Author Topic: ITS as a LEO/VLEO Constellation deployer  (Read 5543 times)

Online Robotbeat

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ITS as a LEO/VLEO Constellation deployer
« on: 03/15/2017 02:20 AM »
SpaceX wants to deploy 12000 satellites, about 2400 per year. At 80 per launch, that's 30 FH launches. That's a lot! A whole bunch of cores and a whole bunch of down range landings. A lot of folding legs, 30 new upper stages, 30 new deployers and maybe fairings (if they haven't solved that, and if they have, recovering them is significant work, too).

I think they'd like to transition to using ITS to deploy the satellites. I'm thinking of giant PPOD type deployers mounted when the unpressurized payload section is. I'm thinking 240 birds per launch, giving you performance margin and a lot of on-board delta-V for inclination changes. Speaking of, because BFS is a lifting body, it could do efficient inclination changes, making it feasible for, say, a Florida launch to actually deploy some birds up to over 75-80 degrees inclination. Maybe even multiple inclinations per launch.

That'd make it easier to get by with fewer launches. All in all, they may be able to do just 10 launches per year for their absolutely mind-bogglingly huge constellation. And no new deployers, fairings, or upper stages. All those things RTLS. And the booster itself flies back to the launch mount, making its recovery even easier. It could quickly be used for other purposes, like lofting Mars payloads.

This is one thing ITS is actually surprisingly useful for besides Mars.
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Online guckyfan

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #1 on: 03/15/2017 07:20 AM »
Are you suggesting to dip BFS into the atmosphere to do inclination changes? That is how I read your post.

Offline JamesH65

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #2 on: 03/15/2017 10:07 AM »
Why bother with the ITS? Would it be easier to build an upper stage dispenser launch by the ITS booster? Give it some engines so it can do inclination changes, and perhaps enough fuel to actually do a powered return? Rather like the original second stage return video SpaceX did some years ago, but larger. Much larger.

An in orbit delivery system.

I have no idea whether the fuel maths works out though.


Online Robotbeat

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #3 on: 03/15/2017 10:43 AM »
Why bother with a new vehicle when you can use a BFS with few modifications? Heck, with cleverness you can use a stock spaceship with custom equipment in the unpressurized section. There's a huge door there already.
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Online Robotbeat

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #4 on: 03/15/2017 10:44 AM »
Are you suggesting to dip BFS into the atmosphere to do inclination changes? That is how I read your post.
Yes. For the VLEO satellites in particular, the altitude is very low, still.
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Online Robotbeat

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #5 on: 03/15/2017 11:48 AM »
I think X-37b might be able to do those kind of inclination changes, too. BFS should be able to do a similar thing. I have no idea why the USAF wants the x37b for, but ITS should be able to do the same job. Except not very stealthy (if that's what they're looking for).

Anyway, yeah, it should open the trade space a little further. Large amounts of on-board propellant AND the ability to generate significant lift.
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Offline jsgirald

Re: ITS as a LEO/VLEO Constellation deployer
« Reply #6 on: 03/15/2017 12:00 PM »
I think X-37b might be able to do those kind of inclination changes, too. BFS should be able to do a similar thing. I have no idea why the USAF wants the x37b for, but ITS should be able to do the same job. Except not very stealthy (if that's what they're looking for).

Anyway, yeah, it should open the trade space a little further. Large amounts of on-board propellant AND the ability to generate significant lift.

Interesting idea, a couple questions:
1) How low is that VLEO thing?

2) I gather a series of dip/reboost maneuvers, right?

3) How bad would that be in terms of TPS?
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Offline JamesH65

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #7 on: 03/15/2017 12:55 PM »
Why bother with a new vehicle when you can use a BFS with few modifications? Heck, with cleverness you can use a stock spaceship with custom equipment in the unpressurized section. There's a huge door there already.

Because modifying a huge, specific use case craft for something completely different will, in all likelihood, be more expensive than creating a dedicated system. Its certainly more than 'a few modifications'. You will need some sort of horribly complicated (and automated) conveyor racking inside the ITS to transfer satellites around so they can be bunged out of the door. A door note, that's not intended to be used in space (AFAICT). If you are fitting 240 satellites, the internal storage system is going to be a nightmare within the constraints of the ITS.

Note though, that development on one may well help with development of the other - e.g. the engines, tankage etc.

Online guckyfan

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #8 on: 03/15/2017 01:04 PM »
You will need some sort of horribly complicated (and automated) conveyor racking inside the ITS to transfer satellites around so they can be bunged out of the door. A door note, that's not intended to be used in space (AFAICT). If you are fitting 240 satellites, the internal storage system is going to be a nightmare within the constraints of the ITS.

I have suggested before, fill the ITS with shelves and use a small robot that picks them up one by one. Not very complicated. Maybe not very volume efficient if it is really simple but with huge volume available that is not the big problem.

A different launch vehicle may be more efficient long term. But with the efficiency of ITS so much bigger than anything available today that can wait for a while. Competitors will need time to catch up. I think SpaceX can afford to build ITS first and a more competetive vehicle for cislunar space after that.

Offline RonM

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #9 on: 03/15/2017 01:21 PM »
As mentioned in several other threads, a special cargo variant of ITS for cislunar operations might be a good idea. No crew areas and a larger payload door.

Offline Ludus

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #10 on: 03/15/2017 02:55 PM »
One of the many uses for the Cargo variant ITS spaceship. Odd that SpaceX has never mentioned it. It would make sense for it to be the first and most common ITS ship. Deploying the Constellation. Lifting hab modules. 9 out of 10 trips to support a Mars colony. It seems like they'd build 10 of them for every passenger or tanker ITS ship.

Online meekGee

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #11 on: 03/16/2017 02:22 AM »
The logic you use is that ITS can lift many more satellites "to space".

But the dV to do a large inclination change for LEO rivals that of going from earth to LEO....  So the launch effort didn't help them any.

Of course maybe the plan is to do the orbital change is made with a hugely efficient electric drive, or other wizardry, but actually I don't think the plan is to use ITS.

UNLESS there's some desire to do a constellation of much larger satellites, though I can't think of what such an application will be, except maybe from-orbit-forest-fire-fighting or something similar.
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Offline Aussie_Space_Nut

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #12 on: 03/16/2017 06:46 AM »
I wonder how much it would cost to insure? That is a lot of very expensive satellites. Too many eggs in 1 basket perhaps?

Offline IRobot

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #13 on: 03/16/2017 08:38 AM »
If SpaceX is doing the whole thing (production and launch), they would probably skip insurance.

Offline envy887

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #14 on: 03/16/2017 12:36 PM »
If SpaceX is doing the whole thing (production and launch), they would probably skip insurance.

Using their ability to mass produce more satellites to make up for any losses.

Offline CraigLieb

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #15 on: 03/28/2017 06:37 PM »
If SpaceX is doing the whole thing (production and launch), they would probably skip insurance.
Even totally captive missions can benefit from risk sharing via insurance.
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Offline Ludus

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #16 on: 04/03/2017 06:12 AM »
SpaceX wants to deploy 12000 satellites, about 2400 per year. At 80 per launch, that's 30 FH launches. That's a lot! A whole bunch of cores and a whole bunch of down range landings. A lot of folding legs, 30 new upper stages, 30 new deployers and maybe fairings (if they haven't solved that, and if they have, recovering them is significant work, too).

I think they'd like to transition to using ITS to deploy the satellites. I'm thinking of giant PPOD type deployers mounted when the unpressurized payload section is. I'm thinking 240 birds per launch, giving you performance margin and a lot of on-board delta-V for inclination changes.

ITS won't likely be available until after SpaceX will want an operational version of the Constellation deployed. That's not 12000, maybe not even 4000 though.

I think the recent focus on faring recovery and even putting second stage recovery back in play is connected. They're going to have to launch a lot of rockets and everything reused will help. If farings are $6M apiece that's $180M a year thrown away just for those inhouse launches.

By the time ITS is ready to take over it may be time for 2.0 and those satellites might be a lot bigger.

I think you're right that this is a major business case for ITS.
« Last Edit: 04/03/2017 06:16 AM by Ludus »

Offline Semmel

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #17 on: 04/03/2017 06:31 AM »
Robotbeat, I absolutely support this idea. It makes sense to loft many many sats at once, simultaneously getting some flights under the belt with BFR ITS and be possibly cheaper than F9 in the process.

But why would you need inclination changes? There are more than enough sats per inclination. They are just on different orbital planes with the same inclination. Drifting between orbital planes is very easy, just adjust the orbital period a little to have a different precession than the rest of the fleet and you are set. Just like sun synchronised orbits.

Online Robotbeat

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #18 on: 04/05/2017 12:11 PM »
Robotbeat, I absolutely support this idea. It makes sense to loft many many sats at once, simultaneously getting some flights under the belt with BFR ITS and be possibly cheaper than F9 in the process.

But why would you need inclination changes? There are more than enough sats per inclination. They are just on different orbital planes with the same inclination. Drifting between orbital planes is very easy, just adjust the orbital period a little to have a different precession than the rest of the fleet and you are set. Just like sun synchronised orbits.
Fair enough. Might need just one inclination per launch. I was just pointing out they could actually do multiple inclinations. Also, and perhaps more important than multiple inclinations, is that they could launch to different inclinations than typically achievable at a certain launch site. In particular it'd allow ITS to reach near polar orbit from Florida.
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Offline Hotblack Desiato

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #19 on: 04/08/2017 08:32 AM »
If the sats are done correctly, they could perform their inclination changes themselves. Since you mentioned VLEO, I'm thinking about 150km or maybe less.

1. Give the birds a winged aerodynamic shape.  You'll need wings anyways to house the solar panels, as a protection against the air.

2. Give the birds an ion engine for station keeping and maneuverability. It should be powerful enough so the birds can climb up from a 140km orbit to higher orbits.

So, the sats are too high for the wings to actually provide lift (the karman line is well below their orbit), but it should be sufficient that they can perform plane changes just by tilting the wings, with the ion engine running to keep the height.

Obviously, the antenna needs to be tiltable too, or should have beam forming capabilities in order to send and receive signals from ground control and from the customers.


Depending on when you want to deploy the constellation, you might not even need a dedicated upper stage (ITS-freighter) to deploy them. Just deploy a few of them every regular tanker flight (50kg per sat means 20 per mt, that doesn't even remotely hurt the tanker). The downside of this method is simple: the tanker needs go dock with the ITS craft, it can't do some fancy inclinations just for a small secondary payload. But the birds can take care of themselves. And the ITS craft needs to be on an orbit that helps with the flight to Mars, everything else would be wasteful.


Offline MP99

Re: ITS as a LEO/VLEO Constellation deployer
« Reply #20 on: 04/08/2017 12:13 PM »
ISTM that the drag losses from using wings means the prop would be better used just making the required dV burn directly.

Cheers, Martin

Online Robotbeat

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #21 on: 04/08/2017 12:42 PM »
ISTM that the drag losses from using wings means the prop would be better used just making the required dV burn directly.

Cheers, Martin
Depends. Hypersonic lift-assisted inclination changes are like up to 40-50% better than pure delta-V.
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Offline MikeAtkinson

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #22 on: 04/08/2017 02:11 PM »
If the sats are done correctly, they could perform their inclination changes themselves. Since you mentioned VLEO, I'm thinking about 150km or maybe less.

1. Give the birds a winged aerodynamic shape.  You'll need wings anyways to house the solar panels, as a protection against the air.

2. Give the birds an ion engine for station keeping and maneuverability. It should be powerful enough so the birds can climb up from a 140km orbit to higher orbits.

So, the sats are too high for the wings to actually provide lift (the karman line is well below their orbit), but it should be sufficient that they can perform plane changes just by tilting the wings, with the ion engine running to keep the height.

Obviously, the antenna needs to be tiltable too, or should have beam forming capabilities in order to send and receive signals from ground control and from the customers.


Depending on when you want to deploy the constellation, you might not even need a dedicated upper stage (ITS-freighter) to deploy them. Just deploy a few of them every regular tanker flight (50kg per sat means 20 per mt, that doesn't even remotely hurt the tanker). The downside of this method is simple: the tanker needs go dock with the ITS craft, it can't do some fancy inclinations just for a small secondary payload. But the birds can take care of themselves. And the ITS craft needs to be on an orbit that helps with the flight to Mars, everything else would be wasteful.

Adding even a small amount of cost to each satellite is a bad idea as that cost is multiplied by 12000. Aerodynamic  wings and a bigger ion engine will add a fair amount of cost hundreds of millions if not billions extra.

Offline MikeAtkinson

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #23 on: 04/08/2017 02:16 PM »
But why would you need inclination changes? There are more than enough sats per inclination. They are just on different orbital planes with the same inclination. Drifting between orbital planes is very easy, just adjust the orbital period a little to have a different precession than the rest of the fleet and you are set. Just like sun synchronised orbits.

Exactly, there are relatively few inclinations with lots of satellites in each inclination. For the vLEO sats the drifting to a different orbital plane cannot take too long because of the limited lifetime of the satellites, but a few weeks is probably OK as it will take that long to check out and commission them

Online Robotbeat

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #24 on: 04/08/2017 03:24 PM »
But you cannot launch to a near polar orbit from Florida without an inclination change and/or huge dogleg. The ability to change inclinations means they don't need a West Coast launch site for ITS.
« Last Edit: 04/08/2017 03:26 PM by Robotbeat »
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Offline DanielW

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #25 on: 04/08/2017 11:55 PM »
But you cannot launch to a near polar orbit from Florida without an inclination change and/or huge dogleg. The ability to change inclinations means they don't need a West Coast launch site for ITS.
But what percentage of the constellation needs to be high inclination? Falcon Heavy could handle those from Vandenberg.

Online Robotbeat

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #26 on: 04/09/2017 12:30 AM »
But you cannot launch to a near polar orbit from Florida without an inclination change and/or huge dogleg. The ability to change inclinations means they don't need a West Coast launch site for ITS.
But what percentage of the constellation needs to be high inclination? Falcon Heavy could handle those from Vandenberg.
Probably hundreds of satellites. Either way, that means you need to keep Falcon Heavy around or be happy with a LOT of F9 flights, plus a probably-unrecoverable satellite deployer. Plus another site to process the satellites.

Again, ITS /will/ have the capability to change inclination relatively efficiently just due to the fact it is a lifting body. And if it succeeds, it'll be much cheaper to launch than even a fully reused Falcon Heavy. There's no real good reason /not/ to use this capability to reach high inclinations
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Offline ZachF

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #27 on: 04/11/2017 05:17 PM »
I think ITS will eventually be used to upkeep the Constellation. Even if there is a ceiling for the number of satellites it can carry, an ITS could allow the next-gen constellation sats to be much larger and more powerful.

Offline MP99

Re: ITS as a LEO/VLEO Constellation deployer
« Reply #28 on: 04/11/2017 05:51 PM »


ISTM that the drag losses from using wings means the prop would be better used just making the required dV burn directly.

Cheers, Martin
Depends. Hypersonic lift-assisted inclination changes are like up to 40-50% better than pure delta-V.

OK, sometimes intuition doesn't serve well.

That sounds like a useful fuel saving.

Cheers, Martin


Online meekGee

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Re: ITS as a LEO/VLEO Constellation deployer
« Reply #29 on: 05/14/2017 05:11 PM »
Bump - In an interview Tom Mueller made the link between ITS and sat launching, though not quite as explicit as "ITS will launch this constellation"
« Last Edit: 05/14/2017 08:51 PM by meekGee »
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