As of 22 December 2020, The CNSA –China National Space Administration Belt and Road Initiative Lunar Mission The “Yutu-2” lunar rover has a mileage exceeding 600 meters, completing the 25th day of work….The Chang’e 4 lander and the “Yutu 2” lunar rover completed the 25th day of the month at 5 o’clock on December 22 and 19:22 on the 21st, respectively. The moon night mode setting was completed according to ground instructions and entered moon night sleep. As of today, the Chang’e-4 lander and the “Yutu-2” lunar rover have been working on the moon for 719 days, and the lunar rover has travelled 600.55 meters in total……
Researchers conduct research and analysis on the detection data obtained in 25 months, and continue to produce scientific results. A recent scientific achievement published in the internationally authoritative academic journal Astrophysical Journal Letters (Xu et al 2020) shows that the lunar neutron and radiation dosimeter mounted on the Chang’e-4 lander detected a solar high-energy particle event on the back of the moon (SEP). This is the first time that a human probe has detected SEP on the surface of the moon, verifying the performance of the instrument, and also made a detailed analysis of the acceleration mechanism and the acceleration source area of the SEP.
Previous observations made by Chang’e-4 indicate that the radiation intensity on the surface of the moon is about 100 times that of the earth (Zhang et al. 2020, Space. Adv.). Since the moon does not have the same atmosphere and magnetic field as the earth, the Galactic cosmic ray (GCR) can easily reach the surface of the moon. Such high-intensity background radiation can cause damage to astronauts working on the surface of the moon. In addition, when solar activity erupts, the solar high-energy particle event will cause the particle flux to increase by thousands of times, and the space radiation will also be greatly enhanced. Therefore, the observation of the arrival of high-energy particles of the sun on the moon is particularly important.
In 2019, the sun is in a very small year, no sunspots have appeared for a long time, and the chance of observing solar high-energy particle events is even smaller. Chang’e-4 captured such an event. The study found that both electrons and protons exhibit good velocity dispersion. By linearly fitting the data points, it is possible to deduce the release time of particles from the acceleration zone and the distance the particles travel in interplanetary space before reaching the moon.
In addition, the proton energy spectrum of this SEP event was further analysed, including the GCR background energy spectrum and the background subtracted energy spectrum. According to the energy spectrum with the background subtracted, the dashed power law spectrum is used to fit it, and it is found that the energy inflection point is about 2.5MeV….
“玉兔二号”月球车行驶里程突破600米，完成第25月昼工作
科研人员对25个月昼所获得的探测数据进行研究分析，持续产出科学成果。近期发表于国际权威学术期刊Astrophysical Journal Letters(Xu et al 2020)上的一篇科学成果表明，搭载在嫦娥四号着陆器上的月球中子和辐射剂量仪在月球背面探测到了一个太阳高能粒子事件（SEP）。这是人类探测器首次在月球表面探测到SEP，验证了仪器性能，也对SEP的加速机制和加速源区做了详细分析。
嫦娥四号之前的就位观测结果表明，月球表面的辐射强度大约是地球上辐射强度的100倍左右（Zhang et al. 2020, Space. Adv.）。由于月球没有像地球一样的大气和磁场，银河宇宙线（Galactic cosmic ray，GCR）可以轻松到达月球表面，这样高强度的背景辐射会对在月球表面作业的宇航员造成损伤。此外，当太阳活动爆发时，太阳高能粒子事件还会导致成千上万倍的粒子流量增长，空间辐射也会极大增强。因此，对太阳高能粒子到达月球的观测尤其重要。
2019年，太阳处于活动极小年，很长时间没有太阳黑子出现，观测到太阳高能粒子事件的机会更是很小。 嫦娥四号捕捉到了这样一个事件。研究发现，无论是电子还是质子都表现出很好的速度弥散，通过对数据点进行线性拟合，可以推出粒子从加速区释放的时间以及粒子到达月球前在行星际空间传输的距离。
此外，进一步分析了这次SEP事件的质子能谱，包括GCR背景的能谱以及扣除背景的能谱。根据扣除背景的能谱，利用破折幂律谱对其进行了拟合，发现能量拐点大概为2.5MeV。
Previously of 26 August 2020, The CNSA –China National Space Administration Belt and Road Initiative Lunar Mission on the One Hundred Kilometer diameter Von Karman Crater Chang’e 4 lander and the “Yutu 2” lunar rover the Chang’e-4 lander and the “Yutu-2” lunar rover have completed 21-month scientific exploration on the back of the moon. They broke through 677 Earth Days On the far back of the moon, the Chang’e 4 lander and the “Yutu 2” lunar rover ended their moon night dormancy at 3:12 on November 10 and 10:17 on November 9 respectively. They were awakened by light and ushered in the first 24 days. Up to now, Chang’e-4 has successfully operated for 677 Earth days.
Based on the data of the panoramic camera spliced images and DOM images of the detection point, the “Yutu-2” lunar rover will continue to drive northwest during the 24th day of the month, targeting the basalt direction or the impact crater area with high reflectivity. Near the noon of the moon, the “Yutu-2” lunar rover plans to take at least one panoramic camera ring shot, and the infrared imaging spectrometer, neutral atom detector, and lunar radar will carry out simultaneous detection.
Go to the nearest impact crater with brighter reflectivity (purple circled area), the red circle is the location of the rock block
As the “Yutu-2” lunar rover continues to move northwest, scientists from the core team of Chang’e-4 use the first-hand data returned to continue to produce scientific results. The scientific team recently published an article in the SCI journal “Science China Information Sciences” and pointed out that the impact during the formation of the Antarctic-Aitken Basin is likely to penetrate the lunar crust and impact deep lunar material.
Since the remote sensing observation of the back of the moon by orbiting satellites, a large number of studies have revealed the existence of mafic anomalies at the bottom of the Antarctic-Aitken Basin, which also have different chemical properties compared to returned samples and lunar meteorites. Chang’e-4 probed the sputter layer at the bottom of the impact crater in the Antarctic-Aitken Basin and found that the characteristics of mafic minerals in this area are similar to remote sensing data.
Research data shows that the mafic minerals in the rocks and lunar soil in the Chang’e 4 landing area are dominated by clinopyroxene, which has the same composition as the rapidly cooling magma system. It is believed that the material in the landing zone of Chang’e 4 mainly comes from the recrystallization of the impact melt. The patrol and detection of “Yutu-2” in this area provided a scientific basis for in-depth understanding of the cause of the mafic anomaly at the bottom of the Antarctic-Aitken Basin….
在遥远的月球背面，嫦娥四号着陆器和“玉兔二号”月球车分别于11月10日3时12分和11月9日10时17分结束月夜休眠，受光照自主唤醒，迎来第24月昼。截至目前，嫦娥四号已顺利工作677个地球日。
基于探测点全景相机拼接影像、DOM影像等数据情况，“玉兔二号”月球车将在第24月昼期间继续向西北方向行驶，目标为玄武岩方向或反射率较高的撞击坑区域。在接近月午时，“玉兔二号”月球车计划进行至少1次全景相机环拍，红外成像光谱仪、中性原子探测仪、测月雷达开展同步探测。
随着“玉兔二号”月球车向西北方向不断前行，嫦娥四号核心团队科学家利用传回的第一手数据，持续产出科学成果。科学团队近期发表在SCI期刊《Science China Information Sciences》上的一篇文章中指出：南极–艾特肯盆地形成时的撞击很可能穿透月壳，撞击出月球深部物质。
自轨道卫星实现对月球背面的遥感观测以来，大量研究揭示南极-艾特肯盆地底部存在镁铁质异常，相比返回样品以及月球陨石，也有着不同的化学特性。嫦娥四号通过对南极-艾特肯盆地撞击坑底部溅射物层的探测，发现该区域镁铁质矿物特征与遥感数据相似。
研究数据显示，嫦娥四号着陆区的石块及月壤中镁铁质矿物以单斜辉石为主，这种辉石成分与快速冷却的岩浆系统一致。研究认为嫦娥四号着陆区物质主要来自撞击熔融体的重结晶。“玉兔二号”在这一区域的巡视探测为深入认识南极-艾特肯盆地底部镁铁质异常区的成因提供了科学依据。
Images and visuals are from Weibo CNSA –China National Space Administration –CLEP- China Luna Exploration Program..
