20.09.2020

Astronomers from NSF’s National Solar Observatory (NSO) will play important roles in two of five concept studies recently announced by NASA. These five endeavors have each been granted $1.25 million by the Heliophysics division of NASA to investigate the feasibility of cutting-edge missions to study the Sun and its connection to Earth.

The Solaris mission, led by Dr. Don Hassler of Southwest Research Institute will study the Sun’s poles; a region inherently challenging to observe. In fact, until now only foreshortened glimpses of alternate poles are possible every six months. Solaris will also focus on understanding what role the Sun’s polar magnetic field plays in the solar cycle; the 11-year sequence of growing and shrinking solar activity that induces space weather effects at Earth.

Solaris will have three science instruments: Solaris Extreme Ultraviolet Imager (S-EUVI), the Solaris Coronagraph (S-COR), and Compact Doppler Magnetograph (CDM). The CDM is a miniaturized, space-based version of the NSF’s Global Oscillation Network Group (GONG) instrument currently distributed at six locations across Earth. Mapping the velocity and magnetic fields at the solar poles from an almost face down perspective will capture key ingredients of the mechanism that drives all explosive activity called the solar dynamo.

“We demonstrated a proof-of-concept for miniaturized GONG at NSO a few years ago” explains Dr. Sanjay Gosain, NSO astronomer and instrument scientist for CDM. “Working with my colleagues at NSO, Drs. Jack Harvey, and Valentin Martinez-Pillet, we came up with a conceptual design for a miniaturized version of the instrument that could easily fit in 10 kg mass category. In collaboration with Southwest Research Institute and the University of Colorado, the design was modified for operation in space, and a space-qualified prototype version, called the Compact Doppler Magnetograph (CDM), was built and tested to fit the orbital and mission requirements of Solaris”.

Key inputs and advice about the performance parameters of the instrument were provided by the NSO, thanks to its unique GONG heritage. After a Jupiter gravity assist, Solaris, if selected to move forward to development, would enter into a sweeping orbit across both solar poles. The speed of the spacecraft during certain segments of the mission has the potential to negatively impact the effectiveness of the instrument. In response, NSO’s Dr. Jack Harvey created a novel approach so the ground-based GONG concept will retain sensitivity while in space. “Our team increased the range and sensitivity of the CDM by using three spectral lines rather than one while still preserving its miniaturized size”, Dr. Harvey explained of the technique.

NSO will also contribute to the development of the Multi-slit Solar Explorer (MUSE) mission concept, led by Dr. Bart de Pontieu of Lockheed Martin Solar & Astrophysics Laboratory, Palo Alto, CA. MUSE will be dedicated to understanding the mystery of why the outer layer of the Sun’s atmosphere is a million degrees hotter than the surface, and how solar flares and eruptions work. Understanding the coronal heating problem closely aligns with the mission of the NSF’s Daniel K. Inouye Solar Telescope. Combining MUSE and the Inouye Solar Telescope will provide diverse and complementary observations of the heating and magnetic structure of the Sun’s atmosphere. The coordination between these two observatories will be led by Dr. Sarah Jaeggli, an astronomer at NSO and instrument scientist for the Inouye Solar Telescope. She will be a coinvestigator for the MUSE mission.

“The Inouye Solar Telescope will provide information about the Sun’s magnetic field in the atmosphere while MUSE will track the evolution of the temperature in the same area,” says Dr. Jaeggli.

The mission’s concept development phase will be for nine months. NASA Heliophysics ultimately expects to award up to $250 million to up to two of the five teams to build and launch their proposed mission in future years.

NSF’s National Solar Observatory is the national center for ground-based solar physics in the United States (www.nso.edu) and is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.

Quelle: National Solar Observatory (NSO)