Predicting the weather in space is hard but this new satellite could make it easier
CUAVA-1 was deployed into orbit from the International Space Station Oct. 6
Satellites and space weather
While the Australian Space Agency was only formed in 2018, Australia has along history in satellite research. In 2002, for example,FedSatwas one of the first satellites in the world to carry a GPS receiver onboard.
Space-based GPS receivers today make it possible to routinely measure the atmosphere all around the world for weather monitoring and prediction. The Bureau of Meteorology and other weather forecasting agencies rely onspace-based GPS datain their forecasting.
Space-based GPS receivers also make it possible to monitor the Earth’s ionosphere. From heights of about 80km to 1,000km, this layer of the atmosphere transitions from a gas of uncharged atoms and molecules to a gas of charged particles, both electrons, and ions. (A gas of charged particles is also called a plasma.)
The ionosphere is the location of thebeautiful auroral displaysthat are common at high latitudes during moderategeomagnetic storms, or “bad space weather”, but there is much more to it.
The ionosphere can cause difficulties for satellite positioning and navigation, but it is also sometimes useful, such as whenground-based radarand radio signals can be bounced off it to scan or communicate over the horizon.
Why space weather is so hard to predict
Understanding the ionosphere is an important part of operational space weather forecasting. We know the ionosphere becomes highly irregular during severe geomagnetic storms. It disrupts radio signals that pass through it and creates surges of electric current in power grids and pipelines.
During severegeomagnetic storms, a large amount of energy is dumped into the Earth’s upper atmosphere near the north and south poles, while also changing currents and flows in the equatorial ionosphere.
This energy dissipates through the system, causing widespread changes throughout the upper atmosphere and altering high-altitude wind patterns above the equator hours later.
In contrast, X-rays and UV radiation from solar flares directly heat the atmosphere (above the ozone layer) above the equator and middle latitudes. These changes influence the amount of drag experienced in low-Earth orbit, making it difficult to predict the paths of satellites and space debris.
Even outside geomagnetic storms, there are “quiet-time” disturbances that affectGPSand other electronic systems.
At present, we can’t make accurate predictions of bad space weather beyond about three days ahead. And the flow-on effects of bad space weather on the Earth’s upper atmosphere, including GPS and communication disturbances and changes in satellite drag, are even harder to forecast ahead of time.
As a result, most space weather prediction agencies are restricted to “nowcasting”: observing the current state of space weather and projecting for the next few hours.
It will take a lot more science to understand the connection between the Sun and the Earth, how energy from the Sun dissipates through the Earth system, and how these system changes influence the technology we increasingly rely on for everyday life.
This means more research and more satellites, especially for the equatorial to mid-latitudes relevant to Australians (and indeed most people on Earth). We hope CUAVA-1 is a step towards a constellation of Australian space weather satellites that will play a key role in future space weather forecasting.
Article byBrett Carter, Senior lecturer,RMIT UniversityandIver Cairns, Professor of Space Physics,University of Sydney
This article is republished fromThe Conversationunder a Creative Commons license. Read theoriginal article.
Story byThe Conversation
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