Global inventory of Helium-3 in lunar regoliths estimated by a multi-channel microwave radiometer on the Chang-E 1 lunar satellite

Abstract

Helium-3 ( 3 He) implanted by solar wind in the lunar regolith is a valuable resource because of its potential as a fusion fuel. On the basis of the Apollo regolith samples, a linear relationship between 3 He abundance and solar wind flux, optical maturity and TiO 2 content has been presented. China successfully launched its first lunar exploration satellite Chang-E 1 (CE-1) on October 24, 2007. A multi-channeled microwave radiometer was aboard the satellite with the purpose of measuring microwave thermal emission from the lunar surface layer. From the multi-channel brightness temperature (T b ) observed by CE-1, the global distribution of the regolith thickness was inverted from the multi-channel T b , and was used to evaluate the total amount of 3 He per unit area in the lunar regolith. The global inventory of 3 He was estimated as being 6.6×10 8 kg; 3.7×10 8 kg for the lunar nearside and 2.9×10 8 kg for the lunar farside. He abundance, regolith thickness, Chang-E 1 Citation:Fa W Z, Jin Y Q. Global inventory of Helium-3 in lunar regoliths estimated by a multi-channel microwave radiometer on the Chang-E 1 lunar satellite.

The Chang’E-1 orbiter plays a distinctive role in China’s first successful selenodetic lunar mission

“…From the results shown in Figure 7, distributions of the thickness of lunar surface regolith as well as 3 He were estimated [34][35][36][37]. According to the results, the lunar regolith varies from ~1 m to 14 m - more reasonable than the results based on the Apollo data.…”

“…For example, Fa & Jin 2010 [37] showed a statistical result that the average regolith thickness of maria is 4.5 m with a dynamical range of 2-12 m, and that of the highlands at the intermediate latitude area (60S-60N) is 7.6 m with a dynamical range of 6-14 m. However, according to the results of [34], the difference between the nearside and farside of the Moon is very small, and the global average of the regolith thickness is about 5 m with a dynamical range of 4-6 m.…”

“…A number of people, some even in CLEP, have proposed to explore the Moon, mine lunar regolith and use the 3 He for fusion [41]. As to the total content of 3 He on the Moon, results of ~1.03 million tons and 0.66 million tons have been obtained by Wang et al [35] and Fa & Jin 2010 [37], respectively, using the same algorithm provided by Melosh [42], which did not consider 4 He at all. The two MRM research groups only slightly varied their data calibration methods.…”

Microwave brightness temperature of cratered lunar surface and inversions of the physical temperature profile and thickness of regolith layer

“…However, because of the different local times of the observations, only those Tb data at similar local times are collected for inversion of the lunar surface temperature. The measurements of multichannel CE‐1Tb have been further applied to invert the global distribution of the regolith layer thickness, from which the total inventory of 3 He (Helium‐3) stored in the lunar regolith layer can be estimated quantitatively [ Fa and Jin , 2007b, 2010b].…”

Preliminary results of TiO2 mapping using Imaging Interferometer data from Chang’E-1

“…Ping et al obtained a global topographic model based on laser altimeter data [5]. Fa et al estimated the global inventory of helium-3 in lunar regolith using data from the multi-channel microwave radiometer [6]. Meng et al attempted to calibrate data from the microwave radiometer and gained insights into mapping the water ice content in the Cabeus crater [7].…”