In-Space Propulsion Using Modular Building Blocks v2.0

[trivvity]

I am curious, however, if the extreme cost of launching fuel-tanker rockets up to re-supply the orbital fuel depot will cost more than the depot will save? In other words, to make this happen, there would be many rocket launches to carry fuel tanks up into space. Each of these rockets would burn a lot of fuel and cost a lot of money. Might this cancel out the original intent of saving money for fuel/launch costs?

[jamesdoehring]

@trivvity That's a great question, trivvity, but it applies to the more general debate on using a heavy lift launch vehicle vs. a number of smaller rockets. This is an empirical question that will be decided over the next few decades. The way I see it, your question can be rephrased as "Is the cost per pound of payload to orbit cheaper using one large rocket or several smaller rockets?"

[jamesdoehring]

@trivvity Fuel and oxygen actually represents about 1% or less of the cost of a rocket launch. A lot of the cost is in paying the salaries of the people who design and manage the rockets. These costs are essentially fixed whether the rockets launch 10 times or 1000 times. It seems likely to me that smaller rockets will prove cheaper due to the economies of scale associated with a greater launch frequency.

[jamesdoehring]

@trivvity Apart from the cost issue, depots can offer more operation flexibility than a single-design heavy lift rocket. There are many smaller rockets on the market, so if one of the them develops a problem, we can switch to another without significantly disrupting launch schedules. If we're using only one design for a massive heavy lift rocket, a mishap will ground the space program for years.