-
#320
by
PM3
on 15 Apr, 2019 22:56
-
Based on the Arabsat FH center core being lost (toppled over in rough seas), I'm guessing the decision makers for this mission feel pretty good that they insisted on a new-build FH center core.
Source for "the decision makers insisted", which implies that someone at SpaceX did not want to build a new center core?
-
#321
by
Lars-J
on 15 Apr, 2019 23:04
-
Based on the Arabsat FH center core being lost (toppled over in rough seas), I'm guessing the decision makers for this mission feel pretty good that they insisted on a new-build FH center core.
Source for "the decision makers insisted", which implies that someone at SpaceX did not want to build a new center core?
What I mean is the prime customer - USAF. I can't seem to find the source for it at the moment, I could be mistaken. I will edit the post if I find it.
-
#322
by
crandles57
on 15 Apr, 2019 23:36
-
Perhaps
https://www.nasaspaceflight.com/2019/03/falcon-heavy-starlink-headline-spacexs-manifest/However, it is important to note that despite reports that all three cores from Arabsat 6A would be reused for STP-2, NASASpaceflight.com understands that the mission will in fact use a brand new center core.
...
STP-2 will then feature the second flights of B1052 and B1053 along with B1057 – a brand new center core.
The existence of a second center core makes sense, as B1055’s landing during Arabsat 6A will likely be one of SpaceX’s most challenging to date. Due to Falcon Heavy’s flight profile, the booster will reach a higher than usual velocity. Consequently, the booster will make a hot reentry and land on OCISLY nearly 1,000 kilometers downrange – making it by far the farthest recovery attempt in SpaceX’s history.
Therefore, by having a second center core for STP-2, SpaceX will eliminate the risk of a significant delay if B1055 were to be lost or require substantial refurbishment.
That isn't clear whether it was SpaceX's decision or the customer, USAF.
-
#323
by
Alexphysics
on 16 Apr, 2019 19:20
-
SpaceX has put an exclusive page on their website just for this mission with descriptions of the payloads and a launch animation
www.spacex.com/stp-2
-
#324
by
gongora
on 16 Apr, 2019 20:11
-
The video shows the deployments being:
Oculus, cubesats : 300 x 860km at 28.5 deg?
Prox-1, NPSat, OTB, GPIM, COSMIC-2 : 720 x 720km at 24 deg?
DSX : 6000 x 12000km at 43 deg?
"Propulsive passivation" I guess means they'll move it away from DSX, passivate and leave in MEO.
-
#325
by
Draggendrop
on 17 Apr, 2019 21:58
-
-
#326
by
Chris Bergin
on 19 Apr, 2019 11:19
-
SpaceX has put an exclusive page on their website just for this mission with descriptions of the payloads and a launch animation
www.spacex.com/stp-2
Looks like they changed the link:
-
#327
by
Comga
on 19 Apr, 2019 16:54
-
Questions on the video:
It ends with a "three hour coast" followed by a "propulsive passivation".
Do we know why they plan to coast that long before passivation?
They were careful to show the passivation emitting cold gas, not igniting and heating up the engine bell.
Do we know why this is labeled "propulsive"?
Can blowing down the cold propellants change the orbit appreciably?
(I ask if we know why because guessing is OK, but sourced knowledge is what I'm after.)
-
#328
by
gongora
on 19 Apr, 2019 17:49
-
They specifically say 4 upper stage engine burns, and the original contract (which has been modified many times since it was signed) called for a relight after the coast. Can they do all of the satellite deployments with the first 3 burns? This was probably intended to be the first long coast demo flight, but with the STP-2 delays they've already done it a few times on other flights. More practice doesn't hurt.
-
#329
by
Comga
on 19 Apr, 2019 18:46
-
They specifically say 4 upper stage engine burns, and the original contract (which has been modified many times since it was signed) called for a relight after the coast. Can they do all of the satellite deployments with the first 3 burns? This was probably intended to be the first long coast demo flight, but with the STP-2 delays they've already done it a few times on other flights. More practice doesn't hurt.
But they clearly show the passivation as not igniting the engine.
It looks very intentional, as they have the stage lighting three times earlier in the video.
They could have glossed over the orbital insertion.
Do we know if its a continuous burn to the initial 300 x 860 km orbit, or if they do a coast and burn?
Scattered around we do have enough data to calculate how long a burn it would take to drop the perigee of the 6,000 by 12,000 km final orbit to ~200 km, for quick decay, but it shouldn't be much. There must be a good reason for not doing that.
-
#330
by
Lars-J
on 19 Apr, 2019 21:07
-
They specifically say 4 upper stage engine burns, and the original contract (which has been modified many times since it was signed) called for a relight after the coast. Can they do all of the satellite deployments with the first 3 burns? This was probably intended to be the first long coast demo flight, but with the STP-2 delays they've already done it a few times on other flights. More practice doesn't hurt.
But they clearly show the passivation as not igniting the engine.
It looks very intentional, as they have the stage lighting three times earlier in the video.
They could have glossed over the orbital insertion.
Don't treat the video as gospel. There very little to go on there, and what is there is not detailed enough.
-
#331
by
aviators99
on 20 Apr, 2019 15:28
-
One of the Facebook groups has an "event time" of 2300. Is this the current plan? With all of the deployments, I imagine the window is very, very small, right?
-
#332
by
ChrisGebhardt
on 20 Apr, 2019 15:47
-
One of the Facebook groups has an "event time" of 2300. Is this the current plan? With all of the deployments, I imagine the window is very, very small, right?
No daily launch windows have been announced, nor are any pending approval right now on the Eastern Range for STP-2.
Random Facebook event aside, basic rule here on NSF is that as soon as a date and time are known, we let folks know because of the immense interest and planning that people need to do to attend the launches.
-
#333
by
Alexphysics
on 20 Apr, 2019 15:48
-
If it is the SpaceX facebook group, all the times there are just placeholders because Facebook requires some time for an event to be posted on the group, the launch time is currently not publicly known
-
#334
by
GWR64
on 20 Apr, 2019 17:28
-
How comes the upper stage with the last burn from the LEO to the MEO? COSMIC-2 -> DSX
Something is wrong in the animation.
-
#335
by
PM3
on 24 Apr, 2019 13:52
-
Satellite data; some FCC filings missing
-
#336
by
soltasto
on 24 Apr, 2019 14:05
-
Satellite data; some FCC filings missing
GPIM is from NASA so they shouldn't need any FCC permit.
The Formosat 7 satellites are from NSPO but it also is a collaboration with NOAA so maybe the NOAA side will sort it out by themselves.
I'm not quite sure about the BRICSat 2 and the PSat 2 cubesats as they should be operated by the US Naval Academy Satellite Lab that has strong ties with the government, but I have no idea about their licensing.
-
#337
by
GWR64
on 24 Apr, 2019 20:42
-
Satellite data; some FCC filings missing
Thanks,
I still think, from 720 km cirkular to 6000 x 12000 km with the last ignition,
it does not work. Something does not fit with the animation.
-
#338
by
gongora
on 24 Apr, 2019 21:00
-
Satellite data; some FCC filings missing
Thanks,
I still think, from 720 km cirkular to 6000 x 12000 km with the last ignition,
it does not work. Something does not fit with the animation.
They say they're doing four burns of the second stage. It's not clear now if they still have to relight the engine after coast, or if that would be counted as one of the four burns. They may be able to use two burns to reach one of the deployment orbits.
-
#339
by
soltasto
on 24 Apr, 2019 22:05
-
It can be like this:
First burn (Insertion Burn): 300kmx860kmx28.5°
First payload deploy.
Second Burn -> fire the engine at the descending node while climbing to 720 km altitude, also make a slight inclination change there (not fully prograde, but also a bit radial in and normal): 720kmx720kmx24°
Second payload deploy
Now, two options:
Option 1 (More efficient, requires more time)
Third burn -> Make a burn at the Ascending node, rise the apogee to 12000km: 720kmx12000kmx24°
Fourth burn -> Make a burn at the Descending node (Also the Apogee), rise the Perigee and change the inclination (not fully prograde, also a bit anti-normal): 6000kmx12000kmx43°
DSX deploy
Option 2 (Less efficient, requires less time)
Third burn -> Make a burn at the Ascending node, rise the apogee to 6000km: 720kmx6000kmx24°
Fourth burn -> Make a burn at the Descending node (Also the Apogee), rise the Apogee and change the inclination (not fully prograde, also a bit anti-normal): 6000kmx12000kmx43°
DSX deploy
