Danuri — Korea's first lunar orbiter
Korea's first Moon mission, launched on 5 August 2022. To save fuel it took a long loop out toward the Sun and reached lunar orbit four and a half months later.
Available views: Orbit ✓ · Sky — (not visible in the sky)
The story
On 5 August 2022 Danuri, Korea's first lunar orbiter, left Cape Canaveral in the United States on a Falcon 9 rocket. A direct trip to the Moon takes about three days, but Danuri chose a route that took four and a half months. It flew out toward the Sun to about 1.56 million km and then fell back to be captured by the Moon. That turning point was roughly four times farther away than the Moon itself.
The reason for the long way round was fuel. While Danuri was being designed, its mass grew from 550 kg to 678 kg. On a direct route it would not have carried enough propellant to slow down at the Moon. The slower path, which borrows help from the Sun's gravity, is called a ballistic lunar transfer. It saved about a quarter of the fuel.
Danuri entered lunar orbit in December 2022 and settled into its planned orbit, 100 km above the surface, at the end of that month. Korea became the seventh nation to send a spacecraft to the Moon. The orbiter carries five Korean instruments, including cameras and measuring devices, and one NASA camera called ShadowCam.
The name joins the Korean words for ‘Moon’ and ‘to enjoy’, and it was chosen in a public contest. The mission was designed to last one year, but plenty of fuel remained, so it has been extended twice. The current plan is to operate until the end of 2027 and then crash the orbiter into the Moon on purpose in March 2028. The orbit view replays Danuri's path as it leaves Earth, swings far out toward the Sun and comes back to the Moon.
Mission goals
Danuri is the first time Korean space development has gone beyond Earth orbit. Tracking a spacecraft 380,000 km away, talking to it and planning its orbit were all done by Korea in real operations for the first time. That experience feeds directly into Korea's plan for a lunar lander, targeted for 2032.
NASA's ShadowCam is a good example of cooperation. Near the Moon's south pole there are crater floors where sunlight never reaches. These are called permanently shadowed regions, and water may survive there as ice. ShadowCam is sensitive enough to take pictures using the faint light reflected from nearby crater walls. Its images help researchers study where future landers and astronauts could safely go.
Danuri also tested an internet-style link for deep space. Signals in space often drop out, so the system has to store data and pass it on without losing it. In November 2022, while still on its way to the Moon and more than a million km from Earth, Danuri used this method to send a BTS music video back home.
Mission chronology and background
The Danuri programme began in 2016. The first target was a 2020 launch, but the growing mass and the new trajectory design pushed it back to 2022. Development cost about 230 billion won, and the launch was bought from SpaceX in the United States.
When the one-year design life was nearly over, engineers checked the remaining fuel and found a comfortable margin. The mission was extended first through 2025 and then again to the end of 2027. During the extension the orbit is lowered from 100 km to 60 km for closer views. At the very end the team plans to test techniques useful for landing and then crash Danuri into the surface in March 2028.
Each instrument has its own job. The polarimetric camera measures the direction in which light vibrates, which reveals the size of the grains in lunar soil. The gamma-ray spectrometer maps which elements are on the surface and how much of each. The magnetometer measures the weak patches of magnetism left here and there on the Moon. The data are made public for researchers in Korea and abroad.
Where to see it — sky and simulator
Danuri is far too small and distant to see, even with a telescope. Instead, zoom in on Earth in the orbit view and follow the Moon: Danuri's orbit is drawn around it, with one lap roughly every two hours. Seen from Earth's distance the orbit is tiny, so zoom in well to see it as a small ring hugging the Moon.
Pick the Danuri launch from the event list in the orbit view to replay the flight from August to December 2022. At 8× speed the path is easy to follow as it bulges far out toward the Sun and then curls back to the Moon. It makes a clear contrast with the short direct route.
For the real Moon, select it in the sky view. You get its height above the horizon, its direction and its phase from where you are. The south polar region that ShadowCam photographs lies near the bottom edge of the Moon's disk as we see it. On a night when the Moon is high, binoculars show the rugged, cratered country along that southern edge.
See this for yourself — replay the moment in the orbit view
FAQ
Why did it take four and a half months?
A direct trip would have needed more fuel than it could carry. By flying out to 1.56 million km and using the Sun's gravity to come back, it saved about a quarter of its fuel.
What is ShadowCam?
A very sensitive camera built by NASA. It photographs crater floors near the Moon's south pole that never see sunlight, helping researchers study where ice may lie and where landing could be safe.
Is Danuri still working?
Yes. With fuel to spare it has been extended twice; it is planned to observe until the end of 2027 and then be crashed into the Moon in March 2028.
Where was the BTS video sent from?
From more than a million km away in November 2022, while Danuri was still on its way to the Moon. It was part of a test of internet-style communication in space.
Related
- Apollo 11 lunar landing
- Artemis II launch
- Artemis III — docking test in Earth orbit
- The Moon — object index
- Earth — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.