Abstract
Wikipedia overview of orbital propellant depots. Key reference data points used for orientation: NASA's 2011 Simple Depot concept stored ~30 t total propellant (5 t LH2 + 25.7 t LOX). SpaceX Starship tanker carries ~100 t propellant per LEO flight; Musk estimates 8 launches suffice to refill a Starship for interplanetary trajectory while NASA estimates 16 due to cryogenic boiloff. ULA ACES (proposed, unfunded) carries ~73 t. Former NASA admin Mike Griffin (2005): "at a conservatively low government price of $10,000 per kg in LEO, 250 tonnes of fuel for two missions per year is worth $2.5 billion." Tier E used for orientation; the Starship tanker and Mike Griffin figures are re-cited from primary sources elsewhere in q6's source set.
Key claims
- not-saved-tier-E
Reviewer notes
Tier E orientation. The 30 t/depot, 100 t/Starship-tanker, and 8 vs 16 launches-per-refuel figures are heavily reused downstream; the primary sources (SpaceX Starship Wikipedia, Casey Handmer's blog) are the source-review-eligible references for these.