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#40
by
Zannanza
on 22 Feb, 2014 05:34
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While it could make GSO if a performance shortfall occurs, overcoming a performance shortfall will consume Xenon and reduce the operational lifetime of the satellite. SEP is not free.
Just did a quick search
1kg of Xenon costs ~$1200 and sending 1kg of Xenon to space on F9 costs $4,109
not a big deal for aerospace contracts, especially when you consider the extra cost of switching to a FH (FH can do a duo or even triple for the heaviest comm sats with its advertised 21,200 kg capacity to GTO)
also, electric propulsion has terribly high isp when compared with chemicals therefore the same delta v can be achieved with much much less fuel, just that you need to be patient.
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#41
by
faramund
on 22 Feb, 2014 06:12
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I think when people talk about the cost of SEP, they also add in the opportunity cost of lost revenues because of the time it takes to reach the correct orbit. They also talk about concerns about spending much longer passing through the Van Allen belts.
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#42
by
guckyfan
on 22 Feb, 2014 06:56
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I think when people talk about the cost of SEP, they also add in the opportunity cost of lost revenues because of the time it takes to reach the correct orbit. They also talk about concerns about spending much longer passing through the Van Allen belts.
I guess that is why at least some designs use both. Chemical propulsion for getting from GTO to GSO or at least near and SEP for station keeping. So even with some underperformance they at least should get ouf of much of the Van Allen Belt fast.
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#43
by
Avron
on 22 Feb, 2014 12:16
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I think when people talk about the cost of SEP, they also add in the opportunity cost of lost revenues because of the time it takes to reach the correct orbit. They also talk about concerns about spending much longer passing through the Van Allen belts.
I guess that is why at least some designs use both. Chemical propulsion for getting from GTO to GSO or at least near and SEP for station keeping. So even with some underperformance they at least should get ouf of much of the Van Allen Belt fast.
In terms of station keeping, can that be done while the sat is operational, as it sounds like an option using the FH capabilities and more Xenon attached to the sat ( not sure how) to provide sat operators much improved flexibility. 2016 is some time out, this maybe there is chance to design in this additional Xenon capability
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#44
by
fatjohn1408
on 25 Feb, 2014 09:12
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(Both the SES-8 and Thaicom-6 missions did apparently reserve some propellant for restart tests)
Has this been documented somewhere properly?
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#45
by
Comga
on 25 Feb, 2014 21:00
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(Both the SES-8 and Thaicom-6 missions did apparently reserve some propellant for restart tests)
Has this been documented somewhere properly?
We were told the opposite. Musk said that SpaceX did
not reserve capacity on those flights.
Just because they relit the engine doesn't mean that they reserved propellant.
edit: typo
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#46
by
woods170
on 11 Apr, 2014 07:42
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http://www.spacenews.com/article/launch-report/40165ses-books-spacex-falcon-9-for-hybrid-satellite%E2%80%99s-debutThe two satellites, SES-9 and SES-10, both weigh about 5,300 kilograms and carry a mix of electric and chemical propellant systems. The question is, what tradeoffs is SES making to be able to fit their launches on the Falcon 9?
<snip>
For SES-10, built by Airbus Defence and Space, only the chemical propulsion system will be used for its Falcon-9 launch set for 2016. To compensate for the Falcon-9’s limits, the satellite will carry larger-than-usual chemical propellant tanks and make an extra couple of orbit-raising burns, meaning the time to final position will not be that much longer than with chemical propellant only.
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#47
by
gongora
on 02 Aug, 2016 14:57
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Tweet from Peter B. de Selding
SES: We expect SES-10 satellite, w/ 27 incremental xponders + replacement of AMC-3/-4 over LatAm, to launch in October on SpaceX Falcon 9.
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#48
by
jpo234
on 30 Aug, 2016 07:35
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#49
by
NaN
on 30 Aug, 2016 07:49
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#50
by
Kaputnik
on 30 Aug, 2016 08:55
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Has anybody confirmed which core is being used for this flight?
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#51
by
Mariusuiram
on 30 Aug, 2016 09:08
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Has anybody confirmed which core is being used for this flight?
I believe it is the CRS-8 core which is what people expected. But dont have a direct source other than Echologic on reddit.
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#52
by
jpo234
on 30 Aug, 2016 09:21
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Has anybody confirmed which core is being used for this flight?
23
From the
LA Times article:
SES’ satellite will launch on a first-stage booster that landed in April after delivering supplies to the International Space Station. That was the first rocket to land on a floating droneship.
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#53
by
Ben the Space Brit
on 30 Aug, 2016 09:42
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Well, all available digital extremities crossed that this goes well! It should be interesting to learn how much the recycling cost. It will be several times the 'operational' cost, of course, as I imagine multiple redundant checks and tests as this was the first attempt. However, it would still be interesting to see what the cost compared to a fresh core was.
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#54
by
TrevorMonty
on 30 Aug, 2016 09:47
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At 5300kg to GTO, this will most likely final flight of this booster. Even if they recover to barge it may not fly again.
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#55
by
Chris Bergin
on 30 Aug, 2016 10:33
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#56
by
Chris Bergin
on 30 Aug, 2016 10:57
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#57
by
Ben the Space Brit
on 30 Aug, 2016 12:05
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This is is probably just my optimism at work but, if SES-10 has its own boost motor (presumably expended after GOI), then SpaceX might be able to negotiate a lower S/C Sep altitude and thus save a little prop for the attempted core recovery. Even if F9-023 isn't in a reflyable condition after the mission, examining the first booster to fly and recover twice would be a scientific and engineering goldmine.
Why do I think that this is possible? Because SES have been talking about flying SES-10 on a recycled booster for a while. They may have been planning on this and had the spacecraft assembled appropriately.
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#58
by
Chris Bergin
on 30 Aug, 2016 12:33
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#59
by
rockets4life97
on 30 Aug, 2016 12:57
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There seems to be some discrepancy in what was done to re-certify the booster.
The BBC is reporting that the booster was sent to McGregor and re-fired.
The LA Times is reporting that all of the engines were removed from the booster and sent to McGregor for individual testing. After the engines were re-certified, they were put back into the booster and then the whole booster went to McGregor for a test firing.
Both stories are compatible if the longer version (LA Times) is true.
