ICON satellite launched on mission to study the edge of space
In a mission that could have important implications for global communications, NASA has launched a spacecraft to study the ionosphere and the effects of the lower atmosphere upon it. On October 10 at 8:31 pm EDT, the refrigerator-sized Ionospheric Connection Explorer (ICON) took off from Cape Canaveral Air Force Station in Florida attached to a Northrop Grumman Pegasus XL rocket.
The Pegasus rocket, which was docked to the fuselage of a Northrop Grumman Stargazer L-1011 aircraft, was dropped at 9:59 pm EDT at an altitude of 39,000 ft (11,900 m) before it ignited automatically, sending the science satellite into 27-degree orbit at an altitude of 360 mi (580 km). ICON's solar panels deployed properly and the spacecraft's systems are all healthy as it begins a commissioning period before it starts its science mission next month.
The ionosphere is the layer of the Earth's upper atmosphere ranging from 85 km (53 mi) up to 600 km (370 mi). As the edge of space from the point of view of us Earthlings, it has a lot of important effects. It impacts GPS, shortwave radio, satellite transmissions, and other radio-based technologies because of its ability to block or reflect electromagnetic waves. Equally important, because it can expand and contract, it can also cause satellite orbits to decay prematurely or increase radiation exposure to astronauts or high-altitude aviators.
This means that understanding how the ionosphere works is of great interest to scientists, but NASA says that it isn't easy to study with conventional satellites or high-altitude balloons. To fill this gap, ICON is bringing to bear four instruments: the Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) for measuring the speed and temperature of neutrally charged particles in the Earth’s atmosphere, an Ion Velocity Meter for measuring the speed of charged particles, and a pair of spectroscopes operating in the extreme and far-ultraviolet spectra for identifying the composition of charged and neutral particles.
The goal is to learn more about the ionosphere by looking at phenomena like airglow, which are colorful bands that occur in the upper atmosphere by means of a process similar to that which produces auroras. Like an aurora, airglow is caused by gases being ionized by the Sun, but airglows occur across the globe rather than in just the high northern and southern latitudes. By studying these, NASA hopes to learn more about the ionosphere's density, composition, dynamics, and structure.
"ICON has an important job to do – to help us understand the dynamic space environment near our home," says Nicola Fox, director of heliophysics at NASA Headquarters in Washington. "ICON will be the first mission to simultaneously track what’s happening in Earth’s upper atmosphere and in space to see how the two interact, causing the kind of changes that can disrupt our communications systems."
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