ISRO GSLV MkIII-M1 / Chandrayānam-2 (Chandrayaan-2) Mission: July 15, 2019

[riscol]

The likelihood of that to occur is rather low when taking into account of couple of factors such as size of the Chinese Rover, the size of the Indian lander, the big surface, the moon's gravity is 1/6 of Earth's so the force of impact wouldn't be as devastating even if Yutu were in the vicinity. The chances of hitting on the Chinese Rover or couple of dozens of meters from it is simply negligible. I'm sure China as a responsible space power wouldn't have ignored such a duty.

 

[atan651]

Let's fully enjoy this year's mooncake festival (9/13).

 

[lonelyman]

Chandrayaan 2 is on a mission unlike any before. Leveraging nearly a decade of scientific research and engineering development, India's second lunar expedition will shed light on a completely unexplored section of the Moon — its South Polar region. This mission will help us gain a better understanding of the origin and evolution of the Moon by conducting detailed topographical studies, comprehensive mineralogical analyses, and a host of other experiments on the lunar surface. While there, we will also explore discoveries made by Chandrayaan 1, such as the presence of water molecules on the Moon and new rock types with unique chemical composition.

Chandrayaan-2 will be launched from Satish Dhawan Space Center at Sriharikota on-board GSLV Mk-III on 15th July 2019. It will be injected into an earth parking 170 x40400 km orbit. A series of maneuvers will be carried out to raise its orbit and put Chandrayaan-2 on Lunar Transfer Trajectory. On entering Moon's sphere of influence, on-board thrusters will slow down the spacecraft for Lunar Capture. The Orbit of Chandrayaan-2 around the moon will be circularized to 100x100 km orbit through a series of orbital maneuvers. On the day of landing, the lander will separate from the Orbiter and then perform a series of complex maneuvers comprising of rough braking and fine braking. Imaging of the landing site region prior to landing will be done for finding safe and hazard-free zones. The lander-Vikram will finally land near South Pole of the moon on 6th September 2019. Subsequently, Rover will roll out and carry out experiments on Lunar surface for a period of 1 Lunar day which is equal to 14 Earth days. Orbiter will continue its mission for a duration of one year.

Science experiments
Chandrayaan-2 has several science payloads to expand the lunar scientific knowledge through detailed study of topography, seismography, mineral identification and distribution, surface chemical composition, thermo-physical characteristics of top soil and composition of the tenuous lunar atmosphere, leading to a new understanding of the origin and evolution of the Moon.

The Orbiter payloads will conduct remote-sensing observations from a 100 km orbit while the Lander and Rover payloads will perform in-situ measurements near the landing site.

For understanding of the Lunar composition, it is planned to identify the elements and mapping its distribution on the lunar surface both at global and In-situ level. In addition detailed 3 dimensional mapping of the lunar regolith will be done. Measurements on the near surface plasma environment and electron density in the Lunar ionosphere will be studied. Thermo-physical property of the lunar surface and seismic activities will also be measured. Water molecule distribution will be studied using infra red spectroscopy, synthetic aperture radiometry & polarimetry as well as mass spectroscopy techniques.

Boasting Indians don’t admit defeat even though lander smashed into pieces

Like they never admit their plane got shot down but come up with bullshit like bison shot down F-16

 

[Galactic Penguin SST]

This is quite an achievement for India, and probably for the first time ever, this Chandrayaan-2 thingy has nearly monopolized the main Chinese military forum, with nearly all threads dedicated to this latest abysmal failure!

https://archive.fo/2oILE/49cce386fa29ad6a76b2bda9456c7782886b2959.png ; http://web.archive.org/web/20190909205641/https://i.imgur.com/Tj9GxqZ.png ; http://web.archive.org/web/20190909182218/https://lt.cjdby.net/forum-11-1.html ; http://archive.is/awysj
▲ 1. Chinese military forum front page today.

https://archive.fo/whD5d/c2f82e522ebfed3dd683c63078a461d628ee54cb.jpeg ; https://archive.fo/whD5d/0baa331938ff06bb5bd7a0272f6e54c9e7e992bd/scr.png ; http://web.archive.org/web/20190909...0190107/80bdd9a6c2194cd0a4bffa9cc2dea371.jpeg
▲ 2. Yutu-2 S.A.R. Pragyan.

https://archive.fo/Dp1Tl/7b23bdef46793008b9a0fe6a8d651b92daa44cc4.gif ; https://archive.fo/Dp1Tl/0179f9e1339f938d170b429e90b07bd23993fba2/scr.png ; http://web.archive.org/web/20190909...20171004/2970d22b668f41819ea1392942fa6e52.gif
▲ 2. Yutu-2 S.A.R. Pragyan.

 

[Galactic Penguin SST]

What is not so surprising is the level of connivance and patronage of the U.S. overlord, testified by the fact that even three days after the epochal crash of the Vikram lunar lander, the NASA Deep Space Network (DSN) that is a worldwide network of U.S. spacecraft communication facilities, is still wasting U.S. taxpayers money and precious time in "trying to establish communication" with the dead wreckage!

Only to please the Indian/Israeli partners it seems...

In the first screen capture of the DSN website, shown below, it is obvious that the Madrid radio antenna called DSS 54, is only sending (wasting!) 10.22 kW radiowaves at 2.1GHz for nothing as indicated by the black color.

The indicated uplink signal data rate is clearly null.

Only a downward traffic indicates a working source.

https://archive.fo/GqPpL/02b382068d2c3452a35a664646ce16417a8e7080.png ; https://archive.fo/GqPpL/ab45501544ec0c3f77132cb1c78884222b83f0e3/scr.png ; http://web.archive.org/web/20190910215337/https://i.imgur.com/RnQlLNQ.png ; https://eyes.nasa.gov/dsn/dsn.html
▲ 1. DSS 54 antenna is only sending (wasting!) 10.22 kW radiowaves at 2.1GHz for nothing.

In the second screen capture of the DSN website, no round-trip light time, meaning no connection, and no range (distance).

https://archive.fo/IXmi8/57a0d80978f837fa895611e10d996f5230347ba0.png ; https://archive.fo/IXmi8/c553965dbbf72b3c7b0552c74d6696f4d3a073eb/scr.png ; http://web.archive.org/web/20190910215652/https://i.imgur.com/jnDcHkT.png
▲ 2. No round-trip light time, meaning no connection, and no range.

https://archive.fo/Yiypb/9084a124cc1b72aef068b3542450db4221b5f2a9.gif ; https://archive.fo/Yiypb/19fede8e3c6204802b6fce30fc8a3e60b2967be3/scr.png ; http://web.archive.org/web/20190910215946/https://i.imgur.com/Ua4EO24.gif ; http://web.archive.org/web/20190910220113/https://lt.cjdby.net/thread-2584544-1-1.html ; http://archive.fo/Y2ulw
▲ 3. That's the end of a pipedream.

 

[Galactic Penguin SST]

Vikram's Impact Crater, Ejecta And Wreckage

According to the ISRO's propaganda wording on 18th September 2019, the Vikram lander, in its ‘last moment’ of impacting the lunar surface on September 7 has helped expose subsurface material.

This sheer sophistry cannot conceal what was known from day one by ISRO, that the crash had caused an artificial crater big enough to be photographed by the orbiter.

Vikram could not play its intended role of achieving a soft-landing and enabling the robotic rover Pragyan to roll out, to conduct lunar surface exploration, its hard impact on the lunar surface has left a little crater, big enough for Chandrayaan-2’s powerful Imaging Infra-Red Spectrometer (IIRS)

Another ISRO scientist said Vikram, weighing 1,471 kg (245 kg on moon as its gravity is one-sixth that of earth’s), would have raised a considerable lunar dust plume on impacting the lunar surface near the south pole although the velocity with which it impacted was much less than that of the MIP, weighing 34 kg (5.6 kg on moon).

http://web.archive.org/web/20190929...look-for-water-on-moon-says-isro-2035311.html
http://archive.is/SLFB9

And indeed, its Chandrayaan-2 orbiter 0.3 meter ground resolution camera has imaged the wreckage, but refusing to make it public and waiting for the U.S. NASA LRO orbiter to take image of only 1 meter resolution only shows the desperation of ISRO to fool the world masses!

Below the ejecta left after the Israeli lander Beresheet crashed on the lunar surface on 11 April 2019, as imaged from the LRO orbiter. Extending over 100 meters, indeed large enough to be spotted.

https://archive.fo/NNyGQ/565d5ca51dcfcd00ec0448b09a8393a7f4584d69.gif ; http://web.archive.org/web/20190929...ctures/769/content_BeresheetImpact_1100px.gif ; http://web.archive.org/web/20190929142206/https://www.lroc.asu.edu/posts/1101 ; http://archive.fo/j732l
▲ 1. The Beresheet impact occurred on 11 April 2019 and LRO passed overhead 11 days later.

2019: A Chinese Space Odyssey

19 September 2019

China's lunar exploration program has released images that give us a glimpse of the mysterious artifact discovered on the far side of the moon.

Yutu-2, the lunar rover for China's Chang'e-4 mission, grabbed attention last month after its drive team spotted something unusual while roving close to a small crater. The Chinese-language science outreach publication Our Space, which announced the findings on Aug. 17, used the term "胶状物" (jiao zhuang wu), which can be translated as "gel-like." This notion sparked wide interest and speculation among lunar scientists.

Scientists have now gotten a look at that curious material, thanks to a post (Chinese) released over the weekend by Our Space via its WeChat social media account. Along with new images of the stuff on the moon, the post details how the Yutu-2 team carefully approached the crater in order to analyze the specimen, despite risks.

https://archive.is/Qbl8b/00e5f24e86fcb240dcf1ed31c36f312bfd27f881.jpg ; https://archive.is/Qbl8b/78de481794a7f5b8c4cc4a524f2d268299b22cde/scr.png ; https://archive.is/3Bttz/919b5402474730e16a6f0ce6ad57df9f6d7d1be3 ; http://web.archive.org/web/20190927...x_fmt=jpeg&tp=webp&wxfrom=5&wx_lazy=1&wx_co=1 ; http://archive.is/3Bttz ; http://web.archive.org/web/20190927142824/https://mp.weixin.qq.com/s/c7edQwOcN0gL9lQuylWRCA
▲ 1. China's Yutu-2 moon rover captured this image from the edge of the small crater where it found a mysterious artifact.

https://twitter.com/x/status/1176434971965181952

https://twitter.com/f99600406/status/1176434971965181952
▲ 1. 2019: A Chinese Space Odyssey.


http://web.archive.org/web/20190927142824/https://mp.weixin.qq.com/s/c7edQwOcN0gL9lQuylWRCA
http://archive.is/3Bttz

 

[KapitaanAli]

October 03, 2019

Our Sun emits a continuous outflowing stream of electrons and protons into the solar system, called the solar wind. The solar wind plasma which has charged particles embedded in the extended magnetic field of the Sun, moves at speeds of a few hundred km per second. It interacts with solar system bodies including Earth and its moon. Since the Earth has a global magnetic field, it obstructs the solar wind plasma and this interaction results in the formation of a magnetic envelope around Earth, called the magnetosphere.

The Earth’s magnetosphere is compressed into a region approximately three to four times the Earth radius (~22000 km above the surface) on the side facing the Sun, but is stretched into a long tail (geotail) on the opposite side that goes beyond the orbit of Moon. Approximately, once every 29 days, Moon traverses the geotail for about 6 days centered around full moon. Thus Chandrayaan-2 also crosses this geotail and its instruments can study properties of geotail at a few hundred thousand kilometers from Earth.

The CLASS instrument on Chandrayaan-2 is designed to detect direct signatures of elements present in the lunar soil. This is best observed when a solar flare on the Sun provides a rich source of x-rays to illuminate the lunar surface; secondary x-ray emission resulting from this can be detected by CLASS to directly detect the presence of key elements like Na, Ca, Al, Si, Ti and Fe.

While this kind of “flash photography” requires one to await an opportune time for Sun to be active, CLASS in its first few days of observation, could detect charged particles and its intensity variations during its first passage through the geotail during Sept.

The figure shows the change in intensity of particle events (believed to be mostly electrons), sometimes as much as 10 times the levels outside the geotail, indicating complex interplay with the magnetic field.

More detailed studies in future along with observations from other space missions, will enable a multi-point study, essential to unravel the “dance of electrons to the music of magnetic fields” around Moon.

___________________________

October 04, 2019

 

[Cobra Arbok]

October 03, 2019

Our Sun emits a continuous outflowing stream of electrons and protons into the solar system, called the solar wind. The solar wind plasma which has charged particles embedded in the extended magnetic field of the Sun, moves at speeds of a few hundred km per second. It interacts with solar system bodies including Earth and its moon. Since the Earth has a global magnetic field, it obstructs the solar wind plasma and this interaction results in the formation of a magnetic envelope around Earth, called the magnetosphere.

The Earth’s magnetosphere is compressed into a region approximately three to four times the Earth radius (~22000 km above the surface) on the side facing the Sun, but is stretched into a long tail (geotail) on the opposite side that goes beyond the orbit of Moon. Approximately, once every 29 days, Moon traverses the geotail for about 6 days centered around full moon. Thus Chandrayaan-2 also crosses this geotail and its instruments can study properties of geotail at a few hundred thousand kilometers from Earth.

The CLASS instrument on Chandrayaan-2 is designed to detect direct signatures of elements present in the lunar soil. This is best observed when a solar flare on the Sun provides a rich source of x-rays to illuminate the lunar surface; secondary x-ray emission resulting from this can be detected by CLASS to directly detect the presence of key elements like Na, Ca, Al, Si, Ti and Fe.

While this kind of “flash photography” requires one to await an opportune time for Sun to be active, CLASS in its first few days of observation, could detect charged particles and its intensity variations during its first passage through the geotail during Sept.

The figure shows the change in intensity of particle events (believed to be mostly electrons), sometimes as much as 10 times the levels outside the geotail, indicating complex interplay with the magnetic field.

More detailed studies in future along with observations from other space missions, will enable a multi-point study, essential to unravel the “dance of electrons to the music of magnetic fields” around Moon.

___________________________

October 04, 2019

The entire world including reasonable Pakistanis have praised ISRO and India for the mostly-successful mission, and yet trolls on PDF are acting like this is a major setback for India.

 

[KapitaanAli]

October 10, 2019

Many violent phenomena continuously keep occurring on surface of the Sun and its atmosphere known as the corona. This solar activity follows an eleven-year cycle, which means, it goes through its 'solar maxima' and 'solar minima' once every eleven years. While the cumulative emission of solar X-rays emitted over a year varies with the solar cycle, these are often punctuated with extremely large x-ray intensity variations over very short periods, few minutes to hours. Such episodes are known as solar flares.

Chandrayaan-2 orbiter utilizes X-rays emitted by the Sun in a clever way to study elements on the lunar surface. Solar X-rays excite atoms of constituent elements on the lunar surface. These atoms when de-excited emit their characteristic X-rays (a fingerprint of each atom). By detecting these characteristic X-rays, it becomes possible to identify various major elements of the lunar surface. However, in order to determine their concentration, it is essential to have simultaneous knowledge of the incident solar X-ray spectrum.

The Chandrayaan-2 orbiter carries two instruments, Chandrayaan 2 Large Area Soft X-ray Spectrometer (CLASS) and Solar X-ray Monitor (XSM), to measure the lunar elemental composition using this technique. Here, the CLASS payload detects the characteristic lines from the lunar surface and the XSM payload simultaneously measures the solar X-ray spectrum.

Currently, the solar cycle is heading towards minima and the Sun has been extremely quiet for past few months. On 30th September 2019 00:00 UTC - 1stOctober 2019 23:59 UTC, a series of small flares were observed by XSM.

The figure shows the solar X-ray flux as measured by XSM (in blue) during this period, and for comparison, the flux measured by X-ray sensor on the Geostationary Operational Environmental Satellite (GOES-15) is also shown (in orange), which is considered the standard for solar X-ray intensity measurement.It shows that XSM is able to detect the intensity variations of the Sun much beyond the sensitivity limit of GOES. The gaps seen in GOES light curve around 09:00 UTC are due to instrumental artifacts. The GOES data was obtained from the National Center for Environmental Information of National Oceanic and Atmospheric Administration, USA.

Apart from the better sensitivity, XSM also measures the spectrum of solar X-ray in the energy range of 1 - 15 keV with highest energy resolution so far for any broadband solar X-ray spectrometer over intervals as short as 1 second.

Although this solar flare observed at present may not enable the study of the lunar surface composition due to the large angle between Sun, lunar surface and Chandrayaan-2 (close to 90 deg in this case against a desirable low value, close to zero), such XSM observations provide very useful data to understand various processes on the Sun.

 

[Galactic Penguin SST]

The entire world including reasonable Pakistanis have praised ISRO and India for the mostly-successful mission, and yet trolls on PDF are acting like this is a major setback for India.

The crash of India's first ever lunar lander is a terrible setback because the multi-decades-long gap between China and Bharat is not shortening but even widening!

China has just posted an image of its Mars probe Huoxing-1, with an orbiter, a lander and a rover, due to be launched by next summer and arrive in Mars orbit in 2021 on time to land on the 100th anniversary of the CCP's founding (July 23, 1921, Shanghai French Concession). Thus marking the CCP's start of the Red Planet's conquest. This will be followed by a return sample mission.

India will not be able to even start research on a Mars lander if it can not find first the real cause behind the Vikram lander's failure. To date, the faulty thruster explanation is far from the truth. As some Indian experts have acknowledged that the overall control system was more likely the root cause.

And indeed, since the Fobos-Grunt Mars probe's failure that was launched on November 8, 2011, we knew that Russia could no longer land on the Moon!

Today's Russia is not the Soviet Union, having exhausted its rare earth reserve during the cold war. The production of radiation resistant microchips are the monopoly of China, endowed with the world's first rare earth mineral reserve of 100 million tonnes.

Russia has to import these critical electronics from China as does the U.S.A.

Think about it, only one other nation can send spaceprobes to land on other planets and moons, that have higher level of secondary radiations nearing the surface than in interplanetary space.

And it is the one that sits on 216 millions tonnes of rare earth mineral, Choson Korea of Kim Jong Un!

https://archive.is/f3g5A/0e26bbfea542ee89dfde65a8803110d60a953b20.jpg ; https://archive.is/f3g5A/aa081d6a708ce4b550c3afcf1536c49ca404e362/scr.png ; http://web.archive.org/web/20190920042654/https://i.imgur.com/5BxNjd9.jpg
▲ 1. China as the world's first Rare Earth Elements exporter, 2019.

https://archive.is/hToMp/0bccf7e8628f61f01ad37a66175153a75a39a88b.jpg ; https://archive.is/hToMp/89c507d6a1ab67c0bf7a0874966b0b074e72d8e5/scr.png ; http://web.archive.org/web/20191011224403/https://pbs.twimg.com/media/EGkL_oJX4AA6ZnM.jpg ; http://web.archive.org/web/20191011231915/https://new.qq.com/omn/20191011/20191011A06WCQ00.html ; http://archive.fo/zJmiJ
▲ 2. Chinese Mars probe Huoxing-1, with its first rover.

https://archive.fo/7gLVE/4bf0ea700ae94d43bded00e80e44c8d7aed933f1 ; https://archive.fo/7gLVE/3bcd2d1589acb56b03d27415d914059ef5bad886/scr.png ; http://web.archive.org/web/20191011231338/https://inews.gtimg.com/newsapp_bt/0/10492803059/1000 ; http://web.archive.org/web/20191011...inews.gtimg.com/newsapp_bt/0/10492803059/1000 ; http://web.archive.org/web/20191011231915/https://new.qq.com/omn/20191011/20191011A06WCQ00.html ; http://archive.fo/zJmiJ
▲ 3. Chinese Mars probe Huoxing-1, reentry vehicle with lander and rover.

https://archive.fo/hHn2A/1a722ce7631eb5e2fef08a153a854e3cdb2e2b22 ; https://archive.fo/hHn2A/fc56aee24cfe1518aa20d7ea495afda913df2759/scr.png ; http://web.archive.org/web/20191011231550/https://inews.gtimg.com/newsapp_bt/0/10492804023/1000 ; http://web.archive.org/web/20191011...inews.gtimg.com/newsapp_bt/0/10492804023/1000 ; http://web.archive.org/web/20191011231915/https://new.qq.com/omn/20191011/20191011A06WCQ00.html ; http://archive.fo/zJmiJ
▲ 4. Chinese Mars probe Huoxing-1, orbiter.

 

[mike2000 is back]

What is not so surprising is the level of connivance and patronage of the U.S. overlord, testified by the fact that even three days after the epochal crash of the Vikram lunar lander, the NASA Deep Space Network (DSN) that is a worldwide network of U.S. spacecraft communication facilities, is still wasting U.S. taxpayers money and precious time in "trying to establish communication" with the dead wreckage!

Only to please the Indian/Israeli partners it seems...

In the first screen capture of the DSN website, shown below, it is obvious that the Madrid radio antenna called DSS 54, is only sending (wasting!) 10.22 kW radiowaves at 2.1GHz for nothing as indicated by the black color.

The indicated uplink signal data rate is clearly null.

Only a downward traffic indicates a workin second screen capture of the DSN website, no round-trip light time, meaning no connection, and no range (distance).

.

https://archive.fo/Yiypb/9084a124cc1b72aef068b3542450db4221b5f2a9.gif ; https://archive.fo/Yiypb/19fede8e3c6204802b6fce30fc8a3e60b2967be3/scr.png ; http://web.archive.org/web/20190910215946/https://i.imgur.com/Ua4EO24.gif ; http://web.archive.org/web/20190910220113/https://lt.cjdby.net/thread-2584544-1-1.html ; http://archive.fo/Y2ulw
▲ 3. That's the end of a pipedream.

Ahahahah...... that image is kind of funny.. Is it real of photoshopped?

 

[Galactic Penguin SST]

India will not be able to start the production of its next Chandrayan-3 lunar lander if it can not find first the real cause behind the Vikram lander's failure. To date, the faulty thruster explanation is far from the truth. As some Indian experts have acknowledged that the overall control system was more likely the root cause.

The production of radiation resistant microchips is the monopoly of China, endowed with the world's first rare earth mineral reserve of 100 million tonnes.

Both Russia and the U.S. have to import these critical electronics from China.

After the obvious failure with the prayers addressed to Lord Ganesha, India has only one solution left.

On 12th October 2019, in Chennai, Modi-ji was rolling out the red carpet to mend his relations with Xi Jin Ping-tongzhi because India can never succeed in space exploration and especially in lunar landings, without the import of Chinese microchips!

https://archive.is/m3lkC/f1ab5e26ab485f01deff0dfa144f313821c1e98b.jpg ; https://archive.is/m3lkC/a0b52ab406358d0f1f3c40b97cdf1d970d74f7d2/scr.png ; http://web.archive.org/web/20191011170420/https://pbs.twimg.com/media/EGnMPHiUcAAdjrv.jpg ; https://twitter.com/narendramodi/status/1182701020368912384
▲ 1. The import of Chinese electronic parts is key to succeed in lunar landings. Chinese President Xi Jin Ping-tongzhi and Indian Prime Minister Narendra Modi-ji sharing advices on lunar landings in their informal meeting in Mamallapuram, India, 12th October 2019.

 

[KapitaanAli]

Oct 17, 2019
Chandrayaan-2 begins spectroscopic studies of lunar surface

Imaging Infrared Spectrometer (IIRS) on-board Chandrayaan-2 is designed to measure the reflected sunlight and emitted part of Moon light from the lunar surface in narrow and contiguous spectral channels (bands) ranging from ~800 – 5000 nanometer (0.8-5.0 micrometer (µm)). It uses a grating to split and disperse the reflected sunlight (and emitted component) into different spectral bands. The major objective of IIRS is to understand the origin and evolution of the Moon in a geologic context by mapping the lunar surface mineral and volatile composition using signatures in the reflected solar spectrum.

The first illuminated image of the lunar surface was acquired by IIRS. The image covers part of the lunar farside in the northern hemisphere. Few prominent craters are seen in the image (Sommerfield, Stebbins and Kirkwood).

Preliminary analysis suggests that IIRS could successfully measure the variations in the reflected solar radiation that bounces off the lunar surface from different kinds of surface types, namely, crater central peaks (e.g., Stebbins), crater floors (e.g., Stebbins and Sommerfield), very fresh reworked ejecta associated with small craterlets within the crater floor of a large crater (e.g., Sommerfield) and also the sun-illuminated inner rims of craters (e.g., Kirkwood). The variations in the spectral radiance are primarily due to the mineralogical/compositional variations that exist in the lunar surface and also due to the effect of space weathering. More detailed analysis that follows, is expected to yield important results on the heterogeneity of lunar surface composition.

 

[KapitaanAli]

October 22, 2019
Initial imaging and observations by Chandrayaan-2 Dual-Frequency Synthetic Aperture Radar (DF-SAR)

Moon has been continuously bombarded by meteorites, asteroids and comets since its formation. This has resulted in the formation of innumerable impact craters that form the most distinct geographic features on its surface. Impact craters are approximately circular depressions on the surface of the moon, ranging from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins.In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. The study of the nature, size, distribution and composition of impact craters and associated ejecta features reveal valuable information about the origin and evolution of craters. Weathering processes result in many of the crater physical features and ejecta material get covered by layers of regolith, making some of them undetectable using optical cameras. Synthetic Aperture Radar (SAR) is a powerful remote sensing instrument for studying planetary surfaces and subsurface due to the ability of the radar signal to penetrate the surface. It is also sensitive to the roughness, structure and composition of the surface material and the buried terrain.

Previous lunar-orbiting SAR systems such as the S-band hybrid-polarimetric SAR on ISRO’s Chandrayaan-1 and the S & X-band hybrid-polarimetric SAR on NASA’s LRO, provided valuable data on the scattering characterisation of ejecta materials of lunar impact craters. However, L & S band SAR on Chandraayan-2 is designed to produce greater details about the morphology and ejecta materials of impact craters due to its ability of imaging with higher resolution (2 - 75m slant range) and full-polarimetric modes in standalone as well as joint modes in S and L-band with wide range of incidence angle coverage (9.5° - 35°). In addition, the greater depth of penetration of L-band (3-5 meters) enables probing the buried terrain at greater depths. The L & S band SAR payload helps in unambiguously identifying and quantitatively estimating the lunar polar water-ice in permanently shadowed regions.

A convenient approach towards discerning the radar information is to prepare images using two derived parameters, ‘m’ the degree of polarization and ‘ä’ the relative phase between the transmit-receive polarized signals.

Figure 1 shows the m-ä decomposition images of the first datasets acquired over lunar south polar regions in L-band high-resolution (2m slant-range resolution) hybrid polarimetric mode. It produces colour composite images where ‘even-bounce’, ‘volume or diffused’ and ‘odd-bounce’ scatterings of a pixel are represented in red (R), green (G), and blue (B) image planes, respectively. It is important to note that the obtained resolution is one-order better than the earlier best by a lunar-radar.

Figure 1: Conceptual diagram explaining different types of Radar scattering mechanismson lunar surface and sub-surface

Figure-2 presents many interesting facts about the secondary craters of different ages and origins in the lunar south polar region. The yellowish tone around crater rims in the image shows ejecta fields. The distribution of ejecta fields, whether uniformly distributed in all directions or oriented towards a particular side of a crater, indicates the nature of the impact. The image shows craters of vertical impact and oblique impact on the top-right and bottom-right, respectively. Similarly, the roughness of the ejecta materials associated with the impact craters indicates the degree of weathering a crater has undergone. Three similar sized craters along a row on the bottom-right of the image shows examples of young crater, moderately weathered crater and an old degraded crater. Many of the ejecta fields seen in the image are not visible in high-resolution optical image over the same region, indicating the ejecta fields are buried beneath regolith layers.

Figure 2

Chandrayaan-2 Orbiter’s DF-SAR has been operated in full-polarimetry mode- a gold standard in SAR polarimetry, and is the first-ever by any planetary SAR instrument. Figure 3 shows an L-band fully-polarimetric, 20m slant-range resolution image of Pitiscus-T crater. The image is a colour composite of different transmit-receive polarization responses of the imaged region.

Figure-3

 

[KapitaanAli]

Oct 31, 2019
Detection of Argon-40 in the lunar exosphere

Planetary scientists prefer to call the thin gaseous envelope around the Moon as the ‘Lunar exosphere’ since it is so tenuous that the gas atoms very rarely collide with each other. While the Earth’s atmosphere near the mean sea level contains ~1019 atoms in a cubic centimetre of volume, the lunar exosphere contains ~ 104 to 106atoms in a cubic centimetre.

Argon-40 (40Ar), which is one of the isotopes of the noble gas Argon, is an important constituent of the lunar exosphere. It originates from the radioactive disintegration of Potassium-40 (40K), which has a half-life of ~1.2 X 109 years. The radioactive 40K nuclide, which is present deep below the lunar surface, disintegrates to 40Ar, which, in turn, diffuses through the intergranular space and makes way up to the lunar exosphere through seepages and faults.



Schematic of the origin and dynamics of 40Ar in lunar exosphere

The Chandra’s Atmospheric Composition Explorer-2 (CHACE-2) payload aboard the Chandrayaan-2 orbiter, is a neutral mass spectrometer-based payload which can detect constituents in the lunar neutral exosphere in the range of 1-300 amu (atomic mass unit). As part of its early operation, it has detected 40Ar in the lunar exosphere from an altitude of ~100 km, capturing the day-night variations of concentration. 40Ar being a condensable gas at the temperatures and pressures that prevail on the lunar surface, condenses during lunar night. After lunar dawn, the 40Ar starts getting released to the lunar exosphere (blue shaded region in figure).



Variation of Argon-40 observed during one orbit of Chandrayaan-2 during dayside and nightside of the Moon. The observed partial pressure has to be refined for the background and other effects to infer the density of lunar exospheric argon. The observations when Chandrayaan-2 was on the nightside is indicated by the black solid rectangle at the top of the panel and the two vertical dashed lines. Being in a polar orbit, Chandrayaan-2 enters the dayside of the Moon crossing the north pole, traverses through the dayside and enters the nightside after crossing the southpole.