If all goes well next week, South Korea will join the small number of countries to have sent spacecraft to the Moon—and scientists around the world are looking forward to the results. The Korea Pathfinder Lunar Orbiter (KPLO) carries “a cadre of instruments that will yield important information about the Moon,” says Clive Neal, a lunar scientist at the University of Notre Dame who is not involved in the mission.
The $200 million KPLO will launch on a SpaceX Falcon-9 rocket from Cape Canaveral on 2 August. It should enter a polar orbit 100 kilometers above the lunar surface and conduct observations for at least a year.
South Korea is eying the Moon after having put more than a dozen communications, weather, and Earth-observing satellites into Earth orbit. “We want to develop critical technology for space exploration as well as for scientific investigation,” says Eunhyuk Kim, project scientist for KPLO’s developer, the Korean Aerospace Research Institute (KARI). In 2016, after nearly a decade of planning for a Moon orbiter, KARI called for payload proposals, later selecting four from Korean teams and setting aside space for one from NASA, which has contributed technical support to the mission. (A sixth payload will test communications technologies.)
The KPLO payload breaking new ground in lunar observations is the Wide-Angle Polarimetric Camera (PolCam), which will catch the polarization of sunlight reflected at various angles from lunar surface particles, revealing details about their size across nearly the entire Moon. Because the grains break down under space weathering, size data will allow estimates of how long a particular crater or surface feature has been exposed, supplementing age approximations for impacts and geological processes by crater counting and other methods.
And PolCam’s observations of volcanic deposits on the Moon’s surface will “provide important information about the nature of the lunar interior,” says William Farrand, a planetary geologist at the Space Science Institute in Boulder, Colorado, who will study KPLO data under a cooperative agreement between KARI and NASA.
The Moon mission presented the principal investigator of the project, theoretical astrophysicist Sungsoo Kim of Kyung Hee University, Seoul, with a long-awaited opportunity. “I always thought that astronomers should participate in space exploration [but] we had to come up with something that hadn’t been done before,” he says. His team was familiar with the use of polarimetry in optical astronomy to probe magnetic fields in distant objects, such as the clouds of dust and gas known as nebulae, and they started to study how it might be applied to the Moon.
“We were surprised to learn that no previous mission has done lunar polarimetry from a lunar orbit,” says Chae Kyung Sim, a planetary scientist at the Korea Astronomy and Space Science Institute (KASI) and a member of Sungsoo Kim’s team. This means there have been limited polarimetric observations of the Moon’s near side from Earth and none whatsoever of the far side.
NASA’s payload, ShadowCam, is similar to a camera that has been orbiting the Moon aboard the agency’s Lunar Reconnaissance Orbiter since 2009. Both were developed by a team at Arizona State University. But ShadowCam “is several hundred times more sensitive and so able to observe inside permanently shadowed regions” at the poles, Eunhyeuk Kim says.
“There’s a treasure trove of Solar System data locked away in the layers of the permanently shadowed craters,” says Rachel Klima, a planetary geologist at the Johns Hopkins University Applied Physics Laboratory. The images will hopefully show the condition of the ice expected to be found in these regions and also indicate whether rovers will be able to navigate into and out of the craters, which will help future mission planners understand how to take samples there, says Klima, who is also collaborating on KPLO data.
Other scientific payloads include a magnetometer to measure the still poorly understood magnetism in the lunar environment. There haven’t been missions studying the Moon’s magnetic field for more than 10 years. A gamma ray spectrometer will provide more information on the distribution of elements on the lunar surface. And two cameras that make up the Lunar Terrain Imager will capture stereoscopic images of lunar features and scout for landing sites for a future South Korean lander.
KPLO comes on the heels of the first successful launch of South Korea’s own rocket, the three-stage KSLV-II, or Nuri, on 21 June. Also developed by KARI, Nuri put a dummy satellite and four smaller CubeSats into orbit. “We now have the capability of launching our own satellites using our own launch vehicle,” says Eunhyeuk Kim says. KARI is already planning a more powerful rocket that could carry a lander to the Moon by the early 2030s. And South Korea even has hopes for missions to Mars and near-Earth asteroids in the mid-2030s. But Eunhyeuk Kim doesn’t foresee a sudden burst of scientific missions using Nuri. Unfortunately, “It’s still more expensive than the Falcon 9,” the vehicle developed by SpaceX, he says.
KASI has its own ambitions. The institute is studying the possibility of putting its growing polarimetry expertise to work on an asteroid mission. And the NASA Langley Research Center turned to the South Korean team to jointly develop PolCube, an Earth-observing CubeSat with optics based on the PolCam design. Planned for launch in 2024, PolCube will analyze fine dust particles hovering over cities.
KPLO is just the first of a sudden rush of lunar probes. The United States, Japan, Russia, and the United Arab Emirates all have one or more Moon missions scheduled to launch by the end of the year; India plans to launch its third lunar exploration mission in 2023. “I don’t think there are any lunar scientists that wouldn’t want to see more lunar missions from wherever they can get them,” Klima says.