Thread by @Chethan_Dash

#UPDATE #Thread #Moon #India

In another finding, data from #Chandrayaan2 has shown that plasma density in Moon’s ionosphere in the wake region is at least one order of magnitude more than that present in the day side. 1/n

Pic: @isro

#Chandrayaan2 carried several payloads, among which, the Dual Frequency Radio Science (#DFRS) was designed to study the lunar ionosphere. It was conceptualised and jointly developed by SPL of VSSC; URSC and Istrac. 2/n

Pointing out that the Moon’s ionosphere, which derives its origin from the atmosphere believed to be very tenuous, @isro said, the plasma density was considered to be only a few hundred ions per cubic centimetre. 3/n

“…However, measurements made using #DFRS have shown that Moon’s ionosphere has a plasma density of the order of 104 cm-3, in the wake region which is at least one order of magnitude more than that is present in the day side,” @isro added. 4/n

#DFRS uses two coherent signals at the S-band and X-band of radio frequencies, transmitted from #Chandrayaan2 orbiter and received at the ground station in Byalalu to explore lunar plasma ambiance using radio occultation (RO) technique. 5/n

“Simultaneous measurements by two coherent radio signals help to mitigate the effect of Earth’s atmosphere & uncertainties due to various sources. For RO observations, an algorithm to estimate integrated electron density profile was developed...,” Isro said. 6/n

@isro said that 12 RO experiments have been conducted in campaign mode on four different occasions based on carefully selected geometry suitable for RO measurements. 7/n

“Detailed analysis shows that total electron content along the ray path in Lunar ionosphere can be as large as 1.5 TECU (1 TECU = 1,016 m-2) with uncertainty of 0.15 TECU, in the wake region. Large electron content is also seen near polar regions during solar twilight… 8/n

…These findings are unique and first-of-its-kind as they show substantial post-sunset enhancement in plasma density compared to the dayside values reported so far by earlier missions,” @isro said. 9/n

Arguing that observed large enhancements in electron density in the wake region open new dimensions in understanding lunar dark side plasma environments, researchers said that in the wake region... 10/n

…neither the solar radiation nor the solar wind interacts directly with the available neutral particles, but still, the plasma is getting generated. 11/n

“Numerical simulations of dark side of plasma envi using a 3D Lunar Ionospheric Model suggest production of ions by charge exchange reactions may play a pivotal role in producing a significantly large plasma density in wake region, which can sustain for a longer period.” 12/n

@isro added that the model suggests that the dominant ions in the wake region are Ar+ (Argon ion), and Ne+ (Neon ion) which have a comparatively longer lifetime than the molecular ions (CO2+, and H2O+) that are dominant at other regions. 13/n

“On the other hand, a fraction of the ions produced by solar radiation during the daytime is swept by solar wind, leading to reduced daytime plasma density,” @isro said. n/n