Author Topic: Business Case for Propellant Depots in 2015  (Read 10088 times)

Offline DarkenedOne

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Re: Business Case for Propellant Depots in 2015
« Reply #20 on: 07/13/2011 06:25 PM »
It seems to me if you want to repair or upgrade a sat, you'd need an Atlas and a Centaur to deliver parts, materials. You'd also need some way to install the parts -- telerobotic hands? And once the repair device accomplished it's mission, where would it get propellant to reach another satellite?

If your going to launch an expendable upper stage to repair a satellite, it makes more sense to use the same stages to send up a replacement satellite.

The case for this paradigm shift doesn't close until we have a less expensive way to deliver propellant to orbit.

Honestly I wish people would look up some numbers when they make these assertions. 

Upper stages are cheap compared to the satellites they launch.  The military's new AEHF sat cost around 1.1 billion per satellite, yet the rocket that launched it is well under $200 million.  The ISS cost over a hundred billion dollars.  Refueling with expendable upper stages only costs a few hundred million a year. 

The refueling spaceship is more of the cost concern.  If it is expendable it will be pretty expensive, however companies like the MDA plan to keep it in orbit and just send up fuel. 

The truth is that we have been doing this stuff cost effectively for space stations for decades now, as in it is far cheaper to refuel the ISS than it is to rebuild the ISS.  The only real difference is doing this to satellites using unmanned refueling spacecraft.
« Last Edit: 07/13/2011 06:36 PM by DarkenedOne »

Offline jimgagnon

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Re: Business Case for Propellant Depots in 2015
« Reply #21 on: 07/13/2011 06:51 PM »
However, I will grant you the 'landed cost' of the physical depot being spread over its lifetime of usage.  My concern is the cost of filling the depot over that lifetime.  Assume we use a Falcon Heavy to launch the fuel, each pound of fuel is going to cost $1,000.00 to send to LEO, figure a 20% margin to cover operating expenses for the depot operation plus profit.  This gives your customers a total cost of $1,200 per pound of fuel.  Your customers are already $200 per pound behind a straight-up launch on the Falcon Heavy.

As said, unless you can provide the fuel at a substantial discount to upsizing the launch vehicle then there will not be a commercial case for making use of the depot. 

Clearly, using existing techniques to refuel already lofted depots will be at first expensive. However, the goal is to establish a required need and a line in the sand for competitors to beat. Who knows? Perhaps a company can beat the Falcon 9H price by using a railgun to shoot Ice VIII cannonballs into orbit and electrolyzing them at the depot?

Once we have a established market (quite probably NASA based at first), then the smart money can run in and see if they can do better.

Offline Hop_David

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Re: Business Case for Propellant Depots in 2015
« Reply #22 on: 07/13/2011 07:52 PM »
It seems to me if you want to repair or upgrade a sat, you'd need an Atlas and a Centaur to deliver parts, materials. You'd also need some way to install the parts -- telerobotic hands? And once the repair device accomplished it's mission, where would it get propellant to reach another satellite?

If your going to launch an expendable upper stage to repair a satellite, it makes more sense to use the same stages to send up a replacement satellite.

The case for this paradigm shift doesn't close until we have a less expensive way to deliver propellant to orbit.

Honestly I wish people would look up some numbers when they make these assertions. 

Upper stages are cheap compared to the satellites they launch.  The military's new AEHF sat cost around 1.1 billion per satellite, yet the rocket that launched it is well under $200 million.  The ISS cost over a hundred billion dollars.  Refueling with expendable upper stages only costs a few hundred million a year.

I was talking about GEO communication sats, not 100 billion dollar LEO space stations.

Honestly, I wish people would read the thread before making these incorrect straw man arguments.
« Last Edit: 07/13/2011 07:56 PM by Hop_David »

Offline DarkenedOne

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Re: Business Case for Propellant Depots in 2015
« Reply #23 on: 07/13/2011 08:46 PM »
Honestly I wish people would look up some numbers when they make these assertions. 

Upper stages are cheap compared to the satellites they launch.  The military's new AEHF sat cost around 1.1 billion per satellite, yet the rocket that launched it is well under $200 million.  The ISS cost over a hundred billion dollars.  Refueling with expendable upper stages only costs a few hundred million a year.

I was talking about GEO communication sats, not 100 billion dollar LEO space stations.

Honestly, I wish people would read the thread before making these incorrect straw man arguments.

I know you talking about GEO sats.  I was just using the ISS as an example of a cost-effective refueling op. 

Look you stated,
"If your going to launch an expendable upper stage to repair a satellite, it makes more sense to use the same stages to send up a replacement satellite." 

Lets with vehicles we know of shall we.  Take the Falcon 9 at $50+ million.  Since that price includes the whole rocket we can safely assume that the upper stage cost less than $50 million.  Now lets take the military's latest comm sat, the AEHF sat, which is priced at about $1.1 billion. 

Now ask yourself.  If you were in charge of the AEHF program would you let your billion dollar sat die in orbit because you do want to spend <50 million on an upper stage. 


Offline Hop_David

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Re: Business Case for Propellant Depots in 2015
« Reply #24 on: 07/13/2011 10:21 PM »
Honestly I wish people would look up some numbers when they make these assertions. 

Upper stages are cheap compared to the satellites they launch.  The military's new AEHF sat cost around 1.1 billion per satellite, yet the rocket that launched it is well under $200 million.  The ISS cost over a hundred billion dollars.  Refueling with expendable upper stages only costs a few hundred million a year.

I was talking about GEO communication sats, not 100 billion dollar LEO space stations.

Honestly, I wish people would read the thread before making these incorrect straw man arguments.

I know you talking about GEO sats.  I was just using the ISS as an example of a cost-effective refueling op. 

Look you stated,
"If your going to launch an expendable upper stage to repair a satellite, it makes more sense to use the same stages to send up a replacement satellite." 

Lets with vehicles we know of shall we.  Take the Falcon 9 at $50+ million.  Since that price includes the whole rocket we can safely assume that the upper stage cost less than $50 million.  Now lets take the military's latest comm sat, the AEHF sat, which is priced at about $1.1 billion. 

Now ask yourself.  If you were in charge of the AEHF program would you let your billion dollar sat die in orbit because you do want to spend <50 million on an upper stage. 

AEHF isn't as atypical as I.S.S.  But still not typical. The price tag for the AEHF constellation is in the same ballpark as JWST. Which just gagged congress.

If it's sats like these the propellant depots are serving, it'd be a very limited market.

Speaking of AEHF, have you heard of the progress the Hall thrusters are making towards parking AEHF 1 after the botched apogee burn? If they can't do the job, are there plans to send a Falcon 9 to rendezvous with the sat and fix it? You think such a mission would cost $50 million?
« Last Edit: 07/13/2011 10:23 PM by Hop_David »

Offline gbaikie

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Re: Business Case for Propellant Depots in 2015
« Reply #25 on: 07/14/2011 02:42 AM »

Fuel depots on the other hand are essentially satellites.  Once you put them up there they last for decades at extremely low maintenance cost.  The costs of fuel depots is incremental. 


That is going to depend on what fuel(s) you are stockpiling at the depot.  Cryogenic fuels are going to be much more difficult to store for extended periods of time whereas non-cryogenic fuels are going to require larger fuel masses to be stockpiled for outgoing missions.

However, I will grant you the 'landed cost' of the physical depot being spread over its lifetime of usage.  My concern is the cost of filling the depot over that lifetime.  Assume we use a Falcon Heavy to launch the fuel, each pound of fuel is going to cost $1,000.00 to send to LEO, figure a 20% margin to cover operating expenses for the depot operation plus profit.  This gives your customers a total cost of $1,200 per pound of fuel.  Your customers are already $200 per pound behind a straight-up launch on the Falcon Heavy.

It allows one to reuse a rocket. One could ask how much is it worth to reuse a rocket. And there are a number of ways to look at this.

One way to look at it it, is to compare docking with a booster stage with refueling that same stage.
We want to compare apples to apple. So say we need a particular booster stage for a satellite and we can't lift the satellite and bring to LEO fully fuel stage in one launch. So have satellite plus empty stage, and that empty stage being refilled, COMPARED to satellite dropping the empty stage and docking in orbit with lifted fully fueled stage lifted by different launch.

One has two comparable problems- storing rocket fuel in orbit and the time needed to launch the booster stage [before you launching the satellite OR after you launch the satellite]
Docking with another booster in manned operation has been done:
Gemini 10:
"Gemini established that radiation at high altitude was not a problem. After docking with their Agena booster in low orbit, Young and Collins used it to climb another 763.8 kilometers to meet with the dead, drifting Agena left over from the aborted Gemini VIII flight"
http://en.wikipedia.org/wiki/Gemini_10

But docking with a booster in orbit isn't done with satellites nor has  refilling a booster been done with satellites. So we are in the unfortunate position comparing two undeveloped techologies.

One advantage of depot vs boost docking is docking mechanisms could shifted more on the depot and these "docking mechanisms" can be reused for receiving shipment refilling the depot and spacecraft which are needing to be refilled. This *could* include a dedicated tug which handles all the docking of the spacecraft or the refueling vehicles in which their task is simply to get close [within a mile] of the depot.

Whereas if docking with a booster stage in orbit it requires some docking mechanism to be brought with spacecraft and/or booster each launch.     

Quote
As said, unless you can provide the fuel at a substantial discount to upsizing the launch vehicle then there will not be a commercial case for making use of the depot. 
You should be able to do this. Another thing is one going have discarded fuel stages of the which bring up the rocket fuel to depot. These could have commercial value as scrap metal. And mention above these fuel shipment could rather simple [they can be fairly "dumb" and had fuel depot be the "brains"]
The fuel shipments could use wide number of different launchers, and/or have a launcher specialized to do this task [meaning a rocket launcher or even cannon delivery system].
Before a user of the rocket fuel launches, they can know that rocket fuel is already waiting for it in space and ready to be used, and if the launch is delayed, the depot could sell the same rocket to different buyer or wait until the first launch give a second attempt at a launch.


« Last Edit: 07/14/2011 02:50 AM by gbaikie »

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