NASA poised to launch solar watchdog

NASA poised to launch solar watchdog




The sun will soon come under its closest scrutiny yet with NASA's $808 million Solar Dynamics Observatory, which launched on 11 February. The spacecraft will study how solar activity gets its start, revealing more about the sun's wide variability, which can knock out space satellites and power grids and affect Earth's climate.



The Solar Dynamics Observatory (SDO) will circle the Earth once per day, on a geosynchronous orbit that hovers some 36,000 kilometres above the US state of New Mexico. That vantage point will allow it to stream troves of data – 1.5 terabytes a day – back to two antennas located near the city of Las Cruces. (Illustration: NASA CI Lab/Chris Meany)



SDO's cameras will be able to send back IMAX-resolution images of the full disc of the sun every 10 seconds, revealing an unprecedented portrait of the sun's atmosphere and visible surface.

This image gives a preview of SDO's capabilities by comparing the view of NASA's eagle-eyed TRACE telescope (left) with the SOHO satellite (right), which operates at lower resolution but images the full disc of the sun.

SDO will be able to match TRACE's sharp vision over the entire disc of the sun. (Illustration: NASA/Goddard Space Flight Center Scientific Visualization Studio)



SDO's goal is to study how the sun changes. By simultaneously measuring the sun's interior, visible surface and outer corona, the probe will focus on understanding how its magnetic field is structured and how the energy stored in magnetic fields is released.

Working in concert, two instruments could make the first precise measurements of the temperature of long arches of plasma called coronal loops (pictured).

These structures can be as large as several Earths and are precursors to solar flares, dramatic explosions that can release as much energy as a billion megatonnes of TNT. Measuring the loops' temperature will illuminate where they get their energy. (Image: NASA/TRACE)



The sun's activity rises (left) and falls (right) on an 11-year cycle, but its current lull in activity has been unexpectedly long. SDO will operate for at least five years, allowing it to track the rise of the next solar cycle.

The observations could help test competing models for predicting the intensity of the next solar maximum. One new model, which relies on the flow of plasma along a deep solar 'conveyor belt', predicts that the next peak in solar activity will be delayed but strong. (Image: SOHO/EIT)



SDO will also examine the sun in the extreme ultraviolet part of the spectrum (shown here in a false-colour image from the SOHO satellite). This is the most variable type of light emitted by the sun – its intensity can jump by a factor of thousands in just seconds.

In Earth's atmosphere, this light can break apart molecules and knock electrons off atoms, creating a layer of ionised particles that can interfere with radio and GPS communication. Extreme ultraviolet radiation can also heat up and expand Earth's atmosphere, increasing the drag on orbiting satellites. (Image: ESA/NASA/SOHO)