NEWS RELEASE 25-SEP-2020 First measurements of radiation levels on the moon
In the coming years and decades, various nations want to explore the moon, and plan to send astronauts there again for this purpose. But on our inhospitable satellite, space radiation poses a significant risk. The Apollo astronauts carried so-called dosimeters with them, which performed rudimentary measurements of the total radiation exposure during their entire expedition to the moon and back again. In the current issue (25 September) of the prestigious journal Science Advances, Chinese and German scientists report for the first time on time-resolved measurements of the radiation on the moon.
The "Lunar Lander Neutron and Dosimetry" (LND) was developed and built at Kiel University, on behalf of the Space Administration at the German Aerospace Center (DLR), with funding from the Federal Ministry for Economic Affairs and Energy (BMWi). The measurements taken by the LND allow the calculation of the so-called equivalent dose. This is important to estimate the biological effects of space radiation on humans. "The radiation exposure we have measured is a good benchmark for the radiation within an astronaut suit," said Thomas Berger of the German Aerospace Center in Cologne, co-author of the publication.
The measurements show an equivalent dose rate of about 60 microsieverts per hour. In comparison, on a long-haul flight from Frankfurt to New York, it is about 5 to 10 times lower, and on the ground well over 200 times lower. Since astronauts would be on the moon for much longer than passengers flying to New York and back, this represents considerable exposure for humans, said Robert Wimmer-Schweingruber from Kiel University, whose team developed and built the instrument. "We humans are not really made to withstand space radiation. However, astronauts can and should shield themselves as far as possible during longer stays on the moon, for example by covering their habitat with a thick layer of lunar soil," explained second author Wimmer-Schweingruber. "During long-term stays on the moon, the astronauts' risk of getting cancer and other diseases could thus be reduced," added co-author Christine Hellweg from the German Aerospace Center.
The measurements were taken on board the Chinese lunar lander Chang'e-4, which landed on the far side of the moon on 3 January 2019. The device from Kiel takes measurements during the lunar "daylight", and like all other scientific equipment, switches off during the very cold and nearly two-week-long lunar night, to conserve battery power. The device and lander were scheduled to take measurements for at least a year, and have now already exceeded this goal. The data from the device and the lander is transmitted back to earth via the relay satellite Queqiao, which is located behind the moon.
The data obtained also has some relevance with respect to future interplanetary missions. Since the moon has neither a protective magnetic field nor an atmosphere, the radiation field on the surface of the moon is similar to that in interplanetary space, apart from the shielding by the moon itself. "This is why the measurements taken by the LND will also be used to review and further develop models that can be used for future missions. For example, if a manned mission departs to Mars, the new findings enable us to reliably estimate the anticipated radiation exposure in advance. That's why it is important that our detector also allows us to measure the composition of the radiation," said Wimmer-Schweingruber.
China's Chang'e-4 probe resumes work for 23rd lunar day Source: Xinhua | 2020-10-11 20:45:17 | Editor: huaxia
BEIJING, Oct. 11 (Xinhua) -- The lander and rover of the Chang'e-4 probe have resumed work for the 23rd lunar day on the far side of the moon.
The lander woke up at 11:56 a.m. Sunday, Beijing Time, and the rover Yutu-2, or Jade Rabbit-2, woke up at 6:57 p.m. Saturday, said sources with the Lunar Exploration and Space Program Center of the China National Space Administration.
A lunar day is equal to 14 days on Earth, and a lunar night is of the same length. The solar-powered probe switches to dormant mode during the lunar night.
Landing on the moon on Jan. 3, 2019, the Chang'e-4 probe has survived about 647 Earth days on the moon.
During the 23rd lunar day, Yutu-2 will move northwest toward the basalt area or the impact craters with high reflectivity. It will also use an infrared imaging spectrometer onboard to carry out the scientific detection of a lunar rock, which has a diameter of 30 cm, according to the center.
The rover has far exceeded its three-month design lifespan, becoming the longest-working lunar rover on the moon.
Yu Dengyun, deputy chief designer of China's lunar exploration project, introduced at the 71st International Astronautical Conference (IAC): our country's self-developed isotope thermoelectric generator (RTG) is operating well on the Chang'e-4 lander.
China's lunar rover travels 565.9 meters on moon's far side Source: Xinhua| 2020-10-24 15:39:05|Editor: huaxia
BEIJING, Oct. 24 (Xinhua) -- The lander and the rover of the Chang'e-4 probe have been switched to the dormant mode for the lunar night after working stably for the 23rd lunar day, according to the Lunar Exploration and Space Program Center of the China National Space Administration.
The lander was switched to dormant mode at 9:40 p.m. Friday (Beijing Time) as scheduled, and the rover, Yutu-2 (Jade Rabbit-2), at 12:00 p.m. Friday, said the center.
A lunar day is equal to 14 days on Earth, and a lunar night is the same length. The Chang'e-4 probe, which switched to dormant mode during the lunar night due to the lack of solar power, had survived 660 Earth days on the far side of the moon as of Saturday, and the rover has traveled 565.9 meters.
During the 23rd lunar day, Yutu-2 went northwest, traveling toward an area with basalt and an impact crater area with high reflectivity. En route to the destination, the near-infrared spectrometer on the rover was used to detect a rock about 30 cm in diameter. The research team is analyzing the transmitted data.
Scientists carried out the first systematically documented measurements of radiation on the moon with data acquired by the neutron radiation detector onboard. According to the study published in the journal Science Advances, the moon's surface is highly radioactive, approximately two to three times the International Space Station, five to ten times a civil flight and 300 times the surface of the earth in Beijing.
The study provided a reference for the estimation of the lunar surface radiation hazards and the design of radiation protection for future lunar astronauts.
The Chang'e-4 probe, launched on Dec. 8, 2018, made the first-ever soft landing on the Von Karman Crater in the South Pole-Aitken Basin on the far side of the moon on Jan. 3, 2019.
Don’t mistake me as merely a "rabbit", I dare to break into "Longtan" (Dragon lake). Under the precise control of the pilots of the Beijing Aerospace Flight Control Center, on the 23rd Lunar Day, Yutu 2 used the navigation camera to take photo of a large impact crater on the far side. Previously, scientists named the rock surveyed in the third Lunar Day as "Qiyuan". This time they photographed this deep pit and named it "Longtan".↓↓↓
China's Chang'e-4 probe resumes work for 24th lunar day Source: Xinhua| 2020-11-10 09:51:27|Editor: huaxia
BEIJING, Nov. 10 (Xinhua) -- The lander and rover of the Chang'e-4 probe have resumed work for the 24th lunar day on the far side of the moon.
The lander woke up at 3:12 a.m. Tuesday, Beijing Time, and the rover Yutu-2, or Jade Rabbit-2, woke up at 10:17 a.m. Monday, according to the Lunar Exploration and Space Program Center of the China National Space Administration.
Landing on the moon on Jan. 3, 2019, the Chang'e-4 probe has survived 677 Earth days on the moon.
Chang'e-4 lunar day 24 has ended. The lander powered down at 04:00 UTC Nov. 22, with the Yutu-2 rover doing so earlier at 19:10 Nov. 21. Yutu-2 covered 23.7 metres, meaning a total mission drive of 589.6 m. New image shows rim of Von Kármán crater. Chang'e-5 launches later today.