Author Topic: SpaceX F9 : Nusantara Satu (PSN VI)/GTO-1/SpaceIL : Feb. 21/22, 2019: Discussion  (Read 71792 times)

Offline crandles57

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from
https://www.teslarati.com/spacex-falcon-9-booster-highway-spotted-radar-satellite-launch-slip/

Quote
Given that B1046 and B1049 are on the West Coast.....  only B1047 and B1048 remain (in theory) on the East Coast ....... As a result, the only booster that is realistically available for PSN-6/GTO-1 is Falcon 9 B1047 for what would be its third launch.

That reasoning could be wrong: I can't see how they ruled out B1047 being the inflight abort test and B1048 being Nusantara Satu. However, it does seem more likely the other way around as they have more time for any integrating work with B1047 and Nusantara Satu both present. (Is this an issue, when did B1048 arrive at CC?)


Online Spindog

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In any case it appears a lot more third booster flights are on the plate for this year.

Online Alexphysics

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from
https://www.teslarati.com/spacex-falcon-9-booster-highway-spotted-radar-satellite-launch-slip/

Quote
Given that B1046 and B1049 are on the West Coast.....  only B1047 and B1048 remain (in theory) on the East Coast ....... As a result, the only booster that is realistically available for PSN-6/GTO-1 is Falcon 9 B1047 for what would be its third launch.

That reasoning could be wrong: I can't see how they ruled out B1047 being the inflight abort test and B1048 being Nusantara Satu. However, it does seem more likely the other way around as they have more time for any integrating work with B1047 and Nusantara Satu both present. (Is this an issue, when did B1048 arrive at CC?)

What I don't know is what has B1048 that is so special that it'll be used for IFA. Also, from where did he get the booster was being used for IFA? Are we going to fall in the same trap where many people fell with B1042? Everyone thought, for some unknown and special reason, that it was the IFA booster. Either B1047 or B1048 could be the booster for this mission.

Offline whitelancer64

Is the IFA even close enough to have had a booster assigned to it?
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Offline scr00chy

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Is the IFA even close enough to have had a booster assigned to it?
It's currently planned for June.

Offline Comga

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Beresheet would want zero inclination correction. The Moon's orbit is inclined ~5.14° above the ecliptic - which is ~23.4° above the Earth's equatorial plane (equal to the tilt of the Earth's axis). That comes to ~28.5°, which is - not entirely coincidentally - the inclination you get by launching due east from Cape Canaveral.

Any inclination change to assist Nusantara would have to be undone by the lander. So I would expect a greater apogee in preference to inclination change.

Couldn't find it with a simple search, but somewhere it was discussed that Beresheet will execute several perigee boosts to increase apogee, with some intermediate orbit close to halfway to the moon. 
At that point cancelling inclination takes very little delta V.
Setting the GTO burn of the second stage to the optimum balance, or even over-weighting the reduction of inclination, should have little impact on the moon lander's flight.

It just occurred to me that when we did this optimization in graduate orbital mechanics class, the goal was minimum total delta-V.  However, not all velocity change is created equal.  For this kind of flight, GTO and GEO insertions come from different engines, specifically the F9 second stage and the GSO satellite respectively.  That would change the formulation from the minimum total delta-V to the minimum delta-V from the satellite, with full use of the second stage.  Then adding in the possibility of suprasynchronous transfer makes the problem a whole lot more interesting.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline jcm

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For the record,  "Nusantara Satu" translates exactly to "one archipelago" (word order gets reversed so Satu which means 1, comes first) without "Indonesian" in it.

I asked my wife, a native Indonesian and teacher of Bahasa Indonesia (Indonesian language) to non Indonesian speakers, and that's what she told me. The material in the intro post isn't quite right, it has too much stuff in it.

That's very odd since they have also talked about a second sat, Nusantara Dua :

https://kumparan.com/@kumparantech/april-2020-psn-luncurkan-satelit-nusantara-dua-pengganti-palapa-d-1548246721064822411
Doesn't contradict what I said. My point is that "Indonesian" isn't part of the name, except allegorically (in that Indonesia occupies the vast majority of the largest archipelago in the world) because nusantara just means collection of islands. The header got fixed by gongora to remove that.

satu dua tiga   empat lima enam tujuh   delapan sembilan sepuluh
one  two three four    five   six     seven eight      nine         ten

Indonesian is an interesting language. It lacks tense, plural, and gender for the most part, and many words are overloaded. Kepuluan means both island and archipelago depending on context. Pulua just means island and nusantara just means archipelago.


ah ok it sounded like you were saying the name was  "One Archipelago"  (as in, a single, politically united archipelago, and as opposed to "Archipelago 1".)
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Offline ChrisC

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Video of the Static Fire!

Granted that this is a long distance, low resolution shot, but that static fire looked longer than normal.  I count nine seconds of engines burning, before tail off.  Even if you allow for the TEA/TEB start, it seems long.
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Online Alexphysics

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Video of the Static Fire!

Granted that this is a long distance, low resolution shot, but that static fire looked longer than normal.  I count nine seconds of engines burning, before tail off.  Even if you allow for the TEA/TEB start, it seems long.

Which is standard procedure for reused boosters.

Online Llian Rhydderch

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Couldn't find it with a simple search, but somewhere it was discussed that Beresheet will execute several perigee boosts to increase apogee, with some intermediate orbit close to halfway to the moon. 
At that point cancelling inclination takes very little delta V.
Setting the GTO burn of the second stage to the optimum balance, or even over-weighting the reduction of inclination, should have little impact on the moon lander's flight.

It just occurred to me that when we did this optimization in graduate orbital mechanics class, the goal was minimum total delta-V.  However, not all velocity change is created equal.  For this kind of flight, GTO and GEO insertions come from different engines, specifically the F9 second stage and the GSO satellite respectively.  That would change the formulation from the minimum total delta-V to the minimum delta-V from the satellite, with full use of the second stage.  Then adding in the possibility of suprasynchronous transfer makes the problem a whole lot more interesting.

Take a look at the orbital trajectory and maneuvers used to get the LADEE spacecraft to the Moon in 2013. 
This Beresheet spacecraft/lander mission is much like that.

In the Wikipedia article I linked, there is a very helpful "Animation of LADEE's trajectory from September 7, 2013, to October 31, 2013" graphic to illustrate, and the article prose described in the Lunar Transit section is quite thorough, and based on detailed sources on the astrogation for that mission. 
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Offline Norm38

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I really am surprised that the static fire has occurred and it still isn't publically announced which core is being used, which flight this is.  I guess this is the new normal, playing it close to the vest.  None of us need to know of course, and eventually no one will care.  Guess this is what everyday reuse looks like.

Offline ATPTourFan

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Usually first public mention of any prior service by the booster is in the media release which we'll have in about 24 hours.

Offline LouScheffer

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So, with all that, what is the launch profile supposed to look like? The rocket needs to carry this pretty heavy payload to an orbit with 60,000 km apogee while still allowing for ASDS landing of the first stage. When looking at other GTO launches, it doesn't seem possible. What am I missing? [..]
[...]    Another possibility is "burn to depletion".  Most launches target an explicit orbit.  To do that, they need to have slightly more fuel than they really need, typically something like 1%. (So if your performance is normal you have 1% left.  If's it's 3-sigma bad, you have barely enough fuel.  If performance is 3-sigma good, you have 2% remaining.)  If you don't care about the exact orbit, you can use these last reserves by simply burning until the fuel runs out.   This reduces the needed delta-AV for the payload, but it's a pain in the butt since you can't plan any of your post-launch maneuvers in advance, since you don't know what orbit you'll get. 

From fitting to performance curves, SpaceX normally stops with the second stage, with residuals, at 5.5t.  If they burn the last ton (a little more than 1%) of the propellants, they will get an additional 300 m/s, enough for a 67,000 km apogee.   So if SpaceX tries this, in the worst case they get about 40,000 km.  In the average case, about 67,000 km, and in the best case about 150,000 km.
Looks like burn to depletion is the answer.   From the Planetary Society talking to SpaceIL:
Quote
The nominal orbit is 215 by 60,000 kilometers, and may be higher, depending on the Falcon 9's performance.
If you don't know the final orbit, and it depends on the rocket, that's an almost sure sign of burn to depletion.

Offline Comga

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Couldn't find it with a simple search, but somewhere it was discussed that Beresheet will execute several perigee boosts to increase apogee, with some intermediate orbit close to halfway to the moon. 
At that point cancelling inclination takes very little delta V.
Setting the GTO burn of the second stage to the optimum balance, or even over-weighting the reduction of inclination, should have little impact on the moon lander's flight.

It just occurred to me that when we did this optimization in graduate orbital mechanics class, the goal was minimum total delta-V.  However, not all velocity change is created equal.  For this kind of flight, GTO and GEO insertions come from different engines, specifically the F9 second stage and the GSO satellite respectively.  That would change the formulation from the minimum total delta-V to the minimum delta-V from the satellite, with full use of the second stage.  Then adding in the possibility of suprasynchronous transfer makes the problem a whole lot more interesting.

Take a look at the orbital trajectory and maneuvers used to get the LADEE spacecraft to the Moon in 2013. 
This Beresheet spacecraft/lander mission is much like that.

In the Wikipedia article I linked, there is a very helpful "Animation of LADEE's trajectory from September 7, 2013, to October 31, 2013" graphic to illustrate, and the article prose described in the Lunar Transit section is quite thorough, and based on detailed sources on the astrogation for that mission. 

The Planetary Society just put up an article on Beresheet with the flight plan

Quote
Event                                        Time            Apoapsis Periapsis Orbit period   Revs
                                                    (UTC)           (km)     (km)       (hr)
AM1 Optional apogee maneuver  11:50 22 Feb   59998    258          19               2
AM2 Apogee maneuver               02:24 24 Feb   59997    599          19             1.5
PM1 Perigee maneuver               07:29 25 Feb  123246    600          49              5
PM2 Perigee maneuver               11:18 07 Mar  276126    462         152             2
PM3 Perigee maneuver               02:24 20 Mar  396887  1447         258           0.14
OPM Out of plane maneuver        14:25 21 Mar  391974  1422         253            1.3
LOI1 Lunar orbit insertion            14:07 04 Apr   10012    289          14             1.5
LOI1A Lunar orbit insertion          11:29 05 Apr   10002    247          14             2.5
LOI2 Lunar orbit insertion            22:48 06 Apr      752    243          2.6             10
LOI2B Lunar orbit insertion          01:10 08 Apr      245    200          2.2           29.5
DM1 Descent maneuver               17:00 10 Apr     197      15          2.0           14.5

So, yeah, all delta V is not created equal and milking the maximum out of the second stage, a burn to depletion, is the way to go.

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edit: ninjaed on the link by LouScheffer .
« Last Edit: 02/19/2019 04:02 pm by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Brian45

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Will this be the first night time attempt at recovering a fairing? Don't seem to recall any reports of them testing the process at night on the west coast.

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Will this be the first night time attempt at recovering a fairing? Don't seem to recall any reports of them testing the process at night on the west coast.

Iridium-NEXT F7 was a night launch; it took place an hour and a half before sunrise. So, that was probably the first nighttime fairing recovery attempt.
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Offline Raul

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It looks that fairing has extra thermal protection on the tip as GPS III SV01 fairing.
Along with that, both fairings have also circular portholes, that weren’t typical for fairing 2.0 before.

Offline crandles57

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scr00chy, I have some sources that list the actual mass numbers of all three payloads:

https://space.skyrocket.de/doc_sdat/s5.htm
S5 weighs 60 kilograms (~132 pounds).

https://space.skyrocket.de/doc_sdat/psn-6.htm
Nusantara Satu weighs 4,735 kilograms (~10,439 pounds).

https://www.bbc.com/news/world-middle-east-44777305
Beresheet weighs 585 kilograms (~1,290 pounds).

Altogether, the total payload mass is 5,380 kilograms (~11,861 pounds). Also, I'm still under the assumption that the booster WILL land on the drone ship while the final geosynchronous transfer orbit's apogee WILL be 60,000 kilometers (might be a bit higher or lower depending on how much delta-v Stage 2 will use up).

So there are just 3 payloads and
https://www.spaceflightindustries.com/2018/09/11/spaceflight-offers-rideshare-launches-to-geosynchronous-transfer-orbit/
saying
Quote
The manifest for this Falcon 9 GTO rideshare mission is completely full. It features several undisclosed payloads along with an unmanned lunar spacecraft from SpaceIL, an Israeli nonprofit organization that was competing in the Google Lunar XPrize to land a spacecraft on the Moon. The first rideshare satellites will separate in GTO and then the SSL host spacecraft will continue on to Geostationary Orbit (GEO) where the remaining rideshare satellites will be separated.

is wrong - at least the several has turned out to be just one sat namely S5?

It appears to be ASDS landing and to achieve this, it has to be burn to depletion, so what happens to the second stage?

Offline gongora

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SpaceNews said yesterday the whole payload stack is 4850kg and Nusantara Satu is 4100.
https://spacenews.com/falcon-9-launch-the-final-leg-of-indonesian-satellites-roundabout-journey/
« Last Edit: 02/21/2019 01:22 pm by gongora »

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