SORCE Satellite Outlasts Mission Life And Keeps On Truckin’

Lee Rannals for — Your Universe Online

Some missions in space complete their operations just after predicted, while others earn the Iron Man award for outlasting their primary mission. In the case of SORCE–a satellite designed to study solar storms–it’s earned itself an Iron Man.

Solar Radiation and Climate Experiment (SORCE), designed and built by the University of Colorado, is a NASA satellite that gives scientists a look at some of the most intense solar eruptions ever seen.

Friday will mark the 10th year that the satellite lifted off from this gravity-bound earth, and embarked on a space mission to help grab a better understanding of our star, the Sun.

SORCE has experienced both a solar minimum at the beginning of 2008, and is now witnessing a new solar maximum.

“We were there to see it transform from a fairly normal solar cycle to a very low-activity solar cycle,” Tom Woods, associate director of CU-Boulder´s Laboratory for Atmospheric and Space Physics (LASP), said in a statement. “Of course we couldn´t predict or know that, but it´s very exciting.”

SORCE sends data down twice a day to University of Colorado undergraduates working at LASP mission control. Scientists analyze that data to help them gain a better understanding of how energy from the sun affects Earth’s climate.

The sun’s activity can either help enhance or offset global warming activity, and having the instruments onboard SORCE really helps scientists grow their perspective on the matter.

“About 10 to 15 percent of the climate warming since 1970 is due to the sun,” Woods, the pricinpal investigator for SORCE, said. “That´s going to change now. Now that solar activity is low, the global warming trend could slow down some, but not nearly enough to offset the anthropogenic effects on global warming.”

The current solar maximum is being compared to periods in the early 19th century known as the Dalton Minimum, and the last half of the 17th century known as Maunder Minimum, when astronomers observed very few sunspots.

SORCE has also been a big contributor to the long-term record of total solar irradiance, which is the magnitude of the sun’s energy when it reaches the top of the Earth’s atmosphere. The Total Irradiance Monitor (TIM) onboard SORCE is taking the most accurate and most precise measurements of total solar irradiance ever before.

“The total solar irradiance provides nearly all the energy powering the Earth´s climate system, exceeding all other energy sources combined by 2,500 times,” said Greg Kopp, LASP senior research scientist and co-investigator responsible for the TIM instrument. “Any change in total irradiance can thus have large effects on our climate.”

The satellite mission has also started a new record for measurements of visible and near-infrared light emitted from the sun. SORCE’s Spectral Irradiance Monitor (SIM) helps to take solar spectral irradiance measurements.

Instruments onboard SORCE help scientists see all the wavelengths, including those in the ultraviolet range. SORCE has opened up a new perspective when looking at the sun, leading to discoveries like the energy emitted in some wavelengths of light vary out of phase with the sun’s overall activity.

Originally, SORCE’s instruments were designed to last for five years. However, the instruments onboard the sun-observing satellite have doubled their life expectancy.

According to the University of Colorado, LASP scientists are building new instruments to take over when SORCE gives out.

“It´s important to have continuous measurements of solar irradiance since we´re looking for small changes in the sun´s output over decades and even centuries,” Kopp said. “Detecting such small changes using measurements disconnected in time would make this even more difficult.”

A new SIM instrument built by LASP researchers is scheduled to launch in 2016 on a National Oceanic and Atmospheric Administration (NOAA) satellite. Woods said that although SORCE could last through this year, he doesn’t believe its battery will last until 2016.

If SORCE keeps on trucking through 2013, all the way until 2014, then the satellite will have lasted a complete solar cycle.

“Eleven years is special to us,” Woods remarked. “Instead of having a big science conference this year, we´re planning it for next January.”