Bharat Rakshak

could be large meteorites embedded in lunar surface ?

^^ Meteorites on impact would have been vaporized almost totally on impact. I doubt large embedded structures of meteorites would remain.

even on moon ? without any atmosphere to burn it down and a much lower gravitational pull ?
even on earth many meteorites survive as small pieces after impact, where the structure is already weakened and eroded by the atmosphere and the impact velocity is that much higher.

even on moon ? without any atmosphere to burn it down and a much lower gravitational pull ?

IIRC it's the power of impact that causes vaporization of most of the meteor. Temperatures rise so much that the whole meteor evaporates. So very large meteor structures are not possible.

Rahul M,

The 'shard' (first seen by lunar orbiter 3) is over a mile high.. and one of the tower photographed by zond 3 on the far side of the moon is estimated to be close to ten miles high. Neither is surrounded by a crater. Just too weird..

Hope, the moon is not a "Green Cheese" to 'embed' miles long meteorites in it and ends up something like a blowfish in due course of time.
IMHO, meteorites don't collide with objects in a 90° straight trajectory, instead they take shallow angle of trajectories, especially with huge bodies like moon, which are many times bigger than meteorites.

And FYI, in space, objects move some good hundred km/second. Not inch by inch. Any encounter of two bodies ends up in a huge collision.

ss_roy, just a random idea.

harbans, that's what I'm saying.
'g' (or whatever its lunar equivalent is called) will be much lesser on moon --> much lower impact speed --> much lower kinetic energy --> much less energy to convert into heat.

a rough back of the envelope calculation tells me a body falling on earth will have around 21 times more potential energy to convert into KE and heat than an equivalent mass falling on the lunar surface.


not sure why the impact will be in a shallow trajectory just because the moon is a larger body.
care to explain ?


hello there, no need to take that condescending tone. I'm aware of what the velocities are like.
btw, any encounter between two bodies is always called a collision, huge or not.

Rahul ji, velocity of impact you're referring to comes into being if you drop an object of mass m from a hieght h both on moon and Earth. Indeed the one on the moon will impact at lower speed. But the influence of g on a meteorite collision on the moon surface has little value when the object itself is moving at many tens of kms per second. Almost every bit of the meteorite would be vaporized.

harbans ji, you are wrong to think that it is not the gravitational force that creates that tens of km/s impact. why do you think the re-entry parts of missiles enter earth with such tremendous velocity ? or why the space shuttle has to do so much coasting maneuvers before it can slow down enough to land ?
fact is most meteorites when they are 'captured' by a celestial object have very little initial velocity (relative to the celestial body) of their own to begin with.
in most cases the situation is (very roughly) more or less equivalent to bringing in an object from infinity, which is what I calculated. would be glad to be corrected of course.

incidentally, I found a pic of quite a large meteorite though not as large as the moon examples.
http://upload.wikimedia.org/wikipedia/c ... e_AMNH.jpg

fact is most meteorites when they are 'captured' by a celestial object have very little initial velocity (relative to the celestial body) of their own to begin with.

Rahul ji, i do not disagree that g does not play a part. It does. But when an object is on a collision course say with the moon or earth orbit at 80,000 km/hr would that really matter if g was a 6th of earths? Plus many of these asteroids and meteorites are ejecta from some deep space explosions so they do have massive velocities to start with. Fact is all objects in the universe already have velocities from the day of the big bang i presume..Fact is there may be several asteroids or metorites with sufficient velocities not to be pulled in by the Earth or Moons gravitational pull and pass by harmlessly.

Okay here's a nobel prize winner theory for those shardy things

Part 1: A meteorite hits the moon's surface at night, and out from a nearby huge hole leading to an ice/water reservoir below (like the type LCROSS is hoping to find), erupts a column of melted ice high into the skies, and .... freezes..

Someone please fill in the part 2 of the theory -- how the heck is it still staying there, unmelted??

i am outta here...

On a more serious note, ss_roy, I did manage to locate the "shard" in that image (with much difficulty) at the bottom of the picture against the moon's horizon

harbans ji, nitpicking : meteorites are supposedly from early days of solar system, not big bang.

it's true that many or most meteorites have high velocity to begin with but not all do. all it would take is one large, relatively slow meteorite from the asteroid belt for example to be captured by the moon. as the image I posted earlier shows some meteorites can survive such collisions. this scenario is not inconceivable right ?

then again, as ssroy points out, this theory doesn't explain the lack of a crater.

anyway, we are moving far off from the topic.
regards.

p.s. sumishi, wonderful idea, you deserve at least half a nobel !

Thanks bro!

Rahul ji, i got your point. But it's not necessary the object striking is from the asteroid belt or our solar system origin remnants. The incoming velocity would depend on where it came from (the asteroid belt, farther out, outside the solar system...) and what other massive objects it passed near on its way here ( passing by a massive object may either speed it up, make no difference, or slow it down, depending on the relative motions of the two). Lots of variables really.

The escape velocity from Earth is about 25,000 mph. That is the outward velocity an object must have if it is to leave the vicinity of the Earth's gravitational field. It is also the velocity acquired by an object originally at rest at a large distance from Earth, during its fall to Earth. Since most asteroids already had a significant velocity before they began falling to Earth, most of them will be traveling significantly more that 25,000 mph at the time they enter the Earth's atmosphere.

Anyways here's a good link for those interested on impact particulars if one strikes on Earth..i played around for some time here:

http://www.lpl.arizona.edu/impacteffect ... s_select=0

FWIW - on the "impact" of a meteorite on moon (or any other object for that matter)

One will not go wrong, if one just uses (forget "g" etc) the relative velocity of object (before it hits moon) and just uses (1/2mv^2) as total energy which will end up heating it up (and any dust cloud etc it raises)

Velocity of moon (wrt to say sun) is pretty much known (about 30Km/sec)
Velocity of the object (again from first principle ) - you can get pretty good value if you know where it came from ( Total energy is prop to "a" (or semi major axis) and all you have to do is to subtract PE due to gravitational potential due to sun (prop to distance from the Sun)

Relative direction you have to calculate (it depends on particular object)
(You may have to add - gravitational effect due to moon - but it really does not matter if you know the "v" before the impact)

Bottom line: depending upon the object and its velocity it may vaporise or it may not.

Many objects (eg comets) are just nothing but a dirty snow-ball (almost made of ice... and some are nothing but pure iron ... so mass may vary quite a bit too.

Just to add: If "large distance from earth" means really "large" then the escape velocity is about 4 times mentioned above..(about 42 Km/sec) (to as not only the thingie escapes earth but sun too..).. and if one consider VERY large (eg out side our galaxy) then it is of the order of 1000 Km/sec or 100 times the value posted...

The key point, of course, as Harbans put it, it is important to know where the object came from, to estimate relative velocity. (For example, if an object is coming from outside or 'edge' of our solar system. the relative velocity, in worse case, may be as much as 70Km/sec).. of course on earth most of the objects reach terminal velocity before they hit earth... and if objects are small enough (eg size of a bacteria ) they may even arrive quite a bit intact. (Bacteria's, if they come from space will survive )

Show me even one site from a credible organization which mentions this "Moon Shard"

Is there a site from NASA? Encyclopedia Britannica? Something?

No, I don't think so.

As an aside on "credible" organizations, my take is that no organization is credible. Any organization is basically a conglomerate of humans who have innate propensity to play devious politics and drive events through biases, ego clashes and one-upmanships.

The accepted geo-centric model of the universe held sway for so long till Copernicus, and later Kepler and Galileo, came along to upset the apple cart. Galileo's trial for the helio-centric heresey (he was threatened with torture and imprisonment) is a blot on the history of the credible church.

Einstein could come up with his relativity theories with such elegance because his mind was not indoctrinated by the tunnel visions imparted by normal school education. His theories showed up the limited applicability of Newton's laws. The infallible Newtonians took a fall.

But then, Einstien too, as he bacame older and more set in his ways, could not come to grips with Quantum Mechanics. "God does not play dice!" This was a result of his belief in ordered reality. The greatest scientist in recent history falters!

So who/what is credible today, need not be tomorrow. BBC's news are so negatively slanted against India. Credible?

My two pennies worth...

Sanjay M,

If it is present in a space probe photo (follow my previous links) and casts shadows (with correct orientation) on the moon- it exists!

Is it an alien artifact or a natural formation, Who knows? But we should try to have a closer look.

Okay, no more on this, it makes me laugh too much.

Here's a nice article on G Madhavan Nair:

http://timesofindia.indiatimes.com/news ... 083917.cms

A hilarious take on the water discovery on The Daily Show. Aasif Mandvi is awesome.

http://www.thedailyshow.com/watch/tue-s ... space-naan

Here's another humourous moon musing on Chandrayaan:

http://www.mid-day.com/opinion/2009/oct ... pinion.htm

ISRO to Replicate Lunar Surface for Testing



Uhh, wow - what happened to emphasis on low cost?

Look, I want Chandrayaan-2 to succeed, but I don't see how producing a large sandbox with fine-grained dust should cost Rs 15 crore!

What are they going to do - build it aboard a "vomet comet" airplane to simulate 1/6 Earth G?

Somehow I don't think the mission is going to fail if you drop Rs 10 crore off the price of the sandbox.

Maybe there is something else there in the sandbox.

Perhaps the ability to simulate the temperature extremes on the lunar surface? ISRO is once bitten twice shy with the temperature aspects for sure this time around. Makes sense that they'll want to expose lunar rovers and later Antarikshyatris to a more realistic environment.

Exactly... Why don't they just test their rovers on Indian roads. They precisely simulate lunar, martian and what-not surfaces.

They will have fine dust, pebbles, stones, potholes, rocks, boulders, puddles and slush (now they have discovered water on moon), idhyadi. And the temperature varies from burning to baking to scorching.

And oh, there is an old saying that anyone who managed to learn ride/drive on Indian roads can drive anywhere in the universe.

And of course, GOI spends crores and crores to build these roads.

^^^^

And this pretentious observation adds what to the thread?

re: Lunar environment simulator - 15 crores does seem a little much, however I am pretty sure if they want to simulate lunar environment, they very well can't do it with Earth atmosphere. That certainly means a vacumn chamber. Additionally the extreme temperatures found on the lunar surface would also need to be simulated.

So if they are doing a fair sized vacuum chamber with temperature controls and enough room to enable movement of the lander the price seems ok AFAIAC~ $3 m.

This is not clear -- are they going to replicate a large swath of the moon here on earth and run the two rovers simultaneously? Thats what it reads like. I'm more inclined to think that they will use the terrestrial rover to game play navigation strategies for specific obstacles before having the moon rover do the same.

You have to simulate high vacuum, ionizing radiation (all types), the right kind of dust (composition, size) and temperature extremes beyond those that occur on earth.

The rover has to survive all of this abuse and still keep on working. Plus the facility is used to test workarounds for problems if anything goes wrong on the moon.

I think that operating a deep-sea robot submersible would be more difficult than operating a wheeled vehicle in a vacuum. At least there's no crushing pressure, or any water currents.

Haha, thank you. Best clip I've seen in a while!

Best 3-D images

Guess we missed this. All talk and no pictures.

Some more links

Lunar surprise
Interview with Dr J.N. Goswami
To Squeeze it out
A settled question?
Telltale signs

TMC.

So ISRO uses CAD CAM to design everything. Amazing and Jai Ho!

NASA rocket on crash course with moon

For all the naysayers so far. MIP worked and saw trace of water well above the surface layer on the moon.

For those interested in watching LCROSS bomb the moon check these sites giving live coverage:

http://www.mmto.org/lcross/

http://www.nasa.gov/help/multimedia/odplayer.html

Oh well .. no spectacular videos...
But here is a story about the crash:
U.S. Spacecraft Crash on Moon in Search of Water

Jayant Narlikar Urges For Checking The Presence Of Life On Moon

Well this is as inconceivable as "water on the moon" was some time ago..

But of course, goes without saying. India needs soil samples from the poles. The Chandrayaan 2 mission needs to be proiritised, this is an extremely important goal.


He mentioned that the balloon testes, which were conducted in 2001 and 2005, have proved the presence of micro-organisms at a height of 41 km from earth’s surface.

Don't these writers proof read their stuff, I don't unless it is for publication.

Guys,

Found two clips from space forums on Chang E 1 3D mapping. Maybe can shed some light on their effort.
http://video.sina.com.cn/news/c/v/2009-09-29/121045507.shtml

http://space.tv.cctv.com/video/VIDE1210773634173393

The moon does look pretty amazing in 3D.