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Astro Bob: South Korea's first moon mission looks back at Earth

The Danuri probe recently entered lunar orbit and delivered stunning scenes of the planet.

Danuri Earth
Earth's clouds and atmosphere stand in stark contrast to the crater-pocked, airless lunar surface in a photo the Korean Pathfinder Lunar Orbiter took on Dec. 28.
Contributed / Korea Aerospace Research Institute (KARI)
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South Korea launched its first mission to the moon on Aug. 5, 2022 and achieved lunar orbit four months later on Dec. 16. Named Danuri — a blending of the Korean words dal (moon) and nuri (enjoy) — it will map the moon's surface and resources to lay the groundwork for future robotic and human visits.

NASA is partnering with the Korean Aerospace Research Institute on the mission, providing technical assistance as well as expertise in space communications and navigation. The two agencies recently tested a new space-based Internet by sending photos and videos to various locations in South Korea. Among them was the hit "Dynamite" by the South Korean boy band BTS.

Danuri shadowcam nasa.jpg
In this artist's view, NASA's extremely light-sensitive ShadowCam photographs the permanently dark floor of a lunar crater. The moon axis is tilted only slightly (about 1.5° relative to Earth's orbit), so sunlight doesn't reach the bottoms of craters in the extreme polar regions.
Contributed / NASA

The orbiter carries six instruments, five from South Korea and NASA's ShadowCam , which will look for water-ice deposits in permanently shadowed craters clustered in the moon's polar regions. Faint sunlight reflected from the uppermost walls of nearby craters is their only illumination. ShadowCam's super-sensitive camera will peer into the darkness and send back images that will look as though they were taken in daylight.

Water will be a crucial resource for future lunar exploration. Naturally, astronauts will need a steady supply for drinking and other functions. But if you break water apart into oxygen and hydrogen and liquefy those gases, you've got rocket fuel for return trips to Earth or other destinations.

KPLO artist view
This is an artist's view of the Republic of Korea's Danuri moon orbiter in orbit taking measurements of the lunar surface and magnetic fields.
Contributed / Korea Aerospace Research Institute

Danuri, which will orbit for about a year, also carries a high-resolution image to map the lunar surface for potential landing sites for future missions, a magnetometer to measure the strength of lunar magnetic fields and a gamma-ray spectrometer to measure the chemical composition of the surface.

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Cosmic rays, which are high-speed particles (mostly protons) mainly ejected by supernova explosions, permeate the galaxy. They strike and excite the atoms of elements in the moon's surface rocks. Each element gives off gamma rays of a specific energy, which the spectrometer detects and identifies.

Full Earth
Danuri took this photo of Earth floating over the moon's edge on Dec. 24. The Earth is almost fully illuminated (Full Earth). Since the phase Earth displays at the moon is complementary to the moon's phase, the moon was new at the time. Foreground craters are sunlit because the spacecraft was orbiting the lunar far side.
Contributed / Korea Aerospace Research Institute (KARI)

Danuri will also survey for other lunar resources such as uranium, aluminum, silicon and helium-3 , a potential fuel source for nuclear fusion reactors. It's thought that the sun's steady stream of particles called the solar wind has embedded significant amounts of this rare helium isotope in the moon's crust.

While you and I are having fun photographing moonrises and taking moonlit walks, Danuri and its handlers are finding their own "moon enjoyment" through scientific observation. The two intersect in the beautiful images you can follow at the institute's Twitter account.

Read more from Astro Bob
Although a full moon will interfere, Comet ZTF will pass right next to one of the sky's brightest stars Sunday night.

Related Topics: SCIENCE AND NATURE
"Astro" Bob King is a freelance writer and retired photographer for the Duluth News Tribune. You can reach him at nightsky55@gmail.com.
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