Hold on to your hats, or in this case, your helmets: Scientists have finally pinpointed the so-called edge of space — the boundary between Earth’s atmosphere and outer space.
With data from a new instrument developed by scientists at the University of Calgary, scientists confirmed that space begins 73 miles (118 kilometers) above Earth’s surface.
A lot remains very fuzzy, however, as the boundary is surrounded by a host of misconceptions and confusing, conflicting definitions.
For starters, astronauts can say they’ve been to space after only passing the 50-mile (80-kilometer) mark.
Meanwhile the boundary recognized by many in the space industry is also a somewhat arbitrary 62 miles (100 kilometers). Scientist Theodore von Kármán long ago calculated that at this altitude the atmosphere is so thin that it’s negligible, and conventional aircraft can no longer function because they can’t go fast enough to get any kind of aerodynamic lift. This 62-mile boundary is accepted by the Federation Aeronautique Internationale (FAI), which sets aeronautical standards.
The United States, however, has never officially adopted a set boundary standard because it would complicate the issue of overflight rights of satellites and other orbiting bodies, according to NASA.
NASA’s mission control uses 76 miles (122 kilometers) as their re-entry altitude because that’s where the shuttle switches from steering with thrusters to maneuvering with air surfaces, NASA states. Others point out that the “Now Entering Space” sign should be posted way out at 13 million miles (21 million kilometers) because that’s the boundary where Earth’s gravity is no longer dominant.
For the first time, scientists have been able to “see” and trace lightning inside a plume of ash spewing from an actively erupting volcano.
When Alaska’s Mount Redoubt volcano began rumbling back to life in January, a team of researchers scrambled to set up a system called a Lightning Mapping Array that would be able to peer through the dust and gas of any eruption that occurred to the lightning storm happening within. Lightning is known to flash in the tumultuous clouds belched out during volcanic eruptions.
“The lightning activity was as strong or stronger than we have seen in large Midwestern thunderstorms,” Krehbiel said. “The radio frequency noise was so strong and continuous that people living in the area would not have been able to watch broadcast VHF television stations.”
Lightning mapping arrays are increasingly being used by meteorologists to issue weather warnings, but have only been deployed at volcanoes twice before.
Thousands of individual segments of a single lightning stroke can be mapped with these arrays, and later analyzed to reveal how lightning initiates and spreads through a thunderstorm, or in a volcanic plume.
After setting up the arrays, researchers waited nearly two months for Redoubt’s first eruption, but the wait was worth it.
“For the first time, we had the Lightning Mapping Array on site before the initial eruption,” said scientist Sonja Behnke of New Mexico Tech.
The eruptions that continued to occur on March 22 and 23 provided plenty of data, and the arrays returned dramatic information about the electricity created within volcanic plumes, and the resulting lightning. As of today, Redoubt has erupted several times since its initial eruption on March 22.
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