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#51 2016-06-03 06:54:08

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,333

Re: On Orbit fuel depot

Using how long satelites stay in orbit for life span

The average life span of a LEO satellite is approximately 5 years, but the average life span for a GEO satellite is approximately 8 years

and the quantity of gas bottles lofted to orbit for the depot we now have a bench mark to build support vehicles to make use of them other wise we have a very dangerous situation if they stay with any seperation between each of them and more so as a larger target for space junk to strike....

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#52 2016-06-03 16:21:03

kbd512
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Registered: 2015-01-02
Posts: 3,098

Re: On Orbit fuel depot

SpaceNut wrote:

Using how long satelites stay in orbit for life span

The average life span of a LEO satellite is approximately 5 years, but the average life span for a GEO satellite is approximately 8 years

and the quantity of gas bottles lofted to orbit for the depot we now have a bench mark to build support vehicles to make use of them other wise we have a very dangerous situation if they stay with any seperation between each of them and more so as a larger target for space junk to strike....

It would be to the benefit of everyone if NASA devoted more time and money to the Q-thruster technology.  If it doesn't work, we can always continue using reaction mass.  If it does work, then satellites will be self-deployed once in orbit.  Space junk will have a limited life in LEO before reentry occurs.  If there's even a chance of eliminating propellants for maneuvering and orbit changes, that opportunity should be vigorously pursued.  The potential cost savings is truly staggering and the reduction in the quantity of space junk floating around Earth will measurably reduce associated flight risks.

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#53 2016-06-26 21:59:12

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,333

Re: On Orbit fuel depot

With a depot in orbit of hydazine for the GEO satelites and xenon gas for the ion drives used to guide the refueling station to each we could make use of the refueling satelites to build up the depot in orbit.

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#54 2017-07-06 21:27:19

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,333

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#55 2017-07-08 10:18:39

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,754
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Re: On Orbit fuel depot

Propellants,  if loaded into very strong canisters with a small solid motor,  can be shot into orbit with a large light gas gun more economically than any possible rocket launch.  "Strong" is the key word here:  tens of thousands of launch gees.  The light gas gun puts you into a surface-grazing transfer ellipse. 

The small solid is what circularizes you into LEO.  It,  too,  must be very stout,  which puts extremely severe restrictions onto the solid motor design.  Such things are not "off-the-shelf" in any sense of the word.  I have done such motor designs for gun-launch ground testing,  so I know they are possible.  But not easy.  Not at all.

Now,  this sort of scheme is too uncontrolled to do precision orbital entry for rendezvous purposes.  You will need some sort of space tug to go and get these propellant loads.  If nobody is in a hurry,  some sort of solar electric propulsion might be a pretty good choice for that.  Think a steady stream of small loads fetched and added to a depot.  Storables like MMH and NTO should be transportable that way,  for way under $100/pound.  Cryogenics?  Not so sure. 

Falcon-Heavy flown expendably promises fully-loaded payload delivery at around $1000/pound.  (Current launchers are closer to $2500/pound.)  A good guess says that being flown recoverably might cut that in half to around $500/pound.  If second stages could be recovered and reused,  a wild guess then says cost maybe gets cut in half again to around $250/pound. 

At that per-pound cost level,  given all the wild guess uncertainties,  rocket launch and light gas gun launch get to be sort-of cost-competitive.  Rocket launch avoids the high-gee restrictions of gas gun launch,  and enables precision rendezvous.  That should be worth some cost difference.

Exciting prospects either way,  no?

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#56 2017-07-08 11:10:57

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,333

Re: On Orbit fuel depot

What it does for space is not launching fuel as payload when we need a very large structure in orbit together. It reduces the subassmbly complexity of parts in LEO. All of which when we couple the cheap launch of fuel up to this large structure makes going further faster more pausible.

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#57 2017-07-08 13:24:03

Terraformer
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From: Lancashire
Registered: 2007-08-27
Posts: 3,160
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Re: On Orbit fuel depot

I wonder how cheaply we could launch propellent, and other resources, for using an OTRAG style system of mass produced rocket stages?

If we could get the cost for launching 1 tonne payloads down to $200k, and have a depot available, then that opens up a lot of possibilities. Such as launching our interplanetary vessel in one or two launches of Falcon Heavy, and doing a lot of the outfitting, provisioning, and fuelling on orbit. We could support a Lunar base, even without Lunar propellent production. If we've developed tugs to collect the packages, then we can use them to collect dead satellites and start clearing up our orbit before Kessler punishes us for littering.


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#58 2018-09-22 19:20:29

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,333

Re: On Orbit fuel depot

I posted alot of stuff for this topic elsewhere due to topic drift which means now to put all the thoughts together on a narrow topic I will need to search for them...

The reasons for orbiting fuel depots are?
1. To have for emergency refuel or to send fuel elsewhere.
2. To refuel because the rocket is empty after launch.
3. To off load carrying more mass than needed out of a gravity well.
4. Because we can not make all the fuel from insitu resources that we need to launch from mars surface.

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#59 2019-11-09 11:59:22

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,333

Re: On Orbit fuel depot

The benefits for LEO is great if we can store and achieve the mass quantities for long duration as its needed in the Starship design but thats a methane Lox system. But going with a Lunar depot would need other fuel types as we lack carbon in large quantities to create the fuel for use of which a mars depot seems very sound once we get over the energy collection issues..

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#60 2020-01-02 19:10:10

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,333

Re: On Orbit fuel depot

What we know about reuseability has to do with space x recycling of first stages and the capsule but with no experience with refueling either of these once on orbit. The Dragons thrusters could be done as we have been doing the ISS with those fuel types but thats not going to get us out of LEO as these are not powerful enough to be able to go anywhere but back to earth.
Getting usueability for lunar or at mars is only going to work if the refueling is of the same type of fuels that we can make at either places.
The moon we are hopefully for LH2 LOX but its not a confirmed thing for quantity that can be done.
The Mars is in a simular situation with the LCH4 Lox is a time and energy requirement to quantity needed that is the issue.

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