Author Topic: Safir launch with Fajr satellite - February 2, 2015  (Read 26402 times)

Offline Steven Pietrobon

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Re: Safir launch with Fajr satellite - February 2, 2015
« Reply #60 on: 02/09/2015 05:13 am »
Here's a screen capture of that poster of the Fajr 1 launch vehicle. It looks like the serial number has been airbrushed out.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Satori

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Re: Safir launch with Fajr satellite - February 2, 2015
« Reply #61 on: 02/28/2015 11:34 am »
Fajr reentered on February 26.

Offline InvalidAttitude

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Re: Safir launch with Fajr satellite - February 2, 2015
« Reply #62 on: 03/01/2015 02:25 pm »
At least we know the cold gas thrusters worked, but not in the right direction.

Offline Skyrocket

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Re: Safir launch with Fajr satellite - February 2, 2015
« Reply #63 on: 03/02/2015 10:10 am »
At least we know the cold gas thrusters worked, but not in the right direction.

There is no evidence, that the cold gas thrusters worked at all. The re-entry was apparently from natural orbital decay without help from thrusters.

Offline InvalidAttitude

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Re: Safir launch with Fajr satellite - February 2, 2015
« Reply #64 on: 03/05/2015 10:35 am »
At least we know the cold gas thrusters worked, but not in the right direction.

There is no evidence, that the cold gas thrusters worked at all. The re-entry was apparently from natural orbital decay without help from thrusters.

But I think its decayed much faster than naturally should.

Online jcm

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Re: Safir launch with Fajr satellite - February 2, 2015
« Reply #65 on: 03/07/2015 01:59 am »
At least we know the cold gas thrusters worked, but not in the right direction.

There is no evidence, that the cold gas thrusters worked at all. The re-entry was apparently from natural orbital decay without help from thrusters.

But I think its decayed much faster than naturally should.

Nope, well within the range of plausible drag coefficients.  Perfectly consistent with natural decay.
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Offline gwiz

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Re: Safir launch with Fajr satellite - February 2, 2015
« Reply #66 on: 03/07/2015 03:58 pm »
Decay of Fajr only a bit more rapid than the final stage, which came down this morning.

Offline mfengin

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Re: Safir launch with Fajr satellite - February 2, 2015
« Reply #67 on: 05/03/2015 04:36 pm »
Hello Guys,

After I saw your discussion, I decided to make a simulation to see if decay was natural or not. Then I run a simulation on free flyer by using the NORAD initial TLE data of Fajr. I took 0.25 m2 as a surface area of the satellite by taking consider as 50 kg type satellite. After the simulation, the result was 55 days. I attached the simulation result of Fajr. 

Therefore when it is analysed the TLE data, especially on 25.02.2015, Delta V changes seems around 5 m/s. Overall it does not seems natural. I think, thrusters were misfired or did not work as expected. What do you think?

   

Offline Steven Pietrobon

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Re: Safir launch with Fajr satellite - February 2, 2015
« Reply #68 on: 05/04/2015 05:31 am »
I think most people think there was some problem that prevented the thrusters being used to raise the orbit.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.