SUSTAINABLE HEAVY LIFT VEHICLE DEVELOPMENT OPTIONS

摘要

The development of a sustainable heavy lift vehicle is the most critical project for human space explorationbeyond Earth orbit. Current launch vehicles do not have sufficient payload mass and volume to Earth escape velocitynecessary for acceptable mission reliability. Many other critical developments are required including in-spacepropulsion, radiation protection and others, but sustainable heavy lift capability is the necessary foundation.Sustainable heavy lift development is especially difficult due to funding limitations in a struggling world economy,low mission rates, multiple uncertain missions and legacy system closeout. Our studies show that sustainable heavylift requires incremental development, low fixed costs and flexibility for a wide variety of missions. Funding profilesare flat with very limited ability to absorb non-recurring spikes and stretched out development adds costs and inhibitsprogress. Incremental development can fit under funding profiles while enabling near term exploration with a growthpath. Low mission rate, flexible missions and long system life make it difficult to offset development investmentsand support production and operations infrastructure. This drives a compelling need for low fixed costs that must bea major consideration for the vehicle configuration and during all phases of development. The explorationarchitecture and launch needs will continue to evolve for decades. The heavy lift system needs to be flexible forcurrently unknown exploration missions and be available for science, space servicing and other user missions.Sustainable heavy lift vehicle concepts covering the human exploration design space are presented along withincremental growth development roadmaps.