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Old 21st February 2013, 16:20   #91
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I just can imagine how gravity assist might be put to work! Imagine a spacecraft going on a journey to some planet in a particular system, which has a few planets and the course will have to be plotted in such a way where our spacecraft takes a near orbit approach to the other planet, using its gravity to accelerate and then power out on its original path, Slingshotting with the help of gravity from planets, this will save a lot of energy and time!
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Old 21st February 2013, 21:25   #92
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I just can imagine how gravity assist might be put to work! Imagine a spacecraft going on a journey to some planet in a particular system, which has a few planets and the course will have to be plotted in such a way where our spacecraft takes a near orbit approach to the other planet, using its gravity to accelerate and then power out on its original path, Slingshotting with the help of gravity from planets, this will save a lot of energy and time!
never really understood that slingshotting. I understand that when you get near a planet gravity will start pulling you towards, adjusting the trajectory and accelerate, but as soon as you pass it wouldn't be the opposite be true as well? You will start slowing down because the gravity pulls.

I can see how you could adjust the trajectory, but on the speed wouldn't be that be same before and after you leave the gravity field of that particular planet. How can you pick up more speed?

Jeroen
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Old 21st February 2013, 22:50   #93
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I can see how you could adjust the trajectory, but on the speed wouldn't be that be same before and after you leave the gravity field of that particular planet. How can you pick up more speed?
Jeroen
Lets say i anticipated this question . The answer i am going to give you is purely out of my understanding( which in all senses is limited stupid).

Here is where we talk about plotting a course for the journey that KiloAlpha(our humble rocket scientist) explained about. The trick here is to go tangentially till you gain a little momentum from the gravitational pull. going too close would mean the issue of being attracted to the planet and end up wasting more energy. The trick is to plot a course wherein you will have the corresponding directional vector so that maximum influence of gravity can be experienced in such a way as to accelerate the space craft.
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Old 22nd February 2013, 00:23   #94
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never really understood that slingshotting. I understand that when you get near a planet gravity will start pulling you towards, adjusting the trajectory and accelerate, but as soon as you pass it wouldn't be the opposite be true as well? You will start slowing down because the gravity pulls.

I can see how you could adjust the trajectory, but on the speed wouldn't be that be same before and after you leave the gravity field of that particular planet. How can you pick up more speed?

Jeroen
the key is that the slingshotting planet is in motion relative to the observer (earth in this case). From your question, I get a feeling you are assuming it to be stationary. take a look again at the train photo in alphokilo's post with both assumptions.
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Old 22nd February 2013, 11:01   #95
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VivekJi Got it absolutely spot on. I related this theory with the train image so as to understand what it was about.
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Old 24th February 2013, 09:00   #96
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the key is that the slingshotting planet is in motion relative to the observer (earth in this case). From your question, I get a feeling you are assuming it to be stationary. take a look again at the train photo in alphokilo's post with both assumptions.

Got it. Actually what I'm saying is true as well, but the increase in speed comes from the relative speed of the planet you're slingshotting around

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Old 5th November 2013, 15:57   #97
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Posting back after a longgg break. That too with a proud news - we are on the way to Mars. From Redfort to Red planet! Way to go ISRO!

http://isro.gov.in/pslv-c25/c25-status.aspx

One comment from Prof. U. C. Rao (former ISRO Chairman) speech today that I loved: (he heard this comment from his NASA friend)

"Indians spend thousands of crores on diwali crackers which dont rise more than few feet, whereas for such a prestigious mission we get only 450 crores".

A slap in the face of the sitting Minister of State for science!
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Old 5th November 2013, 16:38   #98
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Posting back after a longgg break. That too with a proud news - we are on the way to Mars. From Redfort to Red planet! Way to go ISRO!

http://isro.gov.in/pslv-c25/c25-status.aspx

One comment from Prof. U. C. Rao (former ISRO Chairman) speech today that I loved: (he heard this comment from his NASA friend)

"Indians spend thousands of crores on diwali crackers which dont rise more than few feet, whereas for such a prestigious mission we get only 450 crores".

A slap in the face of the sitting Minister of State for science!
The western press appears to be calling this the fourth nation to enter the space race. The others being the USA, Russia, China and Europe. Somebody aught to tell those reporters Europe isnt a country.

Im all for scientific advancement, and I just love space programs. Having said that, all efforts combined of these four are going to amount to very little. Its just on too limited scale and to fragmented. Given where we are today in the world, we should stop all these programs and put the resources too good uses here on earth. Or take space exploration seriously, pull our resources, throw in a whole lot more and take it seriously.

Jeroen
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Old 5th November 2013, 16:39   #99
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Hold on to your horses - so far the vehicle has just managed to get into a low earth orbit. Getting to mars is another 300+ day mission.
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Old 5th November 2013, 16:40   #100
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Wow! That's wonderful news.

Can you elaborate about the mission? Is it a fly-by?
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Old 5th November 2013, 17:23   #101
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Somebody aught to tell those reporters Europe isnt a country.
Journalistic dumbness!

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Im all for scientific advancement, and I just love space programs. Having said that, all efforts combined of these four are going to amount to very little. Its just on too limited scale and to fragmented. Given where we are today in the world, we should stop all these programs and put the resources too good uses here on earth. Or take space exploration seriously, pull our resources, throw in a whole lot more and take it seriously.

Jeroen
I am sure you know it already! The least known/researched planet in this universe is our very own Earth! For us humans, grass is always greener on the other side (so to say!)


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Hold on to your horses - so far the vehicle has just managed to get into a low earth orbit. Getting to mars is another 300+ day mission.
I was congratulating and was happy about the "Launch" success and not the "Mission" success! Launch success goes a long way to prove the worthiness of the PSLV workhorse. As you rightly pointed out, mission success defines the ultimate success of ISRO's efforts.

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Wow! That's wonderful news.

Can you elaborate about the mission? Is it a fly-by?
Its a Mars orbiter. The "MOM" (not the Jayalalitha mom) Mars Orbiter Mission satellite will orbit the mars at an altitude of ~300kms (periapsis). It will orbit around mars during its one year(18 months planned) life time and make scientific observations, such as surface topography, coloured imagery of martian surface, IR imagery and methane analysis.

for more and exact info please look:

http://isro.gov.in/pslv-c25/brochure.aspx

http://isro.gov.in/pslv-c25/pdf/pslv-c25-brochure.pdf
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Old 5th November 2013, 22:56   #102
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I am sure you know it already! The least known/researched planet in this universe is our very own Earth! For us humans, grass is always greener on the other side (so to say!)
L]
Well, i would hope we know a little more about earth then say our moon, and I believe we do. The grass might be greener on the other side but it is still a sorry excuse to spend considerable amount s of money that contribute to nothing really, other than fuel a useless space race.

So you have to consider why nations are even in this space race. To me it doesn't look it should be anything a nation should be proud off. Without dampening your spirit, but it is ultimately an utter waste of money and resources when done at this level. There is no long term realistic view or what the program needs to accomplish in say the next twenty five years. Current space program just don't move the needle at all. If you dont want get your backs into, you are better of not doing it at all. Might as well put all those resources and money to other better use. This goes for all four space race nations that have more than their fair share of earthly challenges to content with before capturing space, by sending some space craft to Mars.

Jeroen
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Old 6th November 2013, 09:39   #103
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Well, sometimes knowledge has to be pursued for it's own sake; to expand the envelope, so to speak. If it is to be done only after all the poverty in the country is alleviated, it can't be done at all. There is a saying in Tamil which goes "If you wait for all the waves to disappear before taking a dip in the sea, you never will!"

The technology provides many spin offs which are useful in everyday life, I hear! And may be in the not too distant future, colonizing another planet or at least mining it for minerals is a distinct possibility.

But what can be done is instead of all the countries spending money independently to reinvent the wheel, all of them can pool the resources for space research.
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Old 6th November 2013, 10:11   #104
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Sending a satellite to Mars and showcasing to the world that you have 'arrived' is fine, but why does the Head of a prestigious organization like ISRO have to visit temples to pray that everything goes fine?

http://www.business-standard.com/art...0400512_1.html

At the very least, he should have done it privately. He has ended up spreading more superstition in a country already plagued with this disease of babas/sadhus and what not.

Frankly, the whole act to me looks no better than a truck driver hanging lemon/chillies on his truck for good luck!
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Old 6th November 2013, 11:04   #105
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Sending a satellite to Mars and showcasing to the world that you have 'arrived' is fine, but why does the Head of a prestigious organization like ISRO have to visit temples to pray that everything goes fine?

http://www.business-standard.com/art...0400512_1.html

At the very least, he should have done it privately. He has ended up spreading more superstition in a country already plagued with this disease of babas/sadhus and what not.

Frankly, the whole act to me looks no better than a truck driver hanging lemon/chillies on his truck for good luck!
It is funny that in modern society black magic, good luck charms etc are labelled as superstitious practices, but being religious is not!!

What a contradiction!
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