South Korea is exploring the Moon, with more missions to come

An undated photo provided by the Korea Aerospace Research Institute of the Danuri’s final inspections at the Daejeon, South Korea, facility prior to shipment to Florida. (Korea Aerospace Research Institute via The New York Times)

South Korea set off for the moon on Thursday. But he doesn’t want to stop there.

“We are also considering using the moon as an outpost for space exploration,” Kwon Hyun-joon, director general for space and nuclear power at the South Korean Ministry of Science, said in a written response to questions. “While we look forward to exploring the Moon itself, we also recognize its potential to act as a base for further exploration of deep space, including Mars and beyond.”

South Korea’s lunar spacecraft, named Danuri, was launched on a SpaceX Falcon 9 rocket from Florida, setting off on a roundabout but fuel-efficient path that will see it reach the moon in mid-December. There, it will begin an orbit at an altitude of 62 miles above the moon’s surface. The main mission is scheduled to last one year.

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Originally known as the Korea Pathfinder Lunar Orbiter, the mission was named after Danuri after she became the winner of a naming contest. It is a portmanteau of the Korean words for “moon” and “enjoy”.

Danuri will join spacecraft from NASA, India and China that are currently exploring Earth’s companion. Like the United Arab Emirates, which launched to Mars on a Japanese rocket in 2020, South Korea is the latest country with a small but ambitious space program to embark on an orbit beyond low Earth. And also like the United Arab Emirates’ Hope orbiter, the Danuri mission aims to make significant scientific contributions to global efforts to explore and understand the solar system.

Kwon said the main goal of the Danuri mission was to develop basic technologies such as orbital trajectory design, deep space navigation, a high-thrust propulsion system and a 35-meter antenna to communicate with distant spacecraft.

But the spacecraft’s scientific payload is sophisticated and will help scientists in South Korea and around the world study the moon’s magnetic field, measure the amount of elements and molecules such as uranium, water and helium-3 and photograph the dark craters at the lunar poles, where the sun never shines. In addition to providing one of the instruments, called the ShadowCam, NASA chose nine scientists to participate in Danuri.

One of its most important scientific instruments is a magnetometer. The moon’s interior no longer generates a magnetic field, but it once did, and that primordial field is preserved in lava flows that hardened during this era.

Ian Garrick-Bethell, a professor of planetary science at the University of California, Santa Cruz and a participating scientist on the Danuri mission, said the early magnetic field appears to have been surprisingly strong, potentially up to twice Earth’s strength. current magnetic field.

Garrick-Bethell said it was puzzling that “such a small iron core could have generated such a strong magnetic field.”

He hopes that after the spacecraft’s one-year prime mission is complete, South Korea could choose to move Danuri much closer to the moon’s surface, to within 12 miles or so, where the magnetometer could see much better magnetized rocks.

“Even a few passes at those low altitudes could help limit the magnetized force those rocks have,” he said.

Garrick-Bethell is also looking to use the magnetometer to study the magnetic fields generated inside the moon when it is buffeted by the solar wind, a stream of charged particles that emanate from the sun.

The waxing and waning of the magnetic field strength in the solar wind induces electric currents on the moon, and those electric currents in turn generate magnetic fields that will be measured by Danuri. The characteristics of the magnetic field will give clues about the structure and composition of the interior of the moon.

This work also requires combining the measurements with those made by two NASA spacecraft, THEMIS-ARTEMIS P1 and P2, which travel around the moon in highly elliptical orbits, so they can measure changes in the solar wind while Danuri measures the induced magnetic fields closer to the surface.

“What we would learn from that is kind of a global map of the interior temperature and the potential composition and maybe even the water content of the deep parts of the moon,” Garrick-Bethel said.

Scientists will use another of Danuri’s instruments, a gamma-ray spectrometer, to measure amounts of different elements on the moon’s surface. Danuri’s device can capture a broader spectrum of lower-energy gamma rays than similar instruments on previous lunar missions, “and this range is full of new information for detecting elements on the moon,” said Naoyuki Yamashita, a NASA-based scientist. New Mexico who works for the Arizona Planetary Science Institute. He is also a participating scientist at Danuri.

Yamashita is interested in radon, which is formed from the decay of uranium. Because radon is a gas, it could travel from the interior of the moon to its surface. (This is the same process that sometimes causes radon, which is also radioactive, to build up in home basements.)

The amounts of radioactive elements could provide a history that explains when various parts of the moon’s surface cooled and hardened, Yamashita said, helping scientists determine which of the moon’s lava flows are older or older. youths.

The Korea Aerospace Research Institute, South Korea’s equivalent of NASA, will use Danuri’s high-resolution camera to scan the lunar surface for potential sites for a robotic landing mission in 2031, Kwon said.

A second camera will measure polarized sunlight bouncing off the lunar surface, revealing details about the size of the particles that make up the lunar soil. Because the constant bombardment of solar wind, radiation, and micrometeorites breaks up the ground, the size of the grains found in a crater could give an estimate of its age. (Smaller grains would suggest an older crater.)

The polarized light data will also be used to map the moon’s abundance of titanium, which could one day be mined for use on Earth.

NASA supplied one of the cameras, a ShadowCam, which is sensitive enough to catch the few photons that bounce off the ground and into the moon’s dark, permanently shadowed craters.

Located at the poles of the moon, these craters remain cold forever, below minus 300 degrees Fahrenheit, and contain water ice that has accumulated over eons.

The ice could provide a frozen history of the solar system of 4.5 billion years. It could also be a great resource for future visiting astronauts. Machinery on the moon could extract and melt ice to provide water. That water could then be broken down into oxygen and hydrogen, providing air for astronauts to breathe and rocket boosters for travelers looking to travel from the moon to other destinations.

One of the main purposes of ShadowCam is to find the ice. But even with Danuri’s sophisticated instruments, that could be a challenge. Shuai Li, a researcher at the University of Hawaii and a Danuri participant scientist, thinks the concentrations could be so low that they obviously won’t be brighter than ice-free areas.

“If you don’t look at it carefully, you may not be able to see it,” Li said.

Jean-Pierre Williams, a planetary scientist at the University of California, Los Angeles, and another Danuri mission scientist, hopes to produce detailed temperature maps of the craters by combining ShadowCam images with data collected by NASA’s Lunar Reconnaissance Orbiter. POT.

NASA’s orbiter, which has been studying the moon since 2009, carries an instrument that records lunar surface temperatures. But those measurements are fuzzy over a fairly large area, about 900 feet wide. The resolution of a ShadowCam is approximately 5 feet per pixel. Therefore, ShadowCam images used in conjunction with computer models could make it possible to detect surface temperature variations.

“With these data we can map local and seasonal temperatures,” Williams said. That, in turn, may help scientists understand the stability of the water and carbon dioxide ices in the crater.

The researchers will have to wait several months for the science to begin. The spacecraft is taking a long, energy-efficient route to the moon. It heads toward the sun first, then turns around to be captured in lunar orbit on December 16. This “ballistic trajectory” takes longer but doesn’t require a large engine to fire up to slow the spacecraft down when it reaches the moon.

South Korea has an extensive military missile program and has placed several Earth observation and communications satellites in low-Earth orbit since launching the first one in 1992. And it has been expanding its domestic rocket-launching capabilities so that future missions they do not need to depend on SpaceX. , or in other countries, to reach space. In June, the Korea Aerospace Research Institute successfully placed several satellites into orbit with the second flight of Nuri, its homegrown rocket.

“We will take on challenging projects like lunar landers and asteroid exploration,” Kwon said.

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