Author Topic: SpaceX F9 : Nusantara Satu (PSN VI)/GTO-1/SpaceIL : Feb. 21/22, 2019: Discussion  (Read 135212 times)

Offline TrevorMonty

[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

Watch video. Launches to 500km SSO from Vandenburg, probably as secondary payload.

At 585Kg it could do future launches on new small LVs eg Firefly and Relativity. To big for Launcherone.

With landed mass about 185kg (burns over 400kg fuel) should be able to deliver reasonable size payload.

Which video?

400/585 is not a high enough prop mass fraction to get to the lunar surface from SSO. It would need to be sent considerably higher by the LV, at least to GTO apogee.
Read article and watch video.
www.bbc.co.uk/news/world-middle-east-44777305

As we now know its going from florida as secondary on F9.

Seems like lander is flexible on depart orbits, SSO or GTO.
« Last Edit: 02/16/2019 12:45 pm by gongora »

Online envy887

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

Watch video. Launches to 500km SSO from Vandenburg, probably as secondary payload.

At 585Kg it could do future launches on new small LVs eg Firefly and Relativity. To big for Launcherone.

With landed mass about 185kg (burns over 400kg fuel) should be able to deliver reasonable size payload.

Which video?

400/585 is not a high enough prop mass fraction to get to the lunar surface from SSO. It would need to be sent considerably higher by the LV, at least to GTO apogee.
Read article and watch video.
www.bbc.co.uk/news/world-middle-east-44777305

As we now know its going from florida as secondary on F9.

Seems like lander is flexible on depart orbits, SSO or GTO.

Direct video link (from 2015)

However, the prop mass fraction give is not enough. With storable props, 400 kg will only give ~3,600 m/s and it needs about 6,000 m/s from SSO. The difference is almost exactly a GTO insertion, about 2,500 m/s.

Either it needs more propellant, or the upper stage to restart and put it in higher orbit. The 40,000 km apogee first phasing orbit described in the video would be perfect.
« Last Edit: 02/16/2019 12:45 pm by gongora »

Offline koraldon

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

https://www.ynetnews.com/articles/0,7340,L-5307792,00.html
Launch in December, landing on February 13th. Overall program cost - 95million dollars, weight at launch 600kg
Exciting :)
« Last Edit: 02/16/2019 12:45 pm by gongora »

Offline russianhalo117

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

Watch video. Launches to 500km SSO from Vandenburg, probably as secondary payload.

At 585Kg it could do future launches on new small LVs eg Firefly and Relativity. To big for Launcherone.

With landed mass about 185kg (burns over 400kg fuel) should be able to deliver reasonable size payload.

Which video?

400/585 is not a high enough prop mass fraction to get to the lunar surface from SSO. It would need to be sent considerably higher by the LV, at least to GTO apogee.
Read article and watch video.
www.bbc.co.uk/news/world-middle-east-44777305

As we now know its going from florida as secondary on F9.

Seems like lander is flexible on depart orbits, SSO or GTO.

Direct video link (from 2015)

However, the prop mass fraction give is not enough. With storable props, 400 kg will only give ~3,600 m/s and it needs about 6,000 m/s from SSO. The difference is almost exactly a GTO insertion, about 2,500 m/s.

Either it needs more propellant, or the upper stage to restart and put it in higher orbit. The 40,000 km apogee first phasing orbit described in the video would be perfect.
The updated information is an initial 60,000km elliptical HEO at the time of separation.
« Last Edit: 02/16/2019 12:45 pm by gongora »

Offline russianhalo117

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

Watch video. Launches to 500km SSO from Vandenburg, probably as secondary payload.

Do you mean this video? The one that shows Sparrow deploying from the base of the second stage! I wouldn't trust anything that video shows. By the way, best of luck to SpaceIL on the landing attempt, but they'll need India to fail with Chandrayan 2 this October in order to be fourth, otherwise Israel will end up fifth if India succeeds.


AFAIK Chandrayan 2 lander will not make an immediate landing after arriving.
« Last Edit: 02/16/2019 12:45 pm by gongora »

Offline koraldon

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

I found one presentation on the spacecraft at IAC 2018, maybe there are more - https://iafastro.directory/iac/paper/id/47938/summary/
« Last Edit: 02/16/2019 12:45 pm by gongora »

Offline Comga

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

Watch video. Launches to 500km SSO from Vandenburg, probably as secondary payload.

Do you mean this video? The one that shows Sparrow deploying from the base of the second stage! I wouldn't trust anything that video shows. By the way, best of luck to SpaceIL on the landing attempt, but they'll need India to fail with Chandrayan 2 this October in order to be fourth, otherwise Israel will end up fifth if India succeeds.

While there are some questionable aspects of the video, like the s/c coming out of a hollow second stage, or the fins on the rocket in the early footage, there are kernels that must have basis in facts, however badly interpreted they are by those making the video.

One is a reference to a brief window for landing.
The very specific landing date of February 13, 2019 corresponds to the moment of the first quarter moon, which occurs at 12:26 AM Tel Aviv time on that day.
That would seem to be a good time to land, sunlight and thermal and all, but it's not clear why precision is needed.
« Last Edit: 02/16/2019 12:46 pm by gongora »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Phil Stooke

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

If you want to last as long as possible during the lunar day (meaning 14 Earth days) you want to land as soon as is feasible after sunrise.   For a given landing site there will be just a day or two in each month when the illumination is right for a landing.  The moment of sunrise is probably not ideal, more likely they would be planning to land 10 or 20 hours after sunrise.  Map that to a specific site and you have your need for precision (not a few seconds, obviously, I think that's just for dramatic effect).

The sites being considered as of 18 months ago were described here:

https://www.hou.usra.edu/meetings/lpsc2017/pdf/1914.pdf

(LPSC abstract)

Considering lighting, this might suggest the Wohler site for that date.  Note that the Reiner Gamma site from the 2015 video shown above does not meet their thermal requirements now.
« Last Edit: 02/16/2019 12:47 pm by gongora »

Offline Comga

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

If you want to last as long as possible during the lunar day (meaning 14 Earth days) you want to land as soon as is feasible after sunrise.   For a given landing site there will be just a day or two in each month when the illumination is right for a landing.  The moment of sunrise is probably not ideal, more likely they would be planning to land 10 or 20 hours after sunrise.  Map that to a specific site and you have your need for precision (not a few seconds, obviously, I think that's just for dramatic effect).

The sites being considered as of 18 months ago were described here:

https://www.hou.usra.edu/meetings/lpsc2017/pdf/1914.pdf

(LPSC abstract)

Considering lighting, this might suggest the Wohler site for that date.  Note that the Reiner Gamma site from the 2015 video shown above does not meet their thermal requirements now.

That seems right.
At first quarter the solar elevation at Wohler should be around 45 degrees, while at Brezelius, one of the other candidate landing zones, it would only be ~25 degrees.
Thanks for the paper.
« Last Edit: 02/16/2019 12:47 pm by gongora »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline Steven Pietrobon

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

From the summary, they are not using a throttleable engine. Presumably, they will be pulsing the engines to control the thrust level. They are using COPVs, but didn't state where. Probably for the helium pressurisation tanks.
« Last Edit: 02/16/2019 12:47 pm by gongora »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline mn

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

SpaceIL posted a bunch of little updates today

http://www.spaceil.com/category/news/

(I didn't notice anything specifically new that we didn't already know)
« Last Edit: 02/16/2019 12:48 pm by gongora »

Offline Phil Stooke

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

In earlier presentations the lander was called Sparrow.  I can't find any current statements regarding the name.  Does anyone know if that name is still being used?
« Last Edit: 02/16/2019 12:48 pm by gongora »

Offline Olaf

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

https://spacenews.com/bridenstine-visits-israel-on-first-foreign-trip/
Quote
Bridenstine also met with SpaceIL, the former Google Lunar X Prize team that is continuing to develop its lander even though the prize purse expired in March. SpaceIL announced July 10 that it is planning to launch its lunar lander as a secondary payload on a SpaceX Falcon 9 in December, deploying into a supersynchronous transfer orbit that it will gradually raise until it can maneuver into lunar orbit. SpaceIL said their planned landing date is Feb. 13, 2019.
« Last Edit: 02/16/2019 12:48 pm by gongora »

Offline scr00chy

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

How could it launch to SSO from Canaveral?
« Last Edit: 02/16/2019 12:48 pm by gongora »

Offline Alexphysics

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

A Supersynchronous Transfer Orbit (STO) is not the same as a Sun-Synchronous Orbit (SSO). A STO is a type of GTO where the apogee goes beyond the GEO altitude.
« Last Edit: 02/16/2019 12:48 pm by gongora »

Offline scr00chy

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

A Supersynchronous Transfer Orbit (STO) is not the same as a Sun-Synchronous Orbit (SSO). A STO is a type of GTO where the apogee goes beyond the GEO altitude.
Oh, sorry, misread the original post. Thanks. :)
« Last Edit: 02/16/2019 12:48 pm by gongora »

Offline rpapo

[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

This is a good example of why certain people (like Musk) hate acronyms.
« Last Edit: 02/16/2019 12:49 pm by gongora »
Following the space program since before Apollo 8.

Offline gongora

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

This is a good example of why certain people (like Musk) hate acronyms.

The part he misread wasn't an acronym.
« Last Edit: 02/16/2019 12:49 pm by gongora »

Offline Alexphysics

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

Sometimes is better to say SSO than "Sun-Synchronous Orbit" all the time, that's why certain acronyms are useful, but this is not relevant to this mission
« Last Edit: 02/16/2019 12:51 pm by gongora »

Online envy887

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[edit/gongora: originally posted in the SpaceIL temporary thread before we knew what launch it was on]

It doesn't help that SpaceIL themselves have stated at various times that they would be flying to sun-sync and at other times that they were going to super-sync. The latter appears to be the current plan.
« Last Edit: 02/16/2019 12:51 pm by gongora »

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