Sunday, December 26, 2010

LEO-to-GEO Tug Part 2: Bigger than a Delta-IV Heavy

3,000kg DirecTV 12 Sat
In my last post, I showed the potential of using SpaceX’s Falcon 9 to launch a comsat to LEO and use a reusable LEO-to-GEO transfer tug to move the satellite from low earth orbit to GEO. I also described the largest satellite we can currently put into GEO in a single launch would be a 6,276kg satellite launched on a Delta-IV Heavy for $200M.

But how large of a GEO satellite would be possible using the Falcon 9/Transfer Tug architecture? And how expensive would that satellite be to launch?

Such a Falcon/tug system could launch a 10,000 kg satellite (an increase of ~59% over the current maximum comsat size) into GEO for $171-235M. The price/KG savings is significant ranging from 26-46% over the Delta-IV Heavy. In addition to cost/KG savings, no other commercial launcher can lift 10,000kg to GEO.

Here are my Assumptions:

  • Tug is launched on Falcon 9 with a dry mass of 3,000kg.
  • Tug is co-manifested on a Falcon 9. Launch cost $20M.
  • Tug Development paid for under contract and not a part of this analysis.
  • Tug Manufacturing Costs: $50M
  • Tug refuels itself as needed in LEO from additional Falcon 9 launches (10,000 kg of prop for $50M: $5,000 per kg).
  • Tug lasts five years with amortization factored into price.
  • Tug breakeven price listed in this analysis.
  • Two missions per year assumed (8% Market Share).
  • Operating Cost per year: $10M.
  • LEO to GEO: 4200 m/s of delta-v required.
  • GEO to LEO (with aerobraking): 1500 m/s of delta-v required.
  • Use aerobraking from GEO to LEO.
  • Satellite launched to LEO on a Falcon 9.

LOX/Kerosene Tug – 10,000kg to GEO details:

LOX/Hydrogen Tug 10,000kg to GEO Details:

Click here to play with the interactive spreadsheets.

In Part 3 of this series, I will discuss if a Falcon/Tug system could be used to take a Bigelow Sundancer Module to EML1.


  1. The hydrocarbon vehicle and the hydrogen vehicle should not have the same dry mass for obvious tank volume reasons

  2. Rodney:


    The Hydrogen tanks would need to be larger than the Kerosene tanks. There are definitely some simplifications going on in my analysis. Most of these simplications benefit the LOX/Hydrogen tug.

    Not only larger tanks would be required with liquid hydrogen, but complexities due to boil off, etc. are not added to the dry mass of the LOX/Hyrdogen tug either. Great point.


  3. Colin,

    Your hydrogen tug is well within the spec for the Centauur G Prime; unfueld mass of 3,000 kg, gross mass of 19,501 kg, thrust 146.80 kN, estimated cost $22 million.



    for an 1970s Boeing space tug design. Your assumptions seem well within the doable. The area that needs the most attention really is aerobraking. The Boeing space tug does not assume aerobraking though several variations with large ceramic disks for this purpose were suggested. Minimum might be a space replaceable nose cap of something like SpaceX's PICAX, depending on how many times it could be reused.