, which ignited five seconds later and powered its way into space. The fairings hatched away and the deployment vehicle separated, and the eight small satellites released themselves in pairs over 30-second intervals. Ten minutes after separation, their solar arrays deployed. They then moved into position in orbit and began operation.

By 4:12 pm ET that same day, the CYGNSS team had successfully made contact with all eight satellites. "It is an amazingly rewarding feeling to spend such an intense and focused time working on CYGNSS and then, in a matter of just a few hours, have the entire constellation suddenly come to life," Ruf said in a brief mission update. "I am excited (and a little exhausted) and really looking forward to diving into the engineering data in the coming days, and then into the science data in the weeks to follow."

This is NASA’s flagship Earth Venture–class mission, which is a new NASA program designed for low-cost, high-technology suborbital (think aircraft and balloons) and orbital (CYGNSS) projects. Two previous missions of this class were aircraft designed for atmospheric research and communications. This is the first spaceborne Earth Venture endeavor. Southwest Research Institute in Boulder, Colorado runs CYGNSS mission operations, and science operations are run from the University of Michigan. The primary $160 million mission will run for two years—enough time to fill in blank spots in the hurricane dataset, get a grip on how storm cores intensify, and hopefully refine the forecast models that lives depend on.  

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science
4 Expert Tips on How to Get the Most Out of August's Total Solar Eclipse
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Richard Bouhet // Getty

As you might have heard, there’s a total solar eclipse crossing the U.S. on August 21. It’s the first total solar eclipse in the country since 1979, and the first coast-to-coast event since June 8, 1918, when eclipse coverage pushed World War I off the front page of national newspapers. Americans are just as excited today: Thousands are hitting the road to stake out prime spots for watching the last cross-country total solar eclipse until 2045. We’ve asked experts for tips on getting the most out of this celestial spectacle.

1. DON’T FRY YOUR EYES—OR BREAK THE BANK

To see the partial phases of the eclipse, you will need eclipse glasses because—surprise!—staring directly at the sun for even a minute or two will permanently damage your retinas. Make sure the glasses you buy meet the ISO 12312-2 safety standards. As eclipse frenzy nears its peak, shady retailers are selling knock-off glasses that will not adequately protect your eyes. The American Astronomical Society keeps a list of reputable vendors, but as a rule, if you can see anything other than the sun through your glasses, they might be bogus. There’s no need to splurge, however: You can order safe paper specs in bulk for as little as 90 cents each. In a pinch, you and your friends can take turns watching the partial phases through a shared pair of glasses. As eclipse chaser and author Kate Russo points out, “you only need to view occasionally—no need to sit and stare with them on the whole time.”

2. DON’T DIY YOUR EYE PROTECTION

There are plenty of urban legends about “alternative” ways to protect your eyes while watching a solar eclipse: smoked glass, CDs, several pairs of sunglasses stacked on top of each other. None works. If you’re feeling crafty, or don’t have a pair of safe eclipse glasses, you can use a pinhole projector to indirectly watch the eclipse. NASA produced a how-to video to walk you through it.

3. GET TO THE PATH OF TOTALITY

Bryan Brewer, who published a guidebook for solar eclipses, tells Mental Floss the difference between seeing a partial solar eclipse and a total solar eclipse is “like the difference between standing right outside the arena and being inside watching the game.”

During totality, observers can take off their glasses and look up at the blocked-out sun—and around at their eerily twilit surroundings. Kate Russo’s advice: Don’t just stare at the sun. “You need to make sure you look above you, and around you as well so you can notice the changes that are happening,” she says. For a brief moment, stars will appear next to the sun and animals will begin their nighttime routines. Once you’ve taken in the scenery, you can use a telescope or a pair of binoculars to get a close look at the tendrils of flame that make up the sun’s corona.

Only a 70-mile-wide band of the country stretching from Oregon to South Carolina will experience the total eclipse. Rooms in the path of totality are reportedly going for as much as $1000 a night, and news outlets across the country have raised the specter of traffic armageddon. But if you can find a ride and a room, you'll be in good shape for witnessing the spectacle.

4. PRESERVE YOUR NIGHT VISION

Your eyes need half an hour to fully adjust to darkness, but the total eclipse will last less than three minutes. If you’ve just been staring at the sun through the partial phases of the eclipse, your view of the corona during totality will be obscured by lousy night vision and annoying green afterimages. Eclipse chaser James McClean—who has trekked from Svalbard to Java to watch the moon blot out the sun—made this rookie mistake during one of his early eclipse sightings in Egypt in 2006. After watching the partial phases, with stray beams of sunlight reflecting into his eyes from the glittering sand and sea, McClean was snowblind throughout the totality.

Now he swears by a new method: blindfolding himself throughout the first phases of the eclipse to maximize his experience of the totality. He says he doesn’t mind “skipping the previews if it means getting a better view of the film.” Afterward, he pops on some eye protection to see the partial phases of the eclipse as the moon pulls away from the sun. If you do blindfold yourself, just remember to set an alarm for the time when the total eclipse begins so you don’t miss its cross-country journey. You'll have to wait 28 years for your next chance.

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Space
NASA Could Send Your Tweet Into Deep Space
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NASA

The inventors of Twitter could never have imagined how their creation would change the world. The social media platform has become the stage upon which some of the most important dramas—and pettiest comedies—of the last few years have played out. And now it'll help beam one lucky person's message into interstellar space, thanks to NASA's #MessageToVoyager contest.

The Voyager 2 and Voyager 1 spacecrafts launched on August 20 and September 5, of 1977. The probes set sail in opposite directions, bound for the outer reaches of space, each bearing a golden record imprinted with messages of peace and welcome from Earth to whomever else the spacecraft might encounter along the way.

The decades since have seen years of astonishing firsts from the two little probes. Voyager 2 has cruised past and sent back images from Jupiter, Saturn, Uranus, and Neptune. Just five years ago, Voyager 1 became the first craft to enter interstellar space.

In celebration of the 40th anniversary of the missions, NASA wants to give the people of Earth the opportunity to send a new message. The agency will transmit the single winning tweet into the area of deep space Voyager 1 now occupies.

To participate, compose a message of up to 60 characters. That includes letters, numbers, spaces, and punctuation. Tag your submission with #MessageToVoyager and post it to Twitter by August 15. You can also share it on Instagram, Facebook, Google+, or Tumblr.

Representatives from NASA, JPL, and the Voyager team will narrow down the entries, and then hold a public vote for the winner.

For full contest rules, check out NASA's #MessageToVoyager website.

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