While Enceladus has significant atmosphere
Paul451 just sent me a PM with a very germane fact:
Quote from: InterestedEngineer on 01/30/2025 06:00 amQuote from: TomH on 01/30/2025 05:00 amExpendable would be best utilized for an unusually large deep space probe, which would be a rare mission. Enceladus and Europa have oceans with a frozen surface. A mission might have:1) A lander2) A stationary communications relay that stays with the lander3) A nuclear powered mini submarine which melts its way through the ice, unspools a communication cable as it does so, then leaves a signal relay station at the bottom of the ice. The sub then goes off to explore the submerged world.Again, this would be rare and it would be high mass. If done in an architecture with non-distributed mass, a disposable US makes sense. A fairing is jettisoned upon reaching vacuum, and the US is re-propped in LEO, possibly again in cis-lunar space. The second stage in essence is reused as both a third stage, and possibly even a fourth stage, simply by taking on additional prop at specified waypoints.Why would you jettison a fairing? You waste up to 10km/sec of aerocapture potentialYou eliminate all atmospheric paraphernalia on the US: tiles, elonerons, and jettison the fairing. The lander itself has its own much smaller TPS and landing system. This is advantageous in mass trades. Rather than managing the mass of an entire Starship entering the atmosphere of Enceladus, you have something similar to (but larger than) a Curiosity/Perseverance EDL architecture.
Quote from: TomH on 01/30/2025 05:00 amExpendable would be best utilized for an unusually large deep space probe, which would be a rare mission. Enceladus and Europa have oceans with a frozen surface. A mission might have:1) A lander2) A stationary communications relay that stays with the lander3) A nuclear powered mini submarine which melts its way through the ice, unspools a communication cable as it does so, then leaves a signal relay station at the bottom of the ice. The sub then goes off to explore the submerged world.Again, this would be rare and it would be high mass. If done in an architecture with non-distributed mass, a disposable US makes sense. A fairing is jettisoned upon reaching vacuum, and the US is re-propped in LEO, possibly again in cis-lunar space. The second stage in essence is reused as both a third stage, and possibly even a fourth stage, simply by taking on additional prop at specified waypoints.Why would you jettison a fairing? You waste up to 10km/sec of aerocapture potential
Expendable would be best utilized for an unusually large deep space probe, which would be a rare mission. Enceladus and Europa have oceans with a frozen surface. A mission might have:1) A lander2) A stationary communications relay that stays with the lander3) A nuclear powered mini submarine which melts its way through the ice, unspools a communication cable as it does so, then leaves a signal relay station at the bottom of the ice. The sub then goes off to explore the submerged world.Again, this would be rare and it would be high mass. If done in an architecture with non-distributed mass, a disposable US makes sense. A fairing is jettisoned upon reaching vacuum, and the US is re-propped in LEO, possibly again in cis-lunar space. The second stage in essence is reused as both a third stage, and possibly even a fourth stage, simply by taking on additional prop at specified waypoints.
