Propellant Depot Panel Questions
I'd like to solicit questions regarding the technical or business aspects of orbital propellant depots for the panel I'll be chairing this coming Friday. I've got a great lineup of panelists (Rand Simberg of TransTerrestrial Musings, Dallas Bienhoff of Boeing, and Frank Zegler of ULA), so if you have any good questions about propellant depots, just post a comment here, and I'll try and pick the best two or three to start off the Q&A part of the panel discussion.
Labels: Commercial Space, Propellant Depots, Space Development
posted by Jon Goff at 3:31 PM
8 Comments:
1)In the existing GEO comsat markets what would the marginal cost be of adding on-orbit refueling capabilities to the existing comm sats? Or is the productive lifetime of a comsat limited by technology and not fuel?
2)Are any of the positive expulsion technologies (bladders etc...) re-loadable? With out a positive expulsion system one needs propellant settling maneuvers?
3)What are the most common on-orbit propellants?
What aare the most probable in situ (lunar asteroid etc...) propellant sources likely to be?
4)Why propellant depots and not refuelable space tugs?
5)Other than Exploration missions (Limited commercial activity) who needs propellant depots?
How difficult would it be to modify an existing upper stage to become a prototype depot after delivering its' primary payload?
I don't know if it is fair for me to ask since I won't be there.
John,
I don't know if it is fair for me to ask since I won't be there.
No worries, it's perfectly fair. I'd actually like questions from people who won't be able to make it.
~Jon
Another question occured to me. Why is there so much resistance to depots? (For some level of much, of course.)
It seems like such an obviously worthwhile capability that I have a hard time understanding resistance, especially if someone else is foting the bill.
My off the cuff answer to the sales problem is divide and conquer. Sell the satelite operators on the possibility of much larger and long lived satelites on the same launcher they are comfortable with. Just one detour to refuel, and write another relatively small check.
Sell the launch providers on the possibility of launching much larger satelites on their standard vehicle. Mention the possibility of getting some quantity discount on vehicle purchases so they can clear more profit on normal launches, and some profit on the tanker flights that make quantity discounts more likely. Also sell them on prop as a fast simple secondary.
Sell the vehicle builders on the prospect of providing more standard vehicles to launch providers on spec, that the providers can use for low profit prop runs if a high profit payload does not appear in the time frame. Sell the possibility of prop runs to anybody with surplus vehicles of any origin.
Sell somebody on operating a depot with no responsibility for launch reliability. No resposibility for payload dependability. Just a simple gas station that buys from the tankers and sells to the customers. No ITAR problems with buying from the cheapest and selling to anybody that can berth.
I wish I could tell which of this is insultingly obvious, which might be useful, and which is hare brained.
I'd ask the panelists what size they think would be best to start with: 5 tonne, 20 tonne or the whole banana, 100 tonne?
I see the 5 tonner helping the satellite guys and possibly producing a business case that can close first.
100 tonnes seems to be in the ballpark for the Lunar/Martian mission size and 20 tonnes helps big GOE satellites & LEo human missions to places that aren't the ISS. Or so I surmise...
One question I'd have, is what orbits can a depot service? Since it takes fuel to go to a depot and then to return to the old orbit, it seems to me that either a depot serves a narrow range of orbits or we move the depot.
Karl Hallowell said...
One question I'd have, is what orbits can a depot service? Since it takes fuel to go to a depot and then to return to the old orbit, it seems to me that either a depot serves a narrow range of orbits or we move the depot.
Or have multiple depots.
Wouldn't both increase storage time and greatly decrease costs (no tanks) to store propellants as ice (water and some other high-freezing point chemicals) and chemically process them into liquid propellants on a just-in-time basis?
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