My 24th birthday

It was a spur of the moment , I decided to pack my bags and go on a solitary vacation for my 24th birthday. Aish was going to live the most adventurous and spectacular moments of her life! I frantically searched for places. Deepa (my roomie) pointed 'Palm Springs'. Humongous peaks, beautiful palm trees, rustic desert landscape, strolling in the valley, mild 24/7 massage spa accelerated my propensity towards this place.

It was 12 July 2014, about 5:00 am in the morning. Aish was really excited about travelling and especially checking things off her bucket list. The take off from Tucson runways are always exciting! Massive mountains , conspicuous cacti - I lost myself gazing the beauty of Tucson. That was not the first time I was flying from Tucson. But, every time I did, it was special and spectacular!

As we approached Palm Springs, I saw the massive desert city sheltered by San Bernardino, Santa Rosa and San Jacinto mountains. A thought flashed and Sky Diving made its debut! The plan was simple - I'm going to get crazy and seize the moment for next three days in my life and Sky diving seemed to be a perfect addition.

View from the Top 

As I was delving into my thoughts, the pilot announced that we will be on ground in a few minutes. As the plane descended, I could see the bright desert landscape. We landed and my Day 1 begins here:

Day 1 : I reached Palm Springs mountain resort which was close to the downtown. I unpacked and was all set to ride the world's largest rotating tram (http://www.pstramway.com/).  Everytime the tram rotated and inched the slope, there was a wave of excitement. We were all strangers, but we joined hands to happily feel the adventure! The valley was breathtaking and at the end of our 10 minute ride, I was at the second highest point in Southern California, San Jacinto mountains.

The tram cables

The Tram!

Day 2 : That was one moment! Skydiving @ Perris Valley. The airplane, 'Shark' was ready to ascend. I humbly agree, it was not a fearless moment. But, the excitement surpassed the fear! We reached 12,500 feet and it was our turn to jump. My brain paused; My heart mellifluously spoke; Life was happening right there! I moved with wind , just like a bird. The aerodynamic lift, thrust from the parachute, and the gorgeous view of the valley from the mid air  invoked the puerile memories of watching Disney movies. Indeed, my 24th birthday was a fairy tale. 

Tandem Jump @ Perris

A sense of accomplishment and confidence sprung in my heart. The city had much more to delight me. As we drove back to Palm Springs from Perris, I could vividly see the LA smog. The smog thickened as we approached Loma Linda. I could see for myself why chemists loved California smog! I was charmed too!

Day 3 : Nothing beats a refreshing spa massage after two days of adventures! It was a hard moment to bid adieu to the city which stood with a mighty valor , yet humbled before its audience with its mesmerizing beauty!

Blogging and graduate school - Are you kidding?

Are you a PhD student/ a researcher, busy to breathe, and busy to get excited kind? Have you transformed into a grad student who has placed the blog on the back burner? Hold on, I felt the same way. Perhaps, blogging could be a game changer!

It was a Sunday evening , when I was frantically piecing together a bunch of scientific figures for my talk. That's really what drove me to blog again. I realized ,I missed the art of scientific storytelling very much. This was indeed a game changer! Here I am, happy to jump start my blog to help you connect with my research. If you buzz around , this is the sort of interesting information you will learn about my research. 

1. What makes the cultural capitals of India appear hazy during the winter months and what makes the summer skies vigorously turn brown in the southwestern United States? - Are emissions the only culprit?

Desert dust storms

Rashtrapathi Bhavan, Delhi : Morning haze



2. How can we combine data from different platforms and sources to optimize the data analysis - yup, you got me! I'm not a data assimilation expert. But, that's where I'm heading!

An example of Ozone data assimilation system (Lahoz et al., 2010

3. How can we design more efficient satellite missions and instruments to tackle major air pollution issues?

While you wait for my other blogs , stay hungry, stay foolish! Looking forward to your comments and creativity!

Blissful Bayesian....

That was a pleasant Friday evening. I was counting the papers that will go into my pile for the weekend. I needed some form of blissful optimism and a sheer motivation.

I started flipping through the pages of this ebook " The theory that would not die: Bayes' Rule Cracked the Enigma Code, Hunted Down Russian Submarines, and Emerged Triumphant from Two Centuries of Controversy" by McGrayne.

So, tell me, what comes to your mind when I say 'Bayes' theorem'? Questions on red urns and white balls from the high school math book? But, when i started reading the book, I was surprised. I realized how powerful this tool is. I wondered why I never learnt Bayes' was all about updating our initial beliefs based on the new evidences. Well, this is what we do in every walk of our life. Face recognition, separation of spam emails in our inbox, weather forecast, and the million dollar question of climate change, everything revolves around this idea of updating our prior belief. Wow, that was amazing to realize! If you had watched the TV show 'fringes' most forensic discussions in this show involve Bayes' in some form or the other.

It inspired my thoughts and made my evening. I was aspired and I said 'Come on , break the leg' and carried the pile. As I walked , I resolved I would atleast take them out of my bag this weekend.

Stay online. Back as a blogger to share new experiences as a Ph.D. student. Let's see how these stories strengthens my prior belief on 'life as a scientist'.

Message from a haboob city!

I haven't posted for a long while. To break the lull, lets do some brainstorming !

"Haboobs/Dust storms/Sand storms" - If you were to listen to these phrases, What would immediately strike your imagination? - MIP3 and Tom Cruise being chased by a towering wall of dust? Remote martian deserts with twirling dust devils? Climax from most of the sci-fi 'end of the world' movies? In a time where we proclaim about global warming, drought periods and climate change, it might not be wildly imaginative to say that they we no more need a movie to show such extreme behemoth events, we have them all happening right in our pale blue dot! Well, that's exciting! Oops! Dangerous! well, this is how I typically reacted when I initially heard about the July 5,2011 haboob in one of my graduate classes.

"A hundred year event - A mile high , 100 mile wide dust storm roared through Phoenix bringing the visibility levels to zero", quoted a reputed news report. People of Phoenix freaked out saying they have never seen such a massive dust event in their lifetime. That was the giant Phoenix "HABOOB" (July 5,2011) and this is what my research delves into.

HABOOBS

We all know about dust storms and the fact that dust particles lofted during these events are harmful to human health. But,why would there be coined a sophisticated term to describe them and why should we talk care when we have ample science questions in the queue? I had similar questions too.
The answer would become apparent if you sneak a peek in to this video http://www.youtube.com/watch?v=8vQMuwRjI6s. This was the tumbling giant Phoenix haboob (July 5, 2011).

WHAT ARE WE INDEED WITNESSING DURING A HABOOB?

If you were to picture blowing dust from all directions and a beautiful dust cloud , probably you are getting only half of the story. I hear your question - why, when and how does this start if this is not a quotidian blowing dust event?

Haboob is a common term in Africa and middle east Asia during the summer time monsoon . But this was less common in US, until the day when NWS folks, weather agencies and NASA itself turned their eyes to look at something so massive overtaking the western United States. The story begins on a hot summer day when a line of thunderstorms form over a region. When the meteorological conditions are right, they collapse creating what is called as a 'downburst' (cold parcel of precipitation outflowing from the thunderstorms and reaching the surface).

Such down bursts create strong winds and the thunderstorm outflow or the cooler air mass that reached the surface moves towards the region of lower elevation. As they progress, they pick up everything in their way and act as a self fueling engine. They trigger storms , cause air to rise up and descend and thereby creating a line of thunderstorms.

Haboobs = thunderstorm+downburst+strong winds + dust - so, this is indeed complex !

STORY OF PHOENIX

Unfortunately, Phoenix happens to be a valley at the lowest elevation when compared to its neighboring areas. So, the outflows from Tucson thunderstorms and those from the north typically move towards Phoenix. Also, the potential dust source regions extending from Tucson to Phoenix fuel the event. As it approaches Phoenix, dust walls from several pathways (typically, from north west of Phoenix, from Yuma and from Tucson) converge leading to such an incredible amount of moving dust. Dust storms occurring from these meteorological processes are called 'haboobs'.

It is highly rapid and spontaneous. Hence, this appears as a challenge for forecasters. My research uses a weather/chemistry model, satellite observations and ground truth to predict such massive dust storms and analyse the fate of dust from the haboobs.

If you are interested to learn more about my research and modeling and prediction of such massive dust storms , please stop by the abstracts and talks posted in my website : https://sites.google.com/site/spaceaish/graduate-conferences/agu-2012

A Radiant evening under starry skies

Every night as I walk back from my office, I gaze up and wonder what is it that breathes fire into the equations and makes a Universe which is inexplicably beautiful and enormously awesome! It was yet another amazing night at a ‘Star-Party’ organised by UoA Astronomy Club.

In the shadow of the super-jumbo, its soaring flares and dazzling Planets:

For the first time, I saw the stupendous Sun with H-Alpha filter. The filter can turn off all the wavelengths other than red. H-alpha is a grossly expensive filter used for solar flares and sun sport viewing. As we approched dusk, we set our telescopes for catching some of the dramatic objects of Tucson’s night sky. Saturn with continually shrouded thick clouds was the forerunner to signal the splendid arrivals. 30 degree zenith from Taurus, Saturn appeared with its dusty rings and gravitated satellites – Rhea, Enceladus and Titan.

Every night I crossed the Bio-5 dept in UoA, I saw an object at 50 azimuths from Taurus. I always thought that was Mars. For all my surprise, I found today that was Antaris (rival of Mars). (Antaris is a look-alike of Mars). The best visible, familiar Mars made the final entry with its beautiful Mie-scattering effects (May be Martian aerosols are the best ones to place the bet when it comes to Planetary Aerosol Science. You can probably imagine the entire chemical cycle cooking up in the heart of dust storms almost every Martian day).

When the world went Kepler crazy!

From the flurry of results gleaned from Kepler and other orbiting satellites, we are taking tender steps into the fabulous discoveries of Planets in this Universe. When Kepler discovered Gliese 581 planet series in Goldlilock (habitable) zone outside the Solar system, the world went crazy! Peer reviewed papers, endless analyses, fuzzy engineering and geeky insights soared to prove microbial or intelligent life elsewhere in the ‘waiting to be unravelled’ category. But the debate continued – is it worth investing in such scientific expts? Why hitch hike on Gliese when we have not yet solved the Arctic-Antarctic ozone puzzle on Earth? (Wondering why Arctic? Take a look – Nature 478,469–475 (27 October 2011 doi: 10.1038 /nature10556).

As we get closer and closer to cornering the unifying theory of Universe on one side, we cannot single out Earth and justify science on the other side. They must occur simulatenously. To put it in perspective, ‘Comparative planetology’ is the need of the hour! Scouting through a couple of examples might convince you on this concept. I was in Aspen for a conference on Exoplanets last January (Exoclimes - http://www.astro.ex.ac.uk/exoclimes/). Some breathtaking points I learnt from the conference:

Mirror Mirror ….

“Sorry I was an early bird, but please do include me now” - Oxygen warming- this happened in the early history of Earth and is now seen in Exoplanets.

Hot Jupiters out there - “I’m a hot jupiter too. Study me to understand Ur own Jupiter! I have oceans, I’m tidally locked just like Ur Earth’s moon and I have atmosphere!”Many such Jupiter sized Planets exist outside our solar system. Infact, one of the authors had used MODIS images and algorithms to model exoplanets. I went speechless!

The dusty ferric mass – “I have more mighty dust storms! Look how powerful I’m! I completely inactivated the little rover you sent to spy on my surface when you tear Ur brains to tease out the chemistry and physics of Haboobs and Dust devils in your south west and Sahara, I have enough. Also, when you are mulling over better GPS systems for future, you can push your technology and creativity forward by experimenting with Pseudolites in my surface. Why not use my foot prints to better understand your home planet? By the way, if you still wonder, who I am- I’m Mars, the pretty red dot! “

Spilling the beans!

Everytime Astronomers say “star”, they’re probably looking for a way to say “life” because Life, star and Planets are inter connected. To satisty the great expectations on Earth and to solve the mysteries here, studying Earth just within Earth is not sufficient. Confluencing datasets from Earth and other planets is the ultimate decider of the veracity of our results.

The starry and magnificient star party left me with the thought that someday, we might scout the serendipitous moments with the computer touch screens taking less than a minute to whirl us from one planet to another from one marvel to another - Mercury’s frightening thermal inertia, Earth’s rewarding monsoons, mighty Martian dust devils, titan’s methane lakes and light curves from Exoplanets will be featured all in one room in a way similar to images from different satellites and different landscapes of Earth which we have today!!!

.mat to .avi conversion bugs

Animations and Modelling are the order of the day for Earth Atmospheric Scientists. Matlab movies although visually pleasing sometimes end up being a trouble maker. It is not difficult to create a movie out of 50 images in Matlab. But what makes it challenging is to retain the same fps(frames per second) after we convert .mat to .avi or .mp4 file. When i did this, my fps spec in Matlab had no impact on the .avi file i had created. 2 frames per sec or 10 frames per sec appeared the same when the .avi file (created in Matlab) was played in media player. Neither did media player allowed me to change the fps. If you are thinking to regenerate them using any other movie format, forget it! Decoders can go wrong anywhere ! So, buckle up! Here we go heading towards the solution! Microsoft GIF animator. Import your file, select all images in the left, change to animation tab , specify the repeat mode-->switch to image tab--> wow! there it is-! change the number of frames per second, width, height and you are done! Insert into MS-PPT- as sweet as a nut! I'm not sure if this is a Matlab bug. Any other suggestions from readers are most welcome! Thanks in advance! Enjoy Modelling!

Speaking of DNA science ....

What would it require to think like Einstein or be a charismatic pioneer like Steve Jobs or solve the half length puzzle left by Leonardo da vinci? In other words, how would it be to inherit a glorious life of our ancestors (some hundreds of years back) who were once stalwarts in different fields? Before you read ahead, pause... and ponder... 'Is it plausible to argue from modern bio sciences perspective that we can bring back the genetic cognitive skills and unique potential of the ancestors in their present generation'?

I was perfunctorily flipping through a you tube clipping on the movie '7am Arivu' on a busy monday night. I took a break to see if there is something interesting happening in Kollywood. As I was watching this movie, I mulled over the above question for a while and my answer was No. I said to myself, such strategies can turn true just for a two hour science fiction movie.

A day after, I realized I was wrong. It was so surprising to hear about a pionering research field in stem cells and life sciences that actually focus on DNA activation to reshape an individual's cognitive skills and personalities such that he can retrieve any unique feature which his/her ancestors had in the past. Also, these stem cells are capable of re-activating a part like Brain cells which usually dont show signs of growth unlike other parts in the body. These techniques are being researched to solve medical questions on Brain-death, Coma etc. Isn't that amazing? Thanks to Navneetha for an interesting chat on this technology. Good to see a film conveying a scientific message in Kollywood after a long time.

Summer at CREST,IIA

A classical style Architecture with Grey handsome building blocks; The Campus harboring exotic and indigenous Floral types; An island of snakes and jackfruit trees; Silent yet vibrant labs - This is where I spent my summer 2011. It’s dear to me for two reasons – partly because the ambience was very much alluring and partly because I could meet a few interesting people without whom my stay and also my research could not have been as rewarding as they were. I would count them to be a purple patch of my undergraduate life as I got to live my dreams of being at IIA.



Mesmering beauty!

The weather yarely turns from mild sunny afternoons to darkened evening. Congenial research Atmosphere with pleasantly mottled trees adds to the pulchritude of CREST. G2, My room in the ground floor - I would call it a heaven! I was even wondering if someone designed the room with the prior knowledge about my ‘Dream-lab’. Huh! Yeah, I had always yearned to work at a place where I would relish the beauty of gardens as soon as I open the curtains of the room!



Gestures not to scale!

Sonam, Peppu, Mrunalinee and Anusha – my chat buddies at CREST. ‘Impacted and elliptically transformed Spherical Balls’ – That was the Bonda which was made in the canteen!!! This is a sample of our lunch time scientific chats… The prey was Mrunalinee – A dimension problem in our description, finally concluded it saying, the gestures were not to scale!!

Census of our activities

Nothing could really substitute the dinner time chats, mid night star gazing, Open Air theatre dance classes, Cooking at pantry, CRESTFEST 2011 which made our final rocking days of dance performances at IIA auditorium. Another member of our group was my sweet ‘Taffie’ …Poor creature, I have scared it a couple of times by my shrieks.




Clean-Room world

I could still remember that our laughter would have torn the roofs apart when we renamed CREST as ‘Culinary Research and Education for Students and Trainees’  we had another Handsel of visiting the clean rooms of Astrosat’s telescope. Special credits to Raj for his vivid demos….We went crazy when we wore the clean room suits and more animated when we were given the masks and gloves as take home gifts 


Normalization of deviance – My research on 2m telescopic IR data

Venus Image captured through IIA 2m telescope on 3rd December 2010:



Waiting and wondering how much CREST enthralled me, my mind alerts me not to lecture my readers to boredom. So, I’m leaving my research thesis to find a place in my website. For all those intrigued by the Planet Venus and yearning to trace its Cloud Physics, please find my technical Report in my website.

Watch out for Mars, Hellas!

Hellas, Next stop for Water in Mars!
“You bloom quickly, you do what you need to do, and you go dormant” – Ms.Pratt, Bio-Geochemist, Indiana University.
This holds good not only for Martian Microbes but also for transient water locked up inside the Polygonal cracks in Mars. The Martian Water Exploratory program got more moxie when the recent NASA’s images from MRO mission revealed dark shifting streaks in Hellas Impact Basin.


What’s not in Morsels of Hellas!

The discovery points out to flow of liquid brine in Hellas in summer. It was highly surprising when I superficially read the history of this region. SHARAD radar in MRO previously discovered 250m thick water-Ice on upper crater and 300-450m on middle and lower crater in Hellas. Mars Express HRSC images located 3.5-4km massif and Glaciers with viscous material running down from the rim of the crater. Starting from VIKING’s temperature measurements, Hellas has been much enticing due to its low altitude, favorably high temperature (-18C in late afternoon to -46C at nights- from VIKING), and high Atmospheric vapor pressure of over10mb.the below image shows some gullies identified by MGS, Mars Orbital Camera


Pretty Evidences for Perplexing questions:

Question 1: Why the streaks vanish each winter?
Question 2: What darkens the soil?

The dark streaks point to events caused by Liquid water albeit absence of Spectroscopic signatures of pure water. The albedo variations and sharpness of streaks calls for the younger ages of the streaks. The small ridges shown in the image explain the deformed ice. This provides the key for liquid water beneath the Martian Regolith. The deformed sub surface ice may break through the Crust in short lived outbursts enabling the downhill transport of debris. Fluids migrate through these fractures which are caused by rupture of subsurface liquid reservoirs. The below image shows the Marstian glaciers in Hellas captured by the HRSC camera in Mars Express (ESA)



Numerous Martian Gullies detected in the same basin hypothesizes the flow of Underground fluid either pure water/brine/acidic/Alkaline. The dark deposits in the rim of the basin are caused by internal erosion. The Atmospheric pressure of 11mb at the bottom of the basin (subsurface) and temperature above triple point of water beneath the Martian Soil in Hellas reinforce the striking presence of Ground Ice which melts in summer causing the dark streaks. Thus the morphological features in the image presumably suggest carving by Ground water/Ice, perhaps through capillary action rather than flowing brine on the surface of Mars.

P.S: The aforementioned points complement the research evidence submitted by UA team.
This link can make the reading further interesting :http://www.skyandtelescope.com/news/126800063.html

Looking Back.. Days at CEG...

11.33am on May 12th 2011- the countdown began! Hang on! That was not a countdown for launch. Rather that was for departing my CEG officially as a student after surrendering my Smart Card. The countdown paused as I walked through my tantalizing campus and its evergreen spots. Reminiscing my blissful days, I was heading out towards the CEG parking lot (where my vehicle often assumed special place as locking my vehicle had escaped my memory plenty of times in CEG). The walk allowed me to pick up tell-tale signatures of nostalgic moments which CEG has given me since 2007 August. Every spot tied me to some specific occurrence of my student days – CPDE, Physics Lab, HOD office, CEG Canteen, our surveying field, and the most cherishable place –Our IRS (Institute of Remote Sensing) – whose walls will re-emit the memoir of 2007 batch in future years.



I vividly remember entering the ‘CEG campus’ way back in 2006, when I was in my 11th standard. I now feel proud to be an alumnus of the same College. My freshman years in college gave me lasting experiences. My First SQC meet was unforgettable! Believe me, this was the place I realised It was high time that I had an active ‘Email id’! Archana, Aarthi, Abhi – friends who made my initial months at CEG and from whom I learnt a lot. Neeraja (my senior) – My Engineering graphics tutor , but for her, my internal tests would have degenerated into a farce. Red Cross camp at a village near Kanchipuram was a giant pooper-scooper that scooped waves of self-confidence from me.



Sensor Design, Microprocessors, RS, and GIS– Everything paraded my mind....Despite listening to plenty of talks – the Million dollar question lingered – What’s GI? To me, it was a deep magnetization effect – Satellites and Remote Sensing, Yup that was my fantasy world! The Pandora box was finally opened when we arrived at 2nd semester and started probing the subjects of Geo-informatics. Then, GI appeared much mottled with farraginous topics than I had expected. Although the sign on the door was then unveiled, we had to really puzzle over the pieces to comprehend the close connection between different subjects.



Speaking of second year brings the most intriguing bird in its flock – Work on ‘Pollution’. My research got gravitated towards Pollution, Climate Change and Global warming. Conferences/Symposiums kept me occupied! I was then able to patch up the titbits of GI.

For every student there would be a Prof of his/her choice and so it was for me. I loved attending Remote Sensing and DIP classes by Vidhya Mam (Asst.Prof at IRS). Lost the opportunity of presenting her a nice greeting card on the last day...Yet, holding it to gift her next week... :)

My Internships –Experiences which gave much Momentum for my undergraduate life! They gave me opportunities to amplify my abstract ideas, think farther yet deeper into my research. My days at RRSC – B’lore, IISC, SAC, and PRL really made a striking difference!

Pre-final year and Final year – Halcyon days in College Life. Every day boasted a special significance. September 22nd 2010– an exceptional day for everyone in 2007 batch – The most precious terrace was opened and the Theodolites decorated IRS’ terrace on a darkening evening even after 8pm in the night! Oh friends! Neither that was an extra class of survey nor we had changed our usual location of survey (playground)...It was a moment when Earthlings enjoyed a rare honor of sighting JUPITER! ‘Jo’ (HW I call Jupiter) was just 3.51 AU away from our home planet. I would humbly direct my readers to my friend’s blog to know more on JOMAP (Jovian Measurement and Positioning) - http://archana4890.blogspot.com/. Thanks to my friend for the great piece of writing!My project helped me to live my passionate days for a planet which is a smorgasbord of volcanoes - Yes, My FYP was on Surface-Atmospheric interaction in Planet Venus!



Times of Geohorizon, Techofes, Kurukshetra 2010 and 2011 radiated much knowledge on team management and leadership. Looking back, they were heady stuffs! We had to make ambitious plans on a broad suite of issues within the stipulated amount of time. Hats off to everyone who made it to reality! Chill-outs with friends, Survey camp, IVs shared the inimitable moments of my life.

These Elysian days ended when I finally surrendered my Identity card. I signed the alumni form and marched my way down the ‘Red Building’. A mild smile occupied my face and I paused to mull it over. I wondered at the long way I have travelled from 13th Aug 2007 to May 12th 2011- From the day, when I ignorantly asked one of my friends, “Face book! Yeah, I have heard. Can you describe me how to use it?” To the day when I narrate the same experience in my blog space. Bye Bye CEG - With deep gratitude to this place and humble bow to many inspirational personas.

CRATER : HOW IT HAD ITS COMING?

I have always wondered why many lovers of Planetary Science are raring to get off to the surface and ponder on the Craters with great alacrity. But, I myself was agog at the processes of Crater formation after a deep reading on plethora of controversial answers given to this question of ‘Crater formation’ in our Solar System. Thanks to Prof.P.Devadas for his book on ‘Igneous and Volcanic Origin of Lunar and Planetary Craters’.

While the telescopic and Spacecraft observations have provided treasure trove of information on the Surface features and Atmospheres of Planets and Satellites, the geophysical processes involved in the formation of craters, crater lets and ridges are still remaining a tangential question. The two most important processes of Crater Formation that are debated are – 1) Igneous and Volcanic Origin 2) Exogenous Impact.




A dogmatic assertion towards Impact Craters exists despite the irrefutable morphological evidences to the contrary. Many Lunar Craters have volcanic fumaroles and vents. The bright rays from these Craters are gas blown deposits from these vents and crater lets. Further, the forces attributed to Impact cannot act so extensively and so uniformly as to cause these circular structures on a large spherical surface with differential crustal hardness. The Lunar craters show the lava flooding on its surface. Such flooding events seem to arise from the central peak. It is evident from the Lunar Orbiter 2 photographs that the bottom most layers have spread farther distances with successive layers progressively on smaller areas. This causes folding of the upper layers.

On examining the Earth-Moon geometry, it is ratified that any exogenous body must first overcome the Gravity of Earth before impacting the surface of the satellite. This is the case in most of the Planet-Facing Satellites. There is a high probability that the exogenous body is pulled towards Earth’s Gravity and burnt in its Atmosphere. It has also been suggested that the primordial Atmospheres of Planets and Satellites were very dense and hence any object entering the satellite would be obliterated by its Atmosphere. This would either cause a soft landing or less impact due to negligible mass of the impacting material. Earth’s moon had a dense Atmosphere in its past. But it lost its Atmosphere to space due to less Gravity.

The surface topography of Mars (Hellas Basin), Venus (Franklin Crater), Callisto (Valhalla Basin), Galileo crater in Ganymede, Tyco crater in Lunar Surface and many other calderas are also attributed to Igneous and Geophysical origin rather than Impact processes.

Thus, the Author concludes that the impact events do occur in Solar System. But, a preconceived idea of Impact craters for all circular basins cannot be accepted. Also, no morphological impact evidences like impact splashes or regolith melting have been found in the surrounding areas. All these factors drive home the message that most of the Planetary Craters are endogenous in Nature.

I would be happy to find some debatable and controversial theories from my Readers in the comments page.