The High Resolution Coronal Imager (Hi-C) is a sub-orbital telescope designed to take high-resolution images of the Sun's

corona Corona (from the Latin for 'crown') most commonly refers to: * Stellar corona, the outer atmosphere of the Sun or another star * Corona (beer), a Mexican beer * Corona, informal term for the coronavirus or disease responsible for the COVID-19 ...

. it has been launched three times, but only the first and the third launches, on July 11, 2012, and May 29, 2018, resulted in a successful mission. It was launched aboard a

Black Brant IX The Black Brant is a family of Canadian-designed sounding rockets originally built by Bristol Aerospace, since absorbed by Magellan Aerospace in Winnipeg, Manitoba. Over 800 Black Brants of various versions have been launched since they were fir ...

sounding rocket A sounding rocket or rocketsonde, sometimes called a research rocket or a suborbital rocket, is an instrument-carrying rocket designed to take measurements and perform scientific experiments during its sub-orbital flight. The rockets are often ...

from

White Sands Missile Range White Sands Missile Range (WSMR) is a United States Army military testing area and firing range located in the US state of New Mexico. The range was originally established in 1941 as the Alamogordo Bombing and Gunnery Range, where the Trinity t ...

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

. The images taken were the highest resolution photos ever of the Sun's corona.

Telescope description

The telescope weighs , and is long. The mirrors are approximately across. Its optics were designed at the

Marshall Space Flight Center Marshall Space Flight Center (officially the George C. Marshall Space Flight Center; MSFC), located in Redstone Arsenal, Alabama (Huntsville, Alabama, Huntsville postal address), is the Federal government of the United States, U.S. government's ...

Huntsville, Alabama Huntsville is the List of municipalities in Alabama, most populous city in the U.S. state of Alabama. The population of the city is estimated to be 241,114 in 2024, making it the List of United States cities by population, 100th-most populous ...

with assistance from the

Smithsonian Astrophysical Observatory The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution, concentrating on Astrophysics, astrophysical studies including Galactic astronomy, galactic and extragalactic astronomy, cosmology, Sun, solar ...

and L-3Com/Tinsley Laboratories of

Richmond, California Richmond is a city in western Contra Costa County, California, United States. The city was municipal corporation, incorporated on August 3, 1905, and has a Richmond, California, City Council, city council.

. Dr. Jonathan Cirtain, from MSFC said: "These mirrors were to be the finest pieces of glass ever fabricated for solar astrophysics."

Imaging system

The imaging system was designed by Apogee Imaging Systems with a resolution of 0.1 arcsec/pixel (14 times higher resolution than the

Solar Dynamics Observatory The Solar Dynamics Observatory (SDO) is a NASA mission which has been observing the Sun since 2010. Launched on 11 February 2010, the observatory is part of the Living With a Star (LWS) program. The goal of the LWS program is to develop the ...

). It was based on a customized version of the E2V CCD203 from

Lockheed Martin The Lockheed Martin Corporation is an American Arms industry, defense and aerospace manufacturer with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta on March 15, 1995. It is headquartered in North ...

, which is a very large 4 channel back illuminated 4,000 × 4,000 pixel

charge-coupled device A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a ...

(CCD).

Missions

The first flight lasted for 10 minutes, reached an altitude of and the telescope captured 165 images of a large

active region In solar physics and observation, an active region is a temporary feature in the Sun's atmosphere characterized by a strong and complex magnetic field. They are often associated with sunspots and are commonly the source of violent eruptions suc ...

. It imaged the Sun in

ultraviolet light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of th ...

at 19.3 nm wavelength. The total cost of the mission was $5 million. On the second flight, in 2018, five and a half minutes (329 seconds) of pictures were taken of an area on the sun 4.4

arcminute A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

s square (the sun's disk being about 30 arcminutes in diameter). Seventy eight images were taken at intervals of 4.4 seconds, with a two-second exposure time, at the

extreme ultraviolet Extreme ultraviolet radiation (EUV or XUV) or high-energy ultraviolet radiation is electromagnetic radiation in the part of the electromagnetic spectrum spanning wavelengths shorter than the hydrogen Lyman-alpha line from 121 nm down to ...

wavelength of 17.2

nanometre 330px, Different lengths as in respect to the Molecule">molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm), or nanometer (American spelling), is a unit of length ...

s which is dominated by Fe IX emission (emission from

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

in the +8 ionization state) indicating temperatures around 800 000

Kelvin The kelvin (symbol: K) is the base unit for temperature in the International System of Units (SI). The Kelvin scale is an absolute temperature scale that starts at the lowest possible temperature (absolute zero), taken to be 0 K. By de ...

. The instrument was able to resolve strands of plasma as narrow as about 200 kilometres wide.

Findings

The first mission revealed never-before-seen "magnetic braids" of plasma roiling in the Sun's outer layers. It was the first time scientists were able to directly observe

magnetic reconnection Magnetic reconnection is a physical process occurring in electrically conducting Plasma (physics), plasmas, in which the magnetic topology is rearranged and magnetic energy is converted to kinetic energy, thermal energy, and particle accelerati ...

in braids, which may be the primary sources of heating in the active solar corona.

References

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External links

The Sun Revealed: Photos of the Million-degree Solar Corona, Space.com

Solar space observatories Space probes launched in 2012 Spacecraft which reentered in 2012