Danuri — Korea's first lunar orbiter

Korea's first Moon mission took the fuel-saving ballistic lunar transfer — 4.5 months the long way round.

The moment of Danuri — Korea's first lunar orbiter: https://nowsky.org/e/danuri-launch — opens at the right place and time, replayable, no login.

Available views: Orbit ✓ · Sky — (not visible in the sky)

The story

On 5 August 2022 Danuri, Korea's first lunar orbiter, left Cape Canaveral on a Falcon 9. Instead of the three-day direct route, it took a four-and-a-half-month path swinging 1.56 million km out toward the Sun and back — a ballistic lunar transfer that saves 25 percent of the fuel.

Lunar orbit insertion on 27 December 2022 made Korea the seventh nation to reach the Moon, after Russia, the United States, Japan, China, Europe and India. From a 100 km orbit it operates a high-resolution camera, a wide-field polarimetric camera, a gamma-ray spectrometer, a magnetometer and NASA's ShadowCam — an instrument that sees into the permanently shadowed craters of the south pole.

ShadowCam's images from inside those shadows were used as reference material in NASA's selection of Artemis landing sites — Korea's first orbiter serving as one of the eyes of international lunar exploration. In a space-internet experiment it also streamed a BTS music video from lunar orbit to Earth.

The name combines the Korean words for "Moon" and "enjoy", chosen by public competition; operations are run from the Korea Aerospace Research Institute in Daejeon. Designed for one year, the mission was extended through 2025. The orbit replay (at 8× speed) shows the transfer path unfolding like a butterfly's wings — one of the most striking orbits in this simulator.

Why it matters

Danuri is the first step of Korean space development beyond Earth orbit. Deep-space navigation, communication and trajectory design were tested in practice for the first time, and the experience underpins Korea's planned lunar lander, targeted for 2032.

The ballistic transfer meant more than fuel savings. Danuri's mass grew during design until a direct route would have left too little propellant, and "falling" to the Moon with the help of the Sun's gravity became the solution. American commercial landers in 2023 used the same approach.

ShadowCam is a concrete example of international cooperation — NASA supplied the instrument and Korea operates the orbiter — and its data on ice in the permanently shadowed regions are shared by Artemis and landers from several nations.

How to watch

Danuri circles the Moon every two hours at 100 km and cannot be seen from the ground. Zoom in on Earth in the orbit view and follow the Moon, and Danuri's orbit is drawn around it.

Choose the Danuri launch in the orbit view's event list to replay the ballistic transfer of 5 August 2022 — out to 1.56 million km toward the Sun and back into the Moon's grasp in December. At 8× speed the butterfly shape is plain.

Select the Moon in the sky view for its altitude, bearing, phase and 24-hour track from your location; zoom in on the disk to judge where along the southern limb the permanently shadowed regions ShadowCam studies lie.

See this for yourself — replay the moment in the orbit view

Background

The Danuri programme began in 2016; its original 2020 launch slipped two years because of mass growth and the trajectory redesign. Development cost 236.7 billion won, and the launch was contracted to SpaceX.

When the one-year design life ended in late 2023 a two-year extension through 2025 was approved on the basis of remaining fuel, and observations continued from a lower orbit. The orbiter is to be deorbited onto the lunar surface at the end of the mission.

Korea's next lunar mission is a lander planned for 2032, to be launched on the successor to the domestically developed Nuri rocket. Images of the south polar region from Danuri's high-resolution camera are being used to select candidate sites.

Danuri’s wide-field polarimetric camera is the first instrument to measure the grain size of the lunar surface by polarisation from orbit, the gamma-ray spectrometer maps elemental abundances, and the magnetometer studies the structure of lunar magnetic anomalies. The space-internet experiment tested delay-tolerant networking (DTN) for deep-space links that drop out frequently, successfully sending images and video from the Moon to Earth. Data from these instruments are released by the Korea Aerospace Research Institute and used by researchers at home and abroad.

FAQ

Why did it take four and a half months?

It flew a ballistic lunar transfer, out to 1.56 million km toward the Sun and back, saving 25 percent of the fuel.

What is ShadowCam?

A NASA-supplied camera that images the permanently shadowed craters of the south pole; its data were used to pick Artemis landing sites.

Is it still operating?

It was extended through 2025 beyond its one-year design life and is to be deorbited onto the Moon at the end.

What is Korea's next lunar mission?

A lunar lander targeted for 2032, planned to fly on the successor to the Nuri rocket.

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Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.