Here’s How The Edge Of Space Crept Closer To Earth By 12 Miles
Way up in the sky, there's an invisible boundary separating the Earth and the entirety of space. Astronomers refer to this as the Karman Line.
It turns out the Karman Line is several miles nearer than the scientific community used to say. The Earth hasn't actually moved, but astrophysicist Jonathan McDowell suggests that this boundary that divides the planet's atmosphere and the rest of outer space is much closer than previously believed.
Outer Space Creeps Nearer
A new study, published online and part of the Acta Astronautica journal's October 2018 issue, revisits the Karman Line and reveals that it is about 12 full miles closer to Earth than the widely accepted distance of 100 kilometers or 62 miles.
By observing the satellites that are in orbit around Earth, McDowell determines that the boundary is at around 80 kilometers or just nearly 50 miles.
According to Science Magazine, out of 43,000 satellites that McDowell studied, at least 50 orbited below 85 kilometers or 53 miles. This makes describing its locations trickier, he points out, adding that it's unhelpful to say that a satellite is coming in and out of space every few hours.
The researcher also analyzed the numbers of satellites' return to Earth, comparing the orbital velocity against the atmosphere's drag. With a model simulating the last 50 years, he checked the boundary's behavior at varying latitudes and longitudes. McDowell found that the atmosphere's tug becomes negligible at 66 to 88 kilometers or 41 to 55 miles.
Despite McDowell challenging the widely accepted boundary, there are plenty who agree with his suggestions.
"[McDowell] lays out a solid case that ... a reasonable position for 'where space begins' is around 80 kilometers," George Whitesides, the CEO of Virgin Galactic, says. He adds that it's consistent with NASA and the Air Force's precedent of awarding astronaut wings to pilots flying above this line.
Why The Karman Line Is Important
Even if the Karman line has been widely believed to be at 62 miles in the last few decades, this is not the first time the boundary has been contested.
As space operations become more complex and countries begin to explore further away from Earth, this invisible line could be a significant part of space law and commercial practices. As Science Magazine points out, the United States even resists having a legal definition of outer space to steer clear of restrictions on their military activity that takes place in high altitude.
Defining an official boundary between the planet and the outer space will help humankind navigate the murky waters of space exploration, especially in legal and commercial matters.