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- We are reliant on satellite services for modern life.<\/strong> We use them for communication, banking, navigation and so much more.<\/li>\n
- In order to use satellites, we need to know exactly where they are.<\/strong> And that also depends on where Earth and the sun are, too.<\/li>\n
- So astronomers use radio waves from distant black holes<\/strong> to help pinpoint our place in the universe. But the radio spectrum is getting crowded.<\/li>\n<\/ul>\n
By Lucia McCallum, University of Tasmania. Edits by EarthSky.<\/span><\/p>\n
Phones and wifi block our view of our place in the universe<\/h3>\n
The scientists who precisely measure the position of Earth are in a bit of trouble. We\u2019re talking about geodesy, the science of accurately measuring and understanding the Earth\u2019s geometric shape, orientation in space, and gravity field. These scientists\u2019 measurements are essential for the satellites we use for navigation, communication and Earth observation every day.<\/p>\n
But you might be surprised to learn that making geodetic measurements depends on tracking the locations of black holes in distant galaxies. <\/p>\n
The problem is, the scientists need to use specific frequency lanes on the radio spectrum highway \u2013 where the available radio frequency spectrum is pictured as being divided into \u201clanes\u201d or smaller bands, similar to lanes on a road \u2013 to track those black holes. <\/p>\n
And with the rise of wifi, mobile phones and satellite internet, travel on that highway is starting to look like a traffic jam.<\/p>\n
Why we need black holes<\/h3>\n
Satellites and the services they provide have become essential for modern life. From precision navigation in our pockets to measuring climate change, running global supply chains and making power grids and online banking possible, our civilization cannot function without its orbiting companions.<\/p>\n
To use satellites, we need to know exactly where they are at any given time. Precise satellite positioning relies on the so-called global geodesy supply chain.<\/p>\n
This supply chain starts by establishing a reliable reference frame as a basis for all other measurements. Satellites are constantly moving around Earth, Earth is constantly moving around the sun, and the sun is constantly moving through the galaxy. So this reference frame needs careful calibration via some relatively fixed external objects.<\/p>\n
As it turns out, the best anchor points for the system are the black holes at the hearts of distant galaxies. Black holes spew out streams of radiation as they devour stars and gas. <\/p>\n
And these black holes are the most distant and stable objects we know. Using a technique called very long baseline interferometry, we can use a network of radio telescopes to lock onto the black hole signals and disentangle Earth\u2019s own rotation and wobble in space from the satellites\u2019 movement.<\/p>\n
Different lanes on the radio highway<\/h3>\n
We use radio telescopes because we want to detect the radio waves coming from the black holes. Radio waves pass cleanly through the atmosphere. And we can receive them during day and night and in all weather conditions. <\/p>\n
But we also use radio waves for communication on Earth. This includes things such as wifi and mobile phones. There is close regulation on the use of different radio frequencies, or different lanes on the radio highway. And a few narrow lanes are reserved for radio astronomy. <\/p>\n
However, in previous decades the radio highway had relatively little traffic. Scientists commonly strayed from the radio astronomy lanes to receive the black hole signals.<\/p>\n
To reach the very high precision needed for modern technology, geodesy today relies on more than just the lanes exclusively reserved for astronomy.<\/p>\n
Radio traffic on the rise<\/h3>\n
In recent years, human-made electromagnetic pollution has vastly increased. When wifi and mobile phone services emerged, scientists reacted by moving to higher frequencies. <\/p>\n
However, they are running out of lanes. Six generations of mobile phone services (each occupying a new lane) are crowding the spectrum. Not to mention, a fleet of thousands of satellites directly send internet connections.<\/p>\n
Today, the multitude of signals are often too strong for geodetic observatories to see through them to the very weak signals that black holes emit. This puts many satellite services at risk.<\/p>\n
How to help find our place in the universe<\/h3>\n
To keep working into the future \u2013 to maintain the services on which we all depend \u2013 geodesy needs some more lanes on the radio highway. When international treaties at world radio conferences divide up the spectrum, geodesists need a seat at the table.<\/p>\n
Other potential fixes might include radio quiet zones around our essential radio telescopes. Work is also underway with satellite providers to avoid pointing radio emissions directly at radio telescopes.<\/p>\n
Any solution has to be global. For our geodetic measurements, we link radio telescopes together from all over the world, allowing us to mimic a telescope the size of Earth. Each nation individually primarily regulates the radio spectrum, making this a huge challenge.<\/p>\n
But perhaps the first step is increasing awareness. If we want satellite navigation to work, our supermarkets to be stocked and our online money transfers arriving safely, we need to make sure we have a clear view of those black holes in distant galaxies. And that means clearing up the radio highway.
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<\/p>\nLucia McCallum, Senior Scientist in Geodesy, University of Tasmania<\/span><\/p>\n
We republished this article from The Conversation under a Creative Commons license. Read the original article.<\/p>\n
Bottom line: Astronomers help us locate our place in the universe by analyzing the radio waves that come from black holes in the distant universe. But the radio spectrum is getting crowded with our everyday technology.<\/p>\n
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\n - In order to use satellites, we need to know exactly where they are.<\/strong> And that also depends on where Earth and the sun are, too.<\/li>\n