Bharat Rakshak

Mangalyaan will fail onlee.
(Those who don't know what this is, pliss to see my location)

Dilbu wrote:Mangalyaan will fail onlee.
(Those who don't know what this is, pliss to see my location)

About time Dilbu Saar!!!

ISRO to test-fire Mangalyaan for Sept 24 Mars rendezvous

"Since the engine has been idle for more than 300 days, we may have to test fire it," Isro chairman K Radhakrishnan said.

May have to test fire it or will have to test fire it? If main engine fails, they will have time to work with the smaller thrusters. Report says even a 5 second firing could send it off course. These guys need stout hearts for sure. Fingers crossed.

Newbie question. How's the Deep Space Network setup for ISRO? From wiki, it says only Bayalu. NASA seems to have three ones (California, Spain, Australia) to cover day/night and for all positions.

Mort Walker wrote:Calling dilbu to please place your reverse nazar here.

Thanks dilbu.

Skekatpuray, ISRO has 2 tracking ships in the Pacific ocean : SCI Nalanda and SCI Yamuna. In addition, NASA's Deep Space Network will also be providing support.

Edit : ISRO also has ground stations in Mauritius, Brunei and Indonesia.

Shaktimaan wrote:Skekatpuray, ISRO has 2 tracking ships in the Pacific ocean : SCI Nalanda and SCI Yamuna. In addition, NASA's Deep Space Network will also be providing support.

Edit : ISRO also has ground stations in Mauritius, Brunei and Indonesia.

Thanks Shaktiman.

Shaktimaan wrote:Skekatpuray, ISRO has 2 tracking ships in the Pacific ocean : SCI Nalanda and SCI Yamuna. In addition, NASA's Deep Space Network will also be providing support.

Edit : ISRO also has ground stations in Mauritius, Brunei and Indonesia.

But are all these stations capable of Deep Space Communication,? I thought only Byalalu antennae are large enough for communicating with Deep space probes like MOM.

Also I think the ships were used only for the launch to take care of some coverage gaps from the land stations, I doubt if these ships are still in the same position.

Test fire of main engine to be done on 22nd for 5 mts and if that fails, backup is secondary thrusters.

The LAM engine has been idle for over 300 days.....Murugaaaa.

MOM will fail onlee.

juvva wrote: Also I think the ships were used only for the launch to take care of some coverage gaps from the land stations, I doubt if these ships are still in the same position.

You are right. SCI Nalanda is in Bay of Bengal and SCI Yamuna is in Arabian ocean.
https://www.marinetraffic.com/en/ais/de ... C_I_YAMUNA
http://www.marinetraffic.com/en/ais/det ... CI_NALANDA

De de ………………Allah ke naam pe Mars ka ek photu he de de baba. Why we have no photu (from MOM) of Mars?

Are you serious? MOM has not reached there yet. (I see. This is a chaddi pulling post)

SwamyG wrote:The LAM engine has been idle for over 300 days.....Murugaaaa.

http://www.thehindu.com/todays-paper/tp ... 399237.ece

In the case of the Mars probe, the engine was fired seven times to propel the spacecraft beyond Earth’s gravitational hold. But after putting the spacecraft on course to Mars on December 1 last year, the engine had to remain idle for nearly 300 days. During such a lengthy coasting phase, valves in the propellant lines that were exposed to propellants might leak and not function properly.

ISRO has therefore put a second set of propellant lines for the liquid engine. One set of propellant lines was closed off after the engine fired to take the spacecraft out of Earth orbit. The other set will be opened when the time comes for the engine to fire again later this month.

Tests had been carried out on the ground to make sure that the engine could be restarted after such prolonged coasting, according to the ISRO chairman, K. Radhakrishnan. To check the engine's performance, it will be fired for about four seconds on September 22.

Then, on September 24, the engine will be fired for around 24 minutes to reduce the spacecraft's velocity by about 1.1 km per second and place it in orbit around Mars, Dr. Radhakrishnan told this correspondent.

http://www.isro.org/chandrayaan/htmls/g ... etwork.htm

They use other networks especially for delta dor measurements

MOM will fail onlee.

timing is more important.. within mars gravity field, i think we need only fewer newton thrusts to get into orbit than that required for trans-mars orbit injections.

Also, MAVEN, if all goes well, will also slow down on Sept 21, just a few days before MOM's firing of rockets, to enter the orbit of Mars.

MOM will fail






/anti-jinx

Wow it takes 13 hours to load - was thinking a few minutes !

Tales 10 minutes for transmitting 1 Mb

prasannasimha wrote:Tales 10 minutes for transmitting 1 Mb

Hmm - I once had a modem like that!

More seriously - I wonder what temperature the Mars probe itself will be at. I presume that the shade side will be cold and sun side hot - so is it kept rotating or shaded from sun by a solar panel or what?

Victor wrote:Test fire of main engine to be done on 22nd for 5 mts and if that fails, backup is secondary thrusters.

Muruga.....

BTW, do they see Rahukalam, Yamakandam....ityadi for this? {ducks for cover}

MOM will fail onlee.

I am sure they even tied a lemon to the probe.

People there in SHAR are deeply religious. All rockets ithyadi will be put in front of Lord Venkateswara at Thirupathi for his blessings. So please do not worry on that side. The mission itself is a complicated one and others failed in the last leg. We need do all the perfect/correct things to do well here. Even if we could just ignite the motors after all these months that it self is proof of our ability and a great achivement. I have no doubt we will get a great insersion into Mars orbit.

shiv wrote: More seriously - I wonder what temperature the Mars probe itself will be at. I presume that the shade side will be cold and sun side hot - so is it kept rotating or shaded from sun by a solar panel or what?

Someone more familiar with MOM can give more exact values, but essentially controlling temperature inside MOM is fairly (relatively) easy and technology is well understood... And the temperature is maintained as required... The requirements typically are ..

For batteries to work efficiently .. (typically between -5 and +20C°)
For propulsion subsystems, (typically between 5 to 40°C) For MOM, it may be that a wider range may be acceptable..
For generic electronics, (-20 and +70°C)

One has space heaters (if needed near equipment), thermostats, heat pumps (or simple radiators) to control (individual equipments - different parts have different temperature and can be insulated etc) but by adjusting the orientation etc the keeping the temperature inside the probe is not that difficult.

prasannasimha wrote:Wow it takes 13 hours to load - was thinking a few minutes !

13 hours to load *and verify*.

They perhaps conduct some sort of a dry run?

How do they "verify" what they have uploaded ? Some system self check ?

We normally use dummy data, with stubs. Do not know what happens on a Sat. But give me some time and I will get an answer from Sat guys.

There could be two issues here:
a) Latency: if the protocol they have requires the receiver to acknowledge successful reception of data before transmitter proceeds, the huge time lag can delay this to a great extent.

b) Bandwidth: In signal theory, there is this principle (i forgot the name) that the bandwidth is dependent upon the frequency of the carrier signal. For long range communications, lower frequency is used and hence less data can be sent in unit time.

Just guessing ...

Well ................. verification of reception of data should be the responsibility of the transmission. If a packet is dropped, then it should be resent. And that mechanism is well understood.

Verification of the entire command set is what I think they are talking about. So, if the instructions (commands) say something like: do this, then that, then ............. How does one verify that? This, for MOMs, for Mars insertion has never been done before, outside of tests on earth. Uploads have been done before, but not an upload for insertion (this specific set of instructions). So, they have to verify that each instruction has been received and that it is actionable.

OK, got an answer ........ but not the answer i was hoping for.

This relates to sats that orbit the earth (this team I work with deal with such sats!!!! sorry), which is why I am not satisfied with the answer.

They told me that when commands are uploaded, the sat sends back 'telemetry", part of which is whether the commands have been accepted. So, there is a non acceptance of commands too and the data streamed back to earth will contain thsi info - that a command was not accepted.

I was not able to get an immediate answer for the case of MOM like sats. Will have to ask that to a different group.

shiv: On mars sun side is not that hot - it is quite cold but shade side (and in deep craters) it is really cold. So the temperature range is quite wide.

So why is MAVEN so expensive than MANGALYAAN?

I hope when PM Modi meets POTUS, he carries a high def pic of one of the rovers taken from Mangalyaan, with a tag "Howdy Partner!!!'. Timing is just perfect...

SwamyG wrote:So why is MAVEN so expensive than MANGALYAAN?

http://www.quora.com/What-is-the-major- ... the-former

You might have to have a Quora Account...