Looking Directly into the Sun with MUSE

Don’t look directly at the sun. Unless you’re MUSE – the Multi-slit Solar Explorer – in which case, that is exactly what you should do.

Designed by Lockheed Martin in our Advanced Technology Center (ATC) in Palo Alto, CA, MUSE was selected by NASA in February 2022 as one of two missions that will study the sun or its surroundings to better understand its impact on Earth and our atmosphere.

MUSE’s mission is to help NASA better understand the sun’s million-degree atmosphere or corona, including its eruptions and explosions, in a way that previous missions haven’t been able to do. The sun’s eruptions – called coronal mass ejections – and explosions – called solar flares – lead to a phenomenon called space weather, which has large implications for Earth.

“In our high-tech society, a lot of our technology is sensitive to the disturbances that are created when the sun gets extremely active,” said Bart De Pontieu, principal physicist at the Lockheed Martin Solar and Astrophysics Laboratory who serves as the mission’s Principal Investigator. “Space weather can cripple satellites, endanger the safety of astronauts, and even cause disturbances on the Earth’s electrical power grid.”

In addition to being responsible for the design and build of the mission, Lockheed Martin will also take the lead in the mission’s science operations and the analysis of the solar observations. 

MUSE will be able to resolve details as small as 250 kilometers in the sun’s hot atmosphere – a higher resolution than any other NASA solar mission – thanks to two high tech instruments on board.

One is a one-of-a-kind multi-slit spectrograph, which makes MUSE such a unique mission.

Since spacecraft can’t fly through the solar atmosphere at the low heights where solar eruptions occur, scientists use remote sensing to diagnose the conditions in this region. MUSE uses a spectrograph to split up the light into different wavelengths. This allows scientists to use the properties of light to measure, at a distance, physical properties like the temperature, velocity and turbulent motions of the solar gas that emits the light. “These are the kinds of measurements we really need to pin down the physical mechanisms of what drives these eruptions and explosions,” said De Pontieu.  

Previous solar missions have used single slit spectrographs, but MUSE’s multi-slit spectrograph can capture information up to 100 times faster, giving us our best look yet at the solar corona and the coronal mass ejections and solar flares.

The second instrument is an imager that will take images in extreme ultraviolet light, allowing us to obtain further information about the temperatures, morphology and dynamics of the Sun’s atmosphere.

“MUSE will be able to give us new insight into the coronal heating problem,” said De Pontieu. “We know that the outer atmosphere of the sun is much hotter than the surface – a puzzle called the coronal heating problem – and MUSE’s high-resolution images and spectra will help us make a breakthrough in determining why that is the case.”

The multi-slit spectrograph and high-resolution imager are key technological advancements that build on heritage missions and previous work at Lockheed Martin’s ATC, including on the multi-slit mask and the specialized grating. 

MUSE is a mission that follows in the footsteps of a long line of heliophysics-oriented missions developed and managed by Lockheed Martin’s ATC, including missions like the Solar Dynamics Observatory and the Interface Region Imaging Spectrograph.

And as it follows, MUSE’s approach is a product of lessons learned on these missions, primarily the need for higher resolution and the ability to faster capture data for rapidly changing phenomena like solar eruptions.

“We had some great instrumentation on previous missions that was lower resolution, mostly focused on imaging or slower single-slit spectroscopy and we learned a lot from that instrumentation,” said De Pontieu. “Now we’re ready to take the next step, which means better determining the physical properties of these solar phenomenon with instruments like our fast multi-slit spectrograph.”

MUSE is set for launch in 2027.