Sa08 Prop Depot Panel Jon Goff
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Jonathan Goff's introduction to the Space Access 08 Propellant Depot Panel.

Jonathan Goff's introduction to the Space Access 08 Propellant Depot Panel.

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Sa08 Prop Depot Panel Jon Goff Presentation Transcript

  • 1. The Case for Orbital Propellant Depots Jonathan Goff Rand Simberg Dallas Bienhoff Frank Zegler Space Access 2008
  • 2. Castles and Foundations
    • “ If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them.”
    • – Henry David Thoreau
    • “ If we are serious about this, then our objective must be more than a disconnected series of missions, each conducted at huge expense and risk, and none building a lasting infrastructure to reduce the expense and risk of future operations . If we are serious, we will build capability, not just on the ground but in space. And our objective must be to make the use of space for human purposes a routine function.” –John Marburger
    • Famous Heinlein quote: “Once you're in orbit, you're halfway to anywhere.”
    • Corollary: As hard as getting to orbit is, it’s only half the challenge of getting anywhere else.
  • 3. What are Propellant Depots
    • Facilities in space that can receive, store, and transfer propellants and other fluids to visiting vehicles.
      • Can be located in LEO, at Lagrange Points, or at any other point of interest
      • Can be supplied from earth, off-world sources, and maybe even from planetary atmospheres
    • Contemporary Analogy: Gas Stations
    Historical Analogy: Naval Coaling Stations in the 19 th /20 th century
  • 4. Why Propellant Depots Now?
    • The “Bahn Principle”
      • The best time to discuss an important new idea is when it is almost ready for primetime.
    • Corollary: The “Greason Principle”
      • The best time to enter a new business field is when the business case actually closes, but nobody else realizes it does.
      • Many of the main emerging entrepreneurial space companies started before SpaceShipOne killed the giggle factor for suborbital space.
      • However, being too far ahead of the curve also carries its own risks.
  • 5. Key Benefits of Propellant Depots
    • No need for HLVs for trips beyond LEO
    • Allows for reusable in-space transportation systems
    • Enables safer, more affordable, more flexible operations beyond LEO
    • Disaggregates earth-to-LEO and deep-space transportation.
    • A key enabler for private lunar expeditions, commercial development, and eventually settlement.
    • Provides a high flight-rate, low-hassle market for future earth-to-orbit transportation systems
    • Provides infrastructure that both takes advantage of and promotes advances in lower-cost transportation
    • Is one of the technologies we must master if we ever want to become a truly spacefaring civilization.
  • 6. Key Technological Challenges
    • While microgravity handling and transfer of storable propellants is a proven technology, there remain some challenges and technical risk for orbital cryogenic storage and transfer.
    • Microgravity Cryogenic Fluid Management Issues
      • Propellant orientation not constrained as in a 1G field
        • Boil-off venting problems: you don’t want to vent liquid
        • Engine feed/propellant transfer problems: you want to avoid accidentally ingesting gas in your feedlines
        • Mass gauging: how do you tell how much you have left if you don’t know what the orientation is?
        • Boil-off: Cryogens like to be cold, sunlight is hot, vacuum is a lousy heat sink, and boiling cryogens build pressure in your tanks. Also vented propellant boil-off is mass you have to ship at great cost out of a gravity well that is wasted.
  • 7. Propellant Settling: A Key Enabler to Microgravity Cryogenic Fluid Management
    • If you can provide a sufficient force to the fluid to force it to take an orientation of your choosing, many of these problems become much easier.
    • This is called “propellant settling”
    • Methods of propellant settling
      • Propulsive Settling (Apollo, Centaur, and others)
      • Diaphragms (common with storable propellants but some work has been done for cryo propellants)
      • Rotational Motion
      • Tethers and Gravity Gradients
      • Surface Tension Devices
      • Magnetic Propellant Positioning
    • If you can settle the propellant, propellant transfer and storage become very similar to terrestrial cryogenic handling.
  • 8. Long-Term Cryo Storage
    • Low Boil-off and Zero Boil-Off (ZBO) Technologies:
      • Multi-layer MLI
      • Sunshields
      • Thermodynamic Vents
      • Vapor-cooled Walls
      • Magnetic Propellant Positioning
      • Cryocoolers
    • Lots of prior art and current research, but still some work to go.
    • While LOX is definitely easier, even LH2 may be long-term storable without too much more hassle.
  • 9. Microgravity Cryogen Transfer and Prox-Ops Issues
    • Settled propellant transfer is much easier than pure microgravity transfer
      • No two-phase flow
      • Very similar to transferring cryogens on earth
      • Every time a cryogenic upper stage relights on orbit, it is performing cryogenic propellant transfer
    • Proximity operations and automated fluid coupling interfaces are also becoming more technologically mature
      • Orbital Express demonstrated Autonomous Rendezvous and Docking, as well as storable propellant transfer.
      • Off-loading most of the “smarts” to a robotic tug may allow for much simpler tanker/customer-side mechanical and fluid interfaces.
  • 10. NASA Ain’t Gonna Do It: The Importance of a Commercial Propellant Depot
    • NASA has no intention of funding a propellant depot development project.
      • It competes too much with existing parochial interests (the Shuttle workforce)
    • A NASA-operated depot would have many drawbacks
      • A NASA-operated depot can’t buy propellant from the cheapest source, if they happen to be “dern furiners”
      • NASA gets money by meeting parochial interests (jobs), not by providing goods or services in an economic manner
      • NASA is always at the whim of Congress for funding
    • We’re only likely to see a propellant depot in our lifetimes if someone can find a way to close the business case.
  • 11. Chickens and Eggs
    • Propellant Depots face a classical “chicken and egg” problem (much like orbital RLVs)
      • Most enabled markets won’t exist until propellant depots are already operational
      • There’s a time lag between when a new technology hits the market and when the market adapts to and incorporates the new capability.
      • Government could prime the pump, but that probably can’t and shouldn’t be counted on.
  • 12. Fried Chicken?
    • There may be ways around chicken and egg problems
    • Suborbital and Orbital RLV projects give some hints at how to proceed
      • Incremental development
      • Get others to pay for some or all of your R&D (XCOR)
    • Suborbital RLVs also help reduce technology development cost by providing a low-cost, quick-turnaround  g environment.
    • Leveraging commercial orbital projects (Bigelow stations, COTS vehicles, etc.) can reduce up-front development cost somewhat
  • 13. Introducing The Panelists
    • Rand Simberg (Wyoming Space and Information Systems)
      • “ Recovering” aerospace veteran/blogger at Transterrestrial Musings
      • Long-time proponent of orbital propellant depots (including a recent Popular Mechanics article)
      • Will discuss business and market aspects of propellant depots
    • Dallas Bienhoff (Boeing)
      • “ Mr Propellant Depot”
      • Has led many projects for Boeing related to propellant depots and cryogenic upper stages (including many AIAA and STAIF papers).
      • Will be discuss Boeing’s work on propellant depots
    • Frank Zegler (ULA)
      • Member of the Atlas V Centaur team
      • Has participated in many projects related to settled propellant transfer, cryo storage, propellant depots, etc. (lots of AIAA papers and patents)
      • Will discuss some of ULA’s propellant depot related work