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#400
by
Fuji
on 19 Nov, 2013 00:44
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Where can I find the initial ground track that shows where over the ground the Centaur-2 burn occurred? I do want to get ahead of youtube UFO reports.
May be this one ?
I want to take the comet ISON photos, but for naked eye object only I can watched this 
Shooting time is 20:07 UTC (I can watched this object untill 20:11)
Can you give your viewing location and the approximate location in the sky of the object you have imaged?
Viewing location: Lat. 35.95 Long. 139.99
Approximate location in the sky : Near the Crater and lower of the Hydra.
The camera clock was 7 minutes fast. So, 20:00 UTC till 20:04 UTC is correct.
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#401
by
Lee Jay
on 19 Nov, 2013 01:01
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It's packed house here at the visitor center viewing location.
This is, what, about 6 miles away? One thing the regulars don't point out all that much is the sound. We were all that distance away, sitting on the asphalt parking lot, and the Atlas shook the ground even from there. The feeling is similar to listening to a good recording of a shuttle launch while sitting on my subwoofer. It's a deep, throaty rumble punctuated by that classic high-pitched popping.
It was great to see my second launch (first was STS-45) in person, and to share it with my family. Nicely done ULA and MAVEN team!
P.S. The Atlants exhibit was amazing!
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#402
by
Galactic Penguin SST
on 19 Nov, 2013 01:18
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#403
by
Artyom.
on 19 Nov, 2013 01:47
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#404
by
Rocket Science
on 19 Nov, 2013 01:52
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It's packed house here at the visitor center viewing location.
This is, what, about 6 miles away? One thing the regulars don't point out all that much is the sound. We were all that distance away, sitting on the asphalt parking lot, and the Atlas shook the ground even from there. The feeling is similar to listening to a good recording of a shuttle launch while sitting on my subwoofer. It's a deep, throaty rumble punctuated by that classic high-pitched popping.
It was great to see my second launch (first was STS-45) in person, and to share it with my family. Nicely done ULA and MAVEN team!
P.S. The Atlas exhibit was amazing!
Sounds like you had a great time Lee Jay!
You sit on your subwoofer alot?
You're right, can't beat the sound of a launch in person!
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#405
by
ChrisC
on 19 Nov, 2013 02:48
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The Atlas exhibit was amazing!
Huh? What? At the KSC Visitors Center? Is that exhibit still going to be up when I'm there at KSC a week from today?
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#406
by
jacqmans
on 19 Nov, 2013 02:52
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Taken about 30 min before launch by me
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#407
by
go4mars
on 19 Nov, 2013 03:53
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Awesome! One aspect that I'm interested in is the greater quantification of atmospheric phenomenon. Ties into many realms. Including applicable stuff like EDL for future landers.
Just in case I missed it, is there a video or series of snapshots of the Earth shrinking away?
Not that I'd watch it in the dark and crank up "Ground Control to Major Tom" with some scotch and a few friends. No promises though.
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#408
by
JimO
on 19 Nov, 2013 05:05
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Can you give your viewing location and the approximate location in the sky of the object you have imaged?
Viewing location: Lat. 35.95 Long. 139.99
Approximate location in the sky : Near the Crater and lower of the Hydra.
The camera clock was 7 minutes fast. So, 20:00 UTC till 20:04 UTC is correct.
Is this S latitude, I presume? What did the object look like? What was direction and rate of motion across the sky?
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#409
by
Galactic Penguin SST
on 19 Nov, 2013 05:09
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Can you give your viewing location and the approximate location in the sky of the object you have imaged?
Viewing location: Lat. 35.95 Long. 139.99
Approximate location in the sky : Near the Crater and lower of the Hydra.
The camera clock was 7 minutes fast. So, 20:00 UTC till 20:04 UTC is correct.
Is this S latitude, I presume? What did the object look like? What was direction and rate of motion across the sky?
He's in Japan, so N latitude I believe. By then the Centaur should be visible from much across the globe.
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#410
by
Star One
on 19 Nov, 2013 06:26
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Was slightly surprised this launch didn't seem to have any rocketcam onboard, cost saving?
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#411
by
Fuji
on 19 Nov, 2013 06:48
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#412
by
AJA
on 19 Nov, 2013 07:52
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Centaur questions:
1. If I heard launch commentary correctly, the Centaur vented (to minimise chances of pressure failure?) some residual Hydrogen and Oxygen (I assume this is prop margin), after the second MECO. Why didn't they burn all of this in the RL-10 instead? Especially when they went so far as to execute RCS hydrazine burn off to maximise performance?
Combustion stability issues and thrust vector indeterminacy, for low flow rates, and for gaseous feed as opposed to cryogenic propellant feed? Or would it have actually imparted too MUCH velocity to the S/C requiring it to expend more fuel for braking and Mars orbit capture?
2. Didn't find anything in the ULA Atlas V MAVEN launch brochure about that interesting pitch manoeuvre (not the PTC roll) the Centaur executed during the coast phase. Was it done to orient the stage to point its transmitters toward the nearest TDRS?
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#413
by
Lee Jay
on 19 Nov, 2013 10:34
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The Atlas exhibit was amazing!
Huh? What? At the KSC Visitors Center? Is that exhibit still going to be up when I'm there at KSC a week from today?
Meant Atlantis.
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#414
by
eriblo
on 19 Nov, 2013 10:37
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1. If I heard launch commentary correctly, the Centaur vented (to minimise chances of pressure failure?) some residual Hydrogen and Oxygen (I assume this is prop margin), after the second MECO. Why didn't they burn all of this in the RL-10 instead? Especially when they went so far as to execute RCS hydrazine burn off to maximise performance?
Combustion stability issues and thrust vector indeterminacy, for low flow rates, and for gaseous feed as opposed to cryogenic propellant feed? Or would it have actually imparted too MUCH velocity to the S/C requiring it to expend more fuel for braking and Mars orbit capture?
Interplanetary trajectories have to be fairly precise, you want to get to a specific point in space at a specific time or the planet you are aiming for is not going to be there. Any deviations from this trajectory (faster, slower, wrong time or direction) will only mean that you will have to do larger course corrections, and if you off by too much you will not be able to compensate...
Since you always want some margin in your burns (in case of underperformance) you will have some propellant left if everything goes as planned.
As to using the RCS thrusters: Somebody who actually knows why might correct me, but I would guess that they reach a point where they know they have more hydrazine left than they need, and using it increases the margin for the main engine?
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#415
by
Jim
on 19 Nov, 2013 11:43
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Centaur questions:
1. If I heard launch commentary correctly, the Centaur vented (to minimise chances of pressure failure?) some residual Hydrogen and Oxygen (I assume this is prop margin), after the second MECO. Why didn't they burn all of this in the RL-10 instead? Especially when they went so far as to execute RCS hydrazine burn off to maximise performance?
Combustion stability issues and thrust vector indeterminacy, for low flow rates, and for gaseous feed as opposed to cryogenic propellant feed? Or would it have actually imparted too MUCH velocity to the S/C requiring it to expend more fuel for braking and Mars orbit capture?
2. Didn't find anything in the ULA Atlas V MAVEN launch brochure about that interesting pitch manoeuvre (not the PTC roll) the Centaur executed during the coast phase. Was it done to orient the stage to point its transmitters toward the nearest TDRS?
1. The stage is rendered inert after the mission, all gases and propellants are vented. There are many factors, but there is a specific trajectory and orbit that mission is designed for and that has a specific velocity upon leaving earth orbit. There are slight variations depending on time of launch in the window and which date in the period. The trajectory is basically a Holman transfer orbit, which is the minimum energy required to get to Mars. The mission is designed for the conditions at both ends. For the mass of the this spacecraft, the energy required for launch and injection determined that an Atlas V 401, and the spacecraft propulsion system was designed for arrival conditions. Adding more velocity would not help the mission, and would upset things, like arrival times (Mars might not be there) or braking velocity required (as you point out. All launch vehicles do the venting/inerting after they perform their task. Venting is easier to manage than restarting the enginee.
The hydrazine burnoff increases performance prelaunch. By incorporating burnoff, there is a gain in performance that is accounted for in preflight planning. There is margin in the hydrazine amounts to account for high useage during the first burn and coast. If the extra margin is not use, it used to be the Centaur carried it for the whole mission, and this required used of the main propellants. So now, the missions are planned for where the hydrazine is used, either via high use rates or by burnoff, so that the hydrazine reserve margin is not sent on to the final orbit and there is a little more main propellants (performance) available preflight.
2. The spacecraft does not communicate with TDRSS. The attitude was for thermal conditions and was determined by the sun.
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#416
by
Bogeyman
on 19 Nov, 2013 12:02
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Just out of curiosity:
Between the two burns during the coasting phase, the spacecraft flew "backwards (engines first)" and turned back into flight position shortly before the second burn.
What was the purpose of that?
Greets, Chris
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#417
by
Silmfeanor
on 19 Nov, 2013 12:19
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Just out of curiosity:
Between the two burns during the coasting phase, the spacecraft flew "backwards (engines first)" and turned back into flight position shortly before the second burn.
What was the purpose of that?
Greets, Chris
Inertia - if a stage flies "forwards" at perigee, it will fly "backwards" at apogee and vice versa.
You can correct the attitude all the time in small steps or just do a big flip just before the burn.
As Jim just posted, it was thermal reasons.
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#418
by
Lee Jay
on 29 Nov, 2013 01:39
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It's packed house here at the visitor center viewing location.
Visitor center viewing location, tight crop from 400mm, and 185mm just to give more of an idea how far away we were.
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#419
by
LeMay
on 29 Nov, 2013 14:46
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Sorry for my English! Has anyone got the parameters of MAVEN's heliocentric orbit and Centaur's heliocentric orbit?
!!
You're right, can't beat the sound of a launch in person! 
