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Sustainability in the Space Industry
Published in Mark W. McElroy, The Space Industry of the Future, 2023
A released draft version of the environmental assessment report for the SpaceX Starship/Super Heavy rocket activities in Boca Chica, Texas, describes that the launch facility’s natural gas power plant is expected to create emissions two orders of magnitude greater than the emissions from rockets at the site [183]. This is for an initial orbital launch rate of five per year and notably is for a rocket that only uses methalox propulsion which is a relatively clean fuel combination compared to some alternatives. This example is given to highlight again the disparity in environmental impacts between ground activities and the launch itself.
Decoding Mission Design Problem for NTP Systems for Outer Planet Robotic Missions
Published in Nuclear Technology, 2022
Saroj Kumar, L. Dale Thomas, Jason T. Cassibry
Designing missions to outer planets is extremely challenging. Because of the large distances of these planetary bodies, the ∆V required for such missions is very high. To date, chemical propulsion systems have been the go-to choice for deep space exploration missions. However, its low propellant efficiency has also been a challenge toward designing a dedicated mission to Ice Giants without requiring a super heavy-lift launch vehicle.6 The highest-performing chemical propulsion engines are limited to a specific impulse of about 450 s, and only minute improvements can be expected.7 On the other hand, nuclear thermal propulsion (NTP) systems have already demonstrated a specific impulse of over 850 s during the Nuclear Engine for Rocket Vehicle Application (NERVA) program, and current engine designs have the potential to achieve a specific impulse of 900 s, i.e., about twice as efficient when compared with the best chemical propulsion engine.8 The limited ∆V capability of a chemical propulsion system and struggle against trip time and distance often necessitate the use of multiple gravity assist trajectories. The increased trip time due to gravity assist trajectories is directly proportional to the total cost of the mission life cycle, which can be a significant number for cost-capped planetary missions.9
Nuclear Power Concepts and Development Strategies for High-Power Electric Propulsion Missions to Mars
Published in Nuclear Technology, 2022
Lee Mason, Steve Oleson, David Jacobson, Paul Schmitz, Lou Qualls, Michael Smith, Brian Ade, Jorge Navarro
The COMPASS study mission design results are summarized in Table I. The mission studies considered crewed opposition missions in 2035, 2039, and 2042 using the same NEP and LOX/LCH4 propulsion elements. That vehicle uses a 1.8-MW(electric) array of EP thrusters [leaving 100 kW(electric) for vehicle housekeeping loads] with a specific impulse of 2600 s to deliver the 45-t crew habitat to Mars and return the crew to Earth in 760 days. The Xe and LOX/LCH4 propellant loads vary across the opportunities, but all the missions can be accomplished using a combination of two Space Launch System (SLS) launch and five Super Heavy commercial launch vehicle (CLV) (e.g., Starship) fuel deliveries. The COMPASS team also evaluated 2035 and 2039 crewed conjunction missions that exceed the 2-year mission goal but increase the crew time at Mars from 40 to 300 days and decrease the Earth launch fleet. The final case shows an all-NEP cargo conjunction mission that can deliver up to 195 t to Mars in 535 days using a duplicate NEP stage as the one envisioned for the crew mission with only one SLS and one Super Heavy CLV tanker.