South Korea set out for the moon on Thursday. But it doesn’t want to stop there.
“We are also considering using the Moon as an outpost for space exploration,” Kwon Hyun-joon, director general of space and nuclear energy at the South Korean Ministry of Science, said in a written response to questions. “While we hope to explore the moon itself, we also recognize its potential to act as a base for future explorations of deep space, such as Mars and beyond.”
South Korea’s lunar spacecraft, called the Danuri, was launched on a SpaceX Falcon 9 rocket from Florida, departing on a roundabout, but fuel-efficient, that will take it to 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.
Subscribe to The Morning from the New York Times
Originally known as the Korea Pathfinder Lunar Orbiter, the mission was named after Danuri after it became the winner in 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 was launched towards Mars on a Japanese rocket in 2020, South Korea is the latest country with a small but ambitious space program for orbit beyond Low Earth. And also like the UAE’s 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 objective of the Danuri mission was to develop basic technologies such as the design of orbital trajectories, deep space navigation, a high-thrust propulsion system and a 35-meter antenna to communicate with distant spacecraft.
But the spacecraft’s science payload is sophisticated and will help scientists in South Korea and the world study the moon’s magnetic field, measuring its amounts of elements and molecules like uranium, water and helium-3 and photographing the dark craters at the lunar poles, where the sun never shines. In addition to providing one of the instruments, called ShadowCam, NASA chose nine scientists to participate in Danuri.
One of their 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 time.
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 initial magnetic field appears to have been surprisingly strong — potentially up to twice the strength of Earth. current magnetic field.
Garrick-Bethell said it was intriguing that “such a tiny iron core could have generated such a strong magnetic field.”
He hopes that after the completion of the year-long spacecraft’s main mission, South Korea may choose to move Danuri much closer to the moon’s surface, within 12 miles or less, where the magnetometer can get a much better view. of magnetized rocks.
“Even some passes at these low altitudes can help constrain how strongly magnetized these rocks are,” he said.
Garrick-Bethell is also looking to use the magnetometer to study the magnetic fields generated inside the moon as it is hit by the solar wind, a stream of charged particles emanating from the sun.
The rise and fall in strength of the magnetic field in the solar wind induces electrical currents in the moon, and these electrical currents, in turn, generate magnetic fields that will be measured by Danuri. The characteristics of the magnetic field will give clues to the structure and composition of the moon’s interior.
This work also requires combining 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 magnetic fields. induced closer to the surface.
“What we would learn from this is sort of a global map of the interior temperature and potentially composition and maybe even water content of the deep parts of the moon,” said Garrick-Bethel.
Scientists will use another Danuri instrument, a gamma-ray spectrometer, to measure amounts of different elements on the moon’s surface. Danuri’s device can pick up a broader spectrum of lower-energy gamma rays than similar instruments on previous lunar missions, “and that range is full of new information for detecting elements on the moon,” said Naoyuki Yamashita, a scientist in New Mexico. who works for the Planetary Science Institute in Arizona. He is also a participating scientist in Danuri.
Yamashita is interested in radon, which forms from the decay of uranium. Since radon is a gas, it can travel from the moon’s interior 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 story explaining when various parts of the moon’s surface cooled and hardened, Yamashita said, helping scientists figure out which lava flows from the moon are older or younger.
The Korean Aerospace Research Institute, the South Korean equivalent of NASA, will use Danuri’s high-resolution camera to explore the lunar surface for possible locations for a robotic mission in 2031, Kwon said.
A second camera will measure polarized sunlight reflecting off the lunar surface, revealing details about the size of the particles that make up the lunar soil. As the constant bombardment by solar wind, radiation and micrometeorites separates the ground, the size of the grains found in a crater can provide an estimate of its age. (Smaller grains would suggest an older crater.)
The polarized light data will also be used to map the abundance of titanium on the Moon, which could one day be mined for use on Earth.
NASA provided one of the cameras, a ShadowCam, that is sensitive enough to pick up the few photons that bounce off the ground into the moon’s dark, permanently shadowed craters.
These craters, located at the moon’s poles, remain cold forever, below minus 300 degrees Fahrenheit, and contain water ice that has accumulated over eons.
Ice can provide a 4.5 billion-year frozen history of the solar system. It could also be a resource reward for future visiting astronauts. Machines on the moon could extract and melt ice to provide water. That water could then be split into oxygen and hydrogen, which would provide breathing air for astronauts and rocket boosters for travelers looking to travel from the moon to other destinations.
One of ShadowCam’s main goals is to find the ice. But even with Danuri’s sophisticated instruments, this can be a challenge. Shuai Li, a researcher at the University of Hawaii and a participating Danuri scientist, thinks the concentrations could be so low that they won’t be obviously brighter than areas that don’t contain ice.
“If you don’t look carefully, you might not be able to see it,” Li said.
Jean-Pierre Williams, a planetary scientist at the University of California, Los Angeles, and another scientist participating in the Danuri mission, hopes to produce detailed temperature maps of the craters by combining ShadowCam images with data collected by NASA’s Lunar Reconnaissance Orbiter.
The NASA orbiter, which has been studying the moon since 2009, carries an instrument that records lunar surface temperatures. But these measurements are blurry over a fairly large area, about 900 feet in diameter. The resolution of a ShadowCam is about 1.5 meters per pixel. Thus, ShadowCam images used in conjunction with computer models can make it possible to discover surface temperature variations.
“With this data, we can map local and seasonal temperatures,” Williams said. That, in turn, could help scientists understand the stability of water ice and carbon dioxide in the crater.
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 first heads towards the sun, then returns to be captured in lunar orbit on December 16. This “ballistic trajectory” takes longer, but it doesn’t require a large engine driven to decelerate the spacecraft once it reaches the moon.
South Korea has an extensive military missile program and has placed several communication and Earth observation satellites into low Earth orbit since launching its first in 1992. And it has been expanding its domestic rocket launch capabilities so future missions do not need to depend on SpaceX , or in other countries, to get to space. In June, the Korean Aerospace Research Institute successfully put several satellites into orbit with the second flight of Nuri, its local rocket.
“We will take on challenging projects such as lunar probes and asteroid exploration,” Kwon said.
© 2022 The New York Times Company