, in the atmosphere, all at the same time." (Harrison Truong/The Stanford Daily)”]Stanford scientists have teamed up with NASA to design a satellite that observes the sun and its effects on the earth. The Solar Dynamics Observatory (SDO) is part of NASA’s “Living With a Star” program and aims to understand how the sun affects our life and environment.
SDO is the first in a series of missions. It consists of three components, each of which is overseen by a different institution. The Helioseismic and Magnetic Imager, which examines activity under the surface of the sun and creates vector magnetograms, is based at Stanford. The Atmospheric Imaging Assembly, which images the solar atmosphere every 10 seconds, is a project overseen by the Lockheed Martin Solar Astrophysics Laboratory in nearby Palo Alto. The University of Colorado manages the Extreme Ultraviolet Variability Experiment, which measures extreme ultraviolet irradiance.
The satellite was launched into space in February and will orbit 22,000 miles from the earth, taking high-resolution photographs of the sun every few seconds for the next five years. The program has been running smoothly since the satellite began regular observations at the beginning of May.
The challenge now is for the scientists to analyze the constant influx of data that SDO is sending to them and to begin to build a picture of the earth’s star.
According to Todd Hoeksema, who is in charge of the magnetic imaging component of Stanford’s project and also works as a scientist at Hansen Experimental Physics Laboratory, this mission is unprecedented.
“In the past we were only able to measure the amount of magnetic field pointed at us,” he said. “These will be the very first vector magnetic field images that are continuous, and with full coverage, taken every 45 seconds.”
Hoeksema said the photo resolutions are equivalent to eight times the resolution of a high-definition television.
One of the main goals of the project is to understand “space weather” and how the variability of the sun affects the earth.
“This is a really big issue if you’re a power company, airline or a GPS company,” said Professor Philip Scherrer, a physics research professor and a member of Stanford’s Helioseismic and Magnetic Imager team.
“Space weather can disrupt many technological systems,” he added.
Coronal mass ejections — billions of tons of plasma released by the sun — have the ability to damage satellites. Up to $1 billion a year is lost on spacecraft damage, Scherrer said.
In 1989, a geomagnetic storm caused by a coronal mass ejection tripped circuit breakers on the Hydro-Quebec transmission system’s power grid, causing it to collapse and leaving six million Quebec residents without power for hours.
The SDO mission aims to develop techniques that would allow scientists to predict solar activity, like the storm that impacted Quebec. While scientists can do little to prevent or change space weather, this would allow companies to take defensive action.
For example, satellite companies could disable interconnected sections within their satellites to reduce the susceptibility of the entire system. Airline companies could also reroute flights that go over the poles in order not to lose radio communications.
Another goal of the mission is to understand the sun on a global scale. Hoeksema explained that in the past, scientists had to pick between viewing a specific part of the sun in high resolution and seeing the whole star in low resolution. This meant that if events at one point of the sun were affecting other parts of the star, they could not examine everything at the same time.
“So for the first time,” Hoeksema said, “SDO is going to put together the whole picture of what’s going on at the surface, in the atmosphere, all at the same time. We can see the global picture now.”