NASA is staring at the Sun (because you can't)

Staring directly at the Sun may not be advisable for humans, but a new tool on the International Space Station has come online to do just that. Part of NASA's efforts to better understand the forces that affect our solar system, while this latest experiment may be looking outward to the Sun, it has big implications for science back home.

It's called the Total and Spectral solar Irradiance Sensor, or TSIS-1, and it actually consists of not one but two sensors working in tandem. First there's the Total Irradiance Monitor, which has actually been operating since mid-January of this year. It's designed to extend what already amounts to forty years of measurements of just how much energy the Sun passes in total to Earth.

The second sensor, meanwhile, goes deeper into the nature of that energy. Dubbed the Spectral Irradiance Monitor, it measures how the Sun's energy is spread through the electromagnetic spectrum, including ultraviolet, visible, and infrared. "Measuring the distribution of the Sun's energy is important" NASA points out, "because each wavelength of light interacts with Earth's atmosphere differently."

For example, tracking ultraviolet light has significant implications on understanding how the ozone layer protects the Earth. "TSIS-1 extends a long data record that helps us understand the Sun's influence on Earth's radiation budget, ozone layer, atmospheric circulation, and ecosystems," Dong Wu, TSIS-1 project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland explains, "and the effects that solar variability has on the Earth system and climate change."

Although only recently operational, the instrument has been present at the ISS since mid-December last year. It was carried to the space station as part of a SpaceX Dragon payload, and subsequently installed. However, a battery of testing needed to be undergone – particularly around the system that points the TSIS-1 at the Sun – before it could begin its measurements.

That's particularly important, given accurate tracking of the solar orbit is vital if the measurements are to be consistent. NASA describes the TSIS-1 as acting like a sunflower, following the Sun from sunrise to sunset. That works on a 90 minute cycle, with the instrument automatically resetting itself after each time.