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KASI succeeds observation using coronagraph jointly developed with NASA (Sep 19)

- Simultaneous measurement of temperature and speed in corona for first time

Providing momentum to develop coronagraph for ISS

Korea Astronomy and Space Science Institute (KASI) announced that the 8-hour verification of key technologies of the coronagraph co-developed with NASA was successfully completed at 22:00 on September 18 (7:00 local time) at Fort Sumner, New Mexico, the US.

The joint research team flew a giant balloon as large as a football field (about 140 meters in width and 216 meters in height) carrying a coronagraph into the stratosphere about 40 km from the ground from the Columbia Scientific Balloon Facility. The researchers measured the temperature and speed of electrons in the corona, extending two million to seven million kilometers from the Sun's surface, for the first time in the world.

The Sun’s corona is the outermost part of the Sun’s atmosphere. The corona's temperature is about one million to five million degrees Celsius, way higher than that of the Sun's surface that is around 6,000 degrees Celsius. The reason of this high temperature is still unknown.

The corona can be observed from the ground during a total eclipse, but it lasts for a short period of time and the opportunities are limited. The coronagraph is thus developed to observe the corona by blocking the Sun's surface.

With the new coronagraph, researchers obtained new information on various physical parameters such as the temperature and speed of electrons in the corona by observing mainly the 400 nanometer wavelength band.

The research team will analyze physical properties of corona based on observed data and expects to get a clue to unravel the scientific mystery of the incomprehensively high temperatures in the corona.

Also, researchers expect that they can improve the accuracy of calculating the model for the solar wind, a stream of charged particles released from the corona, which has a great impact on the Earth and space environment. Researchers also expect to enhance forecasting and warning systems for space weather events caused by solar activity.

KASI developed cameras, control system, and key software for the coronagraph and NASA developed the optical system, the Sun tracking device, and the stratospheric balloon.

Dr. Natchimuthuk Gopalswamy, NASA's researcher in charge of this project, said, "The stratospheric balloon experiment is a novel way to measure the speed and temperature at the nearest point to the Sun where the solar wind is formed. The previous measurements were taken from space. The equipment will gather more precise information in cooperation with other observation research such as the Parker Solar Probe."

"This will present a clue for scientific mysteries such as coronal heating and solar wind acceleration. Another important result is the experience of successful cooperation between two institutes from Korea and the US," emphasized Dr. Gopalswamy.

"We aimed to verify the technologies required for coronagraph development. The important result is that we gained confidence for developing the world's best equipment for the Sun's observation by successful joint development," said Kim Yeon-han, KASI's senior researcher in charge.

The technology verification is part of projects for developing space coronagraphs and the International Space Station (ISS), paving the way for producing globally recognized research outcomes and establishing a cooperation framework in response to solar events by developing the next-generation coronagraph with NASA.

To this end, both sides organized a joint working group in 2016, and successfully carried out an experiment to simultaneously measure the temperature and speed, key theory of a coronagraph, on the ground during a total eclipse in the US in August 2017.

The recent balloon experiment was a two-phase technology verification test to look at the technologies of video camera, control system, and software used for the coronagraph.

The joint research team will accelerate the development of the coronagraph to be used for the ISS based on the technology and research outcomes.

Director General Choi Won-ho of the Space, Nuclear, and Big Science Policy Bureau of the Ministry of Science and ICT said, "The development of the coronagraph demonstrates Korea's globally competitive space observation technology. We will further enhance our space capabilities by expanding joint research in the field of space."

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